From caabe240574aec05b2f5667414ce80f9075c2ba1 Mon Sep 17 00:00:00 2001 From: David Howells Date: Sat, 20 Oct 2012 01:19:29 +0100 Subject: MODSIGN: Move the magic string to the end of a module and eliminate the search Emit the magic string that indicates a module has a signature after the signature data instead of before it. This allows module_sig_check() to be made simpler and faster by the elimination of the search for the magic string. Instead we just need to do a single memcmp(). This works because at the end of the signature data there is the fixed-length signature information block. This block then falls immediately prior to the magic number. From the contents of the information block, it is trivial to calculate the size of the signature data and thus the size of the actual module data. Signed-off-by: David Howells Signed-off-by: Linus Torvalds --- kernel/module_signing.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) (limited to 'kernel/module_signing.c') diff --git a/kernel/module_signing.c b/kernel/module_signing.c index 6b09f6983ac0..d492a23df99c 100644 --- a/kernel/module_signing.c +++ b/kernel/module_signing.c @@ -183,27 +183,33 @@ static struct key *request_asymmetric_key(const char *signer, size_t signer_len, /* * Verify the signature on a module. */ -int mod_verify_sig(const void *mod, unsigned long modlen, - const void *sig, unsigned long siglen) +int mod_verify_sig(const void *mod, unsigned long *_modlen) { struct public_key_signature *pks; struct module_signature ms; struct key *key; - size_t sig_len; + const void *sig; + size_t modlen = *_modlen, sig_len; int ret; - pr_devel("==>%s(,%lu,,%lu,)\n", __func__, modlen, siglen); + pr_devel("==>%s(,%lu)\n", __func__, modlen); - if (siglen <= sizeof(ms)) + if (modlen <= sizeof(ms)) return -EBADMSG; - memcpy(&ms, sig + (siglen - sizeof(ms)), sizeof(ms)); - siglen -= sizeof(ms); + memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms)); + modlen -= sizeof(ms); sig_len = be32_to_cpu(ms.sig_len); - if (sig_len >= siglen || - siglen - sig_len != (size_t)ms.signer_len + ms.key_id_len) + if (sig_len >= modlen) return -EBADMSG; + modlen -= sig_len; + if ((size_t)ms.signer_len + ms.key_id_len >= modlen) + return -EBADMSG; + modlen -= (size_t)ms.signer_len + ms.key_id_len; + + *_modlen = modlen; + sig = mod + modlen; /* For the moment, only support RSA and X.509 identifiers */ if (ms.algo != PKEY_ALGO_RSA || -- cgit v1.2.2