From 3f1e1bea34740069f70c6bc92d0f712345d5c28e Mon Sep 17 00:00:00 2001 From: David Howells Date: Mon, 20 Jul 2015 21:16:27 +0100 Subject: MODSIGN: Use PKCS#7 messages as module signatures Move to using PKCS#7 messages as module signatures because: (1) We have to be able to support the use of X.509 certificates that don't have a subjKeyId set. We're currently relying on this to look up the X.509 certificate in the trusted keyring list. (2) PKCS#7 message signed information blocks have a field that supplies the data required to match with the X.509 certificate that signed it. (3) The PKCS#7 certificate carries fields that specify the digest algorithm used to generate the signature in a standardised way and the X.509 certificates specify the public key algorithm in a standardised way - so we don't need our own methods of specifying these. (4) We now have PKCS#7 message support in the kernel for signed kexec purposes and we can make use of this. To make this work, the old sign-file script has been replaced with a program that needs compiling in a previous patch. The rules to build it are added here. Signed-off-by: David Howells Tested-by: Vivek Goyal --- kernel/module_signing.c | 220 ++++++++++-------------------------------------- 1 file changed, 44 insertions(+), 176 deletions(-) (limited to 'kernel/module_signing.c') diff --git a/kernel/module_signing.c b/kernel/module_signing.c index be5b8fac4bd0..8eb20cc66b39 100644 --- a/kernel/module_signing.c +++ b/kernel/module_signing.c @@ -11,10 +11,9 @@ #include #include -#include -#include -#include #include +#include +#include #include "module-internal.h" /* @@ -28,157 +27,53 @@ * - Information block */ struct module_signature { - u8 algo; /* Public-key crypto algorithm [enum pkey_algo] */ - u8 hash; /* Digest algorithm [enum hash_algo] */ - u8 id_type; /* Key identifier type [enum pkey_id_type] */ - u8 signer_len; /* Length of signer's name */ - u8 key_id_len; /* Length of key identifier */ + 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 */ }; /* - * Digest the module contents. + * Verify a PKCS#7-based signature on a module. */ -static struct public_key_signature *mod_make_digest(enum hash_algo hash, - const void *mod, - unsigned long modlen) +static int mod_verify_pkcs7(const void *mod, unsigned long modlen, + const void *raw_pkcs7, size_t pkcs7_len) { - struct public_key_signature *pks; - struct crypto_shash *tfm; - struct shash_desc *desc; - size_t digest_size, desc_size; + struct pkcs7_message *pkcs7; + bool trusted; int ret; - pr_devel("==>%s()\n", __func__); - - /* Allocate the hashing algorithm we're going to need and find out how - * big the hash operational data will be. - */ - tfm = crypto_alloc_shash(hash_algo_name[hash], 0, 0); - if (IS_ERR(tfm)) - return (PTR_ERR(tfm) == -ENOENT) ? ERR_PTR(-ENOPKG) : ERR_CAST(tfm); - - desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); - digest_size = crypto_shash_digestsize(tfm); - - /* We allocate the hash operational data storage on the end of our - * context data and the digest output buffer on the end of that. - */ - ret = -ENOMEM; - pks = kzalloc(digest_size + sizeof(*pks) + desc_size, GFP_KERNEL); - if (!pks) - goto error_no_pks; - - pks->pkey_hash_algo = hash; - pks->digest = (u8 *)pks + sizeof(*pks) + desc_size; - pks->digest_size = digest_size; - - desc = (void *)pks + sizeof(*pks); - desc->tfm = tfm; - desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; - - ret = crypto_shash_init(desc); + 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 (pkcs7_supply_detached_data(pkcs7, mod, modlen) < 0) { + pr_err("PKCS#7 signature with non-detached data\n"); + ret = -EBADMSG; + goto error; + } + + ret = pkcs7_verify(pkcs7); if (ret < 0) goto error; - ret = crypto_shash_finup(desc, mod, modlen, pks->digest); + ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted); if (ret < 0) goto error; - crypto_free_shash(tfm); - pr_devel("<==%s() = ok\n", __func__); - return pks; + if (!trusted) { + pr_err("PKCS#7 signature not signed with a trusted key\n"); + ret = -ENOKEY; + } error: - kfree(pks); -error_no_pks: - crypto_free_shash(tfm); + pkcs7_free_message(pkcs7); pr_devel("<==%s() = %d\n", __func__, ret); - return ERR_PTR(ret); -} - -/* - * Extract an MPI array from the signature data. This represents the actual - * signature. Each raw MPI is prefaced by a BE 2-byte value indicating the - * size of the MPI in bytes. - * - * RSA signatures only have one MPI, so currently we only read one. - */ -static int mod_extract_mpi_array(struct public_key_signature *pks, - const void *data, size_t len) -{ - size_t nbytes; - MPI mpi; - - if (len < 3) - return -EBADMSG; - nbytes = ((const u8 *)data)[0] << 8 | ((const u8 *)data)[1]; - data += 2; - len -= 2; - if (len != nbytes) - return -EBADMSG; - - mpi = mpi_read_raw_data(data, nbytes); - if (!mpi) - return -ENOMEM; - pks->mpi[0] = mpi; - pks->nr_mpi = 1; - return 0; -} - -/* - * Request an asymmetric key. - */ -static struct key *request_asymmetric_key(const char *signer, size_t signer_len, - const u8 *key_id, size_t key_id_len) -{ - key_ref_t key; - size_t i; - char *id, *q; - - pr_devel("==>%s(,%zu,,%zu)\n", __func__, signer_len, key_id_len); - - /* Construct an identifier. */ - id = kmalloc(signer_len + 2 + key_id_len * 2 + 1, GFP_KERNEL); - if (!id) - return ERR_PTR(-ENOKEY); - - memcpy(id, signer, signer_len); - - q = id + signer_len; - *q++ = ':'; - *q++ = ' '; - for (i = 0; i < key_id_len; i++) { - *q++ = hex_asc[*key_id >> 4]; - *q++ = hex_asc[*key_id++ & 0x0f]; - } - - *q = 0; - - pr_debug("Look up: \"%s\"\n", id); - - key = keyring_search(make_key_ref(system_trusted_keyring, 1), - &key_type_asymmetric, id); - if (IS_ERR(key)) - pr_warn("Request for unknown module key '%s' err %ld\n", - id, PTR_ERR(key)); - kfree(id); - - if (IS_ERR(key)) { - switch (PTR_ERR(key)) { - /* Hide some search errors */ - case -EACCES: - case -ENOTDIR: - case -EAGAIN: - return ERR_PTR(-ENOKEY); - default: - return ERR_CAST(key); - } - } - - pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key_ref_to_ptr(key))); - return key_ref_to_ptr(key); + return ret; } /* @@ -186,12 +81,8 @@ static struct key *request_asymmetric_key(const char *signer, size_t signer_len, */ int mod_verify_sig(const void *mod, unsigned long *_modlen) { - struct public_key_signature *pks; struct module_signature ms; - struct key *key; - const void *sig; size_t modlen = *_modlen, sig_len; - int ret; pr_devel("==>%s(,%zu)\n", __func__, modlen); @@ -205,46 +96,23 @@ int mod_verify_sig(const void *mod, unsigned long *_modlen) if (sig_len >= modlen) return -EBADMSG; modlen -= sig_len; - if ((size_t)ms.signer_len + ms.key_id_len >= modlen) - return -EBADMSG; - modlen -= (size_t)ms.signer_len + ms.key_id_len; - *_modlen = modlen; - sig = mod + modlen; - - /* For the moment, only support RSA and X.509 identifiers */ - if (ms.algo != PKEY_ALGO_RSA || - ms.id_type != PKEY_ID_X509) - return -ENOPKG; - if (ms.hash >= PKEY_HASH__LAST || - !hash_algo_name[ms.hash]) + if (ms.id_type != PKEY_ID_PKCS7) { + pr_err("Module is not signed with expected PKCS#7 message\n"); return -ENOPKG; - - key = request_asymmetric_key(sig, ms.signer_len, - sig + ms.signer_len, ms.key_id_len); - if (IS_ERR(key)) - return PTR_ERR(key); - - pks = mod_make_digest(ms.hash, mod, modlen); - if (IS_ERR(pks)) { - ret = PTR_ERR(pks); - goto error_put_key; } - ret = mod_extract_mpi_array(pks, sig + ms.signer_len + ms.key_id_len, - sig_len); - if (ret < 0) - goto error_free_pks; - - ret = verify_signature(key, pks); - pr_devel("verify_signature() = %d\n", ret); + if (ms.algo != 0 || + ms.hash != 0 || + ms.signer_len != 0 || + ms.key_id_len != 0 || + ms.__pad[0] != 0 || + ms.__pad[1] != 0 || + ms.__pad[2] != 0) { + pr_err("PKCS#7 signature info has unexpected non-zero params\n"); + return -EBADMSG; + } -error_free_pks: - mpi_free(pks->rsa.s); - kfree(pks); -error_put_key: - key_put(key); - pr_devel("<==%s() = %d\n", __func__, ret); - return ret; + return mod_verify_pkcs7(mod, modlen, mod + modlen, sig_len); } -- cgit v1.2.3 From 091f6e26eb326adbd718f406e440c838bed8ebb6 Mon Sep 17 00:00:00 2001 From: David Howells Date: Mon, 20 Jul 2015 21:16:28 +0100 Subject: MODSIGN: Extract the blob PKCS#7 signature verifier from module signing Extract the function that drives the PKCS#7 signature verification given a data blob and a PKCS#7 blob out from the module signing code and lump it with the system keyring code as it's generic. This makes it independent of module config options and opens it to use by the firmware loader. Signed-off-by: David Howells Cc: Luis R. Rodriguez Cc: Rusty Russell Cc: Ming Lei Cc: Seth Forshee Cc: Kyle McMartin --- include/keys/system_keyring.h | 5 +++++ init/Kconfig | 29 ++++++++++++++++--------- kernel/module_signing.c | 44 +------------------------------------ kernel/system_keyring.c | 50 +++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 75 insertions(+), 53 deletions(-) (limited to 'kernel/module_signing.c') diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h index 72665eb80692..9791c907cdb7 100644 --- a/include/keys/system_keyring.h +++ b/include/keys/system_keyring.h @@ -28,4 +28,9 @@ static inline struct key *get_system_trusted_keyring(void) } #endif +#ifdef CONFIG_SYSTEM_DATA_VERIFICATION +extern int system_verify_data(const void *data, unsigned long len, + const void *raw_pkcs7, size_t pkcs7_len); +#endif + #endif /* _KEYS_SYSTEM_KEYRING_H */ diff --git a/init/Kconfig b/init/Kconfig index e16d9e587cee..14b3d8422502 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1752,6 +1752,24 @@ config SYSTEM_TRUSTED_KEYRING Keys in this keyring are used by module signature checking. +config SYSTEM_DATA_VERIFICATION + def_bool n + select SYSTEM_TRUSTED_KEYRING + select KEYS + select CRYPTO + select ASYMMETRIC_KEY_TYPE + select ASYMMETRIC_PUBLIC_KEY_SUBTYPE + select PUBLIC_KEY_ALGO_RSA + select ASN1 + select OID_REGISTRY + select X509_CERTIFICATE_PARSER + select PKCS7_MESSAGE_PARSER + help + Provide PKCS#7 message verification using the contents of the system + trusted keyring to provide public keys. This then can be used for + module verification, kexec image verification and firmware blob + verification. + config PROFILING bool "Profiling support" help @@ -1860,16 +1878,7 @@ config MODULE_SRCVERSION_ALL config MODULE_SIG bool "Module signature verification" depends on MODULES - select SYSTEM_TRUSTED_KEYRING - select KEYS - select CRYPTO - select ASYMMETRIC_KEY_TYPE - select ASYMMETRIC_PUBLIC_KEY_SUBTYPE - select PUBLIC_KEY_ALGO_RSA - select ASN1 - select OID_REGISTRY - select X509_CERTIFICATE_PARSER - select PKCS7_MESSAGE_PARSER + select SYSTEM_DATA_VERIFICATION help Check modules for valid signatures upon load: the signature is simply appended to the module. For more information see diff --git a/kernel/module_signing.c b/kernel/module_signing.c index 8eb20cc66b39..70ad463f6df0 100644 --- a/kernel/module_signing.c +++ b/kernel/module_signing.c @@ -10,10 +10,8 @@ */ #include -#include #include #include -#include #include "module-internal.h" /* @@ -36,46 +34,6 @@ struct module_signature { __be32 sig_len; /* Length of signature data */ }; -/* - * Verify a PKCS#7-based signature on a module. - */ -static int mod_verify_pkcs7(const void *mod, unsigned long modlen, - const void *raw_pkcs7, size_t pkcs7_len) -{ - struct pkcs7_message *pkcs7; - bool trusted; - 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 (pkcs7_supply_detached_data(pkcs7, mod, modlen) < 0) { - pr_err("PKCS#7 signature with non-detached data\n"); - ret = -EBADMSG; - goto error; - } - - ret = pkcs7_verify(pkcs7); - if (ret < 0) - goto error; - - ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted); - if (ret < 0) - goto error; - - if (!trusted) { - pr_err("PKCS#7 signature not signed with a trusted key\n"); - ret = -ENOKEY; - } - -error: - pkcs7_free_message(pkcs7); - pr_devel("<==%s() = %d\n", __func__, ret); - return ret; -} - /* * Verify the signature on a module. */ @@ -114,5 +72,5 @@ int mod_verify_sig(const void *mod, unsigned long *_modlen) return -EBADMSG; } - return mod_verify_pkcs7(mod, modlen, mod + modlen, sig_len); + return system_verify_data(mod, modlen, mod + modlen, sig_len); } diff --git a/kernel/system_keyring.c b/kernel/system_keyring.c index 4cda71ee51c7..95f2dcbc7616 100644 --- a/kernel/system_keyring.c +++ b/kernel/system_keyring.c @@ -16,6 +16,7 @@ #include #include #include +#include struct key *system_trusted_keyring; EXPORT_SYMBOL_GPL(system_trusted_keyring); @@ -103,3 +104,52 @@ dodgy_cert: return 0; } late_initcall(load_system_certificate_list); + +#ifdef CONFIG_SYSTEM_DATA_VERIFICATION + +/** + * Verify a PKCS#7-based signature on system data. + * @data: The data to be verified. + * @len: Size of @data. + * @raw_pkcs7: The PKCS#7 message that is the signature. + * @pkcs7_len: The size of @raw_pkcs7. + */ +int system_verify_data(const void *data, unsigned long len, + const void *raw_pkcs7, size_t pkcs7_len) +{ + struct pkcs7_message *pkcs7; + bool trusted; + 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 (pkcs7_supply_detached_data(pkcs7, data, len) < 0) { + pr_err("PKCS#7 signature with non-detached data\n"); + ret = -EBADMSG; + goto error; + } + + ret = pkcs7_verify(pkcs7); + if (ret < 0) + goto error; + + ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted); + if (ret < 0) + goto error; + + if (!trusted) { + pr_err("PKCS#7 signature not signed with a trusted key\n"); + ret = -ENOKEY; + } + +error: + pkcs7_free_message(pkcs7); + pr_devel("<==%s() = %d\n", __func__, ret); + return ret; +} +EXPORT_SYMBOL_GPL(system_verify_data); + +#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ -- cgit v1.2.3 From 99db44350672c8a5ee9a7b0a6f4cd6ff10136065 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 5 Aug 2015 15:22:27 +0100 Subject: PKCS#7: Appropriately restrict authenticated attributes and content type A PKCS#7 or CMS message can have per-signature authenticated attributes that are digested as a lump and signed by the authorising key for that signature. If such attributes exist, the content digest isn't itself signed, but rather it is included in a special authattr which then contributes to the signature. Further, we already require the master message content type to be pkcs7_signedData - but there's also a separate content type for the data itself within the SignedData object and this must be repeated inside the authattrs for each signer [RFC2315 9.2, RFC5652 11.1]. We should really validate the authattrs if they exist or forbid them entirely as appropriate. To this end: (1) Alter the PKCS#7 parser to reject any message that has more than one signature where at least one signature has authattrs and at least one that does not. (2) Validate authattrs if they are present and strongly restrict them. Only the following authattrs are permitted and all others are rejected: (a) contentType. This is checked to be an OID that matches the content type in the SignedData object. (b) messageDigest. This must match the crypto digest of the data. (c) signingTime. If present, we check that this is a valid, parseable UTCTime or GeneralTime and that the date it encodes fits within the validity window of the matching X.509 cert. (d) S/MIME capabilities. We don't check the contents. (e) Authenticode SP Opus Info. We don't check the contents. (f) Authenticode Statement Type. We don't check the contents. The message is rejected if (a) or (b) are missing. If the message is an Authenticode type, the message is rejected if (e) is missing; if not Authenticode, the message is rejected if (d) - (f) are present. The S/MIME capabilities authattr (d) unfortunately has to be allowed to support kernels already signed by the pesign program. This only affects kexec. sign-file suppresses them (CMS_NOSMIMECAP). The message is also rejected if an authattr is given more than once or if it contains more than one element in its set of values. (3) Add a parameter to pkcs7_verify() to select one of the following restrictions and pass in the appropriate option from the callers: (*) VERIFYING_MODULE_SIGNATURE This requires that the SignedData content type be pkcs7-data and forbids authattrs. sign-file sets CMS_NOATTR. We could be more flexible and permit authattrs optionally, but only permit minimal content. (*) VERIFYING_FIRMWARE_SIGNATURE This requires that the SignedData content type be pkcs7-data and requires authattrs. In future, this will require an attribute holding the target firmware name in addition to the minimal set. (*) VERIFYING_UNSPECIFIED_SIGNATURE This requires that the SignedData content type be pkcs7-data but allows either no authattrs or only permits the minimal set. (*) VERIFYING_KEXEC_PE_SIGNATURE This only supports the Authenticode SPC_INDIRECT_DATA content type and requires at least an SpcSpOpusInfo authattr in addition to the minimal set. It also permits an SPC_STATEMENT_TYPE authattr (and an S/MIME capabilities authattr because the pesign program doesn't remove these). (*) VERIFYING_KEY_SIGNATURE (*) VERIFYING_KEY_SELF_SIGNATURE These are invalid in this context but are included for later use when limiting the use of X.509 certs. (4) The pkcs7_test key type is given a module parameter to select between the above options for testing purposes. For example: echo 1 >/sys/module/pkcs7_test_key/parameters/usage keyctl padd pkcs7_test foo @s Signed-off-by: David Howells Reviewed-by: Marcel Holtmann Reviewed-by: David Woodhouse --- arch/x86/kernel/kexec-bzimage64.c | 4 +- crypto/asymmetric_keys/asymmetric_type.c | 11 +++ crypto/asymmetric_keys/pkcs7.asn1 | 6 +- crypto/asymmetric_keys/pkcs7_key_type.c | 14 +++- crypto/asymmetric_keys/pkcs7_parser.c | 138 +++++++++++++++++++++++++++++-- crypto/asymmetric_keys/pkcs7_parser.h | 15 +++- crypto/asymmetric_keys/pkcs7_verify.c | 65 ++++++++++++++- crypto/asymmetric_keys/verify_pefile.c | 7 +- include/crypto/pkcs7.h | 10 ++- include/crypto/public_key.h | 14 ++++ include/keys/system_keyring.h | 4 +- include/linux/oid_registry.h | 4 +- include/linux/verify_pefile.h | 6 +- kernel/module_signing.c | 3 +- kernel/system_keyring.c | 6 +- scripts/sign-file.c | 5 +- 16 files changed, 285 insertions(+), 27 deletions(-) (limited to 'kernel/module_signing.c') diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c index ca83f7ac388b..fab22e72808c 100644 --- a/arch/x86/kernel/kexec-bzimage64.c +++ b/arch/x86/kernel/kexec-bzimage64.c @@ -536,7 +536,9 @@ static int bzImage64_verify_sig(const char *kernel, unsigned long kernel_len) int ret; ret = verify_pefile_signature(kernel, kernel_len, - system_trusted_keyring, &trusted); + system_trusted_keyring, + VERIFYING_KEXEC_PE_SIGNATURE, + &trusted); if (ret < 0) return ret; if (!trusted) diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c index b0e4ed23d668..1916680ad81b 100644 --- a/crypto/asymmetric_keys/asymmetric_type.c +++ b/crypto/asymmetric_keys/asymmetric_type.c @@ -12,6 +12,7 @@ */ #include #include +#include #include #include #include @@ -20,6 +21,16 @@ MODULE_LICENSE("GPL"); +const char *const key_being_used_for[NR__KEY_BEING_USED_FOR] = { + [VERIFYING_MODULE_SIGNATURE] = "mod sig", + [VERIFYING_FIRMWARE_SIGNATURE] = "firmware sig", + [VERIFYING_KEXEC_PE_SIGNATURE] = "kexec PE sig", + [VERIFYING_KEY_SIGNATURE] = "key sig", + [VERIFYING_KEY_SELF_SIGNATURE] = "key self sig", + [VERIFYING_UNSPECIFIED_SIGNATURE] = "unspec sig", +}; +EXPORT_SYMBOL_GPL(key_being_used_for); + static LIST_HEAD(asymmetric_key_parsers); static DECLARE_RWSEM(asymmetric_key_parsers_sem); diff --git a/crypto/asymmetric_keys/pkcs7.asn1 b/crypto/asymmetric_keys/pkcs7.asn1 index 6bf8ff4f7414..1eca740b816a 100644 --- a/crypto/asymmetric_keys/pkcs7.asn1 +++ b/crypto/asymmetric_keys/pkcs7.asn1 @@ -8,7 +8,7 @@ ContentType ::= OBJECT IDENTIFIER ({ pkcs7_note_OID }) SignedData ::= SEQUENCE { version INTEGER ({ pkcs7_note_signeddata_version }), digestAlgorithms DigestAlgorithmIdentifiers, - contentInfo ContentInfo, + contentInfo ContentInfo ({ pkcs7_note_content }), certificates CHOICE { certSet [0] IMPLICIT ExtendedCertificatesAndCertificates, certSequence [2] IMPLICIT Certificates @@ -21,7 +21,7 @@ SignedData ::= SEQUENCE { } ContentInfo ::= SEQUENCE { - contentType ContentType, + contentType ContentType ({ pkcs7_note_OID }), content [0] EXPLICIT Data OPTIONAL } @@ -111,7 +111,7 @@ AuthenticatedAttribute ::= SEQUENCE { } UnauthenticatedAttribute ::= SEQUENCE { - type OBJECT IDENTIFIER ({ pkcs7_note_OID }), + type OBJECT IDENTIFIER, values SET OF ANY } diff --git a/crypto/asymmetric_keys/pkcs7_key_type.c b/crypto/asymmetric_keys/pkcs7_key_type.c index 3d13b042da73..10d34dbd00b9 100644 --- a/crypto/asymmetric_keys/pkcs7_key_type.c +++ b/crypto/asymmetric_keys/pkcs7_key_type.c @@ -14,16 +14,23 @@ #include #include #include +#include #include #include #include #include "pkcs7_parser.h" +static unsigned pkcs7_usage; +module_param_named(usage, pkcs7_usage, uint, S_IWUSR | S_IRUGO); +MODULE_PARM_DESC(pkcs7_usage, + "Usage to specify when verifying the PKCS#7 message"); + /* * Preparse a PKCS#7 wrapped and validated data blob. */ static int pkcs7_preparse(struct key_preparsed_payload *prep) { + enum key_being_used_for usage = pkcs7_usage; struct pkcs7_message *pkcs7; const void *data, *saved_prep_data; size_t datalen, saved_prep_datalen; @@ -32,6 +39,11 @@ static int pkcs7_preparse(struct key_preparsed_payload *prep) kenter(""); + if (usage >= NR__KEY_BEING_USED_FOR) { + pr_err("Invalid usage type %d\n", usage); + return -EINVAL; + } + saved_prep_data = prep->data; saved_prep_datalen = prep->datalen; pkcs7 = pkcs7_parse_message(saved_prep_data, saved_prep_datalen); @@ -40,7 +52,7 @@ static int pkcs7_preparse(struct key_preparsed_payload *prep) goto error; } - ret = pkcs7_verify(pkcs7); + ret = pkcs7_verify(pkcs7, usage); if (ret < 0) goto error_free; diff --git a/crypto/asymmetric_keys/pkcs7_parser.c b/crypto/asymmetric_keys/pkcs7_parser.c index 826e2f3f507b..e6298b7a945a 100644 --- a/crypto/asymmetric_keys/pkcs7_parser.c +++ b/crypto/asymmetric_keys/pkcs7_parser.c @@ -81,6 +81,30 @@ void pkcs7_free_message(struct pkcs7_message *pkcs7) } EXPORT_SYMBOL_GPL(pkcs7_free_message); +/* + * Check authenticatedAttributes are provided or not provided consistently. + */ +static int pkcs7_check_authattrs(struct pkcs7_message *msg) +{ + struct pkcs7_signed_info *sinfo; + bool want; + + sinfo = msg->signed_infos; + if (sinfo->authattrs) { + want = true; + msg->have_authattrs = true; + } + + for (sinfo = sinfo->next; sinfo; sinfo = sinfo->next) + if (!!sinfo->authattrs != want) + goto inconsistent; + return 0; + +inconsistent: + pr_warn("Inconsistently supplied authAttrs\n"); + return -EINVAL; +} + /** * pkcs7_parse_message - Parse a PKCS#7 message * @data: The raw binary ASN.1 encoded message to be parsed @@ -113,6 +137,10 @@ struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen) goto out; } + ret = pkcs7_check_authattrs(ctx->msg); + if (ret < 0) + goto out; + msg = ctx->msg; ctx->msg = NULL; @@ -380,6 +408,25 @@ int pkcs7_note_certificate_list(void *context, size_t hdrlen, return 0; } +/* + * Note the content type. + */ +int pkcs7_note_content(void *context, size_t hdrlen, + unsigned char tag, + const void *value, size_t vlen) +{ + struct pkcs7_parse_context *ctx = context; + + if (ctx->last_oid != OID_data && + ctx->last_oid != OID_msIndirectData) { + pr_warn("Unsupported data type %d\n", ctx->last_oid); + return -EINVAL; + } + + ctx->msg->data_type = ctx->last_oid; + return 0; +} + /* * Extract the data from the message and store that and its content type OID in * the context. @@ -395,31 +442,90 @@ int pkcs7_note_data(void *context, size_t hdrlen, ctx->msg->data = value; ctx->msg->data_len = vlen; ctx->msg->data_hdrlen = hdrlen; - ctx->msg->data_type = ctx->last_oid; return 0; } /* - * Parse authenticated attributes + * Parse authenticated attributes. */ int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct pkcs7_parse_context *ctx = context; + struct pkcs7_signed_info *sinfo = ctx->sinfo; + enum OID content_type; pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value); switch (ctx->last_oid) { + case OID_contentType: + if (__test_and_set_bit(sinfo_has_content_type, &sinfo->aa_set)) + goto repeated; + content_type = look_up_OID(value, vlen); + if (content_type != ctx->msg->data_type) { + pr_warn("Mismatch between global data type (%d) and sinfo %u (%d)\n", + ctx->msg->data_type, sinfo->index, + content_type); + return -EBADMSG; + } + return 0; + + case OID_signingTime: + if (__test_and_set_bit(sinfo_has_signing_time, &sinfo->aa_set)) + goto repeated; + /* Should we check that the signing time is consistent + * with the signer's X.509 cert? + */ + return x509_decode_time(&sinfo->signing_time, + hdrlen, tag, value, vlen); + case OID_messageDigest: + if (__test_and_set_bit(sinfo_has_message_digest, &sinfo->aa_set)) + goto repeated; if (tag != ASN1_OTS) return -EBADMSG; - ctx->sinfo->msgdigest = value; - ctx->sinfo->msgdigest_len = vlen; + sinfo->msgdigest = value; + sinfo->msgdigest_len = vlen; + return 0; + + case OID_smimeCapabilites: + if (__test_and_set_bit(sinfo_has_smime_caps, &sinfo->aa_set)) + goto repeated; + if (ctx->msg->data_type != OID_msIndirectData) { + pr_warn("S/MIME Caps only allowed with Authenticode\n"); + return -EKEYREJECTED; + } + return 0; + + /* Microsoft SpOpusInfo seems to be contain cont[0] 16-bit BE + * char URLs and cont[1] 8-bit char URLs. + * + * Microsoft StatementType seems to contain a list of OIDs that + * are also used as extendedKeyUsage types in X.509 certs. + */ + case OID_msSpOpusInfo: + if (__test_and_set_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) + goto repeated; + goto authenticode_check; + case OID_msStatementType: + if (__test_and_set_bit(sinfo_has_ms_statement_type, &sinfo->aa_set)) + goto repeated; + authenticode_check: + if (ctx->msg->data_type != OID_msIndirectData) { + pr_warn("Authenticode AuthAttrs only allowed with Authenticode\n"); + return -EKEYREJECTED; + } + /* I'm not sure how to validate these */ return 0; default: return 0; } + +repeated: + /* We permit max one item per AuthenticatedAttribute and no repeats */ + pr_warn("Repeated/multivalue AuthAttrs not permitted\n"); + return -EKEYREJECTED; } /* @@ -430,10 +536,25 @@ int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen, const void *value, size_t vlen) { struct pkcs7_parse_context *ctx = context; + struct pkcs7_signed_info *sinfo = ctx->sinfo; + + if (!test_bit(sinfo_has_content_type, &sinfo->aa_set) || + !test_bit(sinfo_has_message_digest, &sinfo->aa_set) || + (ctx->msg->data_type == OID_msIndirectData && + !test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set))) { + pr_warn("Missing required AuthAttr\n"); + return -EBADMSG; + } + + if (ctx->msg->data_type != OID_msIndirectData && + test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) { + pr_warn("Unexpected Authenticode AuthAttr\n"); + return -EBADMSG; + } /* We need to switch the 'CONT 0' to a 'SET OF' when we digest */ - ctx->sinfo->authattrs = value - (hdrlen - 1); - ctx->sinfo->authattrs_len = vlen + (hdrlen - 1); + sinfo->authattrs = value - (hdrlen - 1); + sinfo->authattrs_len = vlen + (hdrlen - 1); return 0; } @@ -511,6 +632,11 @@ int pkcs7_note_signed_info(void *context, size_t hdrlen, struct pkcs7_signed_info *sinfo = ctx->sinfo; struct asymmetric_key_id *kid; + if (ctx->msg->data_type == OID_msIndirectData && !sinfo->authattrs) { + pr_warn("Authenticode requires AuthAttrs\n"); + return -EBADMSG; + } + /* Generate cert issuer + serial number key ID */ if (!ctx->expect_skid) { kid = asymmetric_key_generate_id(ctx->raw_serial, diff --git a/crypto/asymmetric_keys/pkcs7_parser.h b/crypto/asymmetric_keys/pkcs7_parser.h index 790dd7cec82c..a66b19ebcf47 100644 --- a/crypto/asymmetric_keys/pkcs7_parser.h +++ b/crypto/asymmetric_keys/pkcs7_parser.h @@ -21,9 +21,9 @@ struct pkcs7_signed_info { struct pkcs7_signed_info *next; struct x509_certificate *signer; /* Signing certificate (in msg->certs) */ - unsigned index; - bool trusted; - bool unsupported_crypto; /* T if not usable due to missing crypto */ + unsigned index; + bool trusted; + bool unsupported_crypto; /* T if not usable due to missing crypto */ /* Message digest - the digest of the Content Data (or NULL) */ const void *msgdigest; @@ -32,6 +32,14 @@ struct pkcs7_signed_info { /* Authenticated Attribute data (or NULL) */ unsigned authattrs_len; const void *authattrs; + unsigned long aa_set; +#define sinfo_has_content_type 0 +#define sinfo_has_signing_time 1 +#define sinfo_has_message_digest 2 +#define sinfo_has_smime_caps 3 +#define sinfo_has_ms_opus_info 4 +#define sinfo_has_ms_statement_type 5 + time64_t signing_time; /* Issuing cert serial number and issuer's name [PKCS#7 or CMS ver 1] * or issuing cert's SKID [CMS ver 3]. @@ -53,6 +61,7 @@ struct pkcs7_message { struct x509_certificate *crl; /* Revocation list */ struct pkcs7_signed_info *signed_infos; u8 version; /* Version of cert (1 -> PKCS#7 or CMS; 3 -> CMS) */ + bool have_authattrs; /* T if have authattrs */ /* Content Data (or NULL) */ enum OID data_type; /* Type of Data */ diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c index 404f89a0f852..d20c0b4b880e 100644 --- a/crypto/asymmetric_keys/pkcs7_verify.c +++ b/crypto/asymmetric_keys/pkcs7_verify.c @@ -70,9 +70,15 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7, * message digest attribute amongst them which corresponds to the * digest we just calculated. */ - if (sinfo->msgdigest) { + if (sinfo->authattrs) { u8 tag; + if (!sinfo->msgdigest) { + pr_warn("Sig %u: No messageDigest\n", sinfo->index); + ret = -EKEYREJECTED; + goto error; + } + if (sinfo->msgdigest_len != sinfo->sig.digest_size) { pr_debug("Sig %u: Invalid digest size (%u)\n", sinfo->index, sinfo->msgdigest_len); @@ -314,6 +320,18 @@ static int pkcs7_verify_one(struct pkcs7_message *pkcs7, pr_devel("Using X.509[%u] for sig %u\n", sinfo->signer->index, sinfo->index); + /* Check that the PKCS#7 signing time is valid according to the X.509 + * certificate. We can't, however, check against the system clock + * since that may not have been set yet and may be wrong. + */ + if (test_bit(sinfo_has_signing_time, &sinfo->aa_set)) { + if (sinfo->signing_time < sinfo->signer->valid_from || + sinfo->signing_time > sinfo->signer->valid_to) { + pr_warn("Message signed outside of X.509 validity window\n"); + return -EKEYREJECTED; + } + } + /* Verify the PKCS#7 binary against the key */ ret = public_key_verify_signature(sinfo->signer->pub, &sinfo->sig); if (ret < 0) @@ -328,6 +346,7 @@ static int pkcs7_verify_one(struct pkcs7_message *pkcs7, /** * pkcs7_verify - Verify a PKCS#7 message * @pkcs7: The PKCS#7 message to be verified + * @usage: The use to which the key is being put * * Verify a PKCS#7 message is internally consistent - that is, the data digest * matches the digest in the AuthAttrs and any signature in the message or one @@ -339,6 +358,9 @@ static int pkcs7_verify_one(struct pkcs7_message *pkcs7, * * Returns, in order of descending priority: * + * (*) -EKEYREJECTED if a key was selected that had a usage restriction at + * odds with the specified usage, or: + * * (*) -EKEYREJECTED if a signature failed to match for which we found an * appropriate X.509 certificate, or: * @@ -350,7 +372,8 @@ static int pkcs7_verify_one(struct pkcs7_message *pkcs7, * (*) 0 if all the signature chains that don't incur -ENOPKG can be verified * (note that a signature chain may be of zero length), or: */ -int pkcs7_verify(struct pkcs7_message *pkcs7) +int pkcs7_verify(struct pkcs7_message *pkcs7, + enum key_being_used_for usage) { struct pkcs7_signed_info *sinfo; struct x509_certificate *x509; @@ -359,6 +382,44 @@ int pkcs7_verify(struct pkcs7_message *pkcs7) kenter(""); + switch (usage) { + case VERIFYING_MODULE_SIGNATURE: + if (pkcs7->data_type != OID_data) { + pr_warn("Invalid module sig (not pkcs7-data)\n"); + return -EKEYREJECTED; + } + if (pkcs7->have_authattrs) { + pr_warn("Invalid module sig (has authattrs)\n"); + return -EKEYREJECTED; + } + break; + case VERIFYING_FIRMWARE_SIGNATURE: + if (pkcs7->data_type != OID_data) { + pr_warn("Invalid firmware sig (not pkcs7-data)\n"); + return -EKEYREJECTED; + } + if (!pkcs7->have_authattrs) { + pr_warn("Invalid firmware sig (missing authattrs)\n"); + return -EKEYREJECTED; + } + break; + case VERIFYING_KEXEC_PE_SIGNATURE: + if (pkcs7->data_type != OID_msIndirectData) { + pr_warn("Invalid kexec sig (not Authenticode)\n"); + return -EKEYREJECTED; + } + /* Authattr presence checked in parser */ + break; + case VERIFYING_UNSPECIFIED_SIGNATURE: + if (pkcs7->data_type != OID_data) { + pr_warn("Invalid unspecified sig (not pkcs7-data)\n"); + return -EKEYREJECTED; + } + break; + default: + return -EINVAL; + } + for (n = 0, x509 = pkcs7->certs; x509; x509 = x509->next, n++) { ret = x509_get_sig_params(x509); if (ret < 0) diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c index 2421f46184ce..897b734dabf9 100644 --- a/crypto/asymmetric_keys/verify_pefile.c +++ b/crypto/asymmetric_keys/verify_pefile.c @@ -393,6 +393,7 @@ error_no_desc: * @pebuf: Buffer containing the PE binary image * @pelen: Length of the binary image * @trust_keyring: Signing certificates to use as starting points + * @usage: The use to which the key is being put. * @_trusted: Set to true if trustworth, false otherwise * * Validate that the certificate chain inside the PKCS#7 message inside the PE @@ -417,7 +418,9 @@ error_no_desc: * May also return -ENOMEM. */ int verify_pefile_signature(const void *pebuf, unsigned pelen, - struct key *trusted_keyring, bool *_trusted) + struct key *trusted_keyring, + enum key_being_used_for usage, + bool *_trusted) { struct pkcs7_message *pkcs7; struct pefile_context ctx; @@ -462,7 +465,7 @@ int verify_pefile_signature(const void *pebuf, unsigned pelen, if (ret < 0) goto error; - ret = pkcs7_verify(pkcs7); + ret = pkcs7_verify(pkcs7, usage); if (ret < 0) goto error; diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h index e235ab4957ee..441aff9b5aa7 100644 --- a/include/crypto/pkcs7.h +++ b/include/crypto/pkcs7.h @@ -9,6 +9,11 @@ * 2 of the Licence, or (at your option) any later version. */ +#ifndef _CRYPTO_PKCS7_H +#define _CRYPTO_PKCS7_H + +#include + struct key; struct pkcs7_message; @@ -33,7 +38,10 @@ extern int pkcs7_validate_trust(struct pkcs7_message *pkcs7, /* * pkcs7_verify.c */ -extern int pkcs7_verify(struct pkcs7_message *pkcs7); +extern int pkcs7_verify(struct pkcs7_message *pkcs7, + enum key_being_used_for usage); extern int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7, const void *data, size_t datalen); + +#endif /* _CRYPTO_PKCS7_H */ diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h index fda097e079a4..067c242b1e15 100644 --- a/include/crypto/public_key.h +++ b/include/crypto/public_key.h @@ -39,6 +39,20 @@ enum pkey_id_type { extern const char *const pkey_id_type_name[PKEY_ID_TYPE__LAST]; +/* + * The use to which an asymmetric key is being put. + */ +enum key_being_used_for { + VERIFYING_MODULE_SIGNATURE, + VERIFYING_FIRMWARE_SIGNATURE, + VERIFYING_KEXEC_PE_SIGNATURE, + VERIFYING_KEY_SIGNATURE, + VERIFYING_KEY_SELF_SIGNATURE, + VERIFYING_UNSPECIFIED_SIGNATURE, + NR__KEY_BEING_USED_FOR +}; +extern const char *const key_being_used_for[NR__KEY_BEING_USED_FOR]; + /* * Cryptographic data for the public-key subtype of the asymmetric key type. * diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h index 9791c907cdb7..b20cd885c1fd 100644 --- a/include/keys/system_keyring.h +++ b/include/keys/system_keyring.h @@ -15,6 +15,7 @@ #ifdef CONFIG_SYSTEM_TRUSTED_KEYRING #include +#include extern struct key *system_trusted_keyring; static inline struct key *get_system_trusted_keyring(void) @@ -30,7 +31,8 @@ static inline struct key *get_system_trusted_keyring(void) #ifdef CONFIG_SYSTEM_DATA_VERIFICATION extern int system_verify_data(const void *data, unsigned long len, - const void *raw_pkcs7, size_t pkcs7_len); + const void *raw_pkcs7, size_t pkcs7_len, + enum key_being_used_for usage); #endif #endif /* _KEYS_SYSTEM_KEYRING_H */ diff --git a/include/linux/oid_registry.h b/include/linux/oid_registry.h index c2bbf672b84e..93e0ff92fb9b 100644 --- a/include/linux/oid_registry.h +++ b/include/linux/oid_registry.h @@ -41,7 +41,7 @@ enum OID { OID_signed_data, /* 1.2.840.113549.1.7.2 */ /* PKCS#9 {iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)} */ OID_email_address, /* 1.2.840.113549.1.9.1 */ - OID_content_type, /* 1.2.840.113549.1.9.3 */ + OID_contentType, /* 1.2.840.113549.1.9.3 */ OID_messageDigest, /* 1.2.840.113549.1.9.4 */ OID_signingTime, /* 1.2.840.113549.1.9.5 */ OID_smimeCapabilites, /* 1.2.840.113549.1.9.15 */ @@ -54,6 +54,8 @@ enum OID { /* Microsoft Authenticode & Software Publishing */ OID_msIndirectData, /* 1.3.6.1.4.1.311.2.1.4 */ + OID_msStatementType, /* 1.3.6.1.4.1.311.2.1.11 */ + OID_msSpOpusInfo, /* 1.3.6.1.4.1.311.2.1.12 */ OID_msPeImageDataObjId, /* 1.3.6.1.4.1.311.2.1.15 */ OID_msIndividualSPKeyPurpose, /* 1.3.6.1.4.1.311.2.1.21 */ OID_msOutlookExpress, /* 1.3.6.1.4.1.311.16.4 */ diff --git a/include/linux/verify_pefile.h b/include/linux/verify_pefile.h index ac34819214f9..da2049b5161c 100644 --- a/include/linux/verify_pefile.h +++ b/include/linux/verify_pefile.h @@ -12,7 +12,11 @@ #ifndef _LINUX_VERIFY_PEFILE_H #define _LINUX_VERIFY_PEFILE_H +#include + extern int verify_pefile_signature(const void *pebuf, unsigned pelen, - struct key *trusted_keyring, bool *_trusted); + struct key *trusted_keyring, + enum key_being_used_for usage, + bool *_trusted); #endif /* _LINUX_VERIFY_PEFILE_H */ diff --git a/kernel/module_signing.c b/kernel/module_signing.c index 70ad463f6df0..bd62f5cda746 100644 --- a/kernel/module_signing.c +++ b/kernel/module_signing.c @@ -72,5 +72,6 @@ int mod_verify_sig(const void *mod, unsigned long *_modlen) return -EBADMSG; } - return system_verify_data(mod, modlen, mod + modlen, sig_len); + return system_verify_data(mod, modlen, mod + modlen, sig_len, + VERIFYING_MODULE_SIGNATURE); } diff --git a/kernel/system_keyring.c b/kernel/system_keyring.c index 95f2dcbc7616..2570598b784d 100644 --- a/kernel/system_keyring.c +++ b/kernel/system_keyring.c @@ -113,9 +113,11 @@ late_initcall(load_system_certificate_list); * @len: Size of @data. * @raw_pkcs7: The PKCS#7 message that is the signature. * @pkcs7_len: The size of @raw_pkcs7. + * @usage: The use to which the key is being put. */ int system_verify_data(const void *data, unsigned long len, - const void *raw_pkcs7, size_t pkcs7_len) + const void *raw_pkcs7, size_t pkcs7_len, + enum key_being_used_for usage) { struct pkcs7_message *pkcs7; bool trusted; @@ -132,7 +134,7 @@ int system_verify_data(const void *data, unsigned long len, goto error; } - ret = pkcs7_verify(pkcs7); + ret = pkcs7_verify(pkcs7, usage); if (ret < 0) goto error; diff --git a/scripts/sign-file.c b/scripts/sign-file.c index de213e5c0cd3..e9741e879bbd 100755 --- a/scripts/sign-file.c +++ b/scripts/sign-file.c @@ -111,7 +111,7 @@ int main(int argc, char **argv) bool sign_only = false; unsigned char buf[4096]; unsigned long module_size, cms_size; - unsigned int use_keyid = 0; + unsigned int use_keyid = 0, use_signed_attrs = CMS_NOATTR; const EVP_MD *digest_algo; EVP_PKEY *private_key; CMS_ContentInfo *cms; @@ -216,7 +216,8 @@ int main(int argc, char **argv) ERR(!cms, "CMS_sign"); ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo, - CMS_NOCERTS | CMS_BINARY | CMS_NOSMIMECAP | use_keyid), + CMS_NOCERTS | CMS_BINARY | CMS_NOSMIMECAP | + use_keyid | use_signed_attrs), "CMS_sign_add_signer"); ERR(CMS_final(cms, bm, NULL, CMS_NOCERTS | CMS_BINARY) < 0, "CMS_final"); -- cgit v1.2.3