From a4e3b8d79a5c6d40f4a9703abf7fe3abcc6c3b8d Mon Sep 17 00:00:00 2001 From: Mimi Zohar Date: Thu, 22 May 2014 14:02:23 -0400 Subject: KEYS: special dot prefixed keyring name bug fix Dot prefixed keyring names are supposed to be reserved for the kernel, but add_key() calls key_get_type_from_user(), which incorrectly verifies the 'type' field, not the 'description' field. This patch verifies the 'description' field isn't dot prefixed, when creating a new keyring, and removes the dot prefix test in key_get_type_from_user(). Changelog v6: - whitespace and other cleanup Changelog v5: - Only prevent userspace from creating a dot prefixed keyring, not regular keys - Dmitry Reported-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar Acked-by: David Howells diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index cd5bd0c..8a8c233 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -37,8 +37,6 @@ static int key_get_type_from_user(char *type, return ret; if (ret == 0 || ret >= len) return -EINVAL; - if (type[0] == '.') - return -EPERM; type[len - 1] = '\0'; return 0; } @@ -86,6 +84,10 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type, if (!*description) { kfree(description); description = NULL; + } else if ((description[0] == '.') && + (strncmp(type, "keyring", 7) == 0)) { + ret = -EPERM; + goto error2; } } -- cgit v0.10.2 From 3be4beaf7c91ec9c6fefa5f11173af37113d10ae Mon Sep 17 00:00:00 2001 From: Mimi Zohar Date: Tue, 20 Aug 2013 14:36:27 -0400 Subject: KEYS: verify a certificate is signed by a 'trusted' key Only public keys, with certificates signed by an existing 'trusted' key on the system trusted keyring, should be added to a trusted keyring. This patch adds support for verifying a certificate's signature. This is derived from David Howells pkcs7_request_asymmetric_key() patch. Changelog v6: - on error free key - Dmitry - validate trust only for not already trusted keys - Dmitry - formatting cleanup Changelog: - define get_system_trusted_keyring() to fix kbuild issues Signed-off-by: Mimi Zohar Signed-off-by: David Howells Acked-by: Dmitry Kasatkin diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c index 382ef0d..436fbd8 100644 --- a/crypto/asymmetric_keys/x509_public_key.c +++ b/crypto/asymmetric_keys/x509_public_key.c @@ -18,12 +18,62 @@ #include #include #include +#include #include #include "asymmetric_keys.h" #include "public_key.h" #include "x509_parser.h" /* + * Find a key in the given keyring by issuer and authority. + */ +static struct key *x509_request_asymmetric_key(struct key *keyring, + const char *signer, + size_t signer_len, + const char *authority, + size_t auth_len) +{ + key_ref_t key; + char *id; + + /* Construct an identifier. */ + id = kmalloc(signer_len + 2 + auth_len + 1, GFP_KERNEL); + if (!id) + return ERR_PTR(-ENOMEM); + + memcpy(id, signer, signer_len); + id[signer_len + 0] = ':'; + id[signer_len + 1] = ' '; + memcpy(id + signer_len + 2, authority, auth_len); + id[signer_len + 2 + auth_len] = 0; + + pr_debug("Look up: \"%s\"\n", id); + + key = keyring_search(make_key_ref(keyring, 1), + &key_type_asymmetric, id); + if (IS_ERR(key)) + pr_debug("Request for 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); +} + +/* * Set up the signature parameters in an X.509 certificate. This involves * digesting the signed data and extracting the signature. */ @@ -103,6 +153,37 @@ int x509_check_signature(const struct public_key *pub, EXPORT_SYMBOL_GPL(x509_check_signature); /* + * Check the new certificate against the ones in the trust keyring. If one of + * those is the signing key and validates the new certificate, then mark the + * new certificate as being trusted. + * + * Return 0 if the new certificate was successfully validated, 1 if we couldn't + * find a matching parent certificate in the trusted list and an error if there + * is a matching certificate but the signature check fails. + */ +static int x509_validate_trust(struct x509_certificate *cert, + struct key *trust_keyring) +{ + const struct public_key *pk; + struct key *key; + int ret = 1; + + if (!trust_keyring) + return -EOPNOTSUPP; + + key = x509_request_asymmetric_key(trust_keyring, + cert->issuer, strlen(cert->issuer), + cert->authority, + strlen(cert->authority)); + if (!IS_ERR(key)) { + pk = key->payload.data; + ret = x509_check_signature(pk, cert); + key_put(key); + } + return ret; +} + +/* * Attempt to parse a data blob for a key as an X509 certificate. */ static int x509_key_preparse(struct key_preparsed_payload *prep) @@ -155,9 +236,13 @@ static int x509_key_preparse(struct key_preparsed_payload *prep) /* Check the signature on the key if it appears to be self-signed */ if (!cert->authority || strcmp(cert->fingerprint, cert->authority) == 0) { - ret = x509_check_signature(cert->pub, cert); + ret = x509_check_signature(cert->pub, cert); /* self-signed */ if (ret < 0) goto error_free_cert; + } else if (!prep->trusted) { + ret = x509_validate_trust(cert, get_system_trusted_keyring()); + if (!ret) + prep->trusted = 1; } /* Propose a description */ diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h index 8dabc39..72665eb 100644 --- a/include/keys/system_keyring.h +++ b/include/keys/system_keyring.h @@ -17,7 +17,15 @@ #include extern struct key *system_trusted_keyring; - +static inline struct key *get_system_trusted_keyring(void) +{ + return system_trusted_keyring; +} +#else +static inline struct key *get_system_trusted_keyring(void) +{ + return NULL; +} #endif #endif /* _KEYS_SYSTEM_KEYRING_H */ -- cgit v0.10.2 From b3426827c848d252ed4ca5f4d3085551be083e12 Mon Sep 17 00:00:00 2001 From: Dmitry Kasatkin Date: Tue, 17 Jun 2014 11:56:57 +0300 Subject: KEYS: make partial key id matching as a dedicated function To avoid code duplication this patch refactors asymmetric_key_match(), making partial ID string match a separate function. This patch also implicitly fixes a bug in the code. asymmetric_key_match() allows to match the key by its subtype. But subtype matching could be undone if asymmetric_key_id(key) would return NULL. This patch first checks for matching spec and then for its value. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar diff --git a/crypto/asymmetric_keys/asymmetric_keys.h b/crypto/asymmetric_keys/asymmetric_keys.h index 515b634..a63c551 100644 --- a/crypto/asymmetric_keys/asymmetric_keys.h +++ b/crypto/asymmetric_keys/asymmetric_keys.h @@ -9,6 +9,8 @@ * 2 of the Licence, or (at your option) any later version. */ +int asymmetric_keyid_match(const char *kid, const char *id); + static inline const char *asymmetric_key_id(const struct key *key) { return key->type_data.p[1]; diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c index b77eb53..1fd1d30 100644 --- a/crypto/asymmetric_keys/asymmetric_type.c +++ b/crypto/asymmetric_keys/asymmetric_type.c @@ -23,6 +23,34 @@ static LIST_HEAD(asymmetric_key_parsers); static DECLARE_RWSEM(asymmetric_key_parsers_sem); /* + * Match asymmetric key id with partial match + * @id: key id to match in a form "id:" + */ +int asymmetric_keyid_match(const char *kid, const char *id) +{ + size_t idlen, kidlen; + + if (!kid || !id) + return 0; + + /* make it possible to use id as in the request: "id:" */ + if (strncmp(id, "id:", 3) == 0) + id += 3; + + /* Anything after here requires a partial match on the ID string */ + idlen = strlen(id); + kidlen = strlen(kid); + if (idlen > kidlen) + return 0; + + kid += kidlen - idlen; + if (strcasecmp(id, kid) != 0) + return 0; + + return 1; +} + +/* * Match asymmetric keys on (part of) their name * We have some shorthand methods for matching keys. We allow: * @@ -34,9 +62,8 @@ static int asymmetric_key_match(const struct key *key, const void *description) { const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key); const char *spec = description; - const char *id, *kid; + const char *id; ptrdiff_t speclen; - size_t idlen, kidlen; if (!subtype || !spec || !*spec) return 0; @@ -55,23 +82,8 @@ static int asymmetric_key_match(const struct key *key, const void *description) speclen = id - spec; id++; - /* Anything after here requires a partial match on the ID string */ - kid = asymmetric_key_id(key); - if (!kid) - return 0; - - idlen = strlen(id); - kidlen = strlen(kid); - if (idlen > kidlen) - return 0; - - kid += kidlen - idlen; - if (strcasecmp(id, kid) != 0) - return 0; - - if (speclen == 2 && - memcmp(spec, "id", 2) == 0) - return 1; + if (speclen == 2 && memcmp(spec, "id", 2) == 0) + return asymmetric_keyid_match(asymmetric_key_id(key), id); if (speclen == subtype->name_len && memcmp(spec, subtype->name, speclen) == 0) -- cgit v0.10.2 From ffb70f61bab1482a3bd0f85fd8f1e9c9909df2ca Mon Sep 17 00:00:00 2001 From: Dmitry Kasatkin Date: Tue, 17 Jun 2014 11:56:58 +0300 Subject: KEYS: validate certificate trust only with selected key Instead of allowing public keys, with certificates signed by any key on the system trusted keyring, to be added to a trusted keyring, this patch further restricts the certificates to those signed by a particular key on the system keyring. This patch defines a new kernel parameter 'ca_keys' to identify the specific key which must be used for trust validation of certificates. Simplified Mimi's "KEYS: define an owner trusted keyring" patch. Changelog: - support for builtin x509 public keys only - export "asymmetric_keyid_match" - remove ifndefs MODULE - rename kernel boot parameter from keys_ownerid to ca_keys Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 8b2ab54..bdb193a 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -566,6 +566,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. possible to determine what the correct size should be. This option provides an override for these situations. + ca_keys= [KEYS] This parameter identifies a specific key(s) on + the system trusted keyring to be used for certificate + trust validation. + format: id: + ccw_timeout_log [S390] See Documentation/s390/CommonIO for details. diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c index 1fd1d30..c948df5 100644 --- a/crypto/asymmetric_keys/asymmetric_type.c +++ b/crypto/asymmetric_keys/asymmetric_type.c @@ -49,6 +49,7 @@ int asymmetric_keyid_match(const char *kid, const char *id) return 1; } +EXPORT_SYMBOL_GPL(asymmetric_keyid_match); /* * Match asymmetric keys on (part of) their name diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c index 436fbd8..d376195 100644 --- a/crypto/asymmetric_keys/x509_public_key.c +++ b/crypto/asymmetric_keys/x509_public_key.c @@ -24,6 +24,22 @@ #include "public_key.h" #include "x509_parser.h" +static char *ca_keyid; + +#ifndef MODULE +static int __init ca_keys_setup(char *str) +{ + if (!str) /* default system keyring */ + return 1; + + if (strncmp(str, "id:", 3) == 0) + ca_keyid = str; /* owner key 'id:xxxxxx' */ + + return 1; +} +__setup("ca_keys=", ca_keys_setup); +#endif + /* * Find a key in the given keyring by issuer and authority. */ @@ -171,6 +187,9 @@ static int x509_validate_trust(struct x509_certificate *cert, if (!trust_keyring) return -EOPNOTSUPP; + if (ca_keyid && !asymmetric_keyid_match(cert->authority, ca_keyid)) + return -EPERM; + key = x509_request_asymmetric_key(trust_keyring, cert->issuer, strlen(cert->issuer), cert->authority, -- cgit v0.10.2 From 32c4741cb66703a3c282f41d77deff4afd93342a Mon Sep 17 00:00:00 2001 From: Dmitry Kasatkin Date: Tue, 17 Jun 2014 11:56:59 +0300 Subject: KEYS: validate certificate trust only with builtin keys Instead of allowing public keys, with certificates signed by any key on the system trusted keyring, to be added to a trusted keyring, this patch further restricts the certificates to those signed only by builtin keys on the system keyring. This patch defines a new option 'builtin' for the kernel parameter 'keys_ownerid' to allow trust validation using builtin keys. Simplified Mimi's "KEYS: define an owner trusted keyring" patch Changelog v7: - rename builtin_keys to use_builtin_keys Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index bdb193a..90c12c5 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -569,7 +569,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. ca_keys= [KEYS] This parameter identifies a specific key(s) on the system trusted keyring to be used for certificate trust validation. - format: id: + format: { id: | builtin } ccw_timeout_log [S390] See Documentation/s390/CommonIO for details. diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c index d376195..927ce75 100644 --- a/crypto/asymmetric_keys/x509_public_key.c +++ b/crypto/asymmetric_keys/x509_public_key.c @@ -24,6 +24,7 @@ #include "public_key.h" #include "x509_parser.h" +static bool use_builtin_keys; static char *ca_keyid; #ifndef MODULE @@ -34,6 +35,8 @@ static int __init ca_keys_setup(char *str) if (strncmp(str, "id:", 3) == 0) ca_keyid = str; /* owner key 'id:xxxxxx' */ + else if (strcmp(str, "builtin") == 0) + use_builtin_keys = true; return 1; } @@ -180,7 +183,6 @@ EXPORT_SYMBOL_GPL(x509_check_signature); static int x509_validate_trust(struct x509_certificate *cert, struct key *trust_keyring) { - const struct public_key *pk; struct key *key; int ret = 1; @@ -195,8 +197,9 @@ static int x509_validate_trust(struct x509_certificate *cert, cert->authority, strlen(cert->authority)); if (!IS_ERR(key)) { - pk = key->payload.data; - ret = x509_check_signature(pk, cert); + if (!use_builtin_keys + || test_bit(KEY_FLAG_BUILTIN, &key->flags)) + ret = x509_check_signature(key->payload.data, cert); key_put(key); } return ret; diff --git a/include/linux/key.h b/include/linux/key.h index 017b082..65316f7 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -170,6 +170,7 @@ struct key { #define KEY_FLAG_INVALIDATED 7 /* set if key has been invalidated */ #define KEY_FLAG_TRUSTED 8 /* set if key is trusted */ #define KEY_FLAG_TRUSTED_ONLY 9 /* set if keyring only accepts links to trusted keys */ +#define KEY_FLAG_BUILTIN 10 /* set if key is builtin */ /* the key type and key description string * - the desc is used to match a key against search criteria diff --git a/kernel/system_keyring.c b/kernel/system_keyring.c index 52ebc70..875f64e 100644 --- a/kernel/system_keyring.c +++ b/kernel/system_keyring.c @@ -89,6 +89,7 @@ static __init int load_system_certificate_list(void) pr_err("Problem loading in-kernel X.509 certificate (%ld)\n", PTR_ERR(key)); } else { + set_bit(KEY_FLAG_BUILTIN, &key_ref_to_ptr(key)->flags); pr_notice("Loaded X.509 cert '%s'\n", key_ref_to_ptr(key)->description); key_ref_put(key); -- cgit v0.10.2 From 7d2ce2320e8efdc4a6dcbae7b329ed3f0d1cd778 Mon Sep 17 00:00:00 2001 From: Mimi Zohar Date: Tue, 13 Aug 2013 08:47:43 -0400 Subject: ima: define '.ima' as a builtin 'trusted' keyring Require all keys added to the IMA keyring be signed by an existing trusted key on the system trusted keyring. Changelog v6: - remove ifdef CONFIG_IMA_TRUSTED_KEYRING in C code - Dmitry - update Kconfig dependency and help - select KEYS_DEBUG_PROC_KEYS - Dmitry Changelog v5: - Move integrity_init_keyring() to init_ima() - Dmitry - reset keyring[id] on failure - Dmitry Changelog v1: - don't link IMA trusted keyring to user keyring Changelog: - define stub integrity_init_keyring() function (reported-by Fengguang Wu) - differentiate between regular and trusted keyring names. - replace printk with pr_info (D. Kasatkin) - only make the IMA keyring a trusted keyring (reported-by D. Kastatkin) - define stub integrity_init_keyring() definition based on CONFIG_INTEGRITY_SIGNATURE, not CONFIG_INTEGRITY_ASYMMETRIC_KEYS. (reported-by Jim Davis) Signed-off-by: Mimi Zohar Signed-off-by: Dmitry Kasatkin Acked-by: David Howells diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c index b4af4eb..8d4fbff 100644 --- a/security/integrity/digsig.c +++ b/security/integrity/digsig.c @@ -13,7 +13,9 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include +#include #include +#include #include #include @@ -24,7 +26,11 @@ static struct key *keyring[INTEGRITY_KEYRING_MAX]; static const char *keyring_name[INTEGRITY_KEYRING_MAX] = { "_evm", "_module", +#ifndef CONFIG_IMA_TRUSTED_KEYRING "_ima", +#else + ".ima", +#endif }; int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, @@ -56,3 +62,25 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, return -EOPNOTSUPP; } + +int integrity_init_keyring(const unsigned int id) +{ + const struct cred *cred = current_cred(); + int err = 0; + + keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0), + KGIDT_INIT(0), cred, + ((KEY_POS_ALL & ~KEY_POS_SETATTR) | + KEY_USR_VIEW | KEY_USR_READ | + KEY_USR_WRITE | KEY_USR_SEARCH), + KEY_ALLOC_NOT_IN_QUOTA, NULL); + if (!IS_ERR(keyring[id])) + set_bit(KEY_FLAG_TRUSTED_ONLY, &keyring[id]->flags); + else { + err = PTR_ERR(keyring[id]); + pr_info("Can't allocate %s keyring (%d)\n", + keyring_name[id], err); + keyring[id] = NULL; + } + return err; +} diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig index 81a2797..08758fb 100644 --- a/security/integrity/ima/Kconfig +++ b/security/integrity/ima/Kconfig @@ -123,3 +123,13 @@ config IMA_APPRAISE For more information on integrity appraisal refer to: If unsure, say N. + +config IMA_TRUSTED_KEYRING + bool "Require all keys on the .ima keyring be signed" + depends on IMA_APPRAISE && SYSTEM_TRUSTED_KEYRING + depends on INTEGRITY_ASYMMETRIC_KEYS + select KEYS_DEBUG_PROC_KEYS + default y + help + This option requires that all keys added to the .ima + keyring be signed by a key on the system trusted keyring. diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index f79fa8b..c42056e 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -249,4 +249,16 @@ static inline int security_filter_rule_match(u32 secid, u32 field, u32 op, return -EINVAL; } #endif /* CONFIG_IMA_LSM_RULES */ + +#ifdef CONFIG_IMA_TRUSTED_KEYRING +static inline int ima_init_keyring(const unsigned int id) +{ + return integrity_init_keyring(id); +} +#else +static inline int ima_init_keyring(const unsigned int id) +{ + return 0; +} +#endif /* CONFIG_IMA_TRUSTED_KEYRING */ #endif diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index f474c60..0d69643 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -325,8 +325,14 @@ static int __init init_ima(void) hash_setup(CONFIG_IMA_DEFAULT_HASH); error = ima_init(); - if (!error) - ima_initialized = 1; + if (error) + goto out; + + error = ima_init_keyring(INTEGRITY_KEYRING_IMA); + if (error) + goto out; + ima_initialized = 1; +out: return error; } diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index 33c0a70..09c440d 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -124,6 +124,7 @@ struct integrity_iint_cache *integrity_iint_find(struct inode *inode); int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, const char *digest, int digestlen); +int integrity_init_keyring(const unsigned int id); #else static inline int integrity_digsig_verify(const unsigned int id, @@ -133,6 +134,10 @@ static inline int integrity_digsig_verify(const unsigned int id, return -EOPNOTSUPP; } +static inline int integrity_init_keyring(const unsigned int id) +{ + return 0; +} #endif /* CONFIG_INTEGRITY_SIGNATURE */ #ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS -- cgit v0.10.2