From: Roberto Sassu roberto.sassu@huawei.com
One of the desirable features in security is the ability to restrict import of data to a given system based on data authenticity. If data import can be restricted, it would be possible to enforce a system-wide policy based on the signing keys the system owner trusts.
This feature is widely used in the kernel. For example, if the restriction is enabled, kernel modules can be plugged in only if they are signed with a key whose public part is in the primary or secondary keyring.
For eBPF, it can be useful as well. For example, it might be useful to authenticate data an eBPF program makes security decisions on.
After a discussion in the eBPF mailing list, it was decided that the stated goal should be accomplished by introducing four new kfuncs: bpf_lookup_user_key() and bpf_lookup_system_key(), for retrieving a keyring with keys trusted for signature verification, respectively from its serial and from a pre-determined ID; bpf_key_put(), to release the reference obtained with the former two kfuncs, bpf_verify_pkcs7_signature(), for verifying PKCS#7 signatures.
Other than the key serial, bpf_lookup_user_key() also accepts key lookup flags, that influence the behavior of the lookup. bpf_lookup_system_key() accepts pre-determined IDs defined in include/linux/verification.h.
bpf_key_put() accepts the new bpf_key structure, introduced to tell whether the other structure member, a key pointer, is valid or not. The reason is that verify_pkcs7_signature() also accepts invalid pointers, set with the pre-determined ID, to select a system-defined keyring. key_put() must be called only for valid key pointers.
Since the two key lookup functions allocate memory and one increments a key reference count, they must be used in conjunction with bpf_key_put(). The latter must be called only if the lookup functions returned a non-NULL pointer. The verifier denies the execution of eBPF programs that don't respect this rule.
The two key lookup functions should be used in alternative, depending on the use case. While bpf_lookup_user_key() provides great flexibility, it seems suboptimal in terms of security guarantees, as even if the eBPF program is assumed to be trusted, the serial used to obtain the key pointer might come from untrusted user space not choosing one that the system administrator approves to enforce a mandatory policy.
bpf_lookup_system_key() instead provides much stronger guarantees, especially if the pre-determined ID is not passed by user space but is hardcoded in the eBPF program, and that program is signed. In this case, bpf_verify_pkcs7_signature() will always perform signature verification with a key that the system administrator approves, i.e. the primary, secondary or platform keyring.
Nevertheless, key permission checks need to be done accurately. Since bpf_lookup_user_key() cannot determine how a key will be used by other kfuncs, it has to defer the permission check to the actual kfunc using the key. It does it by calling lookup_user_key() with KEY_DEFER_PERM_CHECK as needed permission. Later, bpf_verify_pkcs7_signature(), if called, completes the permission check by calling key_validate(). It does not need to call key_task_permission() with permission KEY_NEED_SEARCH, as it is already done elsewhere by the key subsystem. Future kfuncs using the bpf_key structure need to implement the proper checks as well.
Finally, the last kfunc, bpf_verify_pkcs7_signature(), accepts the data and signature to verify as eBPF dynamic pointers, to minimize the number of kfunc parameters, and the keyring with keys for signature verification as a bpf_key structure, returned by one of the two key lookup functions.
bpf_lookup_user_key() and bpf_verify_pkcs7_signature() can be called only from sleepable programs, because of memory allocation and crypto operations. For example, the lsm.s/bpf attach point is suitable, fexit/array_map_update_elem is not.
The correctness of implementation of the new kfuncs and of their usage is checked with the introduced tests.
The patch set includes a patch from another author (dependency) for sake of completeness. It is organized as follows.
Patch 1 from KP Singh allows kfuncs to be used by LSM programs. Patch 2 allows dynamic pointers to be used as kfunc parameters. Patch 3 exports bpf_dynptr_get_size(), to obtain the real size of data carried by a dynamic pointer. Patch 4 makes available for new eBPF kfuncs some key-related definitions. Patch 5 introduces the bpf_lookup_*_key() and bpf_key_put() kfuncs. Patch 6 introduces the bpf_verify_pkcs7_signature() kfunc. Patch 7 changes the testing kernel configuration to compile everything as built-in. Finally, patches 8-10 introduce the tests.
Changelog
v12: - Blacklist lookup_key and verify_pkcs7_sig tests for s390x (JIT does not support calling kernel function)
v11: - Move stringify_struct() macro to include/linux/btf.h (suggested by Daniel) - Change kernel configuration options in tools/testing/selftests/bpf/config* from =m to =y
v10: - Introduce key_lookup_flags_check() and system_keyring_id_check() inline functions to check parameters (suggested by KP) - Fix descriptions and comment of key-related kfuncs (suggested by KP) - Register kfunc set only once (suggested by Alexei) - Move needed kernel options to the architecture-independent configuration for testing
v9: - Drop patch to introduce KF_SLEEPABLE kfunc flag (already merged) - Rename valid_ptr member of bpf_key to has_ref (suggested by Daniel) - Check dynamic pointers in kfunc definition with bpf_dynptr_kern struct definition instead of string, to detect structure renames (suggested by Daniel) - Explicitly say that we permit initialized dynamic pointers in kfunc definition (suggested by Daniel) - Remove noinline __weak from kfuncs definition (reported by Daniel) - Simplify key lookup flags check in bpf_lookup_user_key() (suggested by Daniel) - Explain the reason for deferring key permission check (suggested by Daniel) - Allocate memory with GFP_ATOMIC in bpf_lookup_system_key(), and remove KF_SLEEPABLE kfunc flag from kfunc declaration (suggested by Daniel) - Define only one kfunc set and remove the loop for registration (suggested by Alexei)
v8: - Define the new bpf_key structure to carry the key pointer and whether that pointer is valid or not (suggested by Daniel) - Drop patch to mark a kfunc parameter with the __maybe_null suffix - Improve documentation of kfuncs - Introduce bpf_lookup_system_key() to obtain a key pointer suitable for verify_pkcs7_signature() (suggested by Daniel) - Use the new kfunc registration API - Drop patch to test the __maybe_null suffix - Add tests for bpf_lookup_system_key()
v7: - Add support for using dynamic and NULL pointers in kfunc (suggested by Alexei) - Add new kfunc-related tests
v6: - Switch back to key lookup helpers + signature verification (until v5), and defer permission check from bpf_lookup_user_key() to bpf_verify_pkcs7_signature() - Add additional key lookup test to illustrate the usage of the KEY_LOOKUP_CREATE flag and validate the flags (suggested by Daniel) - Make description of flags of bpf_lookup_user_key() more user-friendly (suggested by Daniel) - Fix validation of flags parameter in bpf_lookup_user_key() (reported by Daniel) - Rename bpf_verify_pkcs7_signature() keyring-related parameters to user_keyring and system_keyring to make their purpose more clear - Accept keyring-related parameters of bpf_verify_pkcs7_signature() as alternatives (suggested by KP) - Replace unsigned long type with u64 in helper declaration (suggested by Daniel) - Extend the bpf_verify_pkcs7_signature() test by calling the helper without data, by ensuring that the helper enforces the keyring-related parameters as alternatives, by ensuring that the helper rejects inaccessible and expired keyrings, and by checking all system keyrings - Move bpf_lookup_user_key() and bpf_key_put() usage tests to ref_tracking.c (suggested by John) - Call bpf_lookup_user_key() and bpf_key_put() only in sleepable programs
v5: - Move KEY_LOOKUP_ to include/linux/key.h for validation of bpf_verify_pkcs7_signature() parameter - Remove bpf_lookup_user_key() and bpf_key_put() helpers, and the corresponding tests - Replace struct key parameter of bpf_verify_pkcs7_signature() with the keyring serial and lookup flags - Call lookup_user_key() and key_put() in bpf_verify_pkcs7_signature() code, to ensure that the retrieved key is used according to the permission requested at lookup time - Clarified keyring precedence in the description of bpf_verify_pkcs7_signature() (suggested by John) - Remove newline in the second argument of ASSERT_ - Fix helper prototype regular expression in bpf_doc.py
v4: - Remove bpf_request_key_by_id(), don't return an invalid pointer that other helpers can use - Pass the keyring ID (without ULONG_MAX, suggested by Alexei) to bpf_verify_pkcs7_signature() - Introduce bpf_lookup_user_key() and bpf_key_put() helpers (suggested by Alexei) - Add lookup_key_norelease test, to ensure that the verifier blocks eBPF programs which don't decrement the key reference count - Parse raw PKCS#7 signature instead of module-style signature in the verify_pkcs7_signature test (suggested by Alexei) - Parse kernel module in user space and pass raw PKCS#7 signature to the eBPF program for signature verification
v3: - Rename bpf_verify_signature() back to bpf_verify_pkcs7_signature() to avoid managing different parameters for each signature verification function in one helper (suggested by Daniel) - Use dynamic pointers and export bpf_dynptr_get_size() (suggested by Alexei) - Introduce bpf_request_key_by_id() to give more flexibility to the caller of bpf_verify_pkcs7_signature() to retrieve the appropriate keyring (suggested by Alexei) - Fix test by reordering the gcc command line, always compile sign-file - Improve helper support check mechanism in the test
v2: - Rename bpf_verify_pkcs7_signature() to a more generic bpf_verify_signature() and pass the signature type (suggested by KP) - Move the helper and prototype declaration under #ifdef so that user space can probe for support for the helper (suggested by Daniel) - Describe better the keyring types (suggested by Daniel) - Include linux/bpf.h instead of vmlinux.h to avoid implicit or redeclaration - Make the test selfcontained (suggested by Alexei)
v1: - Don't define new map flag but introduce simple wrapper of verify_pkcs7_signature() (suggested by Alexei and KP)
KP Singh (1): bpf: Allow kfuncs to be used in LSM programs
Roberto Sassu (9): btf: Handle dynamic pointer parameter in kfuncs bpf: Export bpf_dynptr_get_size() KEYS: Move KEY_LOOKUP_ to include/linux/key.h bpf: Add bpf_lookup_*_key() and bpf_key_put() kfuncs bpf: Add bpf_verify_pkcs7_signature() kfunc selftests/bpf: Compile kernel with everything as built-in selftests/bpf: Add verifier tests for bpf_lookup_*_key() and bpf_key_put() selftests/bpf: Add additional tests for bpf_lookup_*_key() selftests/bpf: Add test for bpf_verify_pkcs7_signature() kfunc
include/linux/bpf.h | 7 + include/linux/bpf_verifier.h | 3 + include/linux/btf.h | 9 + include/linux/key.h | 11 + include/linux/verification.h | 8 + kernel/bpf/btf.c | 19 + kernel/bpf/helpers.c | 2 +- kernel/bpf/verifier.c | 4 +- kernel/trace/bpf_trace.c | 180 ++++++++ security/keys/internal.h | 2 - tools/testing/selftests/bpf/DENYLIST.s390x | 2 + tools/testing/selftests/bpf/Makefile | 14 +- tools/testing/selftests/bpf/config | 32 +- tools/testing/selftests/bpf/config.x86_64 | 7 +- .../selftests/bpf/prog_tests/lookup_key.c | 112 +++++ .../bpf/prog_tests/verify_pkcs7_sig.c | 399 ++++++++++++++++++ .../selftests/bpf/progs/test_lookup_key.c | 46 ++ .../bpf/progs/test_verify_pkcs7_sig.c | 100 +++++ tools/testing/selftests/bpf/test_verifier.c | 3 +- .../selftests/bpf/verifier/ref_tracking.c | 139 ++++++ .../testing/selftests/bpf/verify_sig_setup.sh | 104 +++++ 21 files changed, 1175 insertions(+), 28 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/lookup_key.c create mode 100644 tools/testing/selftests/bpf/prog_tests/verify_pkcs7_sig.c create mode 100644 tools/testing/selftests/bpf/progs/test_lookup_key.c create mode 100644 tools/testing/selftests/bpf/progs/test_verify_pkcs7_sig.c create mode 100755 tools/testing/selftests/bpf/verify_sig_setup.sh
From: KP Singh kpsingh@kernel.org
In preparation for the addition of new kfuncs, allow kfuncs defined in the tracing subsystem to be used in LSM programs by mapping the LSM program type to the TRACING hook.
Signed-off-by: KP Singh kpsingh@kernel.org Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- kernel/bpf/btf.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 903719b89238..e49b3b6d48ad 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7243,6 +7243,7 @@ static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type) case BPF_PROG_TYPE_STRUCT_OPS: return BTF_KFUNC_HOOK_STRUCT_OPS; case BPF_PROG_TYPE_TRACING: + case BPF_PROG_TYPE_LSM: return BTF_KFUNC_HOOK_TRACING; case BPF_PROG_TYPE_SYSCALL: return BTF_KFUNC_HOOK_SYSCALL;
From: Roberto Sassu roberto.sassu@huawei.com
Allow the bpf_dynptr_kern parameter to be specified in kfuncs. Also, ensure that the dynamic pointer is valid and initialized.
To properly detect whether a parameter is of the desired type, introduce the stringify_struct() macro to compare the returned structure name with the desired name. In addition, protect against structure renames, by halting the build with BUILD_BUG_ON(), so that developers have to revisit the code.
Cc: Joanne Koong joannelkoong@gmail.com Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- include/linux/bpf_verifier.h | 3 +++ include/linux/btf.h | 9 +++++++++ kernel/bpf/btf.c | 18 ++++++++++++++++++ kernel/bpf/verifier.c | 4 ++-- 4 files changed, 32 insertions(+), 2 deletions(-)
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 2e3bad8640dc..55876fbdbae2 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -560,6 +560,9 @@ int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state u32 regno); int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno, u32 mem_size); +bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + enum bpf_arg_type arg_type);
/* this lives here instead of in bpf.h because it needs to dereference tgt_prog */ static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog, diff --git a/include/linux/btf.h b/include/linux/btf.h index ad93c2d9cc1c..f546d368ac5d 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -52,6 +52,15 @@ #define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ #define KF_DESTRUCTIVE (1 << 6) /* kfunc performs destructive actions */
+/* + * Return the name of the passed struct, if exists, or halt the build if for + * example the structure gets renamed. In this way, developers have to revisit + * the code using that structure name, and update it accordingly. + */ +#define stringify_struct(x) \ + ({ BUILD_BUG_ON(sizeof(struct x) < 0); \ + __stringify(x); }) + struct btf; struct btf_member; struct btf_type; diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index e49b3b6d48ad..26cb548420af 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6362,15 +6362,20 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env,
if (is_kfunc) { bool arg_mem_size = i + 1 < nargs && is_kfunc_arg_mem_size(btf, &args[i + 1], ®s[regno + 1]); + bool arg_dynptr = btf_type_is_struct(ref_t) && + !strcmp(ref_tname, + stringify_struct(bpf_dynptr_kern));
/* Permit pointer to mem, but only when argument * type is pointer to scalar, or struct composed * (recursively) of scalars. * When arg_mem_size is true, the pointer can be * void *. + * Also permit initialized dynamic pointers. */ if (!btf_type_is_scalar(ref_t) && !__btf_type_is_scalar_struct(log, btf, ref_t, 0) && + !arg_dynptr && (arg_mem_size ? !btf_type_is_void(ref_t) : 1)) { bpf_log(log, "arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n", @@ -6378,6 +6383,19 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, return -EINVAL; }
+ if (arg_dynptr) { + if (!is_dynptr_reg_valid_init(env, reg, + ARG_PTR_TO_DYNPTR)) { + bpf_log(log, + "arg#%d pointer type %s %s must be initialized\n", + i, btf_type_str(ref_t), + ref_tname); + return -EINVAL; + } + + continue; + } + /* Check for mem, len pair */ if (arg_mem_size) { if (check_kfunc_mem_size_reg(env, ®s[regno + 1], regno + 1)) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 2c1f8069f7b7..aa834e7bb296 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -779,8 +779,8 @@ static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_ return true; }
-static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg, - enum bpf_arg_type arg_type) +bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg, + enum bpf_arg_type arg_type) { struct bpf_func_state *state = func(env, reg); int spi = get_spi(reg->off);
On Tue, 23 Aug 2022 at 19:27, Roberto Sassu roberto.sassu@huaweicloud.com wrote:
From: Roberto Sassu roberto.sassu@huawei.com
Allow the bpf_dynptr_kern parameter to be specified in kfuncs. Also, ensure that the dynamic pointer is valid and initialized.
To properly detect whether a parameter is of the desired type, introduce the stringify_struct() macro to compare the returned structure name with the desired name. In addition, protect against structure renames, by halting the build with BUILD_BUG_ON(), so that developers have to revisit the code.
Cc: Joanne Koong joannelkoong@gmail.com Signed-off-by: Roberto Sassu roberto.sassu@huawei.com
include/linux/bpf_verifier.h | 3 +++ include/linux/btf.h | 9 +++++++++ kernel/bpf/btf.c | 18 ++++++++++++++++++ kernel/bpf/verifier.c | 4 ++-- 4 files changed, 32 insertions(+), 2 deletions(-)
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 2e3bad8640dc..55876fbdbae2 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -560,6 +560,9 @@ int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state u32 regno); int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno, u32 mem_size); +bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env,
struct bpf_reg_state *reg,enum bpf_arg_type arg_type);/* this lives here instead of in bpf.h because it needs to dereference tgt_prog */ static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog, diff --git a/include/linux/btf.h b/include/linux/btf.h index ad93c2d9cc1c..f546d368ac5d 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -52,6 +52,15 @@ #define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ #define KF_DESTRUCTIVE (1 << 6) /* kfunc performs destructive actions */
+/*
- Return the name of the passed struct, if exists, or halt the build if for
- example the structure gets renamed. In this way, developers have to revisit
- the code using that structure name, and update it accordingly.
- */
+#define stringify_struct(x) \
({ BUILD_BUG_ON(sizeof(struct x) < 0); \__stringify(x); })struct btf; struct btf_member; struct btf_type; diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index e49b3b6d48ad..26cb548420af 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6362,15 +6362,20 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env,
if (is_kfunc) { bool arg_mem_size = i + 1 < nargs && is_kfunc_arg_mem_size(btf, &args[i + 1], ®s[regno + 1]);
bool arg_dynptr = btf_type_is_struct(ref_t) &&!strcmp(ref_tname,stringify_struct(bpf_dynptr_kern)); /* Permit pointer to mem, but only when argument * type is pointer to scalar, or struct composed * (recursively) of scalars. * When arg_mem_size is true, the pointer can be * void *.* Also permit initialized dynamic pointers. */ if (!btf_type_is_scalar(ref_t) && !__btf_type_is_scalar_struct(log, btf, ref_t, 0) &&!arg_dynptr && (arg_mem_size ? !btf_type_is_void(ref_t) : 1)) { bpf_log(log, "arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n",@@ -6378,6 +6383,19 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, return -EINVAL; }
if (arg_dynptr) {if (!is_dynptr_reg_valid_init(env, reg,ARG_PTR_TO_DYNPTR)) {
Do you intend to really accept all kinds of dynptr here? In the future we will get more, and by default ARG_PTR_TO_DYNPTR accepts all, so it seems better to start with a small strict subset.
Secondly, you need to also check whether reg is a PTR_TO_STACK inside this arg_dynptr branch. It is incorrect to call is_dynptr_reg_valid_init for any other type of register. It would also be nice to include some tests for that.
bpf_log(log,"arg#%d pointer type %s %s must be initialized\n",i, btf_type_str(ref_t),ref_tname);return -EINVAL;}continue;}/* Check for mem, len pair */ if (arg_mem_size) { if (check_kfunc_mem_size_reg(env, ®s[regno + 1], regno + 1)) {diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 2c1f8069f7b7..aa834e7bb296 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -779,8 +779,8 @@ static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_ return true; }
-static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
enum bpf_arg_type arg_type)+bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
enum bpf_arg_type arg_type){ struct bpf_func_state *state = func(env, reg); int spi = get_spi(reg->off); -- 2.25.1
From: Roberto Sassu roberto.sassu@huawei.com
Export bpf_dynptr_get_size(), so that kernel code dealing with eBPF dynamic pointers can obtain the real size of data carried by this data structure.
Reviewed-by: Joanne Koong joannelkoong@gmail.com Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- include/linux/bpf.h | 1 + kernel/bpf/helpers.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 39bd36359c1e..6041304b402e 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2576,6 +2576,7 @@ void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data, enum bpf_dynptr_type type, u32 offset, u32 size); void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr); int bpf_dynptr_check_size(u32 size); +u32 bpf_dynptr_get_size(struct bpf_dynptr_kern *ptr);
#ifdef CONFIG_BPF_LSM void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype); diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 3c1b9bbcf971..e4637ccb3016 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1442,7 +1442,7 @@ static void bpf_dynptr_set_type(struct bpf_dynptr_kern *ptr, enum bpf_dynptr_typ ptr->size |= type << DYNPTR_TYPE_SHIFT; }
-static u32 bpf_dynptr_get_size(struct bpf_dynptr_kern *ptr) +u32 bpf_dynptr_get_size(struct bpf_dynptr_kern *ptr) { return ptr->size & DYNPTR_SIZE_MASK; }
On Tue, Aug 23, 2022 at 5:02 PM Roberto Sassu roberto.sassu@huaweicloud.com wrote:
From: Roberto Sassu roberto.sassu@huawei.com
Export bpf_dynptr_get_size(), so that kernel code dealing with eBPF dynamic pointers can obtain the real size of data carried by this data structure.
Reviewed-by: Joanne Koong joannelkoong@gmail.com Signed-off-by: Roberto Sassu roberto.sassu@huawei.com
Acked-by: KP Singh kpsingh@kernel.org
From: Roberto Sassu roberto.sassu@huawei.com
In preparation for the patch that introduces the bpf_lookup_user_key() eBPF kfunc, move KEY_LOOKUP_ definitions to include/linux/key.h, to be able to validate the kfunc parameters.
Also, introduce key_lookup_flags_check() directly in include/linux/key.h, to reduce the risk that the check is not in sync with currently defined flags.
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com Reviewed-by: KP Singh kpsingh@kernel.org --- include/linux/key.h | 11 +++++++++++ security/keys/internal.h | 2 -- 2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/include/linux/key.h b/include/linux/key.h index 7febc4881363..b5bbae77a9e7 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -88,6 +88,17 @@ enum key_need_perm { KEY_DEFER_PERM_CHECK, /* Special: permission check is deferred */ };
+#define KEY_LOOKUP_CREATE 0x01 +#define KEY_LOOKUP_PARTIAL 0x02 + +static inline int key_lookup_flags_check(u64 flags) +{ + if (flags & ~(KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL)) + return -EINVAL; + + return 0; +} + struct seq_file; struct user_struct; struct signal_struct; diff --git a/security/keys/internal.h b/security/keys/internal.h index 9b9cf3b6fcbb..3c1e7122076b 100644 --- a/security/keys/internal.h +++ b/security/keys/internal.h @@ -165,8 +165,6 @@ extern struct key *request_key_and_link(struct key_type *type,
extern bool lookup_user_key_possessed(const struct key *key, const struct key_match_data *match_data); -#define KEY_LOOKUP_CREATE 0x01 -#define KEY_LOOKUP_PARTIAL 0x02
extern long join_session_keyring(const char *name); extern void key_change_session_keyring(struct callback_head *twork);
From: Roberto Sassu roberto.sassu@huawei.com
Add the bpf_lookup_user_key(), bpf_lookup_system_key() and bpf_key_put() kfuncs, to respectively search a key with a given key handle serial number and flags, obtain a key from a pre-determined ID defined in include/linux/verification.h, and cleanup.
Introduce system_keyring_id_check() to validate the keyring ID parameter of bpf_lookup_system_key().
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- include/linux/bpf.h | 6 ++ include/linux/verification.h | 8 +++ kernel/trace/bpf_trace.c | 135 +++++++++++++++++++++++++++++++++++ 3 files changed, 149 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 6041304b402e..991da09a5858 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2586,4 +2586,10 @@ static inline void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype) {} static inline void bpf_cgroup_atype_put(int cgroup_atype) {} #endif /* CONFIG_BPF_LSM */
+#ifdef CONFIG_KEYS +struct bpf_key { + struct key *key; + bool has_ref; +}; +#endif /* CONFIG_KEYS */ #endif /* _LINUX_BPF_H */ diff --git a/include/linux/verification.h b/include/linux/verification.h index a655923335ae..f34e50ebcf60 100644 --- a/include/linux/verification.h +++ b/include/linux/verification.h @@ -17,6 +17,14 @@ #define VERIFY_USE_SECONDARY_KEYRING ((struct key *)1UL) #define VERIFY_USE_PLATFORM_KEYRING ((struct key *)2UL)
+static inline int system_keyring_id_check(u64 id) +{ + if (id > (unsigned long)VERIFY_USE_PLATFORM_KEYRING) + return -EINVAL; + + return 0; +} + /* * The use to which an asymmetric key is being put. */ diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 68e5cdd24cef..dfea85c7f4f0 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -20,6 +20,8 @@ #include <linux/fprobe.h> #include <linux/bsearch.h> #include <linux/sort.h> +#include <linux/key.h> +#include <linux/verification.h>
#include <net/bpf_sk_storage.h>
@@ -1181,6 +1183,139 @@ static const struct bpf_func_proto bpf_get_func_arg_cnt_proto = { .arg1_type = ARG_PTR_TO_CTX, };
+#ifdef CONFIG_KEYS +__diag_push(); +__diag_ignore_all("-Wmissing-prototypes", + "kfuncs which will be used in BPF programs"); + +/** + * bpf_lookup_user_key - lookup a key by its serial + * @serial: key handle serial number + * @flags: lookup-specific flags + * + * Search a key with a given *serial* and the provided *flags*. + * If found, increment the reference count of the key by one, and + * return it in the bpf_key structure. + * + * The bpf_key structure must be passed to bpf_key_put() when done + * with it, so that the key reference count is decremented and the + * bpf_key structure is freed. + * + * Permission checks are deferred to the time the key is used by + * one of the available key-specific kfuncs. + * + * Set *flags* with KEY_LOOKUP_CREATE, to attempt creating a requested + * special keyring (e.g. session keyring), if it doesn't yet exist. + * Set *flags* with KEY_LOOKUP_PARTIAL, to lookup a key without waiting + * for the key construction, and to retrieve uninstantiated keys (keys + * without data attached to them). + * + * Return: a bpf_key pointer with a valid key pointer if the key is found, a + * NULL pointer otherwise. + */ +struct bpf_key *bpf_lookup_user_key(u32 serial, u64 flags) +{ + key_ref_t key_ref; + struct bpf_key *bkey; + + if (key_lookup_flags_check(flags) < 0) + return NULL; + + /* + * Permission check is deferred until the key is used, as the + * intent of the caller is unknown here. + */ + key_ref = lookup_user_key(serial, flags, KEY_DEFER_PERM_CHECK); + if (IS_ERR(key_ref)) + return NULL; + + bkey = kmalloc(sizeof(*bkey), GFP_ATOMIC); + if (!bkey) { + key_put(key_ref_to_ptr(key_ref)); + return NULL; + } + + bkey->key = key_ref_to_ptr(key_ref); + bkey->has_ref = true; + + return bkey; +} + +/** + * bpf_lookup_system_key - lookup a key by a system-defined ID + * @id: key ID + * + * Obtain a bpf_key structure with a key pointer set to the passed key ID. + * The key pointer is marked as invalid, to prevent bpf_key_put() from + * attempting to decrement the key reference count on that pointer. The key + * pointer set in such way is currently understood only by + * verify_pkcs7_signature(). + * + * Set *id* to one of the values defined in include/linux/verification.h: + * 0 for the primary keyring (immutable keyring of system keys); + * VERIFY_USE_SECONDARY_KEYRING for both the primary and secondary keyring + * (where keys can be added only if they are vouched for by existing keys + * in those keyrings); VERIFY_USE_PLATFORM_KEYRING for the platform + * keyring (primarily used by the integrity subsystem to verify a kexec'ed + * kerned image and, possibly, the initramfs signature). + * + * Return: a bpf_key pointer with an invalid key pointer set from the + * pre-determined ID on success, a NULL pointer otherwise + */ +struct bpf_key *bpf_lookup_system_key(u64 id) +{ + struct bpf_key *bkey; + + if (system_keyring_id_check(id) < 0) + return NULL; + + bkey = kmalloc(sizeof(*bkey), GFP_ATOMIC); + if (!bkey) + return NULL; + + bkey->key = (struct key *)(unsigned long)id; + bkey->has_ref = false; + + return bkey; +} + +/** + * bpf_key_put - decrement key reference count if key is valid and free bpf_key + * @bkey: bpf_key structure + * + * Decrement the reference count of the key inside *bkey*, if the pointer + * is valid, and free *bkey*. + */ +void bpf_key_put(struct bpf_key *bkey) +{ + if (bkey->has_ref) + key_put(bkey->key); + + kfree(bkey); +} + +__diag_pop(); + +BTF_SET8_START(key_sig_kfunc_set) +BTF_ID_FLAGS(func, bpf_lookup_user_key, KF_ACQUIRE | KF_RET_NULL | KF_SLEEPABLE) +BTF_ID_FLAGS(func, bpf_lookup_system_key, KF_ACQUIRE | KF_RET_NULL) +BTF_ID_FLAGS(func, bpf_key_put, KF_RELEASE) +BTF_SET8_END(key_sig_kfunc_set) + +static const struct btf_kfunc_id_set bpf_key_sig_kfunc_set = { + .owner = THIS_MODULE, + .set = &key_sig_kfunc_set, +}; + +static int __init bpf_key_sig_kfuncs_init(void) +{ + return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, + &bpf_key_sig_kfunc_set); +} + +late_initcall(bpf_key_sig_kfuncs_init); +#endif /* CONFIG_KEYS */ + static const struct bpf_func_proto * bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) {
On Tue, Aug 23, 2022 at 8:02 AM Roberto Sassu roberto.sassu@huaweicloud.com wrote:
From: Roberto Sassu roberto.sassu@huawei.com
Add the bpf_lookup_user_key(), bpf_lookup_system_key() and bpf_key_put() kfuncs, to respectively search a key with a given key handle serial number and flags, obtain a key from a pre-determined ID defined in include/linux/verification.h, and cleanup.
Introduce system_keyring_id_check() to validate the keyring ID parameter of bpf_lookup_system_key().
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com
include/linux/bpf.h | 6 ++ include/linux/verification.h | 8 +++ kernel/trace/bpf_trace.c | 135 +++++++++++++++++++++++++++++++++++ 3 files changed, 149 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 6041304b402e..991da09a5858 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2586,4 +2586,10 @@ static inline void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype) {} static inline void bpf_cgroup_atype_put(int cgroup_atype) {} #endif /* CONFIG_BPF_LSM */
+#ifdef CONFIG_KEYS
Do we need to declare struct key here?
+struct bpf_key {
struct key *key;bool has_ref;+}; +#endif /* CONFIG_KEYS */ #endif /* _LINUX_BPF_H */
On Thu, 2022-08-25 at 22:56 -0700, Song Liu wrote:
On Tue, Aug 23, 2022 at 8:02 AM Roberto Sassu roberto.sassu@huaweicloud.com wrote:
From: Roberto Sassu roberto.sassu@huawei.com
Add the bpf_lookup_user_key(), bpf_lookup_system_key() and bpf_key_put() kfuncs, to respectively search a key with a given key handle serial number and flags, obtain a key from a pre-determined ID defined in include/linux/verification.h, and cleanup.
Introduce system_keyring_id_check() to validate the keyring ID parameter of bpf_lookup_system_key().
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com
include/linux/bpf.h | 6 ++ include/linux/verification.h | 8 +++ kernel/trace/bpf_trace.c | 135 +++++++++++++++++++++++++++++++++++ 3 files changed, 149 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 6041304b402e..991da09a5858 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2586,4 +2586,10 @@ static inline void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype) {} static inline void bpf_cgroup_atype_put(int cgroup_atype) {} #endif /* CONFIG_BPF_LSM */
+#ifdef CONFIG_KEYS
Do we need to declare struct key here?
+struct bpf_key {
struct key *key;bool has_ref;+}; +#endif /* CONFIG_KEYS */ #endif /* _LINUX_BPF_H */
If there is a better place, I will move there.
Thanks
Roberto
On Fri, Aug 26, 2022 at 12:22 AM Roberto Sassu roberto.sassu@huaweicloud.com wrote:
On Thu, 2022-08-25 at 22:56 -0700, Song Liu wrote:
On Tue, Aug 23, 2022 at 8:02 AM Roberto Sassu roberto.sassu@huaweicloud.com wrote:
From: Roberto Sassu roberto.sassu@huawei.com
Add the bpf_lookup_user_key(), bpf_lookup_system_key() and bpf_key_put() kfuncs, to respectively search a key with a given key handle serial number and flags, obtain a key from a pre-determined ID defined in include/linux/verification.h, and cleanup.
Introduce system_keyring_id_check() to validate the keyring ID parameter of bpf_lookup_system_key().
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com
include/linux/bpf.h | 6 ++ include/linux/verification.h | 8 +++ kernel/trace/bpf_trace.c | 135 +++++++++++++++++++++++++++++++++++ 3 files changed, 149 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 6041304b402e..991da09a5858 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2586,4 +2586,10 @@ static inline void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype) {} static inline void bpf_cgroup_atype_put(int cgroup_atype) {} #endif /* CONFIG_BPF_LSM */
+#ifdef CONFIG_KEYS
Do we need to declare struct key here?
+struct bpf_key {
struct key *key;bool has_ref;+}; +#endif /* CONFIG_KEYS */ #endif /* _LINUX_BPF_H */
If there is a better place, I will move there.
I guess you misunderstood. I meant we need
struct key;
struct bpf_key { struct key *key; bool has_ref; };
Otherwise, we may get some warning with certain config.
Thanks, Song
On Fri, 2022-08-26 at 00:25 -0700, Song Liu wrote:
On Fri, Aug 26, 2022 at 12:22 AM Roberto Sassu roberto.sassu@huaweicloud.com wrote:
On Thu, 2022-08-25 at 22:56 -0700, Song Liu wrote:
On Tue, Aug 23, 2022 at 8:02 AM Roberto Sassu roberto.sassu@huaweicloud.com wrote:
From: Roberto Sassu roberto.sassu@huawei.com
Add the bpf_lookup_user_key(), bpf_lookup_system_key() and bpf_key_put() kfuncs, to respectively search a key with a given key handle serial number and flags, obtain a key from a pre-determined ID defined in include/linux/verification.h, and cleanup.
Introduce system_keyring_id_check() to validate the keyring ID parameter of bpf_lookup_system_key().
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com
include/linux/bpf.h | 6 ++ include/linux/verification.h | 8 +++ kernel/trace/bpf_trace.c | 135 +++++++++++++++++++++++++++++++++++ 3 files changed, 149 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 6041304b402e..991da09a5858 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2586,4 +2586,10 @@ static inline void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype) {} static inline void bpf_cgroup_atype_put(int cgroup_atype) {} #endif /* CONFIG_BPF_LSM */
+#ifdef CONFIG_KEYS
Do we need to declare struct key here?
+struct bpf_key {
struct key *key;bool has_ref;+}; +#endif /* CONFIG_KEYS */ #endif /* _LINUX_BPF_H */
If there is a better place, I will move there.
I guess you misunderstood. I meant we need
struct key;
struct bpf_key { struct key *key; bool has_ref; };
Otherwise, we may get some warning with certain config.
Argh, thanks!
Will add it.
Roberto
From: Roberto Sassu roberto.sassu@huawei.com
Add the bpf_verify_pkcs7_signature() kfunc, to give eBPF security modules the ability to check the validity of a signature against supplied data, by using user-provided or system-provided keys as trust anchor.
The new kfunc makes it possible to enforce mandatory policies, as eBPF programs might be allowed to make security decisions only based on data sources the system administrator approves.
The caller should provide the data to be verified and the signature as eBPF dynamic pointers (to minimize the number of parameters) and a bpf_key structure containing a reference to the keyring with keys trusted for signature verification, obtained from bpf_lookup_user_key() or bpf_lookup_system_key().
For bpf_key structures obtained from the former lookup function, bpf_verify_pkcs7_signature() completes the permission check deferred by that function by calling key_validate(). key_task_permission() is already called by the PKCS#7 code.
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com Acked-by: KP Singh kpsingh@kernel.org --- kernel/trace/bpf_trace.c | 45 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index dfea85c7f4f0..b1fb985ba1b3 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1294,12 +1294,57 @@ void bpf_key_put(struct bpf_key *bkey) kfree(bkey); }
+#ifdef CONFIG_SYSTEM_DATA_VERIFICATION +/** + * bpf_verify_pkcs7_signature - verify a PKCS#7 signature + * @data_ptr: data to verify + * @sig_ptr: signature of the data + * @trusted_keyring: keyring with keys trusted for signature verification + * + * Verify the PKCS#7 signature *sig_ptr* against the supplied *data_ptr* + * with keys in a keyring referenced by *trusted_keyring*. + * + * Return: 0 on success, a negative value on error. + */ +int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr, + struct bpf_dynptr_kern *sig_ptr, + struct bpf_key *trusted_keyring) +{ + int ret; + + if (trusted_keyring->has_ref) { + /* + * Do the permission check deferred in bpf_lookup_user_key(). + * See bpf_lookup_user_key() for more details. + * + * A call to key_task_permission() here would be redundant, as + * it is already done by keyring_search() called by + * find_asymmetric_key(). + */ + ret = key_validate(trusted_keyring->key); + if (ret < 0) + return ret; + } + + return verify_pkcs7_signature(data_ptr->data, + bpf_dynptr_get_size(data_ptr), + sig_ptr->data, + bpf_dynptr_get_size(sig_ptr), + trusted_keyring->key, + VERIFYING_UNSPECIFIED_SIGNATURE, NULL, + NULL); +} +#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ + __diag_pop();
BTF_SET8_START(key_sig_kfunc_set) BTF_ID_FLAGS(func, bpf_lookup_user_key, KF_ACQUIRE | KF_RET_NULL | KF_SLEEPABLE) BTF_ID_FLAGS(func, bpf_lookup_system_key, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_key_put, KF_RELEASE) +#ifdef CONFIG_SYSTEM_DATA_VERIFICATION +BTF_ID_FLAGS(func, bpf_verify_pkcs7_signature, KF_SLEEPABLE) +#endif BTF_SET8_END(key_sig_kfunc_set)
static const struct btf_kfunc_id_set bpf_key_sig_kfunc_set = {
From: Roberto Sassu roberto.sassu@huawei.com
Since the eBPF CI does not support kernel modules, change the kernel config to compile everything as built-in.
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com Acked-by: Daniel Müller deso@posteo.net --- tools/testing/selftests/bpf/config | 26 +++++++++++------------ tools/testing/selftests/bpf/config.x86_64 | 2 +- 2 files changed, 14 insertions(+), 14 deletions(-)
diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config index 3fc46f9cfb22..0fdd11e6b742 100644 --- a/tools/testing/selftests/bpf/config +++ b/tools/testing/selftests/bpf/config @@ -7,9 +7,9 @@ CONFIG_BPF_LSM=y CONFIG_BPF_STREAM_PARSER=y CONFIG_BPF_SYSCALL=y CONFIG_CGROUP_BPF=y -CONFIG_CRYPTO_HMAC=m -CONFIG_CRYPTO_SHA256=m -CONFIG_CRYPTO_USER_API_HASH=m +CONFIG_CRYPTO_HMAC=y +CONFIG_CRYPTO_SHA256=y +CONFIG_CRYPTO_USER_API_HASH=y CONFIG_DYNAMIC_FTRACE=y CONFIG_FPROBE=y CONFIG_FTRACE_SYSCALLS=y @@ -24,30 +24,30 @@ CONFIG_IP_NF_FILTER=y CONFIG_IP_NF_RAW=y CONFIG_IP_NF_TARGET_SYNPROXY=y CONFIG_IPV6=y -CONFIG_IPV6_FOU=m -CONFIG_IPV6_FOU_TUNNEL=m +CONFIG_IPV6_FOU=y +CONFIG_IPV6_FOU_TUNNEL=y CONFIG_IPV6_GRE=y CONFIG_IPV6_SEG6_BPF=y -CONFIG_IPV6_SIT=m +CONFIG_IPV6_SIT=y CONFIG_IPV6_TUNNEL=y CONFIG_LIRC=y CONFIG_LWTUNNEL=y CONFIG_MPLS=y -CONFIG_MPLS_IPTUNNEL=m -CONFIG_MPLS_ROUTING=m +CONFIG_MPLS_IPTUNNEL=y +CONFIG_MPLS_ROUTING=y CONFIG_MPTCP=y CONFIG_NET_CLS_ACT=y CONFIG_NET_CLS_BPF=y -CONFIG_NET_CLS_FLOWER=m -CONFIG_NET_FOU=m +CONFIG_NET_CLS_FLOWER=y +CONFIG_NET_FOU=y CONFIG_NET_FOU_IP_TUNNELS=y CONFIG_NET_IPGRE=y CONFIG_NET_IPGRE_DEMUX=y CONFIG_NET_IPIP=y -CONFIG_NET_MPLS_GSO=m +CONFIG_NET_MPLS_GSO=y CONFIG_NET_SCH_INGRESS=y CONFIG_NET_SCHED=y -CONFIG_NETDEVSIM=m +CONFIG_NETDEVSIM=y CONFIG_NETFILTER=y CONFIG_NETFILTER_SYNPROXY=y CONFIG_NETFILTER_XT_CONNMARK=y @@ -60,7 +60,7 @@ CONFIG_NF_DEFRAG_IPV6=y CONFIG_RC_CORE=y CONFIG_SECURITY=y CONFIG_SECURITYFS=y -CONFIG_TEST_BPF=m +CONFIG_TEST_BPF=y CONFIG_USERFAULTFD=y CONFIG_VXLAN=y CONFIG_XDP_SOCKETS=y diff --git a/tools/testing/selftests/bpf/config.x86_64 b/tools/testing/selftests/bpf/config.x86_64 index f0859a1d37ab..ce70c9509204 100644 --- a/tools/testing/selftests/bpf/config.x86_64 +++ b/tools/testing/selftests/bpf/config.x86_64 @@ -47,7 +47,7 @@ CONFIG_CPU_IDLE_GOV_LADDER=y CONFIG_CPUSETS=y CONFIG_CRC_T10DIF=y CONFIG_CRYPTO_BLAKE2B=y -CONFIG_CRYPTO_DEV_VIRTIO=m +CONFIG_CRYPTO_DEV_VIRTIO=y CONFIG_CRYPTO_SEQIV=y CONFIG_CRYPTO_XXHASH=y CONFIG_DCB=y
From: Roberto Sassu roberto.sassu@huawei.com
Add verifier tests for bpf_lookup_*_key() and bpf_key_put(), to ensure that acquired key references stored in the bpf_key structure are released, that a non-NULL bpf_key pointer is passed to bpf_key_put(), and that key references are not leaked.
Also, slightly modify test_verifier.c, to find the BTF ID of the attach point for the LSM program type (currently, it is done only for TRACING).
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- tools/testing/selftests/bpf/config | 1 + tools/testing/selftests/bpf/test_verifier.c | 3 +- .../selftests/bpf/verifier/ref_tracking.c | 139 ++++++++++++++++++ 3 files changed, 142 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config index 0fdd11e6b742..add5a5a919b4 100644 --- a/tools/testing/selftests/bpf/config +++ b/tools/testing/selftests/bpf/config @@ -30,6 +30,7 @@ CONFIG_IPV6_GRE=y CONFIG_IPV6_SEG6_BPF=y CONFIG_IPV6_SIT=y CONFIG_IPV6_TUNNEL=y +CONFIG_KEYS=y CONFIG_LIRC=y CONFIG_LWTUNNEL=y CONFIG_MPLS=y diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index f9d553fbf68a..2dbcbf363c18 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -1498,7 +1498,8 @@ static void do_test_single(struct bpf_test *test, bool unpriv, opts.log_level = DEFAULT_LIBBPF_LOG_LEVEL; opts.prog_flags = pflags;
- if (prog_type == BPF_PROG_TYPE_TRACING && test->kfunc) { + if ((prog_type == BPF_PROG_TYPE_TRACING || + prog_type == BPF_PROG_TYPE_LSM) && test->kfunc) { int attach_btf_id;
attach_btf_id = libbpf_find_vmlinux_btf_id(test->kfunc, diff --git a/tools/testing/selftests/bpf/verifier/ref_tracking.c b/tools/testing/selftests/bpf/verifier/ref_tracking.c index 57a83d763ec1..f18ce867271f 100644 --- a/tools/testing/selftests/bpf/verifier/ref_tracking.c +++ b/tools/testing/selftests/bpf/verifier/ref_tracking.c @@ -84,6 +84,145 @@ .errstr = "Unreleased reference", .result = REJECT, }, +{ + "reference tracking: acquire/release user key reference", + .insns = { + BPF_MOV64_IMM(BPF_REG_1, -3), + BPF_MOV64_IMM(BPF_REG_2, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), + BPF_MOV64_REG(BPF_REG_1, BPF_REG_0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_LSM, + .kfunc = "bpf", + .expected_attach_type = BPF_LSM_MAC, + .flags = BPF_F_SLEEPABLE, + .fixup_kfunc_btf_id = { + { "bpf_lookup_user_key", 2 }, + { "bpf_key_put", 5 }, + }, + .result = ACCEPT, +}, +{ + "reference tracking: acquire/release system key reference", + .insns = { + BPF_MOV64_IMM(BPF_REG_1, 1), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), + BPF_MOV64_REG(BPF_REG_1, BPF_REG_0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_LSM, + .kfunc = "bpf", + .expected_attach_type = BPF_LSM_MAC, + .flags = BPF_F_SLEEPABLE, + .fixup_kfunc_btf_id = { + { "bpf_lookup_system_key", 1 }, + { "bpf_key_put", 4 }, + }, + .result = ACCEPT, +}, +{ + "reference tracking: release user key reference without check", + .insns = { + BPF_MOV64_IMM(BPF_REG_1, -3), + BPF_MOV64_IMM(BPF_REG_2, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0), + BPF_MOV64_REG(BPF_REG_1, BPF_REG_0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_LSM, + .kfunc = "bpf", + .expected_attach_type = BPF_LSM_MAC, + .flags = BPF_F_SLEEPABLE, + .errstr = "arg#0 pointer type STRUCT bpf_key must point to scalar, or struct with scalar", + .fixup_kfunc_btf_id = { + { "bpf_lookup_user_key", 2 }, + { "bpf_key_put", 4 }, + }, + .result = REJECT, +}, +{ + "reference tracking: release system key reference without check", + .insns = { + BPF_MOV64_IMM(BPF_REG_1, 1), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0), + BPF_MOV64_REG(BPF_REG_1, BPF_REG_0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_LSM, + .kfunc = "bpf", + .expected_attach_type = BPF_LSM_MAC, + .flags = BPF_F_SLEEPABLE, + .errstr = "arg#0 pointer type STRUCT bpf_key must point to scalar, or struct with scalar", + .fixup_kfunc_btf_id = { + { "bpf_lookup_system_key", 1 }, + { "bpf_key_put", 3 }, + }, + .result = REJECT, +}, +{ + "reference tracking: release with NULL key pointer", + .insns = { + BPF_MOV64_IMM(BPF_REG_1, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_LSM, + .kfunc = "bpf", + .expected_attach_type = BPF_LSM_MAC, + .flags = BPF_F_SLEEPABLE, + .errstr = "arg#0 pointer type STRUCT bpf_key must point to scalar, or struct with scalar", + .fixup_kfunc_btf_id = { + { "bpf_key_put", 1 }, + }, + .result = REJECT, +}, +{ + "reference tracking: leak potential reference to user key", + .insns = { + BPF_MOV64_IMM(BPF_REG_1, -3), + BPF_MOV64_IMM(BPF_REG_2, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_LSM, + .kfunc = "bpf", + .expected_attach_type = BPF_LSM_MAC, + .flags = BPF_F_SLEEPABLE, + .errstr = "Unreleased reference", + .fixup_kfunc_btf_id = { + { "bpf_lookup_user_key", 2 }, + }, + .result = REJECT, +}, +{ + "reference tracking: leak potential reference to system key", + .insns = { + BPF_MOV64_IMM(BPF_REG_1, 1), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_LSM, + .kfunc = "bpf", + .expected_attach_type = BPF_LSM_MAC, + .flags = BPF_F_SLEEPABLE, + .errstr = "Unreleased reference", + .fixup_kfunc_btf_id = { + { "bpf_lookup_system_key", 1 }, + }, + .result = REJECT, +}, { "reference tracking: release reference without check", .insns = {
From: Roberto Sassu roberto.sassu@huawei.com
Add a test to ensure that bpf_lookup_user_key() creates a referenced special keyring when the KEY_LOOKUP_CREATE flag is passed to this function.
Ensure that the kfunc rejects invalid flags.
Ensure that a keyring can be obtained from bpf_lookup_system_key() when one of the pre-determined keyring IDs is provided.
The test is currently blacklisted for s390x (JIT does not support calling kernel function).
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- tools/testing/selftests/bpf/DENYLIST.s390x | 1 + .../selftests/bpf/prog_tests/lookup_key.c | 112 ++++++++++++++++++ .../selftests/bpf/progs/test_lookup_key.c | 46 +++++++ 3 files changed, 159 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/lookup_key.c create mode 100644 tools/testing/selftests/bpf/progs/test_lookup_key.c
diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x index a708c3dcc154..585ed5d43da8 100644 --- a/tools/testing/selftests/bpf/DENYLIST.s390x +++ b/tools/testing/selftests/bpf/DENYLIST.s390x @@ -66,3 +66,4 @@ select_reuseport # intermittently fails on new s390x set xdp_synproxy # JIT does not support calling kernel function (kfunc) unpriv_bpf_disabled # fentry setget_sockopt # attach unexpected error: -524 (trampoline) +lookup_key # JIT does not support calling kernel function (kfunc) diff --git a/tools/testing/selftests/bpf/prog_tests/lookup_key.c b/tools/testing/selftests/bpf/prog_tests/lookup_key.c new file mode 100644 index 000000000000..2e0cde729dc7 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/lookup_key.c @@ -0,0 +1,112 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH + * + * Author: Roberto Sassu roberto.sassu@huawei.com + */ + +#include <linux/keyctl.h> +#include <test_progs.h> + +#include "test_lookup_key.skel.h" + +#define KEY_LOOKUP_CREATE 0x01 +#define KEY_LOOKUP_PARTIAL 0x02 + +static bool kfunc_not_supported; + +static int libbpf_print_cb(enum libbpf_print_level level, const char *fmt, + va_list args) +{ + char *func; + + if (strcmp(fmt, "libbpf: extern (func ksym) '%s': not found in kernel or module BTFs\n")) + return 0; + + func = va_arg(args, char *); + + if (strcmp(func, "bpf_lookup_user_key") && strcmp(func, "bpf_key_put") && + strcmp(func, "bpf_lookup_system_key")) + return 0; + + kfunc_not_supported = true; + return 0; +} + +void test_lookup_key(void) +{ + libbpf_print_fn_t old_print_cb; + struct test_lookup_key *skel; + u32 next_id; + int ret; + + skel = test_lookup_key__open(); + if (!ASSERT_OK_PTR(skel, "test_lookup_key__open")) + return; + + old_print_cb = libbpf_set_print(libbpf_print_cb); + ret = test_lookup_key__load(skel); + libbpf_set_print(old_print_cb); + + if (ret < 0 && kfunc_not_supported) { + printf("%s:SKIP:bpf_lookup_*_key(), bpf_key_put() kfuncs not supported\n", + __func__); + test__skip(); + goto close_prog; + } + + if (!ASSERT_OK(ret, "test_lookup_key__load")) + goto close_prog; + + ret = test_lookup_key__attach(skel); + if (!ASSERT_OK(ret, "test_lookup_key__attach")) + goto close_prog; + + skel->bss->monitored_pid = getpid(); + skel->bss->key_serial = KEY_SPEC_THREAD_KEYRING; + + /* The thread-specific keyring does not exist, this test fails. */ + skel->bss->flags = 0; + + ret = bpf_prog_get_next_id(0, &next_id); + if (!ASSERT_LT(ret, 0, "bpf_prog_get_next_id")) + goto close_prog; + + /* Force creation of the thread-specific keyring, this test succeeds. */ + skel->bss->flags = KEY_LOOKUP_CREATE; + + ret = bpf_prog_get_next_id(0, &next_id); + if (!ASSERT_OK(ret, "bpf_prog_get_next_id")) + goto close_prog; + + /* Pass both lookup flags for parameter validation. */ + skel->bss->flags = KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL; + + ret = bpf_prog_get_next_id(0, &next_id); + if (!ASSERT_OK(ret, "bpf_prog_get_next_id")) + goto close_prog; + + /* Pass invalid flags. */ + skel->bss->flags = UINT64_MAX; + + ret = bpf_prog_get_next_id(0, &next_id); + if (!ASSERT_LT(ret, 0, "bpf_prog_get_next_id")) + goto close_prog; + + skel->bss->key_serial = 0; + skel->bss->key_id = 1; + + ret = bpf_prog_get_next_id(0, &next_id); + if (!ASSERT_OK(ret, "bpf_prog_get_next_id")) + goto close_prog; + + skel->bss->key_id = UINT32_MAX; + + ret = bpf_prog_get_next_id(0, &next_id); + ASSERT_LT(ret, 0, "bpf_prog_get_next_id"); + +close_prog: + skel->bss->monitored_pid = 0; + test_lookup_key__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_lookup_key.c b/tools/testing/selftests/bpf/progs/test_lookup_key.c new file mode 100644 index 000000000000..c73776990ae3 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_lookup_key.c @@ -0,0 +1,46 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH + * + * Author: Roberto Sassu roberto.sassu@huawei.com + */ + +#include "vmlinux.h" +#include <errno.h> +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +char _license[] SEC("license") = "GPL"; + +__u32 monitored_pid; +__u32 key_serial; +__u32 key_id; +__u64 flags; + +extern struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym; +extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym; +extern void bpf_key_put(struct bpf_key *key) __ksym; + +SEC("lsm.s/bpf") +int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size) +{ + struct bpf_key *bkey; + __u32 pid; + + pid = bpf_get_current_pid_tgid() >> 32; + if (pid != monitored_pid) + return 0; + + if (key_serial) + bkey = bpf_lookup_user_key(key_serial, flags); + else + bkey = bpf_lookup_system_key(key_id); + + if (!bkey) + return -ENOENT; + + bpf_key_put(bkey); + + return 0; +}
From: Roberto Sassu roberto.sassu@huawei.com
Perform several tests to ensure the correct implementation of the bpf_verify_pkcs7_signature() kfunc.
Do the tests with data signed with a generated testing key (by using sign-file from scripts/) and with the tcp_bic.ko kernel module if it is found in the system. The test does not fail if tcp_bic.ko is not found.
First, perform an unsuccessful signature verification without data.
Second, perform a successful signature verification with the session keyring and a new one created for testing.
Then, ensure that permission and validation checks are done properly on the keyring provided to bpf_verify_pkcs7_signature(), despite those checks were deferred at the time the keyring was retrieved with bpf_lookup_user_key(). The tests expect to encounter an error if the Search permission is removed from the keyring, or the keyring is expired.
Finally, perform a successful and unsuccessful signature verification with the keyrings with pre-determined IDs (the last test fails because the key is not in the platform keyring).
The test is currently blacklisted for s390x (JIT does not support calling kernel function).
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- tools/testing/selftests/bpf/DENYLIST.s390x | 1 + tools/testing/selftests/bpf/Makefile | 14 +- tools/testing/selftests/bpf/config | 5 + tools/testing/selftests/bpf/config.x86_64 | 5 - .../bpf/prog_tests/verify_pkcs7_sig.c | 399 ++++++++++++++++++ .../bpf/progs/test_verify_pkcs7_sig.c | 100 +++++ .../testing/selftests/bpf/verify_sig_setup.sh | 104 +++++ 7 files changed, 620 insertions(+), 8 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/verify_pkcs7_sig.c create mode 100644 tools/testing/selftests/bpf/progs/test_verify_pkcs7_sig.c create mode 100755 tools/testing/selftests/bpf/verify_sig_setup.sh
diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x index 585ed5d43da8..5adcbeb54eef 100644 --- a/tools/testing/selftests/bpf/DENYLIST.s390x +++ b/tools/testing/selftests/bpf/DENYLIST.s390x @@ -67,3 +67,4 @@ xdp_synproxy # JIT does not support calling kernel f unpriv_bpf_disabled # fentry setget_sockopt # attach unexpected error: -524 (trampoline) lookup_key # JIT does not support calling kernel function (kfunc) +verify_pkcs7_sig # JIT does not support calling kernel function (kfunc) diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 8d59ec7f4c2d..5ae079e276b3 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -14,6 +14,7 @@ BPFTOOLDIR := $(TOOLSDIR)/bpf/bpftool APIDIR := $(TOOLSINCDIR)/uapi GENDIR := $(abspath ../../../../include/generated) GENHDR := $(GENDIR)/autoconf.h +HOSTPKG_CONFIG := pkg-config
ifneq ($(wildcard $(GENHDR)),) GENFLAGS := -DHAVE_GENHDR @@ -75,7 +76,7 @@ TEST_PROGS := test_kmod.sh \ test_xsk.sh
TEST_PROGS_EXTENDED := with_addr.sh \ - with_tunnels.sh ima_setup.sh \ + with_tunnels.sh ima_setup.sh verify_sig_setup.sh \ test_xdp_vlan.sh test_bpftool.py
# Compile but not part of 'make run_tests' @@ -84,7 +85,7 @@ TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \ test_lirc_mode2_user xdping test_cpp runqslower bench bpf_testmod.ko \ xskxceiver xdp_redirect_multi xdp_synproxy
-TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read +TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read $(OUTPUT)/sign-file
# Emit succinct information message describing current building step # $1 - generic step name (e.g., CC, LINK, etc); @@ -189,6 +190,12 @@ $(OUTPUT)/urandom_read: urandom_read.c urandom_read_aux.c $(OUTPUT)/liburandom_r -fuse-ld=$(LLD) -Wl,-znoseparate-code \ -Wl,-rpath=. -Wl,--build-id=sha1 -o $@
+$(OUTPUT)/sign-file: ../../../../scripts/sign-file.c + $(call msg,SIGN-FILE,,$@) + $(Q)$(CC) $(shell $(HOSTPKG_CONFIG)--cflags libcrypto 2> /dev/null) \ + $< -o $@ \ + $(shell $(HOSTPKG_CONFIG) --libs libcrypto 2> /dev/null || echo -lcrypto) + $(OUTPUT)/bpf_testmod.ko: $(VMLINUX_BTF) $(wildcard bpf_testmod/Makefile bpf_testmod/*.[ch]) $(call msg,MOD,,$@) $(Q)$(RM) bpf_testmod/bpf_testmod.ko # force re-compilation @@ -514,7 +521,8 @@ TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c \ TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko \ $(OUTPUT)/liburandom_read.so \ $(OUTPUT)/xdp_synproxy \ - ima_setup.sh \ + $(OUTPUT)/sign-file \ + ima_setup.sh verify_sig_setup.sh \ $(wildcard progs/btf_dump_test_case_*.c) TRUNNER_BPF_BUILD_RULE := CLANG_BPF_BUILD_RULE TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS) -DENABLE_ATOMICS_TESTS diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config index add5a5a919b4..905a9be8d0a2 100644 --- a/tools/testing/selftests/bpf/config +++ b/tools/testing/selftests/bpf/config @@ -33,6 +33,11 @@ CONFIG_IPV6_TUNNEL=y CONFIG_KEYS=y CONFIG_LIRC=y CONFIG_LWTUNNEL=y +CONFIG_MODULE_SIG=y +CONFIG_MODULE_SRCVERSION_ALL=y +CONFIG_MODULE_UNLOAD=y +CONFIG_MODULES=y +CONFIG_MODVERSIONS=y CONFIG_MPLS=y CONFIG_MPLS_IPTUNNEL=y CONFIG_MPLS_ROUTING=y diff --git a/tools/testing/selftests/bpf/config.x86_64 b/tools/testing/selftests/bpf/config.x86_64 index ce70c9509204..21ce5ea4304e 100644 --- a/tools/testing/selftests/bpf/config.x86_64 +++ b/tools/testing/selftests/bpf/config.x86_64 @@ -145,11 +145,6 @@ CONFIG_MCORE2=y CONFIG_MEMCG=y CONFIG_MEMORY_FAILURE=y CONFIG_MINIX_SUBPARTITION=y -CONFIG_MODULE_SIG=y -CONFIG_MODULE_SRCVERSION_ALL=y -CONFIG_MODULE_UNLOAD=y -CONFIG_MODULES=y -CONFIG_MODVERSIONS=y CONFIG_NAMESPACES=y CONFIG_NET=y CONFIG_NET_9P=y diff --git a/tools/testing/selftests/bpf/prog_tests/verify_pkcs7_sig.c b/tools/testing/selftests/bpf/prog_tests/verify_pkcs7_sig.c new file mode 100644 index 000000000000..20be68d4cce4 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/verify_pkcs7_sig.c @@ -0,0 +1,399 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH + * + * Author: Roberto Sassu roberto.sassu@huawei.com + */ + +#include <stdio.h> +#include <errno.h> +#include <stdlib.h> +#include <unistd.h> +#include <endian.h> +#include <limits.h> +#include <sys/stat.h> +#include <sys/wait.h> +#include <sys/mman.h> +#include <linux/keyctl.h> +#include <test_progs.h> + +#include "test_verify_pkcs7_sig.skel.h" + +#define MAX_DATA_SIZE (1024 * 1024) +#define MAX_SIG_SIZE 1024 + +#define VERIFY_USE_SECONDARY_KEYRING (1UL) +#define VERIFY_USE_PLATFORM_KEYRING (2UL) + +/* In stripped ARM and x86-64 modules, ~ is surprisingly rare. */ +#define MODULE_SIG_STRING "~Module signature appended~\n" + +/* + * Module signature information block. + * + * The constituents of the signature section are, in order: + * + * - Signer's name + * - Key identifier + * - Signature data + * - Information block + */ +struct module_signature { + u8 algo; /* Public-key crypto algorithm [0] */ + u8 hash; /* Digest algorithm [0] */ + u8 id_type; /* Key identifier type [PKEY_ID_PKCS7] */ + u8 signer_len; /* Length of signer's name [0] */ + u8 key_id_len; /* Length of key identifier [0] */ + u8 __pad[3]; + __be32 sig_len; /* Length of signature data */ +}; + +struct data { + u8 data[MAX_DATA_SIZE]; + u32 data_len; + u8 sig[MAX_SIG_SIZE]; + u32 sig_len; +}; + +static bool kfunc_not_supported; + +static int libbpf_print_cb(enum libbpf_print_level level, const char *fmt, + va_list args) +{ + if (strcmp(fmt, "libbpf: extern (func ksym) '%s': not found in kernel or module BTFs\n")) + return 0; + + if (strcmp(va_arg(args, char *), "bpf_verify_pkcs7_signature")) + return 0; + + kfunc_not_supported = true; + return 0; +} + +static int _run_setup_process(const char *setup_dir, const char *cmd) +{ + int child_pid, child_status; + + child_pid = fork(); + if (child_pid == 0) { + execlp("./verify_sig_setup.sh", "./verify_sig_setup.sh", cmd, + setup_dir, NULL); + exit(errno); + + } else if (child_pid > 0) { + waitpid(child_pid, &child_status, 0); + return WEXITSTATUS(child_status); + } + + return -EINVAL; +} + +static int populate_data_item_str(const char *tmp_dir, struct data *data_item) +{ + struct stat st; + char data_template[] = "/tmp/dataXXXXXX"; + char path[PATH_MAX]; + int ret, fd, child_status, child_pid; + + data_item->data_len = 4; + memcpy(data_item->data, "test", data_item->data_len); + + fd = mkstemp(data_template); + if (fd == -1) + return -errno; + + ret = write(fd, data_item->data, data_item->data_len); + + close(fd); + + if (ret != data_item->data_len) { + ret = -EIO; + goto out; + } + + child_pid = fork(); + + if (child_pid == -1) { + ret = -errno; + goto out; + } + + if (child_pid == 0) { + snprintf(path, sizeof(path), "%s/signing_key.pem", tmp_dir); + + return execlp("./sign-file", "./sign-file", "-d", "sha256", + path, path, data_template, NULL); + } + + waitpid(child_pid, &child_status, 0); + + ret = WEXITSTATUS(child_status); + if (ret) + goto out; + + snprintf(path, sizeof(path), "%s.p7s", data_template); + + ret = stat(path, &st); + if (ret == -1) { + ret = -errno; + goto out; + } + + if (st.st_size > sizeof(data_item->sig)) { + ret = -EINVAL; + goto out_sig; + } + + data_item->sig_len = st.st_size; + + fd = open(path, O_RDONLY); + if (fd == -1) { + ret = -errno; + goto out_sig; + } + + ret = read(fd, data_item->sig, data_item->sig_len); + + close(fd); + + if (ret != data_item->sig_len) { + ret = -EIO; + goto out_sig; + } + + ret = 0; +out_sig: + unlink(path); +out: + unlink(data_template); + return ret; +} + +static int populate_data_item_mod(struct data *data_item) +{ + char mod_path[PATH_MAX], *mod_path_ptr; + struct stat st; + void *mod; + FILE *fp; + struct module_signature ms; + int ret, fd, modlen, marker_len, sig_len; + + data_item->data_len = 0; + + if (stat("/lib/modules", &st) == -1) + return 0; + + /* Requires CONFIG_TCP_CONG_BIC=m. */ + fp = popen("find /lib/modules/$(uname -r) -name tcp_bic.ko", "r"); + if (!fp) + return 0; + + mod_path_ptr = fgets(mod_path, sizeof(mod_path), fp); + pclose(fp); + + if (!mod_path_ptr) + return 0; + + mod_path_ptr = strchr(mod_path, '\n'); + if (!mod_path_ptr) + return 0; + + *mod_path_ptr = '\0'; + + if (stat(mod_path, &st) == -1) + return 0; + + modlen = st.st_size; + marker_len = sizeof(MODULE_SIG_STRING) - 1; + + fd = open(mod_path, O_RDONLY); + if (fd == -1) + return -errno; + + mod = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); + + close(fd); + + if (mod == MAP_FAILED) + return -errno; + + if (strncmp(mod + modlen - marker_len, MODULE_SIG_STRING, marker_len)) { + ret = -EINVAL; + goto out; + } + + modlen -= marker_len; + + memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms)); + + sig_len = __be32_to_cpu(ms.sig_len); + modlen -= sig_len + sizeof(ms); + + if (modlen > sizeof(data_item->data)) { + ret = -E2BIG; + goto out; + } + + memcpy(data_item->data, mod, modlen); + data_item->data_len = modlen; + + if (sig_len > sizeof(data_item->sig)) { + ret = -E2BIG; + goto out; + } + + memcpy(data_item->sig, mod + modlen, sig_len); + data_item->sig_len = sig_len; + ret = 0; +out: + munmap(mod, st.st_size); + return ret; +} + +void test_verify_pkcs7_sig(void) +{ + libbpf_print_fn_t old_print_cb; + char tmp_dir_template[] = "/tmp/verify_sigXXXXXX"; + char *tmp_dir; + struct test_verify_pkcs7_sig *skel = NULL; + struct bpf_map *map; + struct data data; + int ret, zero = 0; + + /* Trigger creation of session keyring. */ + syscall(__NR_request_key, "keyring", "_uid.0", NULL, + KEY_SPEC_SESSION_KEYRING); + + tmp_dir = mkdtemp(tmp_dir_template); + if (!ASSERT_OK_PTR(tmp_dir, "mkdtemp")) + return; + + ret = _run_setup_process(tmp_dir, "setup"); + if (!ASSERT_OK(ret, "_run_setup_process")) + goto close_prog; + + skel = test_verify_pkcs7_sig__open(); + if (!ASSERT_OK_PTR(skel, "test_verify_pkcs7_sig__open")) + goto close_prog; + + old_print_cb = libbpf_set_print(libbpf_print_cb); + ret = test_verify_pkcs7_sig__load(skel); + libbpf_set_print(old_print_cb); + + if (ret < 0 && kfunc_not_supported) { + printf( + "%s:SKIP:bpf_verify_pkcs7_signature() kfunc not supported\n", + __func__); + test__skip(); + goto close_prog; + } + + if (!ASSERT_OK(ret, "test_verify_pkcs7_sig__load")) + goto close_prog; + + ret = test_verify_pkcs7_sig__attach(skel); + if (!ASSERT_OK(ret, "test_verify_pkcs7_sig__attach")) + goto close_prog; + + map = bpf_object__find_map_by_name(skel->obj, "data_input"); + if (!ASSERT_OK_PTR(map, "data_input not found")) + goto close_prog; + + skel->bss->monitored_pid = getpid(); + + /* Test without data and signature. */ + skel->bss->user_keyring_serial = KEY_SPEC_SESSION_KEYRING; + + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY); + if (!ASSERT_LT(ret, 0, "bpf_map_update_elem data_input")) + goto close_prog; + + /* Test successful signature verification with session keyring. */ + ret = populate_data_item_str(tmp_dir, &data); + if (!ASSERT_OK(ret, "populate_data_item_str")) + goto close_prog; + + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY); + if (!ASSERT_OK(ret, "bpf_map_update_elem data_input")) + goto close_prog; + + /* Test successful signature verification with testing keyring. */ + skel->bss->user_keyring_serial = syscall(__NR_request_key, "keyring", + "ebpf_testing_keyring", NULL, + KEY_SPEC_SESSION_KEYRING); + + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY); + if (!ASSERT_OK(ret, "bpf_map_update_elem data_input")) + goto close_prog; + + /* + * Ensure key_task_permission() is called and rejects the keyring + * (no Search permission). + */ + syscall(__NR_keyctl, KEYCTL_SETPERM, skel->bss->user_keyring_serial, + 0x37373737); + + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY); + if (!ASSERT_LT(ret, 0, "bpf_map_update_elem data_input")) + goto close_prog; + + syscall(__NR_keyctl, KEYCTL_SETPERM, skel->bss->user_keyring_serial, + 0x3f3f3f3f); + + /* + * Ensure key_validate() is called and rejects the keyring (key expired) + */ + syscall(__NR_keyctl, KEYCTL_SET_TIMEOUT, + skel->bss->user_keyring_serial, 1); + sleep(1); + + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY); + if (!ASSERT_LT(ret, 0, "bpf_map_update_elem data_input")) + goto close_prog; + + skel->bss->user_keyring_serial = KEY_SPEC_SESSION_KEYRING; + + /* Test with corrupted data (signature verification should fail). */ + data.data[0] = 'a'; + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY); + if (!ASSERT_LT(ret, 0, "bpf_map_update_elem data_input")) + goto close_prog; + + ret = populate_data_item_mod(&data); + if (!ASSERT_OK(ret, "populate_data_item_mod")) + goto close_prog; + + /* Test signature verification with system keyrings. */ + if (data.data_len) { + skel->bss->user_keyring_serial = 0; + skel->bss->system_keyring_id = 0; + + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, + BPF_ANY); + if (!ASSERT_OK(ret, "bpf_map_update_elem data_input")) + goto close_prog; + + skel->bss->system_keyring_id = VERIFY_USE_SECONDARY_KEYRING; + + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, + BPF_ANY); + if (!ASSERT_OK(ret, "bpf_map_update_elem data_input")) + goto close_prog; + + skel->bss->system_keyring_id = VERIFY_USE_PLATFORM_KEYRING; + + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, + BPF_ANY); + ASSERT_LT(ret, 0, "bpf_map_update_elem data_input"); + } + +close_prog: + _run_setup_process(tmp_dir, "cleanup"); + + if (!skel) + return; + + skel->bss->monitored_pid = 0; + test_verify_pkcs7_sig__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_verify_pkcs7_sig.c b/tools/testing/selftests/bpf/progs/test_verify_pkcs7_sig.c new file mode 100644 index 000000000000..4ceab545d99a --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_verify_pkcs7_sig.c @@ -0,0 +1,100 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH + * + * Author: Roberto Sassu roberto.sassu@huawei.com + */ + +#include "vmlinux.h" +#include <errno.h> +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +#define MAX_DATA_SIZE (1024 * 1024) +#define MAX_SIG_SIZE 1024 + +typedef __u8 u8; +typedef __u16 u16; +typedef __u32 u32; +typedef __u64 u64; + +struct bpf_dynptr { + __u64 :64; + __u64 :64; +} __attribute__((aligned(8))); + +extern struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym; +extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym; +extern void bpf_key_put(struct bpf_key *key) __ksym; +extern int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_ptr, + struct bpf_dynptr *sig_ptr, + struct bpf_key *trusted_keyring) __ksym; + +u32 monitored_pid; +u32 user_keyring_serial; +u64 system_keyring_id; + +struct data { + u8 data[MAX_DATA_SIZE]; + u32 data_len; + u8 sig[MAX_SIG_SIZE]; + u32 sig_len; +}; + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, 1); + __type(key, __u32); + __type(value, struct data); +} data_input SEC(".maps"); + +char _license[] SEC("license") = "GPL"; + +SEC("lsm.s/bpf") +int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size) +{ + struct bpf_dynptr data_ptr, sig_ptr; + struct data *data_val; + struct bpf_key *trusted_keyring; + u32 pid; + u64 value; + int ret, zero = 0; + + pid = bpf_get_current_pid_tgid() >> 32; + if (pid != monitored_pid) + return 0; + + data_val = bpf_map_lookup_elem(&data_input, &zero); + if (!data_val) + return 0; + + bpf_probe_read(&value, sizeof(value), &attr->value); + + bpf_copy_from_user(data_val, sizeof(struct data), + (void *)(unsigned long)value); + + if (data_val->data_len > sizeof(data_val->data)) + return -EINVAL; + + bpf_dynptr_from_mem(data_val->data, data_val->data_len, 0, &data_ptr); + + if (data_val->sig_len > sizeof(data_val->sig)) + return -EINVAL; + + bpf_dynptr_from_mem(data_val->sig, data_val->sig_len, 0, &sig_ptr); + + if (user_keyring_serial) + trusted_keyring = bpf_lookup_user_key(user_keyring_serial, 0); + else + trusted_keyring = bpf_lookup_system_key(system_keyring_id); + + if (!trusted_keyring) + return -ENOENT; + + ret = bpf_verify_pkcs7_signature(&data_ptr, &sig_ptr, trusted_keyring); + + bpf_key_put(trusted_keyring); + + return ret; +} diff --git a/tools/testing/selftests/bpf/verify_sig_setup.sh b/tools/testing/selftests/bpf/verify_sig_setup.sh new file mode 100755 index 000000000000..ba08922b4a27 --- /dev/null +++ b/tools/testing/selftests/bpf/verify_sig_setup.sh @@ -0,0 +1,104 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 + +set -e +set -u +set -o pipefail + +VERBOSE="${SELFTESTS_VERBOSE:=0}" +LOG_FILE="$(mktemp /tmp/verify_sig_setup.log.XXXXXX)" + +x509_genkey_content="\ +[ req ] +default_bits = 2048 +distinguished_name = req_distinguished_name +prompt = no +string_mask = utf8only +x509_extensions = myexts + +[ req_distinguished_name ] +CN = eBPF Signature Verification Testing Key + +[ myexts ] +basicConstraints=critical,CA:FALSE +keyUsage=digitalSignature +subjectKeyIdentifier=hash +authorityKeyIdentifier=keyid +" + +usage() +{ + echo "Usage: $0 <setup|cleanup <existing_tmp_dir>" + exit 1 +} + +setup() +{ + local tmp_dir="$1" + + echo "${x509_genkey_content}" > ${tmp_dir}/x509.genkey + + openssl req -new -nodes -utf8 -sha256 -days 36500 \ + -batch -x509 -config ${tmp_dir}/x509.genkey \ + -outform PEM -out ${tmp_dir}/signing_key.pem \ + -keyout ${tmp_dir}/signing_key.pem 2>&1 + + openssl x509 -in ${tmp_dir}/signing_key.pem -out \ + ${tmp_dir}/signing_key.der -outform der + + key_id=$(cat ${tmp_dir}/signing_key.der | keyctl padd asymmetric ebpf_testing_key @s) + + keyring_id=$(keyctl newring ebpf_testing_keyring @s) + keyctl link $key_id $keyring_id +} + +cleanup() { + local tmp_dir="$1" + + keyctl unlink $(keyctl search @s asymmetric ebpf_testing_key) @s + keyctl unlink $(keyctl search @s keyring ebpf_testing_keyring) @s + rm -rf ${tmp_dir} +} + +catch() +{ + local exit_code="$1" + local log_file="$2" + + if [[ "${exit_code}" -ne 0 ]]; then + cat "${log_file}" >&3 + fi + + rm -f "${log_file}" + exit ${exit_code} +} + +main() +{ + [[ $# -ne 2 ]] && usage + + local action="$1" + local tmp_dir="$2" + + [[ ! -d "${tmp_dir}" ]] && echo "Directory ${tmp_dir} doesn't exist" && exit 1 + + if [[ "${action}" == "setup" ]]; then + setup "${tmp_dir}" + elif [[ "${action}" == "cleanup" ]]; then + cleanup "${tmp_dir}" + else + echo "Unknown action: ${action}" + exit 1 + fi +} + +trap 'catch "$?" "${LOG_FILE}"' EXIT + +if [[ "${VERBOSE}" -eq 0 ]]; then + # Save the stderr to 3 so that we can output back to + # it incase of an error. + exec 3>&2 1>"${LOG_FILE}" 2>&1 +fi + +main "$@" +rm -f "${LOG_FILE}"
On Tue, 2022-08-23 at 17:00 +0200, Roberto Sassu wrote:
From: Roberto Sassu roberto.sassu@huawei.com
One of the desirable features in security is the ability to restrict import of data to a given system based on data authenticity. If data import can be restricted, it would be possible to enforce a system-wide policy based on the signing keys the system owner trusts.
Hi
is there anything else I need to do, other than rebasing the patches to the latest eBPF code?
Thanks
Roberto
linux-kselftest-mirror@lists.linaro.org
-
KP Singh -
Kumar Kartikeya Dwivedi -
Roberto Sassu -
Song Liu