[PATCH v5 13/18] PKCS#7: Introduce pkcs7_get_message_sig and verify_pkcs7_message_sig
From: Thiago Jung Bauermann <hidden>
Date: 2017-10-18 00:57:34
Also in:
keyrings, linux-crypto, linux-integrity, linux-security-module, lkml
Subsystem:
asymmetric keys, certificate handling, crypto api, the rest · Maintainers:
David Howells, Lukas Wunner, Ignat Korchagin, David Woodhouse, Herbert Xu, "David S. Miller", Linus Torvalds
IMA will need to access the digest used in the signature so that it can verify files containing module-style appended signatures. For this purpose, add function pkcs7_get_message_sig. It will also need to verify an already parsed PKCS#7 message. For this purpose, add function verify_pkcs7_message_signature which takes a struct pkcs7_message for verification instead of the raw bytes that verify_pkcs7_signature takes. Signed-off-by: Thiago Jung Bauermann <redacted> --- certs/system_keyring.c | 60 +++++++++++++++++++++++++---------- crypto/asymmetric_keys/pkcs7_parser.c | 12 +++++++ include/crypto/pkcs7.h | 2 ++ include/linux/verification.h | 10 ++++++ 4 files changed, 68 insertions(+), 16 deletions(-)
diff --git a/certs/system_keyring.c b/certs/system_keyring.c
index 6251d1b27f0c..6a8684959780 100644
--- a/certs/system_keyring.c
+++ b/certs/system_keyring.c@@ -190,33 +190,26 @@ late_initcall(load_system_certificate_list); #ifdef CONFIG_SYSTEM_DATA_VERIFICATION /** - * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. + * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data. * @data: The data to be verified (NULL if expecting internal data). * @len: Size of @data. - * @raw_pkcs7: The PKCS#7 message that is the signature. - * @pkcs7_len: The size of @raw_pkcs7. + * @pkcs7: The PKCS#7 message that is the signature. * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, * (void *)1UL for all trusted keys). * @usage: The use to which the key is being put. * @view_content: Callback to gain access to content. * @ctx: Context for callback. */ -int verify_pkcs7_signature(const void *data, size_t len, - const void *raw_pkcs7, size_t pkcs7_len, - struct key *trusted_keys, - enum key_being_used_for usage, - int (*view_content)(void *ctx, - const void *data, size_t len, - size_t asn1hdrlen), - void *ctx) +int verify_pkcs7_message_sig(const void *data, size_t len, + struct pkcs7_message *pkcs7, + struct key *trusted_keys, + enum key_being_used_for usage, + int (*view_content)(void *ctx, const void *data, + size_t len, size_t asn1hdrlen), + void *ctx) { - struct pkcs7_message *pkcs7; int ret; - pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); - if (IS_ERR(pkcs7)) - return PTR_ERR(pkcs7); - /* The data should be detached - so we need to supply it. */ if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { pr_err("PKCS#7 signature with non-detached data\n");
@@ -258,6 +251,41 @@ int verify_pkcs7_signature(const void *data, size_t len, } error: + pr_devel("<==%s() = %d\n", __func__, ret); + return ret; +} + +/** + * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. + * @data: The data to be verified (NULL if expecting internal data). + * @len: Size of @data. + * @raw_pkcs7: The PKCS#7 message that is the signature. + * @pkcs7_len: The size of @raw_pkcs7. + * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, + * (void *)1UL for all trusted keys). + * @usage: The use to which the key is being put. + * @view_content: Callback to gain access to content. + * @ctx: Context for callback. + */ +int verify_pkcs7_signature(const void *data, size_t len, + const void *raw_pkcs7, size_t pkcs7_len, + struct key *trusted_keys, + enum key_being_used_for usage, + int (*view_content)(void *ctx, + const void *data, size_t len, + size_t asn1hdrlen), + void *ctx) +{ + struct pkcs7_message *pkcs7; + int ret; + + pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); + if (IS_ERR(pkcs7)) + return PTR_ERR(pkcs7); + + ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage, + view_content, ctx); + pkcs7_free_message(pkcs7); pr_devel("<==%s() = %d\n", __func__, ret); return ret;
diff --git a/crypto/asymmetric_keys/pkcs7_parser.c b/crypto/asymmetric_keys/pkcs7_parser.c
index af4cd8649117..e41beda297a8 100644
--- a/crypto/asymmetric_keys/pkcs7_parser.c
+++ b/crypto/asymmetric_keys/pkcs7_parser.c@@ -673,3 +673,15 @@ int pkcs7_note_signed_info(void *context, size_t hdrlen, return -ENOMEM; return 0; } + +/** + * pkcs7_get_message_sig - get signature in @pkcs7 + * + * This function doesn't meaningfully support messages with more than one + * signature. It will always return the first signature. + */ +const struct public_key_signature *pkcs7_get_message_sig( + const struct pkcs7_message *pkcs7) +{ + return pkcs7->signed_infos ? pkcs7->signed_infos->sig : NULL; +}
diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h
index 583f199400a3..6f51d0cb6d12 100644
--- a/include/crypto/pkcs7.h
+++ b/include/crypto/pkcs7.h@@ -28,6 +28,8 @@ extern void pkcs7_free_message(struct pkcs7_message *pkcs7); extern int pkcs7_get_content_data(const struct pkcs7_message *pkcs7, const void **_data, size_t *_datalen, size_t *_headerlen); +extern const struct public_key_signature *pkcs7_get_message_sig( + const struct pkcs7_message *pkcs7); /* * pkcs7_trust.c
diff --git a/include/linux/verification.h b/include/linux/verification.h
index a10549a6c7cd..f04dac2728ec 100644
--- a/include/linux/verification.h
+++ b/include/linux/verification.h@@ -29,6 +29,7 @@ extern const char *const key_being_used_for[NR__KEY_BEING_USED_FOR]; #ifdef CONFIG_SYSTEM_DATA_VERIFICATION struct key; +struct pkcs7_message; extern int verify_pkcs7_signature(const void *data, size_t len, const void *raw_pkcs7, size_t pkcs7_len,
@@ -38,6 +39,15 @@ extern int verify_pkcs7_signature(const void *data, size_t len, const void *data, size_t len, size_t asn1hdrlen), void *ctx); +extern int verify_pkcs7_message_sig(const void *data, size_t len, + struct pkcs7_message *pkcs7, + struct key *trusted_keys, + enum key_being_used_for usage, + int (*view_content)(void *ctx, + const void *data, + size_t len, + size_t asn1hdrlen), + void *ctx); #ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION extern int verify_pefile_signature(const void *pebuf, unsigned pelen,