From: Jeff Xu jeffxu@google.com

This patchset proposes a new mseal() syscall for the Linux kernel.

Modern CPUs support memory permissions such as RW and NX bits. Linux has supported NX since the release of kernel version 2.6.8 in August 2004 [1]. The memory permission feature improves security stance on memory corruption bugs, i.e. the attacker can’t just write to arbitrary memory and point the code to it, the memory has to be marked with X bit, or else an exception will happen.

Memory sealing additionally protects the mapping itself against modifications. This is useful to mitigate memory corruption issues where a corrupted pointer is passed to a memory management syscall. For example, such an attacker primitive can break control-flow integrity guarantees since read-only memory that is supposed to be trusted can become writable or .text pages can get remapped. Memory sealing can automatically be applied by the runtime loader to seal .text and .rodata pages and applications can additionally seal security critical data at runtime. A similar feature already exists in the XNU kernel with the VM_FLAGS_PERMANENT [3] flag and on OpenBSD with the mimmutable syscall [4]. Also, Chrome wants to adopt this feature for their CFI work [2] and this patchset has been designed to be compatible with the Chrome use case.

The new mseal() is an architecture independent syscall, and with following signature:

mseal(void addr, size_t len, unsigned long types, unsigned long flags)

addr/len: memory range. Must be continuous/allocated memory, or else mseal() will fail and no VMA is updated. For details on acceptable arguments, please refer to comments in mseal.c. Those are also fully covered by the selftest.

types: bit mask to specify which syscall to seal.

Five syscalls can be sealed, as specified by bitmasks: MM_SEAL_MPROTECT: Deny mprotect(2)/pkey_mprotect(2). MM_SEAL_MUNMAP: Deny munmap(2). MM_SEAL_MMAP: Deny mmap(2). MM_SEAL_MREMAP: Deny mremap(2). MM_SEAL_MSEAL: Deny adding a new seal type.

Each bit represents sealing for one specific syscall type, e.g. MM_SEAL_MPROTECT will deny mprotect syscall. The consideration of bitmask is that the API is extendable, i.e. when needed, the sealing can be extended to madvise, mlock, etc. Backward compatibility is also easy.

The kernel will remember which seal types are applied, and the application doesn’t need to repeat all existing seal types in the next mseal(). Once a seal type is applied, it can’t be unsealed. Call mseal() on an existing seal type is a no-action, not a failure.

MM_SEAL_MSEAL will deny mseal() calls that try to add a new seal type.

Internally, vm_area_struct adds a new field vm_seals, to store the bit masks.

For the affected syscalls, such as mprotect, a check(can_modify_mm) for sealing is added, this usually happens at the early point of the syscall, before any update is made to VMAs. The effect of that is: if any of the VMAs in the given address range fails the sealing check, none of the VMA will be updated.

The idea that inspired this patch comes from Stephen Röttger’s work in V8 CFI [5], Chrome browser in ChromeOS will be the first user of this API.

In addition, Stephen is working on glibc change to add sealing support into the dynamic linker to seal all non-writable segments at startup. When that work is completed, all applications can automatically benefit from these new protections.

[1] https://kernelnewbies.org/Linux_2_6_8 [2] https://v8.dev/blog/control-flow-integrity [3] https://github.com/apple-oss-distributions/xnu/blob/1031c584a5e37aff177559b9... [4] https://man.openbsd.org/mimmutable.2 [5] https://docs.google.com/document/d/1O2jwK4dxI3nRcOJuPYkonhTkNQfbmwdvxQMyXgea...

Signed-off-by: Jeff Xu jeffxu@google.com --- include/linux/mm.h | 11 ++ include/linux/mm_types.h | 7 ++ include/linux/syscalls.h | 2 + include/uapi/linux/mman.h | 6 + kernel/sys_ni.c | 1 + mm/Kconfig | 8 ++ mm/Makefile | 1 + mm/mmap.c | 14 +++ mm/mseal.c | 230 ++++++++++++++++++++++++++++++++++++++ 9 files changed, 280 insertions(+) create mode 100644 mm/mseal.c

diff --git a/include/linux/mm.h b/include/linux/mm.h index 53efddc4d178..b511932df033 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -30,6 +30,7 @@ #include <linux/kasan.h> #include <linux/memremap.h> #include <linux/slab.h> +#include <uapi/linux/mman.h>

struct mempolicy; struct anon_vma; @@ -257,6 +258,16 @@ extern struct rw_semaphore nommu_region_sem; extern unsigned int kobjsize(const void *objp); #endif

+/* + * MM_SEAL_ALL is all supported flags in mseal(). + */ +#define MM_SEAL_ALL ( \ + MM_SEAL_MSEAL | \ + MM_SEAL_MPROTECT | \ + MM_SEAL_MUNMAP | \ + MM_SEAL_MMAP | \ + MM_SEAL_MREMAP) + /* * vm_flags in vm_area_struct, see mm_types.h. * When changing, update also include/trace/events/mmflags.h diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 36c5b43999e6..17d80f5a73dc 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -660,6 +660,13 @@ struct vm_area_struct { struct vma_numab_state *numab_state; /* NUMA Balancing state */ #endif struct vm_userfaultfd_ctx vm_userfaultfd_ctx; +#ifdef CONFIG_MSEAL + /* + * bit masks for seal. + * need this since vm_flags is full. + */ + unsigned long vm_seals; /* seal flags, see mm.h. */ +#endif } __randomize_layout;

#ifdef CONFIG_SCHED_MM_CID diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index c0cb22cd607d..dbc8d4f76646 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -802,6 +802,8 @@ asmlinkage long sys_process_mrelease(int pidfd, unsigned int flags); asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size, unsigned long prot, unsigned long pgoff, unsigned long flags); +asmlinkage long sys_mseal(unsigned long start, size_t len, unsigned long types, + unsigned long flags); asmlinkage long sys_mbind(unsigned long start, unsigned long len, unsigned long mode, const unsigned long __user *nmask, diff --git a/include/uapi/linux/mman.h b/include/uapi/linux/mman.h index a246e11988d5..5ed4072cf4a6 100644 --- a/include/uapi/linux/mman.h +++ b/include/uapi/linux/mman.h @@ -55,4 +55,10 @@ struct cachestat { __u64 nr_recently_evicted; };

+#define MM_SEAL_MSEAL _BITUL(0) +#define MM_SEAL_MPROTECT _BITUL(1) +#define MM_SEAL_MUNMAP _BITUL(2) +#define MM_SEAL_MMAP _BITUL(3) +#define MM_SEAL_MREMAP _BITUL(4) + #endif /* _UAPI_LINUX_MMAN_H */ diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index 781de7cc6a4e..06fabf379e33 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -192,6 +192,7 @@ COND_SYSCALL(migrate_pages); COND_SYSCALL(move_pages); COND_SYSCALL(set_mempolicy_home_node); COND_SYSCALL(cachestat); +COND_SYSCALL(mseal);

COND_SYSCALL(perf_event_open); COND_SYSCALL(accept4); diff --git a/mm/Kconfig b/mm/Kconfig index 264a2df5ecf5..db8a567cb4d3 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -1258,6 +1258,14 @@ config LOCK_MM_AND_FIND_VMA bool depends on !STACK_GROWSUP

+config MSEAL + default n + bool "Enable mseal() system call" + depends on MMU + help + Enable the mseal() system call. Make memory areas's metadata immutable + by selected system calls, i.e. mprotect(), munmap(), mremap(), mmap(). + source "mm/damon/Kconfig"

endmenu diff --git a/mm/Makefile b/mm/Makefile index ec65984e2ade..643d8518dac0 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -120,6 +120,7 @@ obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o obj-$(CONFIG_PAGE_TABLE_CHECK) += page_table_check.o obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o obj-$(CONFIG_SECRETMEM) += secretmem.o +obj-$(CONFIG_MSEAL) += mseal.o obj-$(CONFIG_CMA_SYSFS) += cma_sysfs.o obj-$(CONFIG_USERFAULTFD) += userfaultfd.o obj-$(CONFIG_IDLE_PAGE_TRACKING) += page_idle.o diff --git a/mm/mmap.c b/mm/mmap.c index 514ced13c65c..414ac31aa9fa 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -730,6 +730,20 @@ static inline bool is_mergeable_vma(struct vm_area_struct *vma, return false; if (!anon_vma_name_eq(anon_vma_name(vma), anon_name)) return false; +#ifdef CONFIG_MSEAL + /* + * If a VMA is sealed, it won't be merged with another VMA. + * This might be useful for diagnosis, i.e. the boundary used + * in the mseal() call will be preserved. + * There are chances of too many mseal() calls can create + * many segmentations. Considering mseal() usually comes + * with a careful memory layout design by the application, + * this might not be an issue in real world. + * Though, we could add merging support later if needed. + */ + if (vma->vm_seals & MM_SEAL_ALL) + return 0; +#endif return true; }

diff --git a/mm/mseal.c b/mm/mseal.c new file mode 100644 index 000000000000..ffe4c4c3f1bc --- /dev/null +++ b/mm/mseal.c @@ -0,0 +1,230 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Implement mseal() syscall. + * + * Copyright (c) 2023 Google, Inc. + * + * Author: Jeff Xu jeffxu@google.com + */ + +#include <linux/mman.h> +#include <linux/mm.h> +#include <linux/syscalls.h> +#include <linux/sched.h> +#include "internal.h" + +static bool can_do_mseal(unsigned long types, unsigned long flags) +{ + /* check types is a valid bitmap */ + if (types & ~MM_SEAL_ALL) + return false; + + /* flags isn't used for now */ + if (flags) + return false; + + return true; +} + +/* + * Check if a seal type can be added to VMA. + */ +static bool can_add_vma_seals(struct vm_area_struct *vma, unsigned long newSeals) +{ + /* When SEAL_MSEAL is set, reject if a new type of seal is added */ + if ((vma->vm_seals & MM_SEAL_MSEAL) && + (newSeals & ~(vma->vm_seals & MM_SEAL_ALL))) + return false; + + return true; +} + +static int mseal_fixup(struct vma_iterator *vmi, struct vm_area_struct *vma, + struct vm_area_struct **prev, unsigned long start, + unsigned long end, unsigned long addtypes) +{ + int ret = 0; + + if (addtypes & ~(vma->vm_seals & MM_SEAL_ALL)) { + /* + * Handle split at start and end. + * Note: sealed VMA doesn't merge with other VMAs. + */ + if (start != vma->vm_start) { + ret = split_vma(vmi, vma, start, 1); + if (ret) + goto out; + } + + if (end != vma->vm_end) { + ret = split_vma(vmi, vma, end, 0); + if (ret) + goto out; + } + + vma->vm_seals |= addtypes; + } + +out: + *prev = vma; + return ret; +} + +/* + * Check for do_mseal: + * 1> start is part of a valid vma. + * 2> end is part of a valid vma. + * 3> No gap (unallocated address) between start and end. + * 4> requested seal type can be added in given address range. + */ +static int check_mm_seal(unsigned long start, unsigned long end, + unsigned long newtypes) +{ + struct vm_area_struct *vma; + unsigned long nstart = start; + + VMA_ITERATOR(vmi, current->mm, start); + + /* going through each vma to check */ + for_each_vma_range(vmi, vma, end) { + if (vma->vm_start > nstart) + /* unallocated memory found */ + return -ENOMEM; + + if (!can_add_vma_seals(vma, newtypes)) + return -EACCES; + + if (vma->vm_end >= end) + return 0; + + nstart = vma->vm_end; + } + + return -ENOMEM; +} + +/* + * Apply sealing. + */ +static int apply_mm_seal(unsigned long start, unsigned long end, + unsigned long newtypes) +{ + unsigned long nstart, nend; + struct vm_area_struct *vma, *prev = NULL; + struct vma_iterator vmi; + int error = 0; + + vma_iter_init(&vmi, current->mm, start); + vma = vma_find(&vmi, end); + + prev = vma_prev(&vmi); + if (start > vma->vm_start) + prev = vma; + + nstart = start; + + /* going through each vma to update */ + for_each_vma_range(vmi, vma, end) { + nend = vma->vm_end; + if (nend > end) + nend = end; + + error = mseal_fixup(&vmi, vma, &prev, nstart, nend, newtypes); + if (error) + break; + + nstart = vma->vm_end; + } + + return error; +} + +/* + * mseal(2) seals the VM's meta data from + * selected syscalls. + * + * addr/len: VM address range. + * + * The address range by addr/len must meet: + * start (addr) must be in a valid VMA. + * end (addr + len) must be in a valid VMA. + * no gap (unallocated memory) between start and end. + * start (addr) must be page aligned. + * + * len: len will be page aligned implicitly. + * + * types: bit mask for sealed syscalls. + * MM_SEAL_MPROTECT: seal mprotect(2)/pkey_mprotect(2). + * MM_SEAL_MUNMAP: seal munmap(2). + * MM_SEAL_MMAP: seal mmap(2). + * MM_SEAL_MREMAP: seal mremap(2). + * MM_SEAL_MSEAL: adding new seal type will be rejected. + * + * flags: reserved. + * + * return values: + * zero: success + * -EINVAL: + * invalid seal type. + * invalid input flags. + * addr is not page aligned. + * addr + len overflow. + * -ENOMEM: + * addr is not a valid address (not allocated). + * end (addr + len) is not a valid address. + * a gap (unallocated memory) between start and end. + * -EACCES: + * MM_SEAL_MSEAL is set, adding a new seal is rejected. + * + * Note: + * user can call mseal(2) multiple times to add new seal types. + * adding an already added seal type is a no-action (no error). + * adding a new seal type after MM_SEAL_MSEAL will be rejected. + * unseal() or removing a seal type is not supported. + */ +static int do_mseal(unsigned long start, size_t len_in, unsigned long types, + unsigned long flags) +{ + int ret = 0; + unsigned long end; + struct mm_struct *mm = current->mm; + size_t len; + + if (!can_do_mseal(types, flags)) + return -EINVAL; + + start = untagged_addr(start); + if (!PAGE_ALIGNED(start)) + return -EINVAL; + + len = PAGE_ALIGN(len_in); + /* Check to see whether len was rounded up from small -ve to zero */ + if (len_in && !len) + return -EINVAL; + + end = start + len; + if (end < start) + return -EINVAL; + + if (end == start) + return 0; + + if (mmap_write_lock_killable(mm)) + return -EINTR; + + ret = check_mm_seal(start, end, types); + if (ret) + goto out; + + ret = apply_mm_seal(start, end, types); + +out: + mmap_write_unlock(current->mm); + return ret; +} + +SYSCALL_DEFINE4(mseal, unsigned long, start, size_t, len, unsigned long, types, unsigned long, + flags) +{ + return do_mseal(start, len, types, flags); +}

From: Jeff Xu jeffxu@google.com

Wire up mseal syscall for all architectures.

Signed-off-by: Jeff Xu jeffxu@google.com --- arch/alpha/kernel/syscalls/syscall.tbl | 1 + arch/arm/tools/syscall.tbl | 1 + arch/arm64/include/asm/unistd.h | 2 +- arch/arm64/include/asm/unistd32.h | 2 ++ arch/ia64/kernel/syscalls/syscall.tbl | 1 + arch/m68k/kernel/syscalls/syscall.tbl | 1 + arch/microblaze/kernel/syscalls/syscall.tbl | 1 + arch/mips/kernel/syscalls/syscall_n32.tbl | 1 + arch/mips/kernel/syscalls/syscall_n64.tbl | 1 + arch/mips/kernel/syscalls/syscall_o32.tbl | 1 + arch/parisc/kernel/syscalls/syscall.tbl | 1 + arch/powerpc/kernel/syscalls/syscall.tbl | 1 + arch/s390/kernel/syscalls/syscall.tbl | 1 + arch/sh/kernel/syscalls/syscall.tbl | 1 + arch/sparc/kernel/syscalls/syscall.tbl | 1 + arch/x86/entry/syscalls/syscall_32.tbl | 1 + arch/x86/entry/syscalls/syscall_64.tbl | 1 + arch/xtensa/kernel/syscalls/syscall.tbl | 1 + include/uapi/asm-generic/unistd.h | 5 ++++- 19 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl index ad37569d0507..b5847d53102a 100644 --- a/arch/alpha/kernel/syscalls/syscall.tbl +++ b/arch/alpha/kernel/syscalls/syscall.tbl @@ -492,3 +492,4 @@ 560 common set_mempolicy_home_node sys_ni_syscall 561 common cachestat sys_cachestat 562 common fchmodat2 sys_fchmodat2 +563 common mseal sys_mseal diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl index c572d6c3dee0..b50c5ca5047d 100644 --- a/arch/arm/tools/syscall.tbl +++ b/arch/arm/tools/syscall.tbl @@ -466,3 +466,4 @@ 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat 452 common fchmodat2 sys_fchmodat2 +453 common mseal sys_mseal diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h index bd77253b62e0..6a28fb91b85d 100644 --- a/arch/arm64/include/asm/unistd.h +++ b/arch/arm64/include/asm/unistd.h @@ -39,7 +39,7 @@ #define __ARM_NR_compat_set_tls (__ARM_NR_COMPAT_BASE + 5) #define __ARM_NR_COMPAT_END (__ARM_NR_COMPAT_BASE + 0x800)

-#define __NR_compat_syscalls 453 +#define __NR_compat_syscalls 454 #endif

#define __ARCH_WANT_SYS_CLONE diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h index 78b68311ec81..1e9b3c098a8e 100644 --- a/arch/arm64/include/asm/unistd32.h +++ b/arch/arm64/include/asm/unistd32.h @@ -911,6 +911,8 @@ __SYSCALL(__NR_set_mempolicy_home_node, sys_set_mempolicy_home_node) __SYSCALL(__NR_cachestat, sys_cachestat) #define __NR_fchmodat2 452 __SYSCALL(__NR_fchmodat2, sys_fchmodat2) +#define __NR_mseal 453 +__SYSCALL(__NR_mseal, sys_mseal)

/* * Please add new compat syscalls above this comment and update diff --git a/arch/ia64/kernel/syscalls/syscall.tbl b/arch/ia64/kernel/syscalls/syscall.tbl index 83d8609aec03..babe34d221ee 100644 --- a/arch/ia64/kernel/syscalls/syscall.tbl +++ b/arch/ia64/kernel/syscalls/syscall.tbl @@ -373,3 +373,4 @@ 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat 452 common fchmodat2 sys_fchmodat2 +453 common mseal sys_mseal diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl index 259ceb125367..27cd3f7dbd5e 100644 --- a/arch/m68k/kernel/syscalls/syscall.tbl +++ b/arch/m68k/kernel/syscalls/syscall.tbl @@ -452,3 +452,4 @@ 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat 452 common fchmodat2 sys_fchmodat2 +453 common mseal sys_mseal diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl index a3798c2637fd..e49861f7c61f 100644 --- a/arch/microblaze/kernel/syscalls/syscall.tbl +++ b/arch/microblaze/kernel/syscalls/syscall.tbl @@ -458,3 +458,4 @@ 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat 452 common fchmodat2 sys_fchmodat2 +453 common mseal sys_mseal diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl index 152034b8e0a0..78d15010cd77 100644 --- a/arch/mips/kernel/syscalls/syscall_n32.tbl +++ b/arch/mips/kernel/syscalls/syscall_n32.tbl @@ -391,3 +391,4 @@ 450 n32 set_mempolicy_home_node sys_set_mempolicy_home_node 451 n32 cachestat sys_cachestat 452 n32 fchmodat2 sys_fchmodat2 +453 n32 mseal sys_mseal diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl index cb5e757f6621..813614fedb72 100644 --- a/arch/mips/kernel/syscalls/syscall_n64.tbl +++ b/arch/mips/kernel/syscalls/syscall_n64.tbl @@ -367,3 +367,4 @@ 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 n64 cachestat sys_cachestat 452 n64 fchmodat2 sys_fchmodat2 +453 n64 mseal sys_mseal diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl index 1a646813afdc..01d88d3a6f3e 100644 --- a/arch/mips/kernel/syscalls/syscall_o32.tbl +++ b/arch/mips/kernel/syscalls/syscall_o32.tbl @@ -440,3 +440,4 @@ 450 o32 set_mempolicy_home_node sys_set_mempolicy_home_node 451 o32 cachestat sys_cachestat 452 o32 fchmodat2 sys_fchmodat2 +453 o32 mseal sys_mseal diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl index e97c175b56f9..d52d08f0a1ea 100644 --- a/arch/parisc/kernel/syscalls/syscall.tbl +++ b/arch/parisc/kernel/syscalls/syscall.tbl @@ -451,3 +451,4 @@ 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat 452 common fchmodat2 sys_fchmodat2 +453 common mseal sys_mseal diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl index 20e50586e8a2..d38deba73a7b 100644 --- a/arch/powerpc/kernel/syscalls/syscall.tbl +++ b/arch/powerpc/kernel/syscalls/syscall.tbl @@ -539,3 +539,4 @@ 450 nospu set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat 452 common fchmodat2 sys_fchmodat2 +453 common mseal sys_mseal diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl index 0122cc156952..cf3243c2978b 100644 --- a/arch/s390/kernel/syscalls/syscall.tbl +++ b/arch/s390/kernel/syscalls/syscall.tbl @@ -455,3 +455,4 @@ 450 common set_mempolicy_home_node sys_set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat sys_cachestat 452 common fchmodat2 sys_fchmodat2 sys_fchmodat2 +453 common mseal sys_mseal sys_mseal diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl index e90d585c4d3e..76f1cd33adaa 100644 --- a/arch/sh/kernel/syscalls/syscall.tbl +++ b/arch/sh/kernel/syscalls/syscall.tbl @@ -455,3 +455,4 @@ 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat 452 common fchmodat2 sys_fchmodat2 +453 common mseal sys_mseal diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl index 4ed06c71c43f..d7728695d780 100644 --- a/arch/sparc/kernel/syscalls/syscall.tbl +++ b/arch/sparc/kernel/syscalls/syscall.tbl @@ -498,3 +498,4 @@ 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat 452 common fchmodat2 sys_fchmodat2 +453 common mseal sys_mseal diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl index 2d0b1bd866ea..6d4cc386df22 100644 --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -457,3 +457,4 @@ 450 i386 set_mempolicy_home_node sys_set_mempolicy_home_node 451 i386 cachestat sys_cachestat 452 i386 fchmodat2 sys_fchmodat2 +453 i386 mseal sys_mseal diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index 814768249eae..73dcfc43d921 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -374,6 +374,7 @@ 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat 452 common fchmodat2 sys_fchmodat2 +453 common mseal sys_mseal

# # Due to a historical design error, certain syscalls are numbered differently diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl index fc1a4f3c81d9..e8fd3bf35d73 100644 --- a/arch/xtensa/kernel/syscalls/syscall.tbl +++ b/arch/xtensa/kernel/syscalls/syscall.tbl @@ -423,3 +423,4 @@ 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat 452 common fchmodat2 sys_fchmodat2 +453 common mseal sys_mseal diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index abe087c53b4b..0c945a798208 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -823,8 +823,11 @@ __SYSCALL(__NR_cachestat, sys_cachestat) #define __NR_fchmodat2 452 __SYSCALL(__NR_fchmodat2, sys_fchmodat2)

+#define __NR_mseal 453 +__SYSCALL(__NR_mseal, sys_mseal) + #undef __NR_syscalls -#define __NR_syscalls 453 +#define __NR_syscalls 454

/* * 32 bit systems traditionally used different

From: Jeff Xu jeffxu@google.com

mprotect(2) changes protection of VMAs in the given address range. Sealing will prevent unintended mprotect call.

What this patch does: When a mprotect(2) is invoked, if one of its VMAs has MM_SEAL_MPROTECT set from previous mseal(2) call, this mprotect(2) will fail, without any VMA modified.

This patch is based on following: 1. do_mprotect_pkey() currently called in two places: SYSCALL_DEFINE3(mprotect,...) SYSCALL_DEFINE4(pkey_mprotect, ...) and not in any other places, therefore omit changing the signature of do_mprotect_pkey(), i.e. not passing checkSeals flag.

2. In do_mprotect_pkey(), calls can_modify_mm() before any update is made on the VMAs.

Signed-off-by: Jeff Xu jeffxu@google.com --- mm/mprotect.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)

diff --git a/mm/mprotect.c b/mm/mprotect.c index 130db91d3a8c..6321c4d0aa3f 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -32,6 +32,7 @@ #include <linux/sched/sysctl.h> #include <linux/userfaultfd_k.h> #include <linux/memory-tiers.h> +#include <uapi/linux/mman.h> #include <asm/cacheflush.h> #include <asm/mmu_context.h> #include <asm/tlbflush.h> @@ -753,6 +754,20 @@ static int do_mprotect_pkey(unsigned long start, size_t len, } }

+ /* + * do_mprotect_pkey() currently called from two places: + * SYSCALL_DEFINE3(mprotect,...) + * SYSCALL_DEFINE4(pkey_mprotect, ...) + * and not from other places. + * Therefore, omit changing the signature of do_mprotect_pkey(). + * Otherwise, we might need to add checkSeals and pass it + * from all callers of do_mprotect_pkey(). + */ + if (!can_modify_mm(current->mm, start, end, MM_SEAL_MPROTECT)) { + error = -EACCES; + goto out; + } + prev = vma_prev(&vmi); if (start > vma->vm_start) prev = vma;

From: Jeff Xu jeffxu@google.com

selftest for sealing mprotect/munmap/mremap/mmap

Signed-off-by: Jeff Xu jeffxu@google.com --- tools/testing/selftests/mm/Makefile | 1 + tools/testing/selftests/mm/mseal_test.c | 1428 +++++++++++++++++++++++ 2 files changed, 1429 insertions(+) create mode 100644 tools/testing/selftests/mm/mseal_test.c

diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile index 6a9fc5693145..0c086cecc093 100644 --- a/tools/testing/selftests/mm/Makefile +++ b/tools/testing/selftests/mm/Makefile @@ -59,6 +59,7 @@ TEST_GEN_FILES += mlock2-tests TEST_GEN_FILES += mrelease_test TEST_GEN_FILES += mremap_dontunmap TEST_GEN_FILES += mremap_test +TEST_GEN_FILES += mseal_test TEST_GEN_FILES += on-fault-limit TEST_GEN_FILES += thuge-gen TEST_GEN_FILES += transhuge-stress diff --git a/tools/testing/selftests/mm/mseal_test.c b/tools/testing/selftests/mm/mseal_test.c new file mode 100644 index 000000000000..d6ae09729394 --- /dev/null +++ b/tools/testing/selftests/mm/mseal_test.c @@ -0,0 +1,1428 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include <sys/mman.h> +#include <stdint.h> +#include <unistd.h> +#include <string.h> +#include <sys/time.h> +#include <sys/resource.h> +#include <stdbool.h> +#include "../kselftest.h" +#include <syscall.h> +#include <errno.h> +#include <stdio.h> +#include <stdlib.h> +#include <assert.h> + +#ifndef MM_SEAL_MSEAL +#define MM_SEAL_MSEAL 0x1 +#endif + +#ifndef MM_SEAL_MPROTECT +#define MM_SEAL_MPROTECT 0x2 +#endif + +#ifndef MM_SEAL_MUNMAP +#define MM_SEAL_MUNMAP 0x4 +#endif + +#ifndef MM_SEAL_MMAP +#define MM_SEAL_MMAP 0x8 +#endif + +#ifndef MM_SEAL_MREMAP +#define MM_SEAL_MREMAP 0x10 +#endif + +#ifndef DEBUG +#define LOG_TEST_ENTER() {} +#else +#define LOG_TEST_ENTER() { printf("%s\n", __func__); } +#endif + +static int sys_mseal(void *start, size_t len, int types) +{ + int sret; + + errno = 0; + sret = syscall(__NR_mseal, start, len, types, 0); + return sret; +} + +int sys_mprotect(void *ptr, size_t size, unsigned long prot) +{ + int sret; + + errno = 0; + sret = syscall(SYS_mprotect, ptr, size, prot); + return sret; +} + +int sys_munmap(void *ptr, size_t size) +{ + int sret; + + errno = 0; + sret = syscall(SYS_munmap, ptr, size); + return sret; +} + +static int sys_madvise(void *start, size_t len, int types) +{ + int sret; + + errno = 0; + sret = syscall(__NR_madvise, start, len, types); + return sret; +} + +void *addr1 = (void *)0x50000000; +void *addr2 = (void *)0x50004000; +void *addr3 = (void *)0x50008000; +void setup_single_address(int size, void **ptrOut) +{ + void *ptr; + + ptr = mmap(NULL, size, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); + assert(ptr != (void *)-1); + *ptrOut = ptr; +} + +void setup_single_fixed_address(int size, void **ptrOut) +{ + void *ptr; + + ptr = mmap(addr1, size, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); + assert(ptr == (void *)addr1); + + *ptrOut = ptr; +} + +void clean_single_address(void *ptr, int size) +{ + int ret; + + ret = munmap(ptr, size); + assert(!ret); +} + +void seal_mprotect_single_address(void *ptr, int size) +{ + int ret; + + ret = sys_mseal(ptr, size, MM_SEAL_MPROTECT); + assert(!ret); +} + +static void test_seal_addseals(void) +{ + LOG_TEST_ENTER(); + int ret; + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + + setup_single_address(size, &ptr); + + /* adding seal one by one */ + ret = sys_mseal(ptr, size, MM_SEAL_MPROTECT); + assert(!ret); + + ret = sys_mseal(ptr, size, MM_SEAL_MMAP); + assert(!ret); + + ret = sys_mseal(ptr, size, MM_SEAL_MREMAP); + assert(!ret); + + ret = sys_mseal(ptr, size, MM_SEAL_MSEAL); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_addseals_combined(void) +{ + LOG_TEST_ENTER(); + int ret; + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + + setup_single_address(size, &ptr); + + ret = sys_mseal(ptr, size, MM_SEAL_MPROTECT); + assert(!ret); + + /* adding multiple seals */ + ret = sys_mseal(ptr, size, + MM_SEAL_MPROTECT | MM_SEAL_MMAP | MM_SEAL_MREMAP | + MM_SEAL_MSEAL); + assert(!ret); + + /* not adding more seal type, so ok. */ + ret = sys_mseal(ptr, size, + MM_SEAL_MMAP | MM_SEAL_MREMAP | MM_SEAL_MSEAL); + assert(!ret); + + /* not adding more seal type, so ok. */ + ret = sys_mseal(ptr, size, MM_SEAL_MSEAL); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_addseals_reject(void) +{ + LOG_TEST_ENTER(); + int ret; + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + + setup_single_address(size, &ptr); + + ret = sys_mseal(ptr, size, MM_SEAL_MPROTECT | MM_SEAL_MSEAL); + assert(!ret); + + ret = sys_mseal(ptr, size, MM_SEAL_MPROTECT); + assert(!ret); + + /* MM_SEAL_MSEAL is set, so not allow new seal type . */ + ret = sys_mseal(ptr, size, + MM_SEAL_MPROTECT | MM_SEAL_MMAP | MM_SEAL_MSEAL); + assert(ret < 0); + + ret = sys_mseal(ptr, size, MM_SEAL_MMAP); + assert(ret < 0); + + ret = sys_mseal(ptr, size, MM_SEAL_MMAP | MM_SEAL_MSEAL); + assert(ret < 0); + + clean_single_address(ptr, size); +} + +static void test_seal_unmapped_start(void) +{ + LOG_TEST_ENTER(); + int ret; + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + + setup_single_address(size, &ptr); + + // munmap 2 pages from ptr. + ret = sys_munmap(ptr, 2 * page_size); + assert(!ret); + + // mprotect will fail because 2 pages from ptr are unmapped. + ret = sys_mprotect(ptr, size, PROT_READ | PROT_WRITE); + assert(ret < 0); + + // mseal will fail because 2 pages from ptr are unmapped. + ret = sys_mseal(ptr, size, MM_SEAL_MSEAL); + assert(ret < 0); + + ret = sys_mseal(ptr + 2 * page_size, 2 * page_size, MM_SEAL_MSEAL); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_unmapped_middle(void) +{ + LOG_TEST_ENTER(); + int ret; + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + + setup_single_address(size, &ptr); + + // munmap 2 pages from ptr + page. + ret = sys_munmap(ptr + page_size, 2 * page_size); + assert(!ret); + + // mprotect will fail, since size is 4 pages. + ret = sys_mprotect(ptr, size, PROT_READ | PROT_WRITE); + assert(ret < 0); + + // mseal will fail as well. + ret = sys_mseal(ptr, size, MM_SEAL_MSEAL); + assert(ret < 0); + + /* we still can add seal to the first page and last page*/ + ret = sys_mseal(ptr, page_size, MM_SEAL_MSEAL | MM_SEAL_MPROTECT); + assert(!ret); + + ret = sys_mseal(ptr + 3 * page_size, page_size, + MM_SEAL_MSEAL | MM_SEAL_MPROTECT); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_unmapped_end(void) +{ + LOG_TEST_ENTER(); + int ret; + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + + setup_single_address(size, &ptr); + + // unmap last 2 pages. + ret = sys_munmap(ptr + 2 * page_size, 2 * page_size); + assert(!ret); + + //mprotect will fail since last 2 pages are unmapped. + ret = sys_mprotect(ptr, size, PROT_READ | PROT_WRITE); + assert(ret < 0); + + //mseal will fail as well. + ret = sys_mseal(ptr, size, MM_SEAL_MSEAL); + assert(ret < 0); + + /* The first 2 pages is not sealed, and can add seals */ + ret = sys_mseal(ptr, 2 * page_size, MM_SEAL_MSEAL | MM_SEAL_MPROTECT); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_multiple_vmas(void) +{ + LOG_TEST_ENTER(); + int ret; + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + + setup_single_address(size, &ptr); + + // use mprotect to split the vma into 3. + ret = sys_mprotect(ptr + page_size, 2 * page_size, + PROT_READ | PROT_WRITE); + assert(!ret); + + // mprotect will get applied to all 4 pages - 3 VMAs. + ret = sys_mprotect(ptr, size, PROT_READ); + assert(!ret); + + // use mprotect to split the vma into 3. + ret = sys_mprotect(ptr + page_size, 2 * page_size, + PROT_READ | PROT_WRITE); + assert(!ret); + + // mseal get applied to all 4 pages - 3 VMAs. + ret = sys_mseal(ptr, size, MM_SEAL_MSEAL); + assert(!ret); + + // verify additional seal type will fail after MM_SEAL_MSEAL set. + ret = sys_mseal(ptr, page_size, MM_SEAL_MSEAL | MM_SEAL_MPROTECT); + assert(ret < 0); + + ret = sys_mseal(ptr + page_size, 2 * page_size, + MM_SEAL_MSEAL | MM_SEAL_MPROTECT); + assert(ret < 0); + + ret = sys_mseal(ptr + 3 * page_size, page_size, + MM_SEAL_MSEAL | MM_SEAL_MPROTECT); + assert(ret < 0); + + clean_single_address(ptr, size); +} + +static void test_seal_split_start(void) +{ + LOG_TEST_ENTER(); + int ret; + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + + setup_single_address(size, &ptr); + + /* use mprotect to split at middle */ + ret = sys_mprotect(ptr, 2 * page_size, PROT_READ | PROT_WRITE); + assert(!ret); + + /* seal the first page, this will split the VMA */ + ret = sys_mseal(ptr, page_size, MM_SEAL_MSEAL); + assert(!ret); + + /* can't add seal to the first page */ + ret = sys_mseal(ptr, page_size, MM_SEAL_MSEAL | MM_SEAL_MPROTECT); + assert(ret < 0); + + /* add seal to the remain 3 pages */ + ret = sys_mseal(ptr + page_size, 3 * page_size, + MM_SEAL_MSEAL | MM_SEAL_MPROTECT); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_split_end(void) +{ + LOG_TEST_ENTER(); + int ret; + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + + setup_single_fixed_address(size, &ptr); + + /* use mprotect to split at middle */ + ret = sys_mprotect(ptr, 2 * page_size, PROT_READ | PROT_WRITE); + assert(!ret); + + /* seal the last page */ + ret = sys_mseal(ptr + 3 * page_size, page_size, MM_SEAL_MSEAL); + assert(!ret); + + /* adding seal to the last page is rejected. */ + ret = sys_mseal(ptr + 3 * page_size, page_size, + MM_SEAL_MSEAL | MM_SEAL_MPROTECT); + assert(ret < 0); + + /* Adding seals to the first 3 pages */ + ret = sys_mseal(ptr, 3 * page_size, MM_SEAL_MSEAL | MM_SEAL_MPROTECT); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_invalid_input(void) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_fixed_address(size, &ptr); + + /* invalid flag */ + ret = sys_mseal(ptr, size, 0x20); + assert(ret < 0); + + ret = sys_mseal(ptr, size, 0x31); + assert(ret < 0); + + ret = sys_mseal(ptr, size, 0x3F); + assert(ret < 0); + + /* unaligned address */ + ret = sys_mseal(ptr + 1, 2 * page_size, MM_SEAL_MSEAL); + assert(ret < 0); + + /* length too big */ + ret = sys_mseal(ptr, 5 * page_size, MM_SEAL_MSEAL); + assert(ret < 0); + + /* start is not in a valid VMA */ + ret = sys_mseal(ptr - page_size, 5 * page_size, MM_SEAL_MSEAL); + assert(ret < 0); + + clean_single_address(ptr, size); +} + +static void test_seal_zero_length(void) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + ret = sys_mprotect(ptr, 0, PROT_READ | PROT_WRITE); + assert(!ret); + + /* seal 0 length will be OK, same as mprotect */ + ret = sys_mseal(ptr, 0, MM_SEAL_MPROTECT); + assert(!ret); + + // verify the 4 pages are not sealed by previous call. + ret = sys_mprotect(ptr, size, PROT_READ | PROT_WRITE); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_twice(void) +{ + LOG_TEST_ENTER(); + int ret; + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + + setup_single_address(size, &ptr); + + ret = sys_mseal(ptr, size, MM_SEAL_MPROTECT); + assert(!ret); + + // apply the same seal will be OK. idempotent. + ret = sys_mseal(ptr, size, MM_SEAL_MPROTECT); + assert(!ret); + + ret = sys_mseal(ptr, size, + MM_SEAL_MPROTECT | MM_SEAL_MMAP | MM_SEAL_MREMAP | + MM_SEAL_MSEAL); + assert(!ret); + + ret = sys_mseal(ptr, size, + MM_SEAL_MPROTECT | MM_SEAL_MMAP | MM_SEAL_MREMAP | + MM_SEAL_MSEAL); + assert(!ret); + + ret = sys_mseal(ptr, size, MM_SEAL_MSEAL); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_mprotect(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + if (seal) + seal_mprotect_single_address(ptr, size); + + ret = sys_mprotect(ptr, size, PROT_READ | PROT_WRITE); + if (seal) + assert(ret < 0); + else + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_start_mprotect(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + if (seal) + seal_mprotect_single_address(ptr, page_size); + + // the first page is sealed. + ret = sys_mprotect(ptr, page_size, PROT_READ | PROT_WRITE); + if (seal) + assert(ret < 0); + else + assert(!ret); + + // pages after the first page is not sealed. + ret = sys_mprotect(ptr + page_size, page_size * 3, + PROT_READ | PROT_WRITE); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_end_mprotect(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + if (seal) + seal_mprotect_single_address(ptr + page_size, 3 * page_size); + + /* first page is not sealed */ + ret = sys_mprotect(ptr, page_size, PROT_READ | PROT_WRITE); + assert(!ret); + + /* last 3 page are sealed */ + ret = sys_mprotect(ptr + page_size, page_size * 3, + PROT_READ | PROT_WRITE); + if (seal) + assert(ret < 0); + else + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_mprotect_unalign_len(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + if (seal) + seal_mprotect_single_address(ptr, page_size * 2 - 1); + + // 2 pages are sealed. + ret = sys_mprotect(ptr, page_size * 2, PROT_READ | PROT_WRITE); + if (seal) + assert(ret < 0); + else + assert(!ret); + + ret = sys_mprotect(ptr + page_size * 2, page_size, + PROT_READ | PROT_WRITE); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_mprotect_unalign_len_variant_2(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + if (seal) + seal_mprotect_single_address(ptr, page_size * 2 + 1); + + // 3 pages are sealed. + ret = sys_mprotect(ptr, page_size * 3, PROT_READ | PROT_WRITE); + if (seal) + assert(ret < 0); + else + assert(!ret); + + ret = sys_mprotect(ptr + page_size * 3, page_size, + PROT_READ | PROT_WRITE); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_mprotect_two_vma(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + /* use mprotect to split */ + ret = sys_mprotect(ptr, page_size * 2, PROT_READ | PROT_WRITE); + assert(!ret); + + if (seal) + seal_mprotect_single_address(ptr, page_size * 4); + + ret = sys_mprotect(ptr, page_size * 2, PROT_READ | PROT_WRITE); + if (seal) + assert(ret < 0); + else + assert(!ret); + + ret = sys_mprotect(ptr + page_size * 2, page_size * 2, + PROT_READ | PROT_WRITE); + if (seal) + assert(ret < 0); + else + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_mprotect_two_vma_with_split(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + // use mprotect to split as two vma. + ret = sys_mprotect(ptr, page_size * 2, PROT_READ | PROT_WRITE); + assert(!ret); + + // mseal can apply across 2 vma, also split them. + if (seal) + seal_mprotect_single_address(ptr + page_size, page_size * 2); + + // the first page is not sealed. + ret = sys_mprotect(ptr, page_size, PROT_READ | PROT_WRITE); + assert(!ret); + + // the second page is sealed. + ret = sys_mprotect(ptr + page_size, page_size, PROT_READ | PROT_WRITE); + if (seal) + assert(ret < 0); + else + assert(!ret); + + // the third page is sealed. + ret = sys_mprotect(ptr + 2 * page_size, page_size, + PROT_READ | PROT_WRITE); + if (seal) + assert(ret < 0); + else + assert(!ret); + + // the fouth page is not sealed. + ret = sys_mprotect(ptr + 3 * page_size, page_size, + PROT_READ | PROT_WRITE); + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_mprotect_partial_mprotect(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + // seal one page. + if (seal) + seal_mprotect_single_address(ptr, page_size); + + // mprotect first 2 page will fail, since the first page are sealed. + ret = sys_mprotect(ptr, 2 * page_size, PROT_READ | PROT_WRITE); + if (seal) + assert(ret < 0); + else + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_mprotect_two_vma_with_gap(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + // use mprotect to split. + ret = sys_mprotect(ptr, page_size, PROT_READ | PROT_WRITE); + assert(!ret); + + // use mprotect to split. + ret = sys_mprotect(ptr + 3 * page_size, page_size, + PROT_READ | PROT_WRITE); + assert(!ret); + + // use munmap to free two pages in the middle + ret = sys_munmap(ptr + page_size, 2 * page_size); + assert(!ret); + + // mprotect will fail, because there is a gap in the address. + // notes, internally mprotect still updated the first page. + ret = sys_mprotect(ptr, 4 * page_size, PROT_READ); + assert(ret < 0); + + // mseal will fail as well. + ret = sys_mseal(ptr, 4 * page_size, MM_SEAL_MPROTECT); + assert(ret < 0); + + // unlike mprotect, the first page is not sealed. + ret = sys_mprotect(ptr, page_size, PROT_READ); + assert(ret == 0); + + // the last page is not sealed. + ret = sys_mprotect(ptr + 3 * page_size, page_size, PROT_READ); + assert(ret == 0); + + clean_single_address(ptr, size); +} + +static void test_seal_mprotect_split(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + //use mprotect to split. + ret = sys_mprotect(ptr, page_size, PROT_READ | PROT_WRITE); + assert(!ret); + + //seal all 4 pages. + if (seal) { + ret = sys_mseal(ptr, 4 * page_size, MM_SEAL_MPROTECT); + assert(!ret); + } + + //madvice is OK. + ret = sys_madvise(ptr, page_size * 2, MADV_WILLNEED); + assert(!ret); + + //mprotect is sealed. + ret = sys_mprotect(ptr, 2 * page_size, PROT_READ); + if (seal) + assert(ret < 0); + else + assert(!ret); + + + ret = sys_mprotect(ptr + 2 * page_size, 2 * page_size, PROT_READ); + if (seal) + assert(ret < 0); + else + assert(!ret); + + clean_single_address(ptr, size); +} + +static void test_seal_mprotect_merge(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + // use mprotect to split one page. + ret = sys_mprotect(ptr, page_size, PROT_READ | PROT_WRITE); + assert(!ret); + + // seal first two pages. + if (seal) { + ret = sys_mseal(ptr, 2 * page_size, MM_SEAL_MPROTECT); + assert(!ret); + } + + ret = sys_madvise(ptr, page_size, MADV_WILLNEED); + assert(!ret); + + // 2 pages are sealed. + ret = sys_mprotect(ptr, 2 * page_size, PROT_READ); + if (seal) + assert(ret < 0); + else + assert(!ret); + + // last 2 pages are not sealed. + ret = sys_mprotect(ptr + 2 * page_size, 2 * page_size, PROT_READ); + assert(ret == 0); + + clean_single_address(ptr, size); +} + +static void test_seal_munmap(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + if (seal) { + ret = sys_mseal(ptr, size, MM_SEAL_MUNMAP); + assert(!ret); + } + + // 4 pages are sealed. + ret = sys_munmap(ptr, size); + if (seal) + assert(ret < 0); + else + assert(!ret); +} + +/* + * allocate 4 pages, + * use mprotect to split it as two VMAs + * seal the whole range + * munmap will fail on both + */ +static void test_seal_munmap_two_vma(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + /* use mprotect to split */ + ret = sys_mprotect(ptr, page_size * 2, PROT_READ | PROT_WRITE); + assert(!ret); + + if (seal) { + ret = sys_mseal(ptr, size, MM_SEAL_MUNMAP); + assert(!ret); + } + + ret = sys_munmap(ptr, page_size * 2); + if (seal) + assert(ret < 0); + else + assert(!ret); + + ret = sys_munmap(ptr + page_size, page_size * 2); + if (seal) + assert(ret < 0); + else + assert(!ret); +} + +/* + * allocate a VMA with 4 pages. + * munmap the middle 2 pages. + * seal the whole 4 pages, will fail. + * note: one of the pages are sealed + * munmap the first page will be OK. + * munmap the last page will be OK. + */ +static void test_seal_munmap_vma_with_gap(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + ret = sys_munmap(ptr + page_size, page_size * 2); + assert(!ret); + + if (seal) { + // can't have gap in the middle. + ret = sys_mseal(ptr, size, MM_SEAL_MUNMAP); + assert(ret < 0); + } + + ret = sys_munmap(ptr, page_size); + assert(!ret); + + ret = sys_munmap(ptr + page_size * 2, page_size); + assert(!ret); + + ret = sys_munmap(ptr, size); + assert(!ret); +} + +static void test_munmap_start_freed(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + + // unmap the first page. + ret = sys_munmap(ptr, page_size); + assert(!ret); + + // seal the last 3 pages. + if (seal) { + ret = sys_mseal(ptr + page_size, 3 * page_size, MM_SEAL_MUNMAP); + assert(!ret); + } + + // unmap from the first page. + ret = sys_munmap(ptr, size); + if (seal) { + assert(ret < 0); + + // use mprotect to verify page is not unmapped. + ret = sys_mprotect(ptr + page_size, 3 * page_size, PROT_READ); + assert(!ret); + } else + // note: this will be OK, even the first page is + // already unmapped. + assert(!ret); +} + +static void test_munmap_end_freed(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + // unmap last page. + ret = sys_munmap(ptr + page_size * 3, page_size); + assert(!ret); + + // seal the first 3 pages. + if (seal) { + ret = sys_mseal(ptr, 3 * page_size, MM_SEAL_MUNMAP); + assert(!ret); + } + + // unmap all pages. + ret = sys_munmap(ptr, size); + if (seal) { + assert(ret < 0); + + // use mprotect to verify page is not unmapped. + ret = sys_mprotect(ptr, 3 * page_size, PROT_READ); + assert(!ret); + } else + assert(!ret); +} + +static void test_munmap_middle_freed(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + + setup_single_address(size, &ptr); + // unmap 2 pages in the middle. + ret = sys_munmap(ptr + page_size, page_size * 2); + assert(!ret); + + // seal the first page. + if (seal) { + ret = sys_mseal(ptr, page_size, MM_SEAL_MUNMAP); + assert(!ret); + } + + // munmap all 4 pages. + ret = sys_munmap(ptr, size); + if (seal) { + assert(ret < 0); + + // use mprotect to verify page is not unmapped. + ret = sys_mprotect(ptr, page_size, PROT_READ); + assert(!ret); + } else + assert(!ret); +} + +void test_seal_mremap_shrink(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + void *ret2; + + setup_single_address(size, &ptr); + + if (seal) { + ret = sys_mseal(ptr, size, MM_SEAL_MREMAP); + assert(!ret); + } + + // shrink from 4 pages to 2 pages. + ret2 = mremap(ptr, size, 2 * page_size, 0, 0); + if (seal) { + assert(ret2 == MAP_FAILED); + assert(errno == EACCES); + } else { + assert(ret2 != MAP_FAILED); + clean_single_address(ret2, 2 * page_size); + } + clean_single_address(ptr, size); +} + +void test_seal_mremap_expand(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + void *ret2; + + setup_single_address(size, &ptr); + // ummap last 2 pages. + ret = sys_munmap(ptr + 2 * page_size, 2 * page_size); + assert(!ret); + + if (seal) { + ret = sys_mseal(ptr, 2 * page_size, MM_SEAL_MREMAP); + assert(!ret); + } + + // expand from 2 page to 4 pages. + ret2 = mremap(ptr, 2 * page_size, 4 * page_size, 0, 0); + if (seal) { + assert(ret2 == MAP_FAILED); + assert(errno == EACCES); + } else { + assert(ret2 == ptr); + clean_single_address(ret2, 4 * page_size); + } + clean_single_address(ptr, size); +} + +void test_seal_mremap_move(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = page_size; + int ret; + void *ret2; + + setup_single_address(size, &ptr); + if (seal) { + ret = sys_mseal(ptr, size, MM_SEAL_MREMAP); + assert(!ret); + } + + // move from ptr to fixed address. + ret2 = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, addr1); + if (seal) { + assert(ret2 == MAP_FAILED); + assert(errno == EACCES); + } else { + assert(ret2 != MAP_FAILED); + clean_single_address(ret2, size); + } + clean_single_address(ptr, size); +} + +void test_seal_mmap_overwrite_prot(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + unsigned long page_size = getpagesize(); + unsigned long size = page_size; + int ret; + void *ret2; + + setup_single_address(size, &ptr); + + if (seal) { + ret = sys_mseal(ptr, size, MM_SEAL_MMAP); + assert(!ret); + } + + // use mmap to change protection. + ret2 = mmap(ptr, size, PROT_NONE, + MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0); + if (seal) { + assert(ret2 == MAP_FAILED); + assert(errno == EACCES); + } else + assert(ret2 == ptr); + + clean_single_address(ptr, size); +} + +void test_seal_mremap_shrink_fixed(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + void *newAddr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + void *ret2; + + setup_single_address(size, &ptr); + setup_single_fixed_address(size, &newAddr); + + if (seal) { + ret = sys_mseal(ptr, size, MM_SEAL_MREMAP); + assert(!ret); + } + + // mremap to move and shrink to fixed address + ret2 = mremap(ptr, size, 2 * page_size, MREMAP_MAYMOVE | MREMAP_FIXED, + newAddr); + if (seal) { + assert(ret2 == MAP_FAILED); + assert(errno == EACCES); + } else + assert(ret2 == newAddr); + + clean_single_address(ptr, size); + clean_single_address(newAddr, size); +} + +void test_seal_mremap_expand_fixed(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + void *newAddr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + void *ret2; + + setup_single_address(page_size, &ptr); + setup_single_fixed_address(size, &newAddr); + + if (seal) { + ret = sys_mseal(newAddr, size, MM_SEAL_MREMAP); + assert(!ret); + } + + // mremap to move and expand to fixed address + ret2 = mremap(ptr, page_size, size, MREMAP_MAYMOVE | MREMAP_FIXED, + newAddr); + if (seal) { + assert(ret2 == MAP_FAILED); + assert(errno == EACCES); + } else + assert(ret2 == newAddr); + + clean_single_address(ptr, page_size); + clean_single_address(newAddr, size); +} + +void test_seal_mremap_move_fixed(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + void *newAddr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + void *ret2; + + setup_single_address(size, &ptr); + setup_single_fixed_address(size, &newAddr); + + if (seal) { + ret = sys_mseal(newAddr, size, MM_SEAL_MREMAP); + assert(!ret); + } + + // mremap to move to fixed address + ret2 = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, newAddr); + if (seal) { + assert(ret2 == MAP_FAILED); + assert(errno == EACCES); + } else + assert(ret2 == newAddr); + + clean_single_address(ptr, page_size); + clean_single_address(newAddr, size); +} + +void test_seal_mremap_move_fixed_zero(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + void *newAddr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + void *ret2; + + setup_single_address(size, &ptr); + + if (seal) { + ret = sys_mseal(ptr, size, MM_SEAL_MREMAP); + assert(!ret); + } + + /* + * MREMAP_FIXED can move the mapping to zero address + */ + ret2 = mremap(ptr, size, 2 * page_size, MREMAP_MAYMOVE | MREMAP_FIXED, + 0); + if (seal) { + assert(ret2 == MAP_FAILED); + assert(errno == EACCES); + } else { + assert(ret2 == 0); + clean_single_address(ret2, 2 * page_size); + } + clean_single_address(ptr, size); +} + +void test_seal_mremap_move_dontunmap(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + void *newAddr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + void *ret2; + + setup_single_address(size, &ptr); + + if (seal) { + ret = sys_mseal(ptr, size, MM_SEAL_MREMAP); + assert(!ret); + } + + // mremap to move, and don't unmap src addr. + ret2 = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_DONTUNMAP, 0); + if (seal) { + assert(ret2 == MAP_FAILED); + assert(errno == EACCES); + } else { + assert(ret2 != MAP_FAILED); + clean_single_address(ret2, size); + } + + clean_single_address(ptr, page_size); +} + +void test_seal_mremap_move_dontunmap_anyaddr(bool seal) +{ + LOG_TEST_ENTER(); + void *ptr; + void *newAddr; + unsigned long page_size = getpagesize(); + unsigned long size = 4 * page_size; + int ret; + void *ret2; + + setup_single_address(size, &ptr); + + if (seal) { + ret = sys_mseal(ptr, size, MM_SEAL_MREMAP); + assert(!ret); + } + + /* + * The 0xdeaddead should not have effect on dest addr + * when MREMAP_DONTUNMAP is set. + */ + ret2 = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_DONTUNMAP, + 0xdeaddead); + if (seal) { + assert(ret2 == MAP_FAILED); + assert(errno == EACCES); + } else { + assert(ret2 != MAP_FAILED); + assert((long)ret2 != 0xdeaddead); + clean_single_address(ret2, size); + } + + clean_single_address(ptr, page_size); +} + +int main(int argc, char **argv) +{ + test_seal_invalid_input(); + test_seal_addseals(); + test_seal_addseals_combined(); + test_seal_addseals_reject(); + test_seal_unmapped_start(); + test_seal_unmapped_middle(); + test_seal_unmapped_end(); + test_seal_multiple_vmas(); + test_seal_split_start(); + test_seal_split_end(); + + test_seal_zero_length(); + test_seal_twice(); + + test_seal_mprotect(false); + test_seal_mprotect(true); + + test_seal_start_mprotect(false); + test_seal_start_mprotect(true); + + test_seal_end_mprotect(false); + test_seal_end_mprotect(true); + + test_seal_mprotect_unalign_len(false); + test_seal_mprotect_unalign_len(true); + + test_seal_mprotect_unalign_len_variant_2(false); + test_seal_mprotect_unalign_len_variant_2(true); + + test_seal_mprotect_two_vma(false); + test_seal_mprotect_two_vma(true); + + test_seal_mprotect_two_vma_with_split(false); + test_seal_mprotect_two_vma_with_split(true); + + test_seal_mprotect_partial_mprotect(false); + test_seal_mprotect_partial_mprotect(true); + + test_seal_mprotect_two_vma_with_gap(false); + test_seal_mprotect_two_vma_with_gap(true); + + test_seal_mprotect_merge(false); + test_seal_mprotect_merge(true); + + test_seal_mprotect_split(false); + test_seal_mprotect_split(true); + + test_seal_munmap(false); + test_seal_munmap(true); + test_seal_munmap_two_vma(false); + test_seal_munmap_two_vma(true); + test_seal_munmap_vma_with_gap(false); + test_seal_munmap_vma_with_gap(true); + + test_munmap_start_freed(false); + test_munmap_start_freed(true); + test_munmap_middle_freed(false); + test_munmap_middle_freed(true); + test_munmap_end_freed(false); + test_munmap_end_freed(true); + + test_seal_mremap_shrink(false); + test_seal_mremap_shrink(true); + test_seal_mremap_expand(false); + test_seal_mremap_expand(true); + test_seal_mremap_move(false); + test_seal_mremap_move(true); + + test_seal_mremap_shrink_fixed(false); + test_seal_mremap_shrink_fixed(true); + test_seal_mremap_expand_fixed(false); + test_seal_mremap_expand_fixed(true); + test_seal_mremap_move_fixed(false); + test_seal_mremap_move_fixed(true); + test_seal_mremap_move_dontunmap(false); + test_seal_mremap_move_dontunmap(true); + test_seal_mremap_move_fixed_zero(false); + test_seal_mremap_move_fixed_zero(true); + test_seal_mremap_move_dontunmap_anyaddr(false); + test_seal_mremap_move_dontunmap_anyaddr(true); + + test_seal_mmap_overwrite_prot(false); + test_seal_mmap_overwrite_prot(true); + + printf("OK\n"); + return 0; +}