Add the bpf_verify_pkcs7_signature() helper, to give the ability to eBPF security modules to check the validity of a PKCS#7 signature against supplied data.
Use the 'keyring' parameter to select the keyring containing the verification key: 0 for the primary keyring, 1 for the primary and secondary keyrings, 2 for the platform keyring.
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- include/uapi/linux/bpf.h | 8 ++++++++ kernel/bpf/bpf_lsm.c | 32 ++++++++++++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 8 ++++++++ 3 files changed, 48 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index f4009dbdf62d..40d0fc0d9493 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5249,6 +5249,13 @@ union bpf_attr { * Pointer to the underlying dynptr data, NULL if the dynptr is * read-only, if the dynptr is invalid, or if the offset and length * is out of bounds. + * + * long bpf_verify_pkcs7_signature(u8 *data, u32 datalen, u8 *sig, u32 siglen, u64 keyring) + * Description + * Verify the PKCS#7 *sig* with length *siglen*, on *data* with + * length *datalen*, with key in *keyring*. + * Return + * 0 on success, a negative value on error. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5455,6 +5462,7 @@ union bpf_attr { FN(dynptr_read), \ FN(dynptr_write), \ FN(dynptr_data), \ + FN(verify_pkcs7_signature), \ /* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index c1351df9f7ee..1cda43cb541a 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -16,6 +16,7 @@ #include <linux/bpf_local_storage.h> #include <linux/btf_ids.h> #include <linux/ima.h> +#include <linux/verification.h>
/* For every LSM hook that allows attachment of BPF programs, declare a nop * function where a BPF program can be attached. @@ -132,6 +133,35 @@ static const struct bpf_func_proto bpf_get_attach_cookie_proto = { .arg1_type = ARG_PTR_TO_CTX, };
+BPF_CALL_5(bpf_verify_pkcs7_signature, u8 *, data, u32, datalen, u8 *, sig, + u32, siglen, u64, keyring) +{ + int ret = -EOPNOTSUPP; + +#ifdef CONFIG_SYSTEM_DATA_VERIFICATION + if (keyring > (unsigned long)VERIFY_USE_PLATFORM_KEYRING) + return -EINVAL; + + ret = verify_pkcs7_signature(data, datalen, sig, siglen, + (struct key *)keyring, + VERIFYING_UNSPECIFIED_SIGNATURE, NULL, + NULL); +#endif + return ret; +} + +static const struct bpf_func_proto bpf_verify_pkcs7_signature_proto = { + .func = bpf_verify_pkcs7_signature, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_MEM, + .arg2_type = ARG_CONST_SIZE_OR_ZERO, + .arg3_type = ARG_PTR_TO_MEM, + .arg4_type = ARG_CONST_SIZE_OR_ZERO, + .arg5_type = ARG_ANYTHING, + .allowed = bpf_ima_inode_hash_allowed, +}; + static const struct bpf_func_proto * bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { @@ -158,6 +188,8 @@ bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return prog->aux->sleepable ? &bpf_ima_file_hash_proto : NULL; case BPF_FUNC_get_attach_cookie: return bpf_prog_has_trampoline(prog) ? &bpf_get_attach_cookie_proto : NULL; + case BPF_FUNC_verify_pkcs7_signature: + return prog->aux->sleepable ? &bpf_verify_pkcs7_signature_proto : NULL; default: return tracing_prog_func_proto(func_id, prog); } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index f4009dbdf62d..40d0fc0d9493 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -5249,6 +5249,13 @@ union bpf_attr { * Pointer to the underlying dynptr data, NULL if the dynptr is * read-only, if the dynptr is invalid, or if the offset and length * is out of bounds. + * + * long bpf_verify_pkcs7_signature(u8 *data, u32 datalen, u8 *sig, u32 siglen, u64 keyring) + * Description + * Verify the PKCS#7 *sig* with length *siglen*, on *data* with + * length *datalen*, with key in *keyring*. + * Return + * 0 on success, a negative value on error. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5455,6 +5462,7 @@ union bpf_attr { FN(dynptr_read), \ FN(dynptr_write), \ FN(dynptr_data), \ + FN(verify_pkcs7_signature), \ /* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper