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gnupg2/backport-0004-CVE-2025-30258-gpg-Fix-regression-for-the-recent-malicious-subkey-D.patch
yixiangzhike cf184233d5 Fix CVE-2025-30258
2025-05-06 15:50:10 +08:00

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From 3339c147b6f5b684900e2721929d52021682a761 Mon Sep 17 00:00:00 2001
From: Werner Koch <wk@gnupg.org>
Date: Thu, 6 Mar 2025 17:17:17 +0100
Subject: [PATCH 4/4] gpg: Fix regression for the recent malicious subkey DoS
fix.
* g10/packet.h (PUBKEY_USAGE_VERIFY): New.
* g10/getkey.c (get_pubkey_for_sig): Pass new flag also to requested
usage.
(finish_lookup): Introduce a verify_mode.
--
Fixes-commit: da0164efc7f32013bc24d97b9afa9f8d67c318bb
GnuPG-bug-id: 7547
Reference link:
https://salsa.debian.org/debian/gnupg2/-/blob/debian/2.2.46-6/debian/patches/from-2.4/gpg-Fix-regression-for-the-recent-malicious-subkey-DoS-fi.patch
Signed-off-by: baogen shang <baogen.shang@windriver.com>
---
g10/getkey.c | 43 +++++++++++++++++++++++++++----------------
g10/packet.h | 1 +
2 files changed, 28 insertions(+), 16 deletions(-)
diff --git a/g10/getkey.c b/g10/getkey.c
index bb23491..ce5c46f 100644
--- a/g10/getkey.c
+++ b/g10/getkey.c
@@ -422,11 +422,12 @@ pk_from_block (PKT_public_key *pk, kbnode_t keyblock, kbnode_t found_key)
/* Specialized version of get_pubkey which retrieves the key based on
- * information in SIG. In contrast to get_pubkey PK is required. IF
+ * information in SIG. In contrast to get_pubkey PK is required. If
* FORCED_PK is not NULL, this public key is used and copied to PK.
* If R_KEYBLOCK is not NULL the entire keyblock is stored there if
* found and FORCED_PK is not used; if not used or on error NULL is
- * stored there. */
+ * stored there. Use this function only to find the key for
+ * verification; it can't be used to select a key for signing. */
gpg_error_t
get_pubkey_for_sig (ctrl_t ctrl, PKT_public_key *pk, PKT_signature *sig,
PKT_public_key *forced_pk, kbnode_t *r_keyblock)
@@ -446,8 +447,9 @@ get_pubkey_for_sig (ctrl_t ctrl, PKT_public_key *pk, PKT_signature *sig,
/* Make sure to request only keys cabable of signing. This makes
* sure that a subkey w/o a valid backsig or with bad usage flags
- * will be skipped. */
- pk->req_usage = PUBKEY_USAGE_SIG;
+ * will be skipped. We also request the verification mode so that
+ * expired and reoked keys are returned. */
+ pk->req_usage = (PUBKEY_USAGE_SIG | PUBKEY_USAGE_VERIFY);
/* First try the new ISSUER_FPR info. */
fpr = issuer_fpr_raw (sig, &fprlen);
@@ -511,10 +513,10 @@ get_pubkey_bykid (ctrl_t ctrl, PKT_public_key *pk, kbnode_t *r_keyblock,
/* Try to get it from the cache. We don't do this when pk is
* NULL as it does not guarantee that the user IDs are cached.
* The old get_pubkey_function did not check PK->REQ_USAGE when
- * reading form the caceh. This is probably a bug. Note that
+ * reading from the cache. This is probably a bug. Note that
* the cache is not used when the caller asked to return the
* entire keyblock. This is because the cache does not
- * associate the public key wit its primary key. */
+ * associate the public key with its primary key. */
pk_cache_entry_t ce;
for (ce = pk_cache; ce; ce = ce->next)
{
@@ -3690,11 +3692,18 @@ finish_lookup (kbnode_t keyblock, unsigned int req_usage, int want_exact,
PKT_public_key *pk;
int req_prim;
int diag_exactfound = 0;
+ int verify_mode = 0;
u32 curtime = make_timestamp ();
if (r_flags)
*r_flags = 0;
+
+ /* The verify mode is used to change the behaviour so that we can
+ * return an expired or revoked key for signature verification. */
+ verify_mode = ((req_usage & PUBKEY_USAGE_VERIFY)
+ && (req_usage & PUBKEY_USAGE_SIG));
+
#define USAGE_MASK (PUBKEY_USAGE_SIG|PUBKEY_USAGE_ENC|PUBKEY_USAGE_CERT)
req_usage &= USAGE_MASK;
@@ -3738,9 +3747,9 @@ finish_lookup (kbnode_t keyblock, unsigned int req_usage, int want_exact,
}
if (DBG_LOOKUP)
- log_debug ("finish_lookup: checking key %08lX (%s)(req_usage=%x)\n",
+ log_debug ("finish_lookup: checking key %08lX (%s)(req_usage=%x%s)\n",
(ulong) keyid_from_pk (keyblock->pkt->pkt.public_key, NULL),
- foundk ? "one" : "all", req_usage);
+ foundk ? "one" : "all", req_usage, verify_mode? ",verify":"");
if (diag_exactfound && DBG_LOOKUP)
log_debug ("\texact search requested and found\n");
@@ -3802,28 +3811,28 @@ finish_lookup (kbnode_t keyblock, unsigned int req_usage, int want_exact,
}
n_subkeys++;
- if (pk->flags.revoked)
+ if (!verify_mode && pk->flags.revoked)
{
if (DBG_LOOKUP)
log_debug ("\tsubkey has been revoked\n");
n_revoked_or_expired++;
continue;
}
- if (pk->has_expired)
+ if (!verify_mode && pk->has_expired)
{
if (DBG_LOOKUP)
log_debug ("\tsubkey has expired\n");
n_revoked_or_expired++;
continue;
}
- if (pk->timestamp > curtime && !opt.ignore_valid_from)
+ if (!verify_mode && pk->timestamp > curtime && !opt.ignore_valid_from)
{
if (DBG_LOOKUP)
log_debug ("\tsubkey not yet valid\n");
continue;
}
- if (want_secret && agent_probe_secret_key (NULL, pk))
+ if (!verify_mode && want_secret && agent_probe_secret_key (NULL, pk))
{
if (DBG_LOOKUP)
log_debug ("\tno secret key\n");
@@ -3831,7 +3840,8 @@ finish_lookup (kbnode_t keyblock, unsigned int req_usage, int want_exact,
}
if (DBG_LOOKUP)
- log_debug ("\tsubkey might be fine\n");
+ log_debug ("\tsubkey might be fine%s\n",
+ verify_mode? " for verification":"");
/* In case a key has a timestamp of 0 set, we make sure
that it is used. A better change would be to compare
">=" but that might also change the selected keys and
@@ -3872,12 +3882,12 @@ finish_lookup (kbnode_t keyblock, unsigned int req_usage, int want_exact,
log_debug ("\tprimary key usage does not match: "
"want=%x have=%x\n", req_usage, pk->pubkey_usage);
}
- else if (pk->flags.revoked)
+ else if (!verify_mode && pk->flags.revoked)
{
if (DBG_LOOKUP)
log_debug ("\tprimary key has been revoked\n");
}
- else if (pk->has_expired)
+ else if (!verify_mode && pk->has_expired)
{
if (DBG_LOOKUP)
log_debug ("\tprimary key has expired\n");
@@ -3885,7 +3895,8 @@ finish_lookup (kbnode_t keyblock, unsigned int req_usage, int want_exact,
else /* Okay. */
{
if (DBG_LOOKUP)
- log_debug ("\tprimary key may be used\n");
+ log_debug ("\tprimary key may be used%s\n",
+ verify_mode? " for verification":"");
latest_key = keyblock;
}
}
diff --git a/g10/packet.h b/g10/packet.h
index 6a8ac79..ca7aad9 100644
--- a/g10/packet.h
+++ b/g10/packet.h
@@ -135,6 +135,7 @@ typedef struct {
gcry_mpi_t data[PUBKEY_MAX_NENC];
} PKT_pubkey_enc;
+#define PUBKEY_USAGE_VERIFY 16384 /* Verify only modifier. */
/* A one-pass signature packet as defined in RFC 4880, Section
5.4. All fields are serialized. */
--
2.33.0
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