lkml.org 
[lkml]   [2018]   [Mar]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v6 06/12] integrity: Introduce asymmetric_sig_has_known_key()
Date
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@linux.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 2d245f44ca26..4c381b992e11 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -179,12 +179,20 @@ 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
\
 
 \ /
  Last update: 2018-03-16 21:42    [W:0.239 / U:0.700 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site