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gpg: Avoid using cached MD5 signature status.

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* g10/sig-check.c (check_key_signature2): Avoid using a cached MD5
signature status.
* g10/keyring.c (keyring_get_keyblock): Ditto.
(write_keyblock): Ditto.

* g10/sig-check.c (do_check): Move reject warning to ...
* g10/misc.c (print_md5_rejected_note): new.
--

Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch 2014-10-11 19:41:51 +02:00
parent f952fe8c6d
commit 9112fed78b
4 changed files with 145 additions and 125 deletions
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14
g10/keyring.c
View File

@ -434,12 +434,19 @@ keyring_get_keyblock (KEYRING_HANDLE hd, KBNODE *ret_kb)
&& (pkt->pkt.ring_trust->sigcache & 1) ) {
/* This is a ring trust packet with a checked signature
* status cache following directly a signature paket.
* Set the cache status into that signature packet. */
* Set the cache status into that signature packet.
*
* We do not use cached signatures made with MD5 to
* avoid using a cached status created with an older
* version of gpg. */
PKT_signature *sig = lastnode->pkt->pkt.signature;
if (sig->digest_algo != DIGEST_ALGO_MD5)
{
sig->flags.checked = 1;
sig->flags.valid = !!(pkt->pkt.ring_trust->sigcache & 2);
}
}
/* Reset LASTNODE, so that we set the cache status only from
* the ring trust packet immediately following a signature. */
lastnode = NULL;
@ -490,9 +497,12 @@ keyring_get_keyblock (KEYRING_HANDLE hd, KBNODE *ret_kb)
&& lastnode->pkt->pkttype == PKT_SIGNATURE
&& (pkt->pkt.ring_trust->sigcache & 1) ) {
PKT_signature *sig = lastnode->pkt->pkt.signature;
if (sig->digest_algo != DIGEST_ALGO_MD5)
{
sig->flags.checked = 1;
sig->flags.valid = !!(pkt->pkt.ring_trust->sigcache & 2);
}
}
*ret_kb = keyblock;
}
free_packet (pkt);
@ -1354,7 +1364,7 @@ write_keyblock (IOBUF fp, KBNODE keyblock)
PKT_signature *sig = node->pkt->pkt.signature;
unsigned int cacheval = 0;
if (sig->flags.checked)
if (sig->flags.checked && sig->digest_algo != DIGEST_ALGO_MD5)
{
cacheval |= 1;
if (sig->flags.valid)

7
g10/main.h
View File

@ -63,9 +63,6 @@ extern int g10_errors_seen;
#else
void g10_exit(int rc);
#endif
void print_pubkey_algo_note( int algo );
void print_cipher_algo_note( int algo );
void print_digest_algo_note( int algo );
/*-- armor.c --*/
char *make_radix64_string( const byte *data, size_t len );
@ -82,6 +79,10 @@ u16 checksum( byte *p, unsigned n );
u16 checksum_mpi( gcry_mpi_t a );
u32 buffer_to_u32( const byte *buffer );
const byte *get_session_marker( size_t *rlen );
void print_pubkey_algo_note( int algo );
void print_cipher_algo_note( int algo );
void print_digest_algo_note( int algo );
void print_md5_rejected_note (void);
int map_cipher_openpgp_to_gcry (int algo);
#define openpgp_cipher_open(_a,_b,_c,_d) gcry_cipher_open((_a),map_cipher_openpgp_to_gcry((_b)),(_c),(_d))
#define openpgp_cipher_get_algo_keylen(_a) gcry_cipher_get_algo_keylen(map_cipher_openpgp_to_gcry((_a)))

16
g10/misc.c
View File

@ -340,6 +340,22 @@ print_digest_algo_note( int algo )
}
void
print_md5_rejected_note (void)
{
static int shown;
if (!shown)
{
fflush (stdout);
log_info
(_("Note: signatures using the %s algorithm are rejected\n"),
"MD5");
shown = 1;
}
}
/* Map OpenPGP algo numbers to those used by Libgcrypt. We need to do
this for algorithms we implemented in Libgcrypt after they become
part of OpenPGP. */

17
g10/sig-check.c
View File

@ -272,16 +272,7 @@ do_check( PKT_public_key *pk, PKT_signature *sig, gcry_md_hd_t digest,
if (sig->digest_algo == GCRY_MD_MD5
&& !opt.flags.allow_weak_digest_algos)
{
static int shown;
if (!shown)
{
log_info
(_("Note: signatures using the %s algorithm are rejected\n"),
"MD5");
shown = 1;
}
print_md5_rejected_note ();
return GPG_ERR_DIGEST_ALGO;
}
@ -549,9 +540,11 @@ check_key_signature2( KBNODE root, KBNODE node, PKT_public_key *check_pk,
/* Check whether we have cached the result of a previous signature
check. Note that we may no longer have the pubkey or hash
needed to verify a sig, but can still use the cached value. A
cache refresh detects and clears these cases. */
cache refresh detects and clears these cases.
For safety reasons we ignore cache entries from MD5 signatures. */
if ( !opt.no_sig_cache ) {
if (sig->flags.checked) { /*cached status available*/
if (sig->flags.checked && sig->digest_algo != DIGEST_ALGO_MD5) {
/*cached status available*/
if( is_selfsig ) {
u32 keyid[2];