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Date: Tue, 22 May 2018 21:12:45 -0300 From: Thiago Jung Bauermann <bauerman@...ux.ibm.com> To: linux-integrity@...r.kernel.org Cc: linux-security-module@...r.kernel.org, keyrings@...r.kernel.org, linux-crypto@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org, Mimi Zohar <zohar@...ux.vnet.ibm.com>, Dmitry Kasatkin <dmitry.kasatkin@...il.com>, James Morris <jmorris@...ei.org>, "Serge E. Hallyn" <serge@...lyn.com>, David Howells <dhowells@...hat.com>, David Woodhouse <dwmw2@...radead.org>, Jessica Yu <jeyu@...nel.org>, Herbert Xu <herbert@...dor.apana.org.au>, "David S. Miller" <davem@...emloft.net>, "AKASHI, Takahiro" <takahiro.akashi@...aro.org>, Thiago Jung Bauermann <bauerman@...ux.ibm.com> Subject: [PATCH v7 06/14] integrity: Introduce asymmetric_sig_has_known_key() IMA will only look for a modsig if the xattr sig references a key which is not in the expected kernel keyring. To that end, introduce asymmetric_sig_has_known_key(). The logic of extracting the key used in the xattr sig is factored out from asymmetric_verify() so that it can be used by the new function. Signed-off-by: Thiago Jung Bauermann <bauerman@...ux.ibm.com> Signed-off-by: Mimi Zohar <zohar@...ux.vnet.ibm.com> --- security/integrity/digsig_asymmetric.c | 44 +++++++++++++++++++++++++--------- security/integrity/integrity.h | 8 +++++++ 2 files changed, 41 insertions(+), 11 deletions(-) diff --git a/security/integrity/digsig_asymmetric.c b/security/integrity/digsig_asymmetric.c index ab6a029062a1..241647970c19 100644 --- a/security/integrity/digsig_asymmetric.c +++ b/security/integrity/digsig_asymmetric.c @@ -79,26 +79,48 @@ static struct key *request_asymmetric_key(struct key *keyring, uint32_t keyid) return key; } -int asymmetric_verify(struct key *keyring, const char *sig, - int siglen, const char *data, int datalen) +static struct key *asymmetric_key_from_sig(struct key *keyring, const char *sig, + int siglen) { - struct public_key_signature pks; - struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig; - struct key *key; - int ret = -ENOMEM; + const struct signature_v2_hdr *hdr = (struct signature_v2_hdr *) sig; if (siglen <= sizeof(*hdr)) - return -EBADMSG; + return ERR_PTR(-EBADMSG); siglen -= sizeof(*hdr); if (siglen != be16_to_cpu(hdr->sig_size)) - return -EBADMSG; + return ERR_PTR(-EBADMSG); if (hdr->hash_algo >= HASH_ALGO__LAST) - return -ENOPKG; + return ERR_PTR(-ENOPKG); + + return request_asymmetric_key(keyring, be32_to_cpu(hdr->keyid)); +} + +bool asymmetric_sig_has_known_key(struct key *keyring, const char *sig, + int siglen) +{ + struct key *key; + + key = asymmetric_key_from_sig(keyring, sig, siglen); + if (IS_ERR_OR_NULL(key)) + return false; + + key_put(key); + + return true; +} + +int asymmetric_verify(struct key *keyring, const char *sig, + int siglen, const char *data, int datalen) +{ + struct public_key_signature pks; + struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig; + struct key *key; + int ret = -ENOMEM; - key = request_asymmetric_key(keyring, be32_to_cpu(hdr->keyid)); + key = asymmetric_key_from_sig(keyring, sig, siglen); if (IS_ERR(key)) return PTR_ERR(key); @@ -109,7 +131,7 @@ int asymmetric_verify(struct key *keyring, const char *sig, pks.digest = (u8 *)data; pks.digest_size = datalen; pks.s = hdr->sig; - pks.s_size = siglen; + pks.s_size = siglen - sizeof(*hdr); ret = verify_signature(key, &pks); key_put(key); pr_debug("%s() = %d\n", __func__, ret); diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index d4f676906442..7f80c3e44d51 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -181,12 +181,20 @@ static inline int integrity_init_keyring(const unsigned int id) #ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS int asymmetric_verify(struct key *keyring, const char *sig, int siglen, const char *data, int datalen); +bool asymmetric_sig_has_known_key(struct key *keyring, const char *sig, + int siglen); #else static inline int asymmetric_verify(struct key *keyring, const char *sig, int siglen, const char *data, int datalen) { return -EOPNOTSUPP; } + +static inline bool asymmetric_sig_has_known_key(struct key *keyring, + const char *sig, int siglen) +{ + return false; +} #endif #ifdef CONFIG_IMA_LOAD_X509
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