From: THOBY Simon Date: Sun, 22 Aug 2021 08:55:26 +0000 (+0000) Subject: IMA: reject unknown hash algorithms in ima_get_hash_algo X-Git-Tag: v5.14.19~6 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=45a47382941d9702ec50608b6e4edd27c2bdd15a;p=thirdparty%2Fkernel%2Fstable.git IMA: reject unknown hash algorithms in ima_get_hash_algo commit cb181da161963eddc9de0000de6ab2c7942be219 upstream. The new function validate_hash_algo() assumed that ima_get_hash_algo() always return a valid 'enum hash_algo', but it returned the user-supplied value present in the digital signature without any bounds checks. Update ima_get_hash_algo() to always return a valid hash algorithm, defaulting on 'ima_hash_algo' when the user-supplied value inside the xattr is invalid. Signed-off-by: THOBY Simon Reported-by: syzbot+e8bafe7b82c739eaf153@syzkaller.appspotmail.com Fixes: 50f742dd9147 ("IMA: block writes of the security.ima xattr with unsupported algorithms") Reviewed-by: Lakshmi Ramasubramanian Signed-off-by: Mimi Zohar Signed-off-by: Greg Kroah-Hartman --- diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 530514df1c9a5..0f868df0f30ea 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -184,7 +184,8 @@ enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value, switch (xattr_value->type) { case EVM_IMA_XATTR_DIGSIG: sig = (typeof(sig))xattr_value; - if (sig->version != 2 || xattr_len <= sizeof(*sig)) + if (sig->version != 2 || xattr_len <= sizeof(*sig) + || sig->hash_algo >= HASH_ALGO__LAST) return ima_hash_algo; return sig->hash_algo; break;