The SGX ENCLS instruction uses EAX to specify an SGX function and may require additional registers, depending on the SGX function. ENCLS invokes the specified privileged SGX function for managing and debugging enclaves. Macros are used to wrap the ENCLS functionality and several wrappers are used to wrap the macros to make the different SGX functions accessible in the code.

The wrappers of the supported SGX functions are cryptic. Add short descriptions of each as a comment.

Suggested-by: Dave Hansen dave.hansen@linux.intel.com Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Reviewed-by tag.

Changes since V1: - Fix commit message and subject to not refer to descriptions as "changelog descriptions" or "shortlog descriptions" (Jarkko). - Improve all descriptions with guidance from Jarkko.

arch/x86/kernel/cpu/sgx/encls.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/encls.h b/arch/x86/kernel/cpu/sgx/encls.h index fa04a73daf9c..0e22fa8f77c5 100644 --- a/arch/x86/kernel/cpu/sgx/encls.h +++ b/arch/x86/kernel/cpu/sgx/encls.h @@ -136,57 +136,71 @@ static inline bool encls_failed(int ret) ret; \ })

+/* Initialize an EPC page into an SGX Enclave Control Structure (SECS) page. */ static inline int __ecreate(struct sgx_pageinfo *pginfo, void *secs) { return __encls_2(ECREATE, pginfo, secs); }

+/* Hash a 256 byte region of an enclave page to SECS:MRENCLAVE. */ static inline int __eextend(void *secs, void *addr) { return __encls_2(EEXTEND, secs, addr); }

+/* + * Associate an EPC page to an enclave either as a REG or TCS page + * populated with the provided data. + */ static inline int __eadd(struct sgx_pageinfo *pginfo, void *addr) { return __encls_2(EADD, pginfo, addr); }

+/* Finalize enclave build, initialize enclave for user code execution. */ static inline int __einit(void *sigstruct, void *token, void *secs) { return __encls_ret_3(EINIT, sigstruct, secs, token); }

+/* Disassociate EPC page from its enclave and mark it as unused. */ static inline int __eremove(void *addr) { return __encls_ret_1(EREMOVE, addr); }

+/* Copy data to an EPC page belonging to a debug enclave. */ static inline int __edbgwr(void *addr, unsigned long *data) { return __encls_2(EDGBWR, *data, addr); }

+/* Copy data from an EPC page belonging to a debug enclave. */ static inline int __edbgrd(void *addr, unsigned long *data) { return __encls_1_1(EDGBRD, *data, addr); }

+/* Track that software has completed the required TLB address clears. */ static inline int __etrack(void *addr) { return __encls_ret_1(ETRACK, addr); }

+/* Load, verify, and unblock an EPC page. */ static inline int __eldu(struct sgx_pageinfo *pginfo, void *addr, void *va) { return __encls_ret_3(ELDU, pginfo, addr, va); }

+/* Make EPC page inaccessible to enclave, ready to be written to memory. */ static inline int __eblock(void *addr) { return __encls_ret_1(EBLOCK, addr); }

+/* Initialize an EPC page into a Version Array (VA) page. */ static inline int __epa(void *addr) { unsigned long rbx = SGX_PAGE_TYPE_VA; @@ -194,6 +208,7 @@ static inline int __epa(void *addr) return __encls_2(EPA, rbx, addr); }

+/* Invalidate an EPC page and write it out to main memory. */ static inline int __ewb(struct sgx_pageinfo *pginfo, void *addr, void *va) {

Add a wrapper for the EMODT ENCLS leaf function used to change the type of an enclave page as maintained in the SGX hardware's Enclave Page Cache Map (EPCM).

EMODT: 1) Updates the EPCM page type of the enclave page. 2) Sets the MODIFIED bit in the EPCM entry of the enclave page. This bit is reset by the enclave by invoking ENCLU leaf function EACCEPT or EACCEPTCOPY.

Access from within the enclave to the enclave page is not possible while the MODIFIED bit is set.

After changing the enclave page type by issuing EMODT the kernel needs to collaborate with the hardware to ensure that no logical processor continues to hold a reference to the changed page. This is required to ensure no required security checks are circumvented and is required for the enclave's EACCEPT/EACCEPTCOPY to succeed. Ensuring that no references to the changed page remain is accomplished with the ETRACK flow.

Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Reviewed-by tag.

Changes since V1: - Split original patch ("x86/sgx: Add wrappers for SGX2 functions") in three to introduce the SGX2 functions separately (Jarkko). - Rewrite commit message to include how the EPCM within the hardware is changed by the SGX2 function as well as the calling conditions (Jarkko).

arch/x86/kernel/cpu/sgx/encls.h | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/encls.h b/arch/x86/kernel/cpu/sgx/encls.h index 2b091912f038..7a1ecf704ec1 100644 --- a/arch/x86/kernel/cpu/sgx/encls.h +++ b/arch/x86/kernel/cpu/sgx/encls.h @@ -221,4 +221,10 @@ static inline int __emodpr(struct sgx_secinfo *secinfo, void *addr) return __encls_ret_2(EMODPR, secinfo, addr); }

+/* Change the type of an EPC page. */ +static inline int __emodt(struct sgx_secinfo *secinfo, void *addr) +{ + return __encls_ret_2(EMODT, secinfo, addr); +} + #endif /* _X86_ENCLS_H */

sgx_encl_load_page() is used to find and load an enclave page into enclave (EPC) memory, potentially loading it from the backing storage. Both usages of sgx_encl_load_page() are during an access to the enclave page from a VMA and thus the permissions of the VMA are considered before the enclave page is loaded.

SGX2 functions operating on enclave pages belonging to an initialized enclave requiring the page to be in EPC. It is thus required to support loading enclave pages into the EPC independent from a VMA.

Split the current sgx_encl_load_page() to support the two usages: A new call, sgx_encl_load_page_in_vma(), behaves exactly like the current sgx_encl_load_page() that takes VMA permissions into account, while sgx_encl_load_page() just loads an enclave page into EPC.

VMA, PTE, and EPCM permissions continue to dictate whether the pages can be accessed from within an enclave.

Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Reviewed-by tag.

Changes since V2: - New patch

arch/x86/kernel/cpu/sgx/encl.c | 57 ++++++++++++++++++++++------------ arch/x86/kernel/cpu/sgx/encl.h | 2 ++ 2 files changed, 40 insertions(+), 19 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index 7c63a1911fae..05ae1168391c 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -131,25 +131,10 @@ static struct sgx_epc_page *sgx_encl_eldu(struct sgx_encl_page *encl_page, return epc_page; }

-static struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl, - unsigned long addr, - unsigned long vm_flags) +static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl, + struct sgx_encl_page *entry) { - unsigned long vm_prot_bits = vm_flags & (VM_READ | VM_WRITE | VM_EXEC); struct sgx_epc_page *epc_page; - struct sgx_encl_page *entry; - - entry = xa_load(&encl->page_array, PFN_DOWN(addr)); - if (!entry) - return ERR_PTR(-EFAULT); - - /* - * Verify that the faulted page has equal or higher build time - * permissions than the VMA permissions (i.e. the subset of {VM_READ, - * VM_WRITE, VM_EXECUTE} in vma->vm_flags). - */ - if ((entry->vm_max_prot_bits & vm_prot_bits) != vm_prot_bits) - return ERR_PTR(-EFAULT);

/* Entry successfully located. */ if (entry->epc_page) { @@ -175,6 +160,40 @@ static struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl, return entry; }

+static struct sgx_encl_page *sgx_encl_load_page_in_vma(struct sgx_encl *encl, + unsigned long addr, + unsigned long vm_flags) +{ + unsigned long vm_prot_bits = vm_flags & (VM_READ | VM_WRITE | VM_EXEC); + struct sgx_encl_page *entry; + + entry = xa_load(&encl->page_array, PFN_DOWN(addr)); + if (!entry) + return ERR_PTR(-EFAULT); + + /* + * Verify that the page has equal or higher build time + * permissions than the VMA permissions (i.e. the subset of {VM_READ, + * VM_WRITE, VM_EXECUTE} in vma->vm_flags). + */ + if ((entry->vm_max_prot_bits & vm_prot_bits) != vm_prot_bits) + return ERR_PTR(-EFAULT); + + return __sgx_encl_load_page(encl, entry); +} + +struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl, + unsigned long addr) +{ + struct sgx_encl_page *entry; + + entry = xa_load(&encl->page_array, PFN_DOWN(addr)); + if (!entry) + return ERR_PTR(-EFAULT); + + return __sgx_encl_load_page(encl, entry); +} + static vm_fault_t sgx_vma_fault(struct vm_fault *vmf) { unsigned long addr = (unsigned long)vmf->address; @@ -196,7 +215,7 @@ static vm_fault_t sgx_vma_fault(struct vm_fault *vmf)

mutex_lock(&encl->lock);

- entry = sgx_encl_load_page(encl, addr, vma->vm_flags); + entry = sgx_encl_load_page_in_vma(encl, addr, vma->vm_flags); if (IS_ERR(entry)) { mutex_unlock(&encl->lock);

@@ -344,7 +363,7 @@ static struct sgx_encl_page *sgx_encl_reserve_page(struct sgx_encl *encl, for ( ; ; ) { mutex_lock(&encl->lock);

- entry = sgx_encl_load_page(encl, addr, vm_flags); + entry = sgx_encl_load_page_in_vma(encl, addr, vm_flags); if (PTR_ERR(entry) != -EBUSY) break;

diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h index fec43ca65065..6b34efba1602 100644 --- a/arch/x86/kernel/cpu/sgx/encl.h +++ b/arch/x86/kernel/cpu/sgx/encl.h @@ -116,5 +116,7 @@ unsigned int sgx_alloc_va_slot(struct sgx_va_page *va_page); void sgx_free_va_slot(struct sgx_va_page *va_page, unsigned int offset); bool sgx_va_page_full(struct sgx_va_page *va_page); void sgx_encl_free_epc_page(struct sgx_epc_page *page); +struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl, + unsigned long addr);

#endif /* _X86_ENCL_H */

sgx_encl_ewb_cpumask() is no longer unique to the reclaimer where it is used during the EWB ENCLS leaf function when EPC pages are written out to main memory and sgx_encl_ewb_cpumask() is used to learn which CPUs might have executed the enclave to ensure that TLBs are cleared.

Upcoming SGX2 enabling will use sgx_encl_ewb_cpumask() during the EMODPR and EMODT ENCLS leaf functions that make changes to enclave pages. The function is needed for the same reason it is used now: to learn which CPUs might have executed the enclave to ensure that TLBs no longer point to the changed pages.

Rename sgx_encl_ewb_cpumask() to sgx_encl_cpumask() to reflect the broader usage.

Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Reviewed-by tag.

Changes since V1: - New patch split from original "x86/sgx: Use more generic name for enclave cpumask function" (Jarkko).

arch/x86/kernel/cpu/sgx/encl.c | 6 +++--- arch/x86/kernel/cpu/sgx/encl.h | 2 +- arch/x86/kernel/cpu/sgx/main.c | 2 +- 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index c6525eba74e8..8de9bebc4d81 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -614,7 +614,7 @@ int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm) }

/** - * sgx_encl_ewb_cpumask() - Query which CPUs might be accessing the enclave + * sgx_encl_cpumask() - Query which CPUs might be accessing the enclave * @encl: the enclave * * Some SGX functions require that no cached linear-to-physical address @@ -639,7 +639,7 @@ int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm) * The following flow is used to support SGX functions that require that * no cached linear-to-physical address mappings are present: * 1) Execute ENCLS[ETRACK] to initiate hardware tracking. - * 2) Use this function (sgx_encl_ewb_cpumask()) to query which CPUs might be + * 2) Use this function (sgx_encl_cpumask()) to query which CPUs might be * accessing the enclave. * 3) Send IPI to identified CPUs, kicking them out of the enclave and * thus flushing all locally cached linear-to-physical address mappings. @@ -656,7 +656,7 @@ int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm) * * Return: cpumask of CPUs that might be accessing @encl */ -const cpumask_t *sgx_encl_ewb_cpumask(struct sgx_encl *encl) +const cpumask_t *sgx_encl_cpumask(struct sgx_encl *encl) { cpumask_t *cpumask = &encl->cpumask; struct sgx_encl_mm *encl_mm; diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h index d2acb4debde5..e59c2cbf71e2 100644 --- a/arch/x86/kernel/cpu/sgx/encl.h +++ b/arch/x86/kernel/cpu/sgx/encl.h @@ -105,7 +105,7 @@ int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start,

void sgx_encl_release(struct kref *ref); int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm); -const cpumask_t *sgx_encl_ewb_cpumask(struct sgx_encl *encl); +const cpumask_t *sgx_encl_cpumask(struct sgx_encl *encl); int sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index, struct sgx_backing *backing); void sgx_encl_put_backing(struct sgx_backing *backing, bool do_write); diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 2de85f459492..fa33922879bf 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -249,7 +249,7 @@ static void sgx_encl_ewb(struct sgx_epc_page *epc_page, * miss cpus that entered the enclave between * generating the mask and incrementing epoch. */ - on_each_cpu_mask(sgx_encl_ewb_cpumask(encl), + on_each_cpu_mask(sgx_encl_cpumask(encl), sgx_ipi_cb, NULL, 1); ret = __sgx_encl_ewb(epc_page, va_slot, backing); }

The ETRACK function followed by an IPI to all CPUs within an enclave is a common pattern with more frequent use in support of SGX2.

Make the (empty) IPI callback function available internally in preparation for usage by SGX2.

Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Reviewed-by tag.

Changes since V1: - Replace "for more usages" by "for usage by SGX2" (Jarkko)

arch/x86/kernel/cpu/sgx/main.c | 2 +- arch/x86/kernel/cpu/sgx/sgx.h | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index ce9e87d5f8ec..6e2cb7564080 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -172,7 +172,7 @@ static int __sgx_encl_ewb(struct sgx_epc_page *epc_page, void *va_slot, return ret; }

-static void sgx_ipi_cb(void *info) +void sgx_ipi_cb(void *info) { }

diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h index 0f17def9fe6f..b30cee4de903 100644 --- a/arch/x86/kernel/cpu/sgx/sgx.h +++ b/arch/x86/kernel/cpu/sgx/sgx.h @@ -90,6 +90,8 @@ void sgx_mark_page_reclaimable(struct sgx_epc_page *page); int sgx_unmark_page_reclaimable(struct sgx_epc_page *page); struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim);

+void sgx_ipi_cb(void *info); + #ifdef CONFIG_X86_SGX_KVM int __init sgx_vepc_init(void); #else

SGX2 functions are not allowed on all page types. For example, ENCLS[EMODPR] is only allowed on regular SGX enclave pages and ENCLS[EMODPT] is only allowed on TCS and regular pages. If these functions are attempted on another type of page the hardware would trigger a fault.

Keep a record of the SGX page type so that there is more certainty whether an SGX2 instruction can succeed and faults can be treated as real failures.

The page type is a property of struct sgx_encl_page and thus does not cover the VA page type. VA pages are maintained in separate structures and their type can be determined in a different way. The SGX2 instructions needing the page type do not operate on VA pages and this is thus not a scenario needing to be covered at this time.

struct sgx_encl_page hosting this information is maintained for each enclave page so the space consumed by the struct is important. The existing sgx_encl_page->vm_max_prot_bits is already unsigned long while only using three bits. Transition to a bitfield for the two members to support the additional information without increasing the space consumed by the struct.

Acked-by: Jarkko Sakkinen jarkko@kernel.org Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Reviewed-by tag.

Changes since V2: - Update changelog to motivate transition to bitfield that was previously done when (now removed) vm_run_prot_bits was added.

Changes since V1: - Add Acked-by from Jarkko.

arch/x86/include/asm/sgx.h | 3 +++ arch/x86/kernel/cpu/sgx/encl.h | 3 ++- arch/x86/kernel/cpu/sgx/ioctl.c | 2 ++ 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h index d67810b50a81..eae20fa52b93 100644 --- a/arch/x86/include/asm/sgx.h +++ b/arch/x86/include/asm/sgx.h @@ -239,6 +239,9 @@ struct sgx_pageinfo { * %SGX_PAGE_TYPE_REG: a regular page * %SGX_PAGE_TYPE_VA: a VA page * %SGX_PAGE_TYPE_TRIM: a page in trimmed state + * + * Make sure when making changes to this enum that its values can still fit + * in the bitfield within &struct sgx_encl_page */ enum sgx_page_type { SGX_PAGE_TYPE_SECS, diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h index 1b15d22f6757..07abfc70c8e3 100644 --- a/arch/x86/kernel/cpu/sgx/encl.h +++ b/arch/x86/kernel/cpu/sgx/encl.h @@ -27,7 +27,8 @@

struct sgx_encl_page { unsigned long desc; - unsigned long vm_max_prot_bits; + unsigned long vm_max_prot_bits:8; + enum sgx_page_type type:16; struct sgx_epc_page *epc_page; struct sgx_encl *encl; struct sgx_va_page *va_page; diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index a66795e0b685..21078c6643f7 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -107,6 +107,7 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs) set_bit(SGX_ENCL_DEBUG, &encl->flags);

encl->secs.encl = encl; + encl->secs.type = SGX_PAGE_TYPE_SECS; encl->base = secs->base; encl->size = secs->size; encl->attributes = secs->attributes; @@ -344,6 +345,7 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src, */ encl_page->encl = encl; encl_page->epc_page = epc_page; + encl_page->type = (secinfo->flags & SGX_SECINFO_PAGE_TYPE_MASK) >> 8; encl->secs_child_cnt++;

if (flags & SGX_PAGE_MEASURE) {

From: Jarkko Sakkinen jarkko@kernel.org

Move sgx_encl_page_alloc() to encl.c and export it so that it can be used in the implementation for support of adding pages to initialized enclaves, which requires to allocate new enclave pages.

Signed-off-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- No changes since V3.

Changes since V2: - New patch Originally submitted at: https://lore.kernel.org/linux-sgx/20220308112833.262805-3-jarkko@kernel.org/

arch/x86/kernel/cpu/sgx/encl.c | 32 ++++++++++++++++++++++++++++++++ arch/x86/kernel/cpu/sgx/encl.h | 3 +++ arch/x86/kernel/cpu/sgx/ioctl.c | 32 -------------------------------- 3 files changed, 35 insertions(+), 32 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index c77a62432862..546423753e4c 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -792,6 +792,38 @@ int sgx_encl_test_and_clear_young(struct mm_struct *mm, return ret; }

+struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl, + unsigned long offset, + u64 secinfo_flags) +{ + struct sgx_encl_page *encl_page; + unsigned long prot; + + encl_page = kzalloc(sizeof(*encl_page), GFP_KERNEL); + if (!encl_page) + return ERR_PTR(-ENOMEM); + + encl_page->desc = encl->base + offset; + encl_page->encl = encl; + + prot = _calc_vm_trans(secinfo_flags, SGX_SECINFO_R, PROT_READ) | + _calc_vm_trans(secinfo_flags, SGX_SECINFO_W, PROT_WRITE) | + _calc_vm_trans(secinfo_flags, SGX_SECINFO_X, PROT_EXEC); + + /* + * TCS pages must always RW set for CPU access while the SECINFO + * permissions are *always* zero - the CPU ignores the user provided + * values and silently overwrites them with zero permissions. + */ + if ((secinfo_flags & SGX_SECINFO_PAGE_TYPE_MASK) == SGX_SECINFO_TCS) + prot |= PROT_READ | PROT_WRITE; + + /* Calculate maximum of the VM flags for the page. */ + encl_page->vm_max_prot_bits = calc_vm_prot_bits(prot, 0); + + return encl_page; +} + /** * sgx_zap_enclave_ptes() - remove PTEs mapping the address from enclave * @encl: the enclave diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h index 9d673d9531f0..253ebdd1c5be 100644 --- a/arch/x86/kernel/cpu/sgx/encl.h +++ b/arch/x86/kernel/cpu/sgx/encl.h @@ -112,6 +112,9 @@ int sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index, void sgx_encl_put_backing(struct sgx_backing *backing, bool do_write); int sgx_encl_test_and_clear_young(struct mm_struct *mm, struct sgx_encl_page *page); +struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl, + unsigned long offset, + u64 secinfo_flags); void sgx_zap_enclave_ptes(struct sgx_encl *encl, unsigned long addr); struct sgx_epc_page *sgx_alloc_va_page(void); unsigned int sgx_alloc_va_slot(struct sgx_va_page *va_page); diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index 2df27dd8b30d..bb8cdb2ad0d1 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -169,38 +169,6 @@ static long sgx_ioc_enclave_create(struct sgx_encl *encl, void __user *arg) return ret; }

-static struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl, - unsigned long offset, - u64 secinfo_flags) -{ - struct sgx_encl_page *encl_page; - unsigned long prot; - - encl_page = kzalloc(sizeof(*encl_page), GFP_KERNEL); - if (!encl_page) - return ERR_PTR(-ENOMEM); - - encl_page->desc = encl->base + offset; - encl_page->encl = encl; - - prot = _calc_vm_trans(secinfo_flags, SGX_SECINFO_R, PROT_READ) | - _calc_vm_trans(secinfo_flags, SGX_SECINFO_W, PROT_WRITE) | - _calc_vm_trans(secinfo_flags, SGX_SECINFO_X, PROT_EXEC); - - /* - * TCS pages must always RW set for CPU access while the SECINFO - * permissions are *always* zero - the CPU ignores the user provided - * values and silently overwrites them with zero permissions. - */ - if ((secinfo_flags & SGX_SECINFO_PAGE_TYPE_MASK) == SGX_SECINFO_TCS) - prot |= PROT_READ | PROT_WRITE; - - /* Calculate maximum of the VM flags for the page. */ - encl_page->vm_max_prot_bits = calc_vm_prot_bits(prot, 0); - - return encl_page; -} - static int sgx_validate_secinfo(struct sgx_secinfo *secinfo) { u64 perm = secinfo->flags & SGX_SECINFO_PERMISSION_MASK;

In the initial (SGX1) version of SGX, pages in an enclave need to be created with permissions that support all usages of the pages, from the time the enclave is initialized until it is unloaded. For example, pages used by a JIT compiler or when code needs to otherwise be relocated need to always have RWX permissions.

SGX2 includes a new function ENCLS[EMODPR] that is run from the kernel and can be used to restrict the EPCM permissions of regular enclave pages within an initialized enclave.

Introduce ioctl() SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS to support restricting EPCM permissions. With this ioctl() the user specifies a page range and the EPCM permissions to be applied to all pages in the provided range. ENCLS[EMODPR] is run to restrict the EPCM permissions followed by the ENCLS[ETRACK] flow that will ensure no cached linear-to-physical address mappings to the changed pages remain.

It is possible for the permission change request to fail on any page within the provided range, either with an error encountered by the kernel or by the SGX hardware while running ENCLS[EMODPR]. To support partial success the ioctl() returns an error code based on failures encountered by the kernel as well as two result output parameters: one for the number of pages that were successfully changed and one for the SGX return code.

The page table entry permissions are not impacted by the EPCM permission changes. VMAs and PTEs will continue to allow the maximum vetted permissions determined at the time the pages are added to the enclave. The SGX error code in a page fault will indicate if it was an EPCM permission check that prevented an access attempt.

No checking is done to ensure that the permissions are actually being restricted. This is because the enclave may have relaxed the EPCM permissions from within the enclave without the kernel knowing. An attempt to relax permissions using this call will be ignored by the hardware.

Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - User provides only new permissions, replacing secinfo. (Jarkko) - Expand comments of sgx_enclave_etrack() to document the context in which the function is safe to use.

Changes since V2: - Include the sgx_ioc_sgx2_ready() utility that previously was in "x86/sgx: Support relaxing of enclave page permissions" that is removed from the next version. - Few renames requested by Jarkko: struct sgx_enclave_restrict_perm -> struct sgx_enclave_restrict_permissions sgx_enclave_restrict_perm() -> sgx_enclave_restrict_permissions() sgx_ioc_enclave_restrict_perm() -> sgx_ioc_enclave_restrict_permissions() - Make EPCM permissions independent from kernel view of permissions. (Jarkko) - Remove attempt at runtime tracking of EPCM permissions (sgx_encl_page->vm_run_prot_bits). - Do not flush page table entries - they are no longer impacted by EPCM permission changes. - Modify changelog to reflect new architecture. - Ensure at least PROT_READ is requested - enclave requires read access to the page for commands like EMODPE and EACCEPT. (Jarkko)

Changes since V1: - Change terminology to use "relax" instead of "extend" to refer to the case when enclave page permissions are added (Dave). - Use ioctl() in commit message (Dave). - Add examples on what permissions would be allowed (Dave). - Split enclave page permission changes into two ioctl()s, one for permission restricting (SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS) and one for permission relaxing (SGX_IOC_ENCLAVE_RELAX_PERMISSIONS) (Jarkko). - In support of the ioctl() name change the following names have been changed: struct sgx_page_modp -> struct sgx_enclave_restrict_perm sgx_ioc_page_modp() -> sgx_ioc_enclave_restrict_perm() sgx_page_modp() -> sgx_enclave_restrict_perm() - ioctl() takes entire secinfo as input instead of page permissions only (Jarkko). - Fix kernel-doc to include () in function name. - Create and use utility for the ETRACK flow. - Fixups in comments - Move kernel-doc to function that provides documentation for Documentation/x86/sgx.rst. - Remove redundant comment. - Make explicit which members of struct sgx_enclave_restrict_perm are for output (Dave).

arch/x86/include/uapi/asm/sgx.h | 21 ++++ arch/x86/kernel/cpu/sgx/ioctl.c | 216 ++++++++++++++++++++++++++++++++ 2 files changed, 237 insertions(+)

diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h index f4b81587e90b..82648c006470 100644 --- a/arch/x86/include/uapi/asm/sgx.h +++ b/arch/x86/include/uapi/asm/sgx.h @@ -29,6 +29,8 @@ enum sgx_page_flags { _IOW(SGX_MAGIC, 0x03, struct sgx_enclave_provision) #define SGX_IOC_VEPC_REMOVE_ALL \ _IO(SGX_MAGIC, 0x04) +#define SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS \ + _IOWR(SGX_MAGIC, 0x05, struct sgx_enclave_restrict_permissions)

/** * struct sgx_enclave_create - parameter structure for the @@ -76,6 +78,25 @@ struct sgx_enclave_provision { __u64 fd; };

+/** + * struct sgx_enclave_restrict_permissions - parameters for ioctl + * %SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS + * @offset: starting page offset (page aligned relative to enclave base + * address defined in SECS) + * @length: length of memory (multiple of the page size) + * @permissions:new permission bits for pages in range described by @offset + * and @length + * @result: (output) SGX result code of ENCLS[EMODPR] function + * @count: (output) bytes successfully changed (multiple of page size) + */ +struct sgx_enclave_restrict_permissions { + __u64 offset; + __u64 length; + __u64 permissions; + __u64 result; + __u64 count; +}; + struct sgx_enclave_run;

/** diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index 5d41aa204761..395b4e58a295 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -660,6 +660,218 @@ static long sgx_ioc_enclave_provision(struct sgx_encl *encl, void __user *arg) return sgx_set_attribute(&encl->attributes_mask, params.fd); }

+/* + * Ensure enclave is ready for SGX2 functions. Readiness is checked + * by ensuring the hardware supports SGX2 and the enclave is initialized + * and thus able to handle requests to modify pages within it. + */ +static int sgx_ioc_sgx2_ready(struct sgx_encl *encl) +{ + if (!(cpu_feature_enabled(X86_FEATURE_SGX2))) + return -ENODEV; + + if (!test_bit(SGX_ENCL_INITIALIZED, &encl->flags)) + return -EINVAL; + + return 0; +} + +/* + * Some SGX functions require that no cached linear-to-physical address + * mappings are present before they can succeed. Collaborate with + * hardware via ENCLS[ETRACK] to ensure that all cached + * linear-to-physical address mappings belonging to all threads of + * the enclave are cleared. See sgx_encl_cpumask() for details. + * + * Must be called with enclave's mutex held from the time the + * SGX function requiring that no cached linear-to-physical mappings + * are present is executed until this ETRACK flow is complete. + */ +static int sgx_enclave_etrack(struct sgx_encl *encl) +{ + void *epc_virt; + int ret; + + epc_virt = sgx_get_epc_virt_addr(encl->secs.epc_page); + ret = __etrack(epc_virt); + if (ret) { + /* + * ETRACK only fails when there is an OS issue. For + * example, two consecutive ETRACK was sent without + * completed IPI between. + */ + pr_err_once("ETRACK returned %d (0x%x)", ret, ret); + /* + * Send IPIs to kick CPUs out of the enclave and + * try ETRACK again. + */ + on_each_cpu_mask(sgx_encl_cpumask(encl), sgx_ipi_cb, NULL, 1); + ret = __etrack(epc_virt); + if (ret) { + pr_err_once("ETRACK repeat returned %d (0x%x)", + ret, ret); + return -EFAULT; + } + } + on_each_cpu_mask(sgx_encl_cpumask(encl), sgx_ipi_cb, NULL, 1); + + return 0; +} + +/** + * sgx_enclave_restrict_permissions() - Restrict EPCM permissions + * @encl: Enclave to which the pages belong. + * @modp: Checked parameters from user on which pages need modifying and + * their new permissions. + * + * Return: + * - 0: Success. + * - -errno: Otherwise. + */ +static long +sgx_enclave_restrict_permissions(struct sgx_encl *encl, + struct sgx_enclave_restrict_permissions *modp) +{ + struct sgx_encl_page *entry; + struct sgx_secinfo secinfo; + unsigned long addr; + unsigned long c; + void *epc_virt; + int ret; + + memset(&secinfo, 0, sizeof(secinfo)); + secinfo.flags = modp->permissions & SGX_SECINFO_PERMISSION_MASK; + + for (c = 0 ; c < modp->length; c += PAGE_SIZE) { + addr = encl->base + modp->offset + c; + + mutex_lock(&encl->lock); + + entry = sgx_encl_load_page(encl, addr); + if (IS_ERR(entry)) { + ret = PTR_ERR(entry) == -EBUSY ? -EAGAIN : -EFAULT; + goto out_unlock; + } + + /* + * Changing EPCM permissions is only supported on regular + * SGX pages. Attempting this change on other pages will + * result in #PF. + */ + if (entry->type != SGX_PAGE_TYPE_REG) { + ret = -EINVAL; + goto out_unlock; + } + + /* + * Apart from ensuring that read-access remains, do not verify + * the permission bits requested. Kernel has no control over + * how EPCM permissions can be relaxed from within the enclave. + * ENCLS[EMODPR] can only remove existing EPCM permissions, + * attempting to set new permissions will be ignored by the + * hardware. + */ + + /* Change EPCM permissions. */ + epc_virt = sgx_get_epc_virt_addr(entry->epc_page); + ret = __emodpr(&secinfo, epc_virt); + if (encls_faulted(ret)) { + /* + * All possible faults should be avoidable: + * parameters have been checked, will only change + * permissions of a regular page, and no concurrent + * SGX1/SGX2 ENCLS instructions since these + * are protected with mutex. + */ + pr_err_once("EMODPR encountered exception %d\n", + ENCLS_TRAPNR(ret)); + ret = -EFAULT; + goto out_unlock; + } + if (encls_failed(ret)) { + modp->result = ret; + ret = -EFAULT; + goto out_unlock; + } + + ret = sgx_enclave_etrack(encl); + if (ret) { + ret = -EFAULT; + goto out_unlock; + } + + mutex_unlock(&encl->lock); + } + + ret = 0; + goto out; + +out_unlock: + mutex_unlock(&encl->lock); +out: + modp->count = c; + + return ret; +} + +/** + * sgx_ioc_enclave_restrict_permissions() - handler for + * %SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS + * @encl: an enclave pointer + * @arg: userspace pointer to a &struct sgx_enclave_restrict_permissions + * instance + * + * SGX2 distinguishes between relaxing and restricting the enclave page + * permissions maintained by the hardware (EPCM permissions) of pages + * belonging to an initialized enclave (after SGX_IOC_ENCLAVE_INIT). + * + * EPCM permissions cannot be restricted from within the enclave, the enclave + * requires the kernel to run the privileged level 0 instructions ENCLS[EMODPR] + * and ENCLS[ETRACK]. An attempt to relax EPCM permissions with this call + * will be ignored by the hardware. + * + * Return: + * - 0: Success + * - -errno: Otherwise + */ +static long sgx_ioc_enclave_restrict_permissions(struct sgx_encl *encl, + void __user *arg) +{ + struct sgx_enclave_restrict_permissions params; + long ret; + + ret = sgx_ioc_sgx2_ready(encl); + if (ret) + return ret; + + if (copy_from_user(&params, arg, sizeof(params))) + return -EFAULT; + + if (sgx_validate_offset_length(encl, params.offset, params.length)) + return -EINVAL; + + if (params.permissions & ~SGX_SECINFO_PERMISSION_MASK) + return -EINVAL; + + /* + * Read access is required for the enclave to be able to use the page. + * SGX instructions like ENCLU[EMODPE] and ENCLU[EACCEPT] require + * read access. + */ + if (!(params.permissions & SGX_SECINFO_R)) + return -EINVAL; + + if (params.result || params.count) + return -EINVAL; + + ret = sgx_enclave_restrict_permissions(encl, &params); + + if (copy_to_user(arg, &params, sizeof(params))) + return -EFAULT; + + return ret; +} + long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) { struct sgx_encl *encl = filep->private_data; @@ -681,6 +893,10 @@ long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) case SGX_IOC_ENCLAVE_PROVISION: ret = sgx_ioc_enclave_provision(encl, (void __user *)arg); break; + case SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS: + ret = sgx_ioc_enclave_restrict_permissions(encl, + (void __user *)arg); + break; default: ret = -ENOIOCTLCMD; break;

With SGX1 an enclave needs to be created with its maximum memory demands allocated. Pages cannot be added to an enclave after it is initialized. SGX2 introduces a new function, ENCLS[EAUG], that can be used to add pages to an initialized enclave. With SGX2 the enclave still needs to set aside address space for its maximum memory demands during enclave creation, but all pages need not be added before enclave initialization. Pages can be added during enclave runtime.

Add support for dynamically adding pages to an initialized enclave, architecturally limited to RW permission at creation but allowed to obtain RWX permissions after trusted enclave runs EMODPE. Add pages via the page fault handler at the time an enclave address without a backing enclave page is accessed, potentially directly reclaiming pages if no free pages are available.

The enclave is still required to run ENCLU[EACCEPT] on the page before it can be used. A useful flow is for the enclave to run ENCLU[EACCEPT] on an uninitialized address. This will trigger the page fault handler that will add the enclave page and return execution to the enclave to repeat the ENCLU[EACCEPT] instruction, this time successful.

If the enclave accesses an uninitialized address in another way, for example by expanding the enclave stack to a page that has not yet been added, then the page fault handler would add the page on the first write but upon returning to the enclave the instruction that triggered the page fault would be repeated and since ENCLU[EACCEPT] was not run yet it would trigger a second page fault, this time with the SGX flag set in the page fault error code. This can only be recovered by entering the enclave again and directly running the ENCLU[EACCEPT] instruction on the now initialized address.

Accessing an uninitialized address from outside the enclave also triggers this flow but the page will remain inaccessible (access will result in #PF) until accepted from within the enclave via ENCLU[EACCEPT].

Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Tested-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Reviewed-by tag. - Add Jarkko's Tested-by tag. - Call sgx_encl_grow() with sgx_encl->lock held as made possible with change to sgx_encl_grow() making calling of reclaimer optional.

Changes since V2: - Remove runtime tracking of EPCM permissions (sgx_encl_page->vm_run_prot_bits) (Jarkko). - Move export of sgx_encl_{grow,shrink}() to separate patch. (Jarkko) - Use sgx_encl_page_alloc(). (Jarkko) - Set max allowed permissions to be RWX (Jarkko). Update changelog to indicate the change and use comment in code as created by Jarkko in: https://lore.kernel.org/linux-sgx/20220306053211.135762-4-jarkko@kernel.org - Do not set protection bits but let it be inherited by VMA (Jarkko)

Changes since V1: - Fix subject line "to initialized" -> "to an initialized" (Jarkko). - Move text about hardware's PENDING state to the patch that introduces the ENCLS[EAUG] wrapper (Jarkko). - Ensure kernel-doc uses brackets when referring to function.

arch/x86/kernel/cpu/sgx/encl.c | 117 +++++++++++++++++++++++++++++++++ 1 file changed, 117 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index 92516aeca405..7ccda6fe1f8f 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -194,6 +194,112 @@ struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl, return __sgx_encl_load_page(encl, entry); }

+/** + * sgx_encl_eaug_page() - Dynamically add page to initialized enclave + * @vma: VMA obtained from fault info from where page is accessed + * @encl: enclave accessing the page + * @addr: address that triggered the page fault + * + * When an initialized enclave accesses a page with no backing EPC page + * on a SGX2 system then the EPC can be added dynamically via the SGX2 + * ENCLS[EAUG] instruction. + * + * Returns: Appropriate vm_fault_t: VM_FAULT_NOPAGE when PTE was installed + * successfully, VM_FAULT_SIGBUS or VM_FAULT_OOM as error otherwise. + */ +static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma, + struct sgx_encl *encl, unsigned long addr) +{ + struct sgx_pageinfo pginfo = {0}; + struct sgx_encl_page *encl_page; + struct sgx_epc_page *epc_page; + struct sgx_va_page *va_page; + unsigned long phys_addr; + u64 secinfo_flags; + vm_fault_t vmret; + int ret; + + if (!test_bit(SGX_ENCL_INITIALIZED, &encl->flags)) + return VM_FAULT_SIGBUS; + + /* + * Ignore internal permission checking for dynamically added pages. + * They matter only for data added during the pre-initialization + * phase. The enclave decides the permissions by the means of + * EACCEPT, EACCEPTCOPY and EMODPE. + */ + secinfo_flags = SGX_SECINFO_R | SGX_SECINFO_W | SGX_SECINFO_X; + encl_page = sgx_encl_page_alloc(encl, addr - encl->base, secinfo_flags); + if (IS_ERR(encl_page)) + return VM_FAULT_OOM; + + epc_page = sgx_alloc_epc_page(encl_page, true); + if (IS_ERR(epc_page)) { + kfree(encl_page); + return VM_FAULT_SIGBUS; + } + + mutex_lock(&encl->lock); + + va_page = sgx_encl_grow(encl, false); + if (IS_ERR(va_page)) { + ret = PTR_ERR(va_page); + goto err_out_unlock; + } + + if (va_page) + list_add(&va_page->list, &encl->va_pages); + + ret = xa_insert(&encl->page_array, PFN_DOWN(encl_page->desc), + encl_page, GFP_KERNEL); + /* + * If ret == -EBUSY then page was created in another flow while + * running without encl->lock + */ + if (ret) + goto err_out_shrink; + + pginfo.secs = (unsigned long)sgx_get_epc_virt_addr(encl->secs.epc_page); + pginfo.addr = encl_page->desc & PAGE_MASK; + pginfo.metadata = 0; + + ret = __eaug(&pginfo, sgx_get_epc_virt_addr(epc_page)); + if (ret) + goto err_out; + + encl_page->encl = encl; + encl_page->epc_page = epc_page; + encl_page->type = SGX_PAGE_TYPE_REG; + encl->secs_child_cnt++; + + sgx_mark_page_reclaimable(encl_page->epc_page); + + phys_addr = sgx_get_epc_phys_addr(epc_page); + /* + * Do not undo everything when creating PTE entry fails - next #PF + * would find page ready for a PTE. + */ + vmret = vmf_insert_pfn(vma, addr, PFN_DOWN(phys_addr)); + if (vmret != VM_FAULT_NOPAGE) { + mutex_unlock(&encl->lock); + return VM_FAULT_SIGBUS; + } + mutex_unlock(&encl->lock); + return VM_FAULT_NOPAGE; + +err_out: + xa_erase(&encl->page_array, PFN_DOWN(encl_page->desc)); + +err_out_shrink: + sgx_encl_shrink(encl, va_page); +err_out_unlock: + mutex_unlock(&encl->lock); + sgx_encl_free_epc_page(epc_page); + kfree(encl_page); + + return VM_FAULT_SIGBUS; +} + static vm_fault_t sgx_vma_fault(struct vm_fault *vmf) { unsigned long addr = (unsigned long)vmf->address; @@ -213,6 +319,17 @@ static vm_fault_t sgx_vma_fault(struct vm_fault *vmf) if (unlikely(!encl)) return VM_FAULT_SIGBUS;

+ /* + * The page_array keeps track of all enclave pages, whether they + * are swapped out or not. If there is no entry for this page and + * the system supports SGX2 then it is possible to dynamically add + * a new enclave page. This is only possible for an initialized + * enclave that will be checked for right away. + */ + if (cpu_feature_enabled(X86_FEATURE_SGX2) && + (!xa_load(&encl->page_array, PFN_DOWN(addr)))) + return sgx_encl_eaug_page(vma, encl, addr); + mutex_lock(&encl->lock);

entry = sgx_encl_load_page_in_vma(encl, addr, vma->vm_flags);

Every enclave contains one or more Thread Control Structures (TCS). The TCS contains meta-data used by the hardware to save and restore thread specific information when entering/exiting the enclave. With SGX1 an enclave needs to be created with enough TCSs to support the largest number of threads expecting to use the enclave and enough enclave pages to meet all its anticipated memory demands. In SGX1 all pages remain in the enclave until the enclave is unloaded.

SGX2 introduces a new function, ENCLS[EMODT], that is used to change the type of an enclave page from a regular (SGX_PAGE_TYPE_REG) enclave page to a TCS (SGX_PAGE_TYPE_TCS) page or change the type from a regular (SGX_PAGE_TYPE_REG) or TCS (SGX_PAGE_TYPE_TCS) page to a trimmed (SGX_PAGE_TYPE_TRIM) page (setting it up for later removal).

With the existing support of dynamically adding regular enclave pages to an initialized enclave and changing the page type to TCS it is possible to dynamically increase the number of threads supported by an enclave.

Changing the enclave page type to SGX_PAGE_TYPE_TRIM is the first step of dynamically removing pages from an initialized enclave. The complete page removal flow is: 1) Change the type of the pages to be removed to SGX_PAGE_TYPE_TRIM using the SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl() introduced here. 2) Approve the page removal by running ENCLU[EACCEPT] from within the enclave. 3) Initiate actual page removal using the ioctl() introduced in the following patch.

Add ioctl() SGX_IOC_ENCLAVE_MODIFY_TYPES to support changing SGX enclave page types within an initialized enclave. With SGX_IOC_ENCLAVE_MODIFY_TYPES the user specifies a page range and the enclave page type to be applied to all pages in the provided range. The ioctl() itself can return an error code based on failures encountered by the kernel. It is also possible for SGX specific failures to be encountered. Add a result output parameter to communicate the SGX return code. It is possible for the enclave page type change request to fail on any page within the provided range. Support partial success by returning the number of pages that were successfully changed.

After the page type is changed the page continues to be accessible from the kernel perspective with page table entries and internal state. The page may be moved to swap. Any access until ENCLU[EACCEPT] will encounter a page fault with SGX flag set in error code.

Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Rename ioctl() SGX_IOC_ENCLAVE_MODIFY_TYPE to SGX_IOC_ENCLAVE_MODIFY_TYPES. (Jarkko) - User provides just page type, replacing secinfo. (Jarkko)

Changes since V2: - Adjust ioctl number after removal of SGX_IOC_ENCLAVE_RELAX_PERMISSIONS. - Remove attempt at runtime tracking of EPCM permissions (sgx_encl_page->vm_run_prot_bits). (Jarkko) - Change names to follow guidance of using detailed names (Jarkko): struct sgx_enclave_modt -> struct sgx_enclave_modify_type sgx_enclave_modt() -> sgx_enclave_modify_type() sgx_ioc_enclave_modt() -> sgx_ioc_enclave_modify_type()

Changes since V1: - Remove the "Earlier changes ..." paragraph (Jarkko). - Change "new ioctl" text to "Add SGX_IOC_ENCLAVE_MOD_TYPE" (Jarkko). - Discussion about EPCM interaction and the EPCM MODIFIED bit is moved to new patch that introduces the ENCLS[EMODT] wrapper while keeping the higher level discussion on page accessibility in this commit log (Jarkko). - Rename SGX_IOC_PAGE_MODT ioctl() to SGX_IOC_ENCLAVE_MODIFY_TYPE (Jarkko). - Rename struct sgx_page_modt to struct sgx_enclave_modt in support of ioctl() rename. - Rename sgx_page_modt() to sgx_enclave_modt() and sgx_ioc_page_modt() to sgx_ioc_enclave_modt() in support of ioctl() rename. - Provide secinfo as parameter to ioctl() instead of just page type (Jarkko). - Update comments to refer to new ioctl() names. - Use new SGX2 checking helper(). - Use ETRACK flow utility. - Move kernel-doc to function that provides documentation for Documentation/x86/sgx.rst. - Remove redundant comment. - Use offset/length validation utility. - Make explicit which members of struct sgx_enclave_modt are for output (Dave).

arch/x86/include/uapi/asm/sgx.h | 19 +++ arch/x86/kernel/cpu/sgx/ioctl.c | 201 ++++++++++++++++++++++++++++++++ 2 files changed, 220 insertions(+)

diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h index 82648c006470..de4d1af628d5 100644 --- a/arch/x86/include/uapi/asm/sgx.h +++ b/arch/x86/include/uapi/asm/sgx.h @@ -31,6 +31,8 @@ enum sgx_page_flags { _IO(SGX_MAGIC, 0x04) #define SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS \ _IOWR(SGX_MAGIC, 0x05, struct sgx_enclave_restrict_permissions) +#define SGX_IOC_ENCLAVE_MODIFY_TYPES \ + _IOWR(SGX_MAGIC, 0x06, struct sgx_enclave_modify_type)

/** * struct sgx_enclave_create - parameter structure for the @@ -97,6 +99,23 @@ struct sgx_enclave_restrict_permissions { __u64 count; };

+/** + * struct sgx_enclave_modify_type - parameters for %SGX_IOC_ENCLAVE_MODIFY_TYPES + * @offset: starting page offset (page aligned relative to enclave base + * address defined in SECS) + * @length: length of memory (multiple of the page size) + * @page_type: new type for pages in range described by @offset and @length + * @result: (output) SGX result code of ENCLS[EMODT] function + * @count: (output) bytes successfully changed (multiple of page size) + */ +struct sgx_enclave_modify_type { + __u64 offset; + __u64 length; + __u64 page_type; + __u64 result; + __u64 count; +}; + struct sgx_enclave_run;

/** diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index 395b4e58a295..8709f131ae40 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -872,6 +872,204 @@ static long sgx_ioc_enclave_restrict_permissions(struct sgx_encl *encl, return ret; }

+/** + * sgx_enclave_modify_type() - Modify type of SGX enclave pages + * @encl: Enclave to which the pages belong. + * @modt: Checked parameters from user about which pages need modifying + * and their new page type. + * + * Return: + * - 0: Success + * - -errno: Otherwise + */ +static long sgx_enclave_modify_type(struct sgx_encl *encl, + struct sgx_enclave_modify_type *modt) +{ + unsigned long max_prot_restore; + enum sgx_page_type page_type; + struct sgx_encl_page *entry; + struct sgx_secinfo secinfo; + unsigned long prot; + unsigned long addr; + unsigned long c; + void *epc_virt; + int ret; + + page_type = modt->page_type & SGX_PAGE_TYPE_MASK; + + /* + * The only new page types allowed by hardware are PT_TCS and PT_TRIM. + */ + if (page_type != SGX_PAGE_TYPE_TCS && page_type != SGX_PAGE_TYPE_TRIM) + return -EINVAL; + + memset(&secinfo, 0, sizeof(secinfo)); + + secinfo.flags = page_type << 8; + + for (c = 0 ; c < modt->length; c += PAGE_SIZE) { + addr = encl->base + modt->offset + c; + + mutex_lock(&encl->lock); + + entry = sgx_encl_load_page(encl, addr); + if (IS_ERR(entry)) { + ret = PTR_ERR(entry) == -EBUSY ? -EAGAIN : -EFAULT; + goto out_unlock; + } + + /* + * Borrow the logic from the Intel SDM. Regular pages + * (SGX_PAGE_TYPE_REG) can change type to SGX_PAGE_TYPE_TCS + * or SGX_PAGE_TYPE_TRIM but TCS pages can only be trimmed. + * CET pages not supported yet. + */ + if (!(entry->type == SGX_PAGE_TYPE_REG || + (entry->type == SGX_PAGE_TYPE_TCS && + page_type == SGX_PAGE_TYPE_TRIM))) { + ret = -EINVAL; + goto out_unlock; + } + + max_prot_restore = entry->vm_max_prot_bits; + + /* + * Once a regular page becomes a TCS page it cannot be + * changed back. So the maximum allowed protection reflects + * the TCS page that is always RW from kernel perspective but + * will be inaccessible from within enclave. Before doing + * so, do make sure that the new page type continues to + * respect the originally vetted page permissions. + */ + if (entry->type == SGX_PAGE_TYPE_REG && + page_type == SGX_PAGE_TYPE_TCS) { + if (~entry->vm_max_prot_bits & (VM_READ | VM_WRITE)) { + ret = -EPERM; + goto out_unlock; + } + prot = PROT_READ | PROT_WRITE; + entry->vm_max_prot_bits = calc_vm_prot_bits(prot, 0); + + /* + * Prevent page from being reclaimed while mutex + * is released. + */ + if (sgx_unmark_page_reclaimable(entry->epc_page)) { + ret = -EAGAIN; + goto out_entry_changed; + } + + /* + * Do not keep encl->lock because of dependency on + * mmap_lock acquired in sgx_zap_enclave_ptes(). + */ + mutex_unlock(&encl->lock); + + sgx_zap_enclave_ptes(encl, addr); + + mutex_lock(&encl->lock); + + sgx_mark_page_reclaimable(entry->epc_page); + } + + /* Change EPC type */ + epc_virt = sgx_get_epc_virt_addr(entry->epc_page); + ret = __emodt(&secinfo, epc_virt); + if (encls_faulted(ret)) { + /* + * All possible faults should be avoidable: + * parameters have been checked, will only change + * valid page types, and no concurrent + * SGX1/SGX2 ENCLS instructions since these are + * protected with mutex. + */ + pr_err_once("EMODT encountered exception %d\n", + ENCLS_TRAPNR(ret)); + ret = -EFAULT; + goto out_entry_changed; + } + if (encls_failed(ret)) { + modt->result = ret; + ret = -EFAULT; + goto out_entry_changed; + } + + ret = sgx_enclave_etrack(encl); + if (ret) { + ret = -EFAULT; + goto out_unlock; + } + + entry->type = page_type; + + mutex_unlock(&encl->lock); + } + + ret = 0; + goto out; + +out_entry_changed: + entry->vm_max_prot_bits = max_prot_restore; +out_unlock: + mutex_unlock(&encl->lock); +out: + modt->count = c; + + return ret; +} + +/** + * sgx_ioc_enclave_modify_type() - handler for %SGX_IOC_ENCLAVE_MODIFY_TYPES + * @encl: an enclave pointer + * @arg: userspace pointer to a &struct sgx_enclave_modify_type instance + * + * Ability to change the enclave page type supports the following use cases: + * + * * It is possible to add TCS pages to an enclave by changing the type of + * regular pages (%SGX_PAGE_TYPE_REG) to TCS (%SGX_PAGE_TYPE_TCS) pages. + * With this support the number of threads supported by an initialized + * enclave can be increased dynamically. + * + * * Regular or TCS pages can dynamically be removed from an initialized + * enclave by changing the page type to %SGX_PAGE_TYPE_TRIM. Changing the + * page type to %SGX_PAGE_TYPE_TRIM marks the page for removal with actual + * removal done by handler of %SGX_IOC_ENCLAVE_REMOVE_PAGES ioctl() called + * after ENCLU[EACCEPT] is run on %SGX_PAGE_TYPE_TRIM page from within the + * enclave. + * + * Return: + * - 0: Success + * - -errno: Otherwise + */ +static long sgx_ioc_enclave_modify_type(struct sgx_encl *encl, void __user *arg) +{ + struct sgx_enclave_modify_type params; + long ret; + + ret = sgx_ioc_sgx2_ready(encl); + if (ret) + return ret; + + if (copy_from_user(&params, arg, sizeof(params))) + return -EFAULT; + + if (sgx_validate_offset_length(encl, params.offset, params.length)) + return -EINVAL; + + if (params.page_type & ~SGX_PAGE_TYPE_MASK) + return -EINVAL; + + if (params.result || params.count) + return -EINVAL; + + ret = sgx_enclave_modify_type(encl, &params); + + if (copy_to_user(arg, &params, sizeof(params))) + return -EFAULT; + + return ret; +} + long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) { struct sgx_encl *encl = filep->private_data; @@ -897,6 +1095,9 @@ long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) ret = sgx_ioc_enclave_restrict_permissions(encl, (void __user *)arg); break; + case SGX_IOC_ENCLAVE_MODIFY_TYPES: + ret = sgx_ioc_enclave_modify_type(encl, (void __user *)arg); + break; default: ret = -ENOIOCTLCMD; break;

The page reclaimer ensures availability of EPC pages across all enclaves. In support of this it runs independently from the individual enclaves in order to take locks from the different enclaves as it writes pages to swap.

When needing to load a page from swap an EPC page needs to be available for its contents to be loaded into. Loading an existing enclave page from swap does not reclaim EPC pages directly if none are available, instead the reclaimer is woken when the available EPC pages are found to be below a watermark.

When iterating over a large number of pages in an oversubscribed environment there is a race between the reclaimer woken up and EPC pages reclaimed fast enough for the page operations to proceed.

Ensure there are EPC pages available before attempting to load a page that may potentially be pulled from swap into an available EPC page.

Acked-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Acked-by tag. - Rename sgx_direct_reclaim() to sgx_reclaim_direct(). (Jarkko) - Add Dave's provided comments to sgx_reclaim_direct(). (Dave)

Changes since v1: - Reword commit message.

arch/x86/kernel/cpu/sgx/ioctl.c | 6 ++++++ arch/x86/kernel/cpu/sgx/main.c | 11 +++++++++++ arch/x86/kernel/cpu/sgx/sgx.h | 1 + 3 files changed, 18 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index f9a1654a49b7..83674d054c13 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -745,6 +745,8 @@ sgx_enclave_restrict_permissions(struct sgx_encl *encl, for (c = 0 ; c < modp->length; c += PAGE_SIZE) { addr = encl->base + modp->offset + c;

+ sgx_reclaim_direct(); + mutex_lock(&encl->lock);

entry = sgx_encl_load_page(encl, addr); @@ -910,6 +912,8 @@ static long sgx_enclave_modify_type(struct sgx_encl *encl, for (c = 0 ; c < modt->length; c += PAGE_SIZE) { addr = encl->base + modt->offset + c;

+ sgx_reclaim_direct(); + mutex_lock(&encl->lock);

entry = sgx_encl_load_page(encl, addr); @@ -1095,6 +1099,8 @@ static long sgx_encl_remove_pages(struct sgx_encl *encl, for (c = 0 ; c < params->length; c += PAGE_SIZE) { addr = encl->base + params->offset + c;

+ sgx_reclaim_direct(); + mutex_lock(&encl->lock);

entry = sgx_encl_load_page(encl, addr); diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 6e2cb7564080..0e8741a80cf3 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -370,6 +370,17 @@ static bool sgx_should_reclaim(unsigned long watermark) !list_empty(&sgx_active_page_list); }

+/* + * sgx_reclaim_direct() should be called (without enclave's mutex held) + * in locations where SGX memory resources might be low and might be + * needed in order to make forward progress. + */ +void sgx_reclaim_direct(void) +{ + if (sgx_should_reclaim(SGX_NR_LOW_PAGES)) + sgx_reclaim_pages(); +} + static int ksgxd(void *p) { set_freezable(); diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h index b30cee4de903..0f2020653fba 100644 --- a/arch/x86/kernel/cpu/sgx/sgx.h +++ b/arch/x86/kernel/cpu/sgx/sgx.h @@ -86,6 +86,7 @@ static inline void *sgx_get_epc_virt_addr(struct sgx_epc_page *page) struct sgx_epc_page *__sgx_alloc_epc_page(void); void sgx_free_epc_page(struct sgx_epc_page *page);

+void sgx_reclaim_direct(void); void sgx_mark_page_reclaimable(struct sgx_epc_page *page); int sgx_unmark_page_reclaimable(struct sgx_epc_page *page); struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim);

EPCM permission changes could be made from within (to relax permissions) or out (to restrict permissions) the enclave. Kernel support is needed when permissions are restricted to be able to call the privileged ENCLS[EMODPR] instruction. EPCM permissions can be relaxed via ENCLU[EMODPE] from within the enclave but the enclave still depends on the kernel to install PTEs with the needed permissions.

Add a test that exercises a few of the enclave page permission flows: 1) Test starts with a RW (from enclave and kernel perspective) enclave page that is mapped via a RW VMA. 2) Use the SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS ioctl() to restrict the enclave (EPCM) page permissions to read-only. 3) Run ENCLU[EACCEPT] from within the enclave to accept the new page permissions. 4) Attempt to write to the enclave page from within the enclave - this should fail with a page fault on the EPCM permissions since the page table entry continues to allow RW access. 5) Restore EPCM permissions to RW by running ENCLU[EMODPE] from within the enclave. 6) Attempt to write to the enclave page from within the enclave - this should succeed since both EPCM and PTE permissions allow this access.

Acked-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Acked-by tag. - User provides only new permissions in SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS ioctl(), replacing secinfo. (Jarkko) - Use SGX page permission bits instead of VMA protection bits.

Changes since V2: - Modify test to support separation between EPCM and PTE/VMA permissions - Fix changelog and comments to reflect new relationship between EPCM and PTE/VMA permissions. - With EPCM permissions controlling access instead of PTE permissions, check for SGX error code now encountered in page fault. - Stop calling SGX_IOC_ENCLAVE_RELAX_PERMISSIONS and ensure that only calling ENCLU[EMODPE] from within enclave is necessary to restore access to the enclave page. - Update to use new struct name struct sgx_enclave_restrict_perm -> struct sgx_enclave_restrict_permissions. (Jarkko)

Changes since V1: - Adapt test to the kernel interface changes: the ioctl() name change and providing entire secinfo as parameter. - Remove the ENCLU[EACCEPT] call after permissions are relaxed since the new flow no longer results in the EPCM PR bit being set. - Rewrite error path to reduce line lengths.

tools/testing/selftests/sgx/defines.h | 15 ++ tools/testing/selftests/sgx/main.c | 214 ++++++++++++++++++++++++ tools/testing/selftests/sgx/test_encl.c | 38 +++++ 3 files changed, 267 insertions(+)

diff --git a/tools/testing/selftests/sgx/defines.h b/tools/testing/selftests/sgx/defines.h index 02d775789ea7..b638eb98c80c 100644 --- a/tools/testing/selftests/sgx/defines.h +++ b/tools/testing/selftests/sgx/defines.h @@ -24,6 +24,8 @@ enum encl_op_type { ENCL_OP_PUT_TO_ADDRESS, ENCL_OP_GET_FROM_ADDRESS, ENCL_OP_NOP, + ENCL_OP_EACCEPT, + ENCL_OP_EMODPE, ENCL_OP_MAX, };

@@ -53,4 +55,17 @@ struct encl_op_get_from_addr { uint64_t addr; };

+struct encl_op_eaccept { + struct encl_op_header header; + uint64_t epc_addr; + uint64_t flags; + uint64_t ret; +}; + +struct encl_op_emodpe { + struct encl_op_header header; + uint64_t epc_addr; + uint64_t flags; +}; + #endif /* DEFINES_H */ diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c index dd74fa42302e..46eac09cd955 100644 --- a/tools/testing/selftests/sgx/main.c +++ b/tools/testing/selftests/sgx/main.c @@ -25,6 +25,18 @@ static const uint64_t MAGIC = 0x1122334455667788ULL; static const uint64_t MAGIC2 = 0x8877665544332211ULL; vdso_sgx_enter_enclave_t vdso_sgx_enter_enclave;

+/* + * Security Information (SECINFO) data structure needed by a few SGX + * instructions (eg. ENCLU[EACCEPT] and ENCLU[EMODPE]) holds meta-data + * about an enclave page. &enum sgx_secinfo_page_state specifies the + * secinfo flags used for page state. + */ +enum sgx_secinfo_page_state { + SGX_SECINFO_PENDING = (1 << 3), + SGX_SECINFO_MODIFIED = (1 << 4), + SGX_SECINFO_PR = (1 << 5), +}; + struct vdso_symtab { Elf64_Sym *elf_symtab; const char *elf_symstrtab; @@ -555,4 +567,206 @@ TEST_F(enclave, pte_permissions) EXPECT_EQ(self->run.exception_addr, 0); }

+/* + * Enclave page permission test. + * + * Modify and restore enclave page's EPCM (enclave) permissions from + * outside enclave (ENCLS[EMODPR] via kernel) as well as from within + * enclave (via ENCLU[EMODPE]). Check for page fault if + * VMA allows access but EPCM permissions do not. + */ +TEST_F(enclave, epcm_permissions) +{ + struct sgx_enclave_restrict_permissions restrict_ioc; + struct encl_op_get_from_addr get_addr_op; + struct encl_op_put_to_addr put_addr_op; + struct encl_op_eaccept eaccept_op; + struct encl_op_emodpe emodpe_op; + unsigned long data_start; + int ret, errno_save; + + ASSERT_TRUE(setup_test_encl(ENCL_HEAP_SIZE_DEFAULT, &self->encl, _metadata)); + + memset(&self->run, 0, sizeof(self->run)); + self->run.tcs = self->encl.encl_base; + + /* + * Ensure kernel supports needed ioctl() and system supports needed + * commands. + */ + memset(&restrict_ioc, 0, sizeof(restrict_ioc)); + + ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS, + &restrict_ioc); + errno_save = ret == -1 ? errno : 0; + + /* + * Invalid parameters were provided during sanity check, + * expect command to fail. + */ + ASSERT_EQ(ret, -1); + + /* ret == -1 */ + if (errno_save == ENOTTY) + SKIP(return, + "Kernel does not support SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS ioctl()"); + else if (errno_save == ENODEV) + SKIP(return, "System does not support SGX2"); + + /* + * Page that will have its permissions changed is the second data + * page in the .data segment. This forms part of the local encl_buffer + * within the enclave. + * + * At start of test @data_start should have EPCM as well as PTE and + * VMA permissions of RW. + */ + + data_start = self->encl.encl_base + + encl_get_data_offset(&self->encl) + PAGE_SIZE; + + /* + * Sanity check that page at @data_start is writable before making + * any changes to page permissions. + * + * Start by writing MAGIC to test page. + */ + put_addr_op.value = MAGIC; + put_addr_op.addr = data_start; + put_addr_op.header.type = ENCL_OP_PUT_TO_ADDRESS; + + EXPECT_EQ(ENCL_CALL(&put_addr_op, &self->run, true), 0); + + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + + /* + * Read memory that was just written to, confirming that + * page is writable. + */ + get_addr_op.value = 0; + get_addr_op.addr = data_start; + get_addr_op.header.type = ENCL_OP_GET_FROM_ADDRESS; + + EXPECT_EQ(ENCL_CALL(&get_addr_op, &self->run, true), 0); + + EXPECT_EQ(get_addr_op.value, MAGIC); + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + + /* + * Change EPCM permissions to read-only. Kernel still considers + * the page writable. + */ + memset(&restrict_ioc, 0, sizeof(restrict_ioc)); + + restrict_ioc.offset = encl_get_data_offset(&self->encl) + PAGE_SIZE; + restrict_ioc.length = PAGE_SIZE; + restrict_ioc.permissions = SGX_SECINFO_R; + + ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS, + &restrict_ioc); + errno_save = ret == -1 ? errno : 0; + + EXPECT_EQ(ret, 0); + EXPECT_EQ(errno_save, 0); + EXPECT_EQ(restrict_ioc.result, 0); + EXPECT_EQ(restrict_ioc.count, 4096); + + /* + * EPCM permissions changed from kernel, need to EACCEPT from enclave. + */ + eaccept_op.epc_addr = data_start; + eaccept_op.flags = SGX_SECINFO_R | SGX_SECINFO_REG | SGX_SECINFO_PR; + eaccept_op.ret = 0; + eaccept_op.header.type = ENCL_OP_EACCEPT; + + EXPECT_EQ(ENCL_CALL(&eaccept_op, &self->run, true), 0); + + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + EXPECT_EQ(eaccept_op.ret, 0); + + /* + * EPCM permissions of page is now read-only, expect #PF + * on EPCM when attempting to write to page from within enclave. + */ + put_addr_op.value = MAGIC2; + + EXPECT_EQ(ENCL_CALL(&put_addr_op, &self->run, true), 0); + + EXPECT_EQ(self->run.function, ERESUME); + EXPECT_EQ(self->run.exception_vector, 14); + EXPECT_EQ(self->run.exception_error_code, 0x8007); + EXPECT_EQ(self->run.exception_addr, data_start); + + self->run.exception_vector = 0; + self->run.exception_error_code = 0; + self->run.exception_addr = 0; + + /* + * Received AEX but cannot return to enclave at same entrypoint, + * need different TCS from where EPCM permission can be made writable + * again. + */ + self->run.tcs = self->encl.encl_base + PAGE_SIZE; + + /* + * Enter enclave at new TCS to change EPCM permissions to be + * writable again and thus fix the page fault that triggered the + * AEX. + */ + + emodpe_op.epc_addr = data_start; + emodpe_op.flags = SGX_SECINFO_R | SGX_SECINFO_W; + emodpe_op.header.type = ENCL_OP_EMODPE; + + EXPECT_EQ(ENCL_CALL(&emodpe_op, &self->run, true), 0); + + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + + /* + * Attempt to return to main TCS to resume execution at faulting + * instruction, PTE should continue to allow writing to the page. + */ + self->run.tcs = self->encl.encl_base; + + /* + * Wrong page permissions that caused original fault has + * now been fixed via EPCM permissions. + * Resume execution in main TCS to re-attempt the memory access. + */ + self->run.tcs = self->encl.encl_base; + + EXPECT_EQ(vdso_sgx_enter_enclave((unsigned long)&put_addr_op, 0, 0, + ERESUME, 0, 0, + &self->run), + 0); + + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + + get_addr_op.value = 0; + + EXPECT_EQ(ENCL_CALL(&get_addr_op, &self->run, true), 0); + + EXPECT_EQ(get_addr_op.value, MAGIC2); + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.user_data, 0); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); +} + TEST_HARNESS_MAIN diff --git a/tools/testing/selftests/sgx/test_encl.c b/tools/testing/selftests/sgx/test_encl.c index 4fca01cfd898..5b6c65331527 100644 --- a/tools/testing/selftests/sgx/test_encl.c +++ b/tools/testing/selftests/sgx/test_encl.c @@ -11,6 +11,42 @@ */ static uint8_t encl_buffer[8192] = { 1 };

+enum sgx_enclu_function { + EACCEPT = 0x5, + EMODPE = 0x6, +}; + +static void do_encl_emodpe(void *_op) +{ + struct sgx_secinfo secinfo __aligned(sizeof(struct sgx_secinfo)) = {0}; + struct encl_op_emodpe *op = _op; + + secinfo.flags = op->flags; + + asm volatile(".byte 0x0f, 0x01, 0xd7" + : + : "a" (EMODPE), + "b" (&secinfo), + "c" (op->epc_addr)); +} + +static void do_encl_eaccept(void *_op) +{ + struct sgx_secinfo secinfo __aligned(sizeof(struct sgx_secinfo)) = {0}; + struct encl_op_eaccept *op = _op; + int rax; + + secinfo.flags = op->flags; + + asm volatile(".byte 0x0f, 0x01, 0xd7" + : "=a" (rax) + : "a" (EACCEPT), + "b" (&secinfo), + "c" (op->epc_addr)); + + op->ret = rax; +} + static void *memcpy(void *dest, const void *src, size_t n) { size_t i; @@ -62,6 +98,8 @@ void encl_body(void *rdi, void *rsi) do_encl_op_put_to_addr, do_encl_op_get_from_addr, do_encl_op_nop, + do_encl_eaccept, + do_encl_emodpe, };

struct encl_op_header *op = (struct encl_op_header *)rdi;

Enclave pages can be added to an initialized enclave when an address belonging to the enclave but without a backing page is accessed from within the enclave.

Accessing memory without a backing enclave page from within an enclave can be in different ways: 1) Pre-emptively run ENCLU[EACCEPT]. Since the addition of a page always needs to be accepted by the enclave via ENCLU[EACCEPT] this flow is efficient since the first execution of ENCLU[EACCEPT] triggers the addition of the page and when execution returns to the same instruction the second execution would be successful as an acceptance of the page.

2) A direct read or write. The flow where a direct read or write triggers the page addition execution cannot resume from the instruction (read/write) that triggered the fault but instead the enclave needs to be entered at a different entry point to run needed ENCLU[EACCEPT] before execution can return to the original entry point and the read/write instruction that faulted.

Add tests for both flows.

Acked-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Acked-by tag.

Changes since V2: - Add inline comment to the mmap() call used in both EAUG tests to explain why the mmap() is expected to succeed. (Jarkko)

Changes since V1: - Replace __cpuid() definition and usage with __cpuid_count(). (Reinette) - Fix accuracy of comments.

tools/testing/selftests/sgx/main.c | 250 +++++++++++++++++++++++++++++ 1 file changed, 250 insertions(+)

diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c index 016ae3e5f398..79c08e347112 100644 --- a/tools/testing/selftests/sgx/main.c +++ b/tools/testing/selftests/sgx/main.c @@ -86,6 +86,15 @@ static bool vdso_get_symtab(void *addr, struct vdso_symtab *symtab) return true; }

+static inline int sgx2_supported(void) +{ + unsigned int eax, ebx, ecx, edx; + + __cpuid_count(SGX_CPUID, 0x0, eax, ebx, ecx, edx); + + return eax & 0x2; +} + static unsigned long elf_sym_hash(const char *name) { unsigned long h = 0, high; @@ -840,4 +849,245 @@ TEST_F(enclave, epcm_permissions) EXPECT_EQ(self->run.exception_addr, 0); }

+/* + * Test the addition of pages to an initialized enclave via writing to + * a page belonging to the enclave's address space but was not added + * during enclave creation. + */ +TEST_F(enclave, augment) +{ + struct encl_op_get_from_addr get_addr_op; + struct encl_op_put_to_addr put_addr_op; + struct encl_op_eaccept eaccept_op; + size_t total_size = 0; + void *addr; + int i; + + if (!sgx2_supported()) + SKIP(return, "SGX2 not supported"); + + ASSERT_TRUE(setup_test_encl(ENCL_HEAP_SIZE_DEFAULT, &self->encl, _metadata)); + + memset(&self->run, 0, sizeof(self->run)); + self->run.tcs = self->encl.encl_base; + + for (i = 0; i < self->encl.nr_segments; i++) { + struct encl_segment *seg = &self->encl.segment_tbl[i]; + + total_size += seg->size; + } + + /* + * Actual enclave size is expected to be larger than the loaded + * test enclave since enclave size must be a power of 2 in bytes + * and test_encl does not consume it all. + */ + EXPECT_LT(total_size + PAGE_SIZE, self->encl.encl_size); + + /* + * Create memory mapping for the page that will be added. New + * memory mapping is for one page right after all existing + * mappings. + * Kernel will allow new mapping using any permissions if it + * falls into the enclave's address range but not backed + * by existing enclave pages. + */ + addr = mmap((void *)self->encl.encl_base + total_size, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_SHARED | MAP_FIXED, self->encl.fd, 0); + EXPECT_NE(addr, MAP_FAILED); + + self->run.exception_vector = 0; + self->run.exception_error_code = 0; + self->run.exception_addr = 0; + + /* + * Attempt to write to the new page from within enclave. + * Expected to fail since page is not (yet) part of the enclave. + * The first #PF will trigger the addition of the page to the + * enclave, but since the new page needs an EACCEPT from within the + * enclave before it can be used it would not be possible + * to successfully return to the failing instruction. This is the + * cause of the second #PF captured here having the SGX bit set, + * it is from hardware preventing the page from being used. + */ + put_addr_op.value = MAGIC; + put_addr_op.addr = (unsigned long)addr; + put_addr_op.header.type = ENCL_OP_PUT_TO_ADDRESS; + + EXPECT_EQ(ENCL_CALL(&put_addr_op, &self->run, true), 0); + + EXPECT_EQ(self->run.function, ERESUME); + EXPECT_EQ(self->run.exception_vector, 14); + EXPECT_EQ(self->run.exception_addr, (unsigned long)addr); + + if (self->run.exception_error_code == 0x6) { + munmap(addr, PAGE_SIZE); + SKIP(return, "Kernel does not support adding pages to initialized enclave"); + } + + EXPECT_EQ(self->run.exception_error_code, 0x8007); + + self->run.exception_vector = 0; + self->run.exception_error_code = 0; + self->run.exception_addr = 0; + + /* Handle AEX by running EACCEPT from new entry point. */ + self->run.tcs = self->encl.encl_base + PAGE_SIZE; + + eaccept_op.epc_addr = self->encl.encl_base + total_size; + eaccept_op.flags = SGX_SECINFO_R | SGX_SECINFO_W | SGX_SECINFO_REG | SGX_SECINFO_PENDING; + eaccept_op.ret = 0; + eaccept_op.header.type = ENCL_OP_EACCEPT; + + EXPECT_EQ(ENCL_CALL(&eaccept_op, &self->run, true), 0); + + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + EXPECT_EQ(eaccept_op.ret, 0); + + /* Can now return to main TCS to resume execution. */ + self->run.tcs = self->encl.encl_base; + + EXPECT_EQ(vdso_sgx_enter_enclave((unsigned long)&put_addr_op, 0, 0, + ERESUME, 0, 0, + &self->run), + 0); + + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + + /* + * Read memory from newly added page that was just written to, + * confirming that data previously written (MAGIC) is present. + */ + get_addr_op.value = 0; + get_addr_op.addr = (unsigned long)addr; + get_addr_op.header.type = ENCL_OP_GET_FROM_ADDRESS; + + EXPECT_EQ(ENCL_CALL(&get_addr_op, &self->run, true), 0); + + EXPECT_EQ(get_addr_op.value, MAGIC); + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + + munmap(addr, PAGE_SIZE); +} + +/* + * Test for the addition of pages to an initialized enclave via a + * pre-emptive run of EACCEPT on page to be added. + */ +TEST_F(enclave, augment_via_eaccept) +{ + struct encl_op_get_from_addr get_addr_op; + struct encl_op_put_to_addr put_addr_op; + struct encl_op_eaccept eaccept_op; + size_t total_size = 0; + void *addr; + int i; + + if (!sgx2_supported()) + SKIP(return, "SGX2 not supported"); + + ASSERT_TRUE(setup_test_encl(ENCL_HEAP_SIZE_DEFAULT, &self->encl, _metadata)); + + memset(&self->run, 0, sizeof(self->run)); + self->run.tcs = self->encl.encl_base; + + for (i = 0; i < self->encl.nr_segments; i++) { + struct encl_segment *seg = &self->encl.segment_tbl[i]; + + total_size += seg->size; + } + + /* + * Actual enclave size is expected to be larger than the loaded + * test enclave since enclave size must be a power of 2 in bytes while + * test_encl does not consume it all. + */ + EXPECT_LT(total_size + PAGE_SIZE, self->encl.encl_size); + + /* + * mmap() a page at end of existing enclave to be used for dynamic + * EPC page. + * + * Kernel will allow new mapping using any permissions if it + * falls into the enclave's address range but not backed + * by existing enclave pages. + */ + + addr = mmap((void *)self->encl.encl_base + total_size, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, MAP_SHARED | MAP_FIXED, + self->encl.fd, 0); + EXPECT_NE(addr, MAP_FAILED); + + self->run.exception_vector = 0; + self->run.exception_error_code = 0; + self->run.exception_addr = 0; + + /* + * Run EACCEPT on new page to trigger the #PF->EAUG->EACCEPT(again + * without a #PF). All should be transparent to userspace. + */ + eaccept_op.epc_addr = self->encl.encl_base + total_size; + eaccept_op.flags = SGX_SECINFO_R | SGX_SECINFO_W | SGX_SECINFO_REG | SGX_SECINFO_PENDING; + eaccept_op.ret = 0; + eaccept_op.header.type = ENCL_OP_EACCEPT; + + EXPECT_EQ(ENCL_CALL(&eaccept_op, &self->run, true), 0); + + if (self->run.exception_vector == 14 && + self->run.exception_error_code == 4 && + self->run.exception_addr == self->encl.encl_base + total_size) { + munmap(addr, PAGE_SIZE); + SKIP(return, "Kernel does not support adding pages to initialized enclave"); + } + + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + EXPECT_EQ(eaccept_op.ret, 0); + + /* + * New page should be accessible from within enclave - attempt to + * write to it. + */ + put_addr_op.value = MAGIC; + put_addr_op.addr = (unsigned long)addr; + put_addr_op.header.type = ENCL_OP_PUT_TO_ADDRESS; + + EXPECT_EQ(ENCL_CALL(&put_addr_op, &self->run, true), 0); + + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + + /* + * Read memory from newly added page that was just written to, + * confirming that data previously written (MAGIC) is present. + */ + get_addr_op.value = 0; + get_addr_op.addr = (unsigned long)addr; + get_addr_op.header.type = ENCL_OP_GET_FROM_ADDRESS; + + EXPECT_EQ(ENCL_CALL(&get_addr_op, &self->run, true), 0); + + EXPECT_EQ(get_addr_op.value, MAGIC); + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + + munmap(addr, PAGE_SIZE); +} + TEST_HARNESS_MAIN

The Thread Control Structure (TCS) contains meta-data used by the hardware to save and restore thread specific information when entering/exiting the enclave. A TCS can be added to an initialized enclave by first adding a new regular enclave page, initializing the content of the new page from within the enclave, and then changing that page's type to a TCS.

Support the initialization of a TCS from within the enclave. The variable information needed that should be provided from outside the enclave is the address of the TCS, address of the State Save Area (SSA), and the entry point that the thread should use to enter the enclave. With this information provided all needed fields of a TCS can be initialized.

Acked-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Acked-by tag.

tools/testing/selftests/sgx/defines.h | 8 +++++++ tools/testing/selftests/sgx/test_encl.c | 30 +++++++++++++++++++++++++ 2 files changed, 38 insertions(+)

diff --git a/tools/testing/selftests/sgx/defines.h b/tools/testing/selftests/sgx/defines.h index b638eb98c80c..d8587c971941 100644 --- a/tools/testing/selftests/sgx/defines.h +++ b/tools/testing/selftests/sgx/defines.h @@ -26,6 +26,7 @@ enum encl_op_type { ENCL_OP_NOP, ENCL_OP_EACCEPT, ENCL_OP_EMODPE, + ENCL_OP_INIT_TCS_PAGE, ENCL_OP_MAX, };

@@ -68,4 +69,11 @@ struct encl_op_emodpe { uint64_t flags; };

+struct encl_op_init_tcs_page { + struct encl_op_header header; + uint64_t tcs_page; + uint64_t ssa; + uint64_t entry; +}; + #endif /* DEFINES_H */ diff --git a/tools/testing/selftests/sgx/test_encl.c b/tools/testing/selftests/sgx/test_encl.c index 5b6c65331527..c0d6397295e3 100644 --- a/tools/testing/selftests/sgx/test_encl.c +++ b/tools/testing/selftests/sgx/test_encl.c @@ -57,6 +57,35 @@ static void *memcpy(void *dest, const void *src, size_t n) return dest; }

+static void *memset(void *dest, int c, size_t n) +{ + size_t i; + + for (i = 0; i < n; i++) + ((char *)dest)[i] = c; + + return dest; +} + +static void do_encl_init_tcs_page(void *_op) +{ + struct encl_op_init_tcs_page *op = _op; + void *tcs = (void *)op->tcs_page; + uint32_t val_32; + + memset(tcs, 0, 16); /* STATE and FLAGS */ + memcpy(tcs + 16, &op->ssa, 8); /* OSSA */ + memset(tcs + 24, 0, 4); /* CSSA */ + val_32 = 1; + memcpy(tcs + 28, &val_32, 4); /* NSSA */ + memcpy(tcs + 32, &op->entry, 8); /* OENTRY */ + memset(tcs + 40, 0, 24); /* AEP, OFSBASE, OGSBASE */ + val_32 = 0xFFFFFFFF; + memcpy(tcs + 64, &val_32, 4); /* FSLIMIT */ + memcpy(tcs + 68, &val_32, 4); /* GSLIMIT */ + memset(tcs + 72, 0, 4024); /* Reserved */ +} + static void do_encl_op_put_to_buf(void *op) { struct encl_op_put_to_buf *op2 = op; @@ -100,6 +129,7 @@ void encl_body(void *rdi, void *rsi) do_encl_op_nop, do_encl_eaccept, do_encl_emodpe, + do_encl_init_tcs_page, };

struct encl_op_header *op = (struct encl_op_header *)rdi;

Removing a page from an initialized enclave involves three steps: first the user requests changing the page type to SGX_PAGE_TYPE_TRIM via an ioctl(), on success the ENCLU[EACCEPT] instruction needs to be run from within the enclave to accept the page removal, finally the user requests page removal to be completed via an ioctl(). Only after acceptance (ENCLU[EACCEPT]) from within the enclave can the kernel remove the page from a running enclave.

Test the behavior when the user's request to change the page type succeeds, but the ENCLU[EACCEPT] instruction is not run before the ioctl() requesting page removal is run. This should not be permitted.

Acked-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Acked-by tag. - Rename SGX_IOC_ENCLAVE_MODIFY_TYPE to SGX_IOC_ENCLAVE_MODIFY_TYPES. (Jarkko) - User provides just page type to SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl(), replacing secinfo. (Jarkko) - Let the SKIP() call involving SGX_IOC_ENCLAVE_MODIFY_TYPES span two lines to address checkpatch.pl warning triggered by new longer name.

Changes since V2: - Rename struct sgx_enclave_modt -> struct sgx_enclave_modify_type

Changes since V1: - Update to support ioctl() name change (SGX_IOC_PAGE_MODT -> SGX_IOC_ENCLAVE_MODIFY_TYPE) and provide secinfo as parameter instead of just page type (Jarkko). - Update test to reflect page removal ioctl() and struct name change: SGX_IOC_PAGE_REMOVE->SGX_IOC_ENCLAVE_REMOVE_PAGES, struct sgx_page_remove -> struct sgx_enclave_remove_pages (Jarkko). - Use ioctl() instead of ioctl in text (Dave).

tools/testing/selftests/sgx/main.c | 114 +++++++++++++++++++++++++++++ 1 file changed, 114 insertions(+)

diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c index a3f22b15a4f8..fc72b04ce2a8 100644 --- a/tools/testing/selftests/sgx/main.c +++ b/tools/testing/selftests/sgx/main.c @@ -1433,4 +1433,118 @@ TEST_F(enclave, tcs_create) munmap(addr, 3 * PAGE_SIZE); }

+/* + * Ensure sane behavior if user requests page removal, does not run + * EACCEPT from within enclave but still attempts to finalize page removal + * with the SGX_IOC_ENCLAVE_REMOVE_PAGES ioctl(). The latter should fail + * because the removal was not EACCEPTed from within the enclave. + */ +TEST_F(enclave, remove_added_page_no_eaccept) +{ + struct sgx_enclave_remove_pages remove_ioc; + struct encl_op_get_from_addr get_addr_op; + struct sgx_enclave_modify_type modt_ioc; + struct encl_op_put_to_addr put_addr_op; + unsigned long data_start; + int ret, errno_save; + + ASSERT_TRUE(setup_test_encl(ENCL_HEAP_SIZE_DEFAULT, &self->encl, _metadata)); + + memset(&self->run, 0, sizeof(self->run)); + self->run.tcs = self->encl.encl_base; + + /* + * Hardware (SGX2) and kernel support is needed for this test. Start + * with check that test has a chance of succeeding. + */ + memset(&modt_ioc, 0, sizeof(modt_ioc)); + ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_MODIFY_TYPES, &modt_ioc); + + if (ret == -1) { + if (errno == ENOTTY) + SKIP(return, + "Kernel does not support SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl()"); + else if (errno == ENODEV) + SKIP(return, "System does not support SGX2"); + } + + /* + * Invalid parameters were provided during sanity check, + * expect command to fail. + */ + EXPECT_EQ(ret, -1); + + /* + * Page that will be removed is the second data page in the .data + * segment. This forms part of the local encl_buffer within the + * enclave. + */ + data_start = self->encl.encl_base + + encl_get_data_offset(&self->encl) + PAGE_SIZE; + + /* + * Sanity check that page at @data_start is writable before + * removing it. + * + * Start by writing MAGIC to test page. + */ + put_addr_op.value = MAGIC; + put_addr_op.addr = data_start; + put_addr_op.header.type = ENCL_OP_PUT_TO_ADDRESS; + + EXPECT_EQ(ENCL_CALL(&put_addr_op, &self->run, true), 0); + + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + + /* + * Read memory that was just written to, confirming that data + * previously written (MAGIC) is present. + */ + get_addr_op.value = 0; + get_addr_op.addr = data_start; + get_addr_op.header.type = ENCL_OP_GET_FROM_ADDRESS; + + EXPECT_EQ(ENCL_CALL(&get_addr_op, &self->run, true), 0); + + EXPECT_EQ(get_addr_op.value, MAGIC); + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + + /* Start page removal by requesting change of page type to PT_TRIM */ + memset(&modt_ioc, 0, sizeof(modt_ioc)); + + modt_ioc.offset = encl_get_data_offset(&self->encl) + PAGE_SIZE; + modt_ioc.length = PAGE_SIZE; + modt_ioc.page_type = SGX_PAGE_TYPE_TRIM; + + ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_MODIFY_TYPES, &modt_ioc); + errno_save = ret == -1 ? errno : 0; + + EXPECT_EQ(ret, 0); + EXPECT_EQ(errno_save, 0); + EXPECT_EQ(modt_ioc.result, 0); + EXPECT_EQ(modt_ioc.count, 4096); + + /* Skip EACCEPT */ + + /* Send final ioctl() to complete page removal */ + memset(&remove_ioc, 0, sizeof(remove_ioc)); + + remove_ioc.offset = encl_get_data_offset(&self->encl) + PAGE_SIZE; + remove_ioc.length = PAGE_SIZE; + + ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_REMOVE_PAGES, &remove_ioc); + errno_save = ret == -1 ? errno : 0; + + /* Operation not permitted since EACCEPT was omitted. */ + EXPECT_EQ(ret, -1); + EXPECT_EQ(errno_save, EPERM); + EXPECT_EQ(remove_ioc.count, 0); +} + TEST_HARNESS_MAIN

Removing a page from an initialized enclave involves three steps: (1) the user requests changing the page type to PT_TRIM via the SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl() (2) on success the ENCLU[EACCEPT] instruction is run from within the enclave to accept the page removal (3) the user initiates the actual removal of the page via the SGX_IOC_ENCLAVE_REMOVE_PAGES ioctl().

Remove a page that has never been accessed. This means that when the first ioctl() requesting page removal arrives, there will be no page table entry, yet a valid page table entry needs to exist for the ENCLU[EACCEPT] function to succeed. In this test it is verified that a page table entry can still be installed for a page that is in the process of being removed.

Suggested-by: Haitao Huang haitao.huang@intel.com Acked-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- Changes since V3: - Add Jarkko's Acked-by tag. - Rename SGX_IOC_ENCLAVE_MODIFY_TYPE to SGX_IOC_ENCLAVE_MODIFY_TYPES. (Jarkko) - User provides just page type to SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl(), replacing secinfo. (Jarkko) - Let the SKIP() call involving SGX_IOC_ENCLAVE_MODIFY_TYPES span two lines to address checkpatch.pl warning triggered by new longer name.

Changes since V2: - Rename struct sgx_enclave_modt -> struct sgx_enclave_modify_type

Changes since V1: - Update to support ioctl() name change (SGX_IOC_PAGE_MODT -> SGX_IOC_ENCLAVE_MODIFY_TYPE) and provide secinfo as parameter instead of just page type (Jarkko). - Update test to reflect page removal ioctl() and struct name change: SGX_IOC_PAGE_REMOVE->SGX_IOC_ENCLAVE_REMOVE_PAGES, struct sgx_page_remove -> struct sgx_enclave_remove_pages (Jarkko). - Ensure test is skipped when SGX2 not supported by kernel.

tools/testing/selftests/sgx/main.c | 80 ++++++++++++++++++++++++++++++ 1 file changed, 80 insertions(+)

diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c index ba1c6c4b5ff2..d49fce1a8df9 100644 --- a/tools/testing/selftests/sgx/main.c +++ b/tools/testing/selftests/sgx/main.c @@ -1790,4 +1790,84 @@ TEST_F(enclave, remove_added_page_invalid_access_after_eaccept) EXPECT_EQ(self->run.exception_addr, data_start); }

+TEST_F(enclave, remove_untouched_page) +{ + struct sgx_enclave_remove_pages remove_ioc; + struct sgx_enclave_modify_type modt_ioc; + struct encl_op_eaccept eaccept_op; + unsigned long data_start; + int ret, errno_save; + + ASSERT_TRUE(setup_test_encl(ENCL_HEAP_SIZE_DEFAULT, &self->encl, _metadata)); + + /* + * Hardware (SGX2) and kernel support is needed for this test. Start + * with check that test has a chance of succeeding. + */ + memset(&modt_ioc, 0, sizeof(modt_ioc)); + ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_MODIFY_TYPES, &modt_ioc); + + if (ret == -1) { + if (errno == ENOTTY) + SKIP(return, + "Kernel does not support SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl()"); + else if (errno == ENODEV) + SKIP(return, "System does not support SGX2"); + } + + /* + * Invalid parameters were provided during sanity check, + * expect command to fail. + */ + EXPECT_EQ(ret, -1); + + /* SGX2 is supported by kernel and hardware, test can proceed. */ + memset(&self->run, 0, sizeof(self->run)); + self->run.tcs = self->encl.encl_base; + + data_start = self->encl.encl_base + + encl_get_data_offset(&self->encl) + PAGE_SIZE; + + memset(&modt_ioc, 0, sizeof(modt_ioc)); + + modt_ioc.offset = encl_get_data_offset(&self->encl) + PAGE_SIZE; + modt_ioc.length = PAGE_SIZE; + modt_ioc.page_type = SGX_PAGE_TYPE_TRIM; + ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_MODIFY_TYPES, &modt_ioc); + errno_save = ret == -1 ? errno : 0; + + EXPECT_EQ(ret, 0); + EXPECT_EQ(errno_save, 0); + EXPECT_EQ(modt_ioc.result, 0); + EXPECT_EQ(modt_ioc.count, 4096); + + /* + * Enter enclave via TCS #1 and approve page removal by sending + * EACCEPT for removed page. + */ + + eaccept_op.epc_addr = data_start; + eaccept_op.flags = SGX_SECINFO_TRIM | SGX_SECINFO_MODIFIED; + eaccept_op.ret = 0; + eaccept_op.header.type = ENCL_OP_EACCEPT; + + EXPECT_EQ(ENCL_CALL(&eaccept_op, &self->run, true), 0); + EXPECT_EEXIT(&self->run); + EXPECT_EQ(self->run.exception_vector, 0); + EXPECT_EQ(self->run.exception_error_code, 0); + EXPECT_EQ(self->run.exception_addr, 0); + EXPECT_EQ(eaccept_op.ret, 0); + + memset(&remove_ioc, 0, sizeof(remove_ioc)); + + remove_ioc.offset = encl_get_data_offset(&self->encl) + PAGE_SIZE; + remove_ioc.length = PAGE_SIZE; + ret = ioctl(self->encl.fd, SGX_IOC_ENCLAVE_REMOVE_PAGES, &remove_ioc); + errno_save = ret == -1 ? errno : 0; + + EXPECT_EQ(ret, 0); + EXPECT_EQ(errno_save, 0); + EXPECT_EQ(remove_ioc.count, 4096); +} + TEST_HARNESS_MAIN