4.9-stable review patch. If anyone has any objections, please let me know.
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From: Eric Biggers ebiggers@google.com
commit 4b34968e77ad09628cfb3c4a7daf2adc2cefc6e8 upstream.
The asymmetric key type allows an X.509 certificate to be added even if its signature's hash algorithm is not available in the crypto API. In that case 'payload.data[asym_auth]' will be NULL. But the key restriction code failed to check for this case before trying to use the signature, resulting in a NULL pointer dereference in key_or_keyring_common() or in restrict_link_by_signature().
Fix this by returning -ENOPKG when the signature is unsupported.
Reproducer when all the CONFIG_CRYPTO_SHA512* options are disabled and keyctl has support for the 'restrict_keyring' command:
keyctl new_session keyctl restrict_keyring @s asymmetric builtin_trusted openssl req -new -sha512 -x509 -batch -nodes -outform der \ | keyctl padd asymmetric desc @s
Fixes: a511e1af8b12 ("KEYS: Move the point of trust determination to __key_link()") Cc: stable@vger.kernel.org # v4.7+ Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: David Howells dhowells@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- crypto/asymmetric_keys/restrict.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/crypto/asymmetric_keys/restrict.c +++ b/crypto/asymmetric_keys/restrict.c @@ -66,8 +66,9 @@ __setup("ca_keys=", ca_keys_setup); * * Returns 0 if the new certificate was accepted, -ENOKEY if we couldn't find a * matching parent certificate in the trusted list, -EKEYREJECTED if the - * signature check fails or the key is blacklisted and some other error if - * there is a matching certificate but the signature check cannot be performed. + * signature check fails or the key is blacklisted, -ENOPKG if the signature + * uses unsupported crypto, or some other error if there is a matching + * certificate but the signature check cannot be performed. */ int restrict_link_by_signature(struct key *trust_keyring, const struct key_type *type, @@ -86,6 +87,8 @@ int restrict_link_by_signature(struct ke return -EOPNOTSUPP;
sig = payload->data[asym_auth]; + if (!sig) + return -ENOPKG; if (!sig->auth_ids[0] && !sig->auth_ids[1]) return -ENOKEY;