| Message ID | 20180419103321.23397-1-kleber.souza@canonical.com |
|---|---|
| State | New |
| Headers | show |
| Series | [SRU,Trusty,CVE-2017-13305] KEYS: encrypted: fix buffer overread in valid_master_desc() | expand |
Clean cherry-pick.
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
On 04/19/2018 12:33 PM, Kleber Sacilotto de Souza wrote: > From: Eric Biggers <ebiggers@google.com> > > CVE-2017-13305 > > With the 'encrypted' key type it was possible for userspace to provide a > data blob ending with a master key description shorter than expected, > e.g. 'keyctl add encrypted desc "new x" @s'. When validating such a > master key description, validate_master_desc() could read beyond the end > of the buffer. Fix this by using strncmp() instead of memcmp(). [Also > clean up the code to deduplicate some logic.] > > Cc: Mimi Zohar <zohar@linux.vnet.ibm.com> > Signed-off-by: Eric Biggers <ebiggers@google.com> > Signed-off-by: David Howells <dhowells@redhat.com> > Signed-off-by: James Morris <james.l.morris@oracle.com> > (cherry picked from commit 794b4bc292f5d31739d89c0202c54e7dc9bc3add) > Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> Looks good. Signed-off-by: Juerg Haefliger <juergh@canonical.com> > --- > security/keys/encrypted-keys/encrypted.c | 31 +++++++++++++++---------------- > 1 file changed, 15 insertions(+), 16 deletions(-) > > diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c > index c4c8df4b214d..258bd532cbf3 100644 > --- a/security/keys/encrypted-keys/encrypted.c > +++ b/security/keys/encrypted-keys/encrypted.c > @@ -141,23 +141,22 @@ static int valid_ecryptfs_desc(const char *ecryptfs_desc) > */ > static int valid_master_desc(const char *new_desc, const char *orig_desc) > { > - if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) { > - if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN) > - goto out; > - if (orig_desc) > - if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN)) > - goto out; > - } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) { > - if (strlen(new_desc) == KEY_USER_PREFIX_LEN) > - goto out; > - if (orig_desc) > - if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN)) > - goto out; > - } else > - goto out; > + int prefix_len; > + > + if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) > + prefix_len = KEY_TRUSTED_PREFIX_LEN; > + else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) > + prefix_len = KEY_USER_PREFIX_LEN; > + else > + return -EINVAL; > + > + if (!new_desc[prefix_len]) > + return -EINVAL; > + > + if (orig_desc && strncmp(new_desc, orig_desc, prefix_len)) > + return -EINVAL; > + > return 0; > -out: > - return -EINVAL; > } > > /* >
On 19.04.2018 12:33, Kleber Sacilotto de Souza wrote: > From: Eric Biggers <ebiggers@google.com> > > CVE-2017-13305 > > With the 'encrypted' key type it was possible for userspace to provide a > data blob ending with a master key description shorter than expected, > e.g. 'keyctl add encrypted desc "new x" @s'. When validating such a > master key description, validate_master_desc() could read beyond the end > of the buffer. Fix this by using strncmp() instead of memcmp(). [Also > clean up the code to deduplicate some logic.] > > Cc: Mimi Zohar <zohar@linux.vnet.ibm.com> > Signed-off-by: Eric Biggers <ebiggers@google.com> > Signed-off-by: David Howells <dhowells@redhat.com> > Signed-off-by: James Morris <james.l.morris@oracle.com> > (cherry picked from commit 794b4bc292f5d31739d89c0202c54e7dc9bc3add) > Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> > --- Applied to trusty/master-next > security/keys/encrypted-keys/encrypted.c | 31 +++++++++++++++---------------- > 1 file changed, 15 insertions(+), 16 deletions(-) > > diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c > index c4c8df4b214d..258bd532cbf3 100644 > --- a/security/keys/encrypted-keys/encrypted.c > +++ b/security/keys/encrypted-keys/encrypted.c > @@ -141,23 +141,22 @@ static int valid_ecryptfs_desc(const char *ecryptfs_desc) > */ > static int valid_master_desc(const char *new_desc, const char *orig_desc) > { > - if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) { > - if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN) > - goto out; > - if (orig_desc) > - if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN)) > - goto out; > - } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) { > - if (strlen(new_desc) == KEY_USER_PREFIX_LEN) > - goto out; > - if (orig_desc) > - if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN)) > - goto out; > - } else > - goto out; > + int prefix_len; > + > + if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) > + prefix_len = KEY_TRUSTED_PREFIX_LEN; > + else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) > + prefix_len = KEY_USER_PREFIX_LEN; > + else > + return -EINVAL; > + > + if (!new_desc[prefix_len]) > + return -EINVAL; > + > + if (orig_desc && strncmp(new_desc, orig_desc, prefix_len)) > + return -EINVAL; > + > return 0; > -out: > - return -EINVAL; > } > > /* >
diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c index c4c8df4b214d..258bd532cbf3 100644 --- a/security/keys/encrypted-keys/encrypted.c +++ b/security/keys/encrypted-keys/encrypted.c @@ -141,23 +141,22 @@ static int valid_ecryptfs_desc(const char *ecryptfs_desc) */ static int valid_master_desc(const char *new_desc, const char *orig_desc) { - if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) { - if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN) - goto out; - if (orig_desc) - if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN)) - goto out; - } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) { - if (strlen(new_desc) == KEY_USER_PREFIX_LEN) - goto out; - if (orig_desc) - if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN)) - goto out; - } else - goto out; + int prefix_len; + + if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) + prefix_len = KEY_TRUSTED_PREFIX_LEN; + else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) + prefix_len = KEY_USER_PREFIX_LEN; + else + return -EINVAL; + + if (!new_desc[prefix_len]) + return -EINVAL; + + if (orig_desc && strncmp(new_desc, orig_desc, prefix_len)) + return -EINVAL; + return 0; -out: - return -EINVAL; } /*