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gnupg/g10/key-check.c

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/* key-check.c - Detect and fix various problems with keys
* Copyright (C) 1998-2010 Free Software Foundation, Inc.
* Copyright (C) 1998-2017 Werner Koch
* Copyright (C) 2015-2018 g10 Code GmbH
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* GnuPG is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses/>.
*/
#include <config.h>
#include "gpg.h"
#include "options.h"
#include "packet.h"
#include "keydb.h"
#include "main.h"
#include "../common/ttyio.h"
#include "../common/i18n.h"
#include "keyedit.h"
#include "key-check.h"
/* Print PREFIX followed by TEXT. With mode > 0 use log_info, with
* mode < 0 use ttyio, else print to stdout. If TEXT is not NULL, it
* may be modified by this function. */
static void
print_info (int mode, const char *prefix, char *text)
{
char *p;
if (!text)
text = "";
else if ((p = strchr (text,'\n')))
*p = 0; /* Strip LF. */
if (mode > 0)
log_info ("%s %s\n", prefix, text);
else
tty_fprintf (mode? NULL:es_stdout, "%s %s\n", prefix, text);
}
/* Order two signatures. The actual ordering isn't important. Our
* goal is to ensure that identical signatures occur together. */
static int
sig_comparison (const void *av, const void *bv)
{
const KBNODE an = *(const KBNODE *) av;
const KBNODE bn = *(const KBNODE *) bv;
const PKT_signature *a;
const PKT_signature *b;
int ndataa;
int ndatab;
int i;
log_assert (an->pkt->pkttype == PKT_SIGNATURE);
log_assert (bn->pkt->pkttype == PKT_SIGNATURE);
a = an->pkt->pkt.signature;
b = bn->pkt->pkt.signature;
/* Signatures with a different help counter are not identical for
* our purpose. */
if (a->help_counter < b->help_counter)
return -1;
if (a->help_counter > b->help_counter)
return 1;
if (a->digest_algo < b->digest_algo)
return -1;
if (a->digest_algo > b->digest_algo)
return 1;
ndataa = pubkey_get_nsig (a->pubkey_algo);
ndatab = pubkey_get_nsig (b->pubkey_algo);
if (ndataa != ndatab)
return (ndataa < ndatab)? -1 : 1;
for (i = 0; i < ndataa; i ++)
{
int c = gcry_mpi_cmp (a->data[i], b->data[i]);
if (c != 0)
return c;
}
/* Okay, they are equal. */
return 0;
}
static gpg_error_t
remove_duplicate_sigs (kbnode_t kb, int *dups, int *modified)
{
gpg_error_t err;
kbnode_t n;
int nsigs;
kbnode_t *sigs; /* Allocated array with the signature packet. */
int i;
int last_i;
int block;
PKT_signature *sig;
/* Count the sigs. */
for (nsigs = 0, n = kb; n; n = n->next)
{
if (is_deleted_kbnode (n))
continue;
else if (n->pkt->pkttype == PKT_SIGNATURE)
nsigs ++;
}
if (!nsigs)
return 0; /* No signatures at all. */
/* Add them all to the SIGS array. */
sigs = xtrycalloc (nsigs, sizeof *sigs);
if (!sigs)
{
err = gpg_error_from_syserror ();
log_error (_("error allocating memory: %s\n"), gpg_strerror (err));
return err;
}
block = 0;
i = 0;
for (n = kb; n; n = n->next)
{
if (is_deleted_kbnode (n))
continue;
if (n->pkt->pkttype != PKT_SIGNATURE)
{
switch (n->pkt->pkttype)
{
case PKT_PUBLIC_SUBKEY:
case PKT_SECRET_SUBKEY:
case PKT_USER_ID:
case PKT_ATTRIBUTE:
/* Bump the block number so that we only consider
* signatures below the same object as duplicates. */
block++;
break;
default:
break;
}
continue;
}
sig = n->pkt->pkt.signature;
sig->help_counter = block;
sigs[i++] = n;
}
log_assert (i == nsigs);
qsort (sigs, nsigs, sizeof (sigs[0]), sig_comparison);
last_i = 0;
for (i = 1; i < nsigs; i ++)
{
log_assert (sigs[last_i]);
log_assert (sigs[last_i]->pkt->pkttype == PKT_SIGNATURE);
log_assert (sigs[i]);
log_assert (sigs[i]->pkt->pkttype == PKT_SIGNATURE);
if (sig_comparison (&sigs[last_i], &sigs[i]) == 0)
{
/* They are the same. Kill the latter. */
if (DBG_PACKET)
{
sig = sigs[i]->pkt->pkt.signature;
log_debug ("Signature appears multiple times, "
"deleting duplicate:\n");
log_debug (" sig: class 0x%x, issuer: %s,"
" timestamp: %s (%lld), digest: %02x %02x\n",
sig->sig_class, keystr (sig->keyid),
isotimestamp (sig->timestamp),
(long long) sig->timestamp,
sig->digest_start[0], sig->digest_start[1]);
}
/* Remove sigs[i] from the keyblock. */
{
kbnode_t z, *prevp;
int to_kill = last_i;
last_i = i;
for (prevp = &kb, z = kb; z; prevp = &z->next, z = z->next)
if (z == sigs[to_kill])
break;
*prevp = sigs[to_kill]->next;
sigs[to_kill]->next = NULL;
release_kbnode (sigs[to_kill]);
sigs[to_kill] = NULL;
++*dups;
*modified = 1;
}
}
else
last_i = i;
}
xfree (sigs);
return 0;
}
/* Perform a few sanity checks on a keyblock is okay and possibly
* repair some damage. Concretely:
*
* - Detect duplicate signatures and remove them.
*
* - Detect out of order signatures and relocate them (e.g., a sig
* over user id X located under subkey Y).
*
* Note: this function does not remove signatures that don't belong or
* components that are not signed! (Although it would be trivial to
* do so.)
*
* If ONLY_SELFSIGS is true, then this function only reorders self
* signatures (it still checks all signatures for duplicates,
* however).
*
* Allowed values for MODE are:
* -1 - print to the TTY
* 0 - print to stdout
* 1 - use log_info.
*
* Returns true if the keyblock was modified. */
int
key_check_all_keysigs (ctrl_t ctrl, int mode, kbnode_t kb,
int only_selected, int only_selfsigs)
{
gpg_error_t err;
PKT_public_key *pk;
KBNODE n, n_next, *n_prevp, n2;
char *pending_desc = NULL;
PKT_public_key *issuer;
KBNODE last_printed_component;
KBNODE current_component = NULL;
int dups = 0;
int missing_issuer = 0;
int reordered = 0;
int bad_signature = 0;
int missing_selfsig = 0;
int modified = 0;
PKT_signature *sig;
(void)missing_selfsig;
log_assert (kb->pkt->pkttype == PKT_PUBLIC_KEY);
pk = kb->pkt->pkt.public_key;
/* First we look for duplicates. */
if (remove_duplicate_sigs (kb, &dups, &modified))
goto leave; /* Error */
/* Now make sure the sigs occur after the component (aka block)
* (public key, subkey, user id) that they sign. */
issuer = NULL;
last_printed_component = NULL;
for (n_prevp = &kb, n = kb;
n;
/* If we moved n, then n_prevp is need valid. */
n_prevp = (n->next == n_next ? &n->next : n_prevp), n = n_next)
{
PACKET *p;
int processed_current_component;
int rc;
int dump_sig_params = 0;
n_next = n->next;
if (is_deleted_kbnode (n))
continue;
p = n->pkt;
if (issuer && issuer != pk)
{
free_public_key (issuer);
issuer = NULL;
}
xfree (pending_desc);
pending_desc = NULL;
switch (p->pkttype)
{
case PKT_PUBLIC_KEY:
log_assert (p->pkt.public_key == pk);
if (only_selected && ! (n->flag & NODFLG_SELKEY))
{
current_component = NULL;
break;
}
if (DBG_PACKET)
log_debug ("public key %s: timestamp: %s (%lld)\n",
pk_keyid_str (pk),
isotimestamp (pk->timestamp),
(long long) pk->timestamp);
current_component = n;
break;
case PKT_PUBLIC_SUBKEY:
if (only_selected && ! (n->flag & NODFLG_SELKEY))
{
current_component = NULL;
break;
}
if (DBG_PACKET)
log_debug ("subkey %s: timestamp: %s (%lld)\n",
pk_keyid_str (p->pkt.public_key),
isotimestamp (p->pkt.public_key->timestamp),
(long long) p->pkt.public_key->timestamp);
current_component = n;
break;
case PKT_USER_ID:
if (only_selected && ! (n->flag & NODFLG_SELUID))
{
current_component = NULL;
break;
}
if (DBG_PACKET)
log_debug ("user id: %s\n",
p->pkt.user_id->attrib_data
? "[ photo id ]"
: p->pkt.user_id->name);
current_component = n;
break;
case PKT_SIGNATURE:
if (! current_component)
/* The current component is not selected, don't check the
sigs under it. */
break;
sig = n->pkt->pkt.signature;
pending_desc = xasprintf (" sig: class: 0x%x, issuer: %s,"
" timestamp: %s (%lld), digest: %02x %02x",
sig->sig_class,
keystr (sig->keyid),
isotimestamp (sig->timestamp),
(long long) sig->timestamp,
sig->digest_start[0], sig->digest_start[1]);
if (keyid_cmp (pk_keyid (pk), sig->keyid) == 0)
issuer = pk;
else /* Issuer is a different key. */
{
if (only_selfsigs)
continue;
issuer = xtrycalloc (1, sizeof *issuer);
if (!issuer)
err = gpg_error_from_syserror ();
else
err = get_pubkey (ctrl, issuer, sig->keyid);
if (err)
{
xfree (issuer);
issuer = NULL;
if (DBG_PACKET)
{
if (pending_desc)
log_debug ("%s", pending_desc);
log_debug (" Can't check signature allegedly"
" issued by %s: %s\n",
keystr (sig->keyid), gpg_strerror (err));
}
missing_issuer ++;
break;
}
}
if ((err = openpgp_pk_test_algo (sig->pubkey_algo)))
{
if (DBG_PACKET && pending_desc)
log_debug ("%s", pending_desc);
log_info (_("can't check signature with unsupported"
" public-key algorithm (%d): %s.\n"),
sig->pubkey_algo, gpg_strerror (err));
break;
}
if ((err = openpgp_md_test_algo (sig->digest_algo)))
{
if (DBG_PACKET && pending_desc)
log_debug ("%s", pending_desc);
log_info (_("can't check signature with unsupported"
" message-digest algorithm %d: %s.\n"),
sig->digest_algo, gpg_strerror (err));
break;
}
/* We iterate over the keyblock. Most likely, the matching
component is the current component so always try that
first. */
processed_current_component = 0;
for (n2 = current_component;
n2;
n2 = (processed_current_component ? n2->next : kb),
processed_current_component = 1)
if (is_deleted_kbnode (n2))
continue;
else if (processed_current_component && n2 == current_component)
/* Don't process it twice. */
continue;
else
{
err = check_signature_over_key_or_uid (ctrl,
issuer, sig, kb, n2->pkt,
NULL, NULL);
if (! err)
break;
}
/* n/sig is a signature and n2 is the component (public key,
subkey or user id) that it signs, if any.
current_component is that component that it appears to
apply to (according to the ordering). */
if (current_component == n2)
{
if (DBG_PACKET)
{
log_debug ("%s", pending_desc);
log_debug (" Good signature over last key or uid!\n");
}
rc = 0;
}
else if (n2)
{
log_assert (n2->pkt->pkttype == PKT_USER_ID
|| n2->pkt->pkttype == PKT_PUBLIC_KEY
|| n2->pkt->pkttype == PKT_PUBLIC_SUBKEY);
if (DBG_PACKET)
{
log_debug ("%s", pending_desc);
log_debug (" Good signature out of order!"
" (Over %s (%d) '%s')\n",
n2->pkt->pkttype == PKT_USER_ID
? "user id"
: n2->pkt->pkttype == PKT_PUBLIC_SUBKEY
? "subkey"
: "primary key",
n2->pkt->pkttype,
n2->pkt->pkttype == PKT_USER_ID
? n2->pkt->pkt.user_id->name
: pk_keyid_str (n2->pkt->pkt.public_key));
}
/* Reorder the packets: move the signature n to be just
after n2. */
/* Unlink the signature. */
log_assert (n_prevp);
*n_prevp = n->next;
/* Insert the sig immediately after the component. */
n->next = n2->next;
n2->next = n;
reordered ++;
modified = 1;
rc = 0;
}
else
{
if (DBG_PACKET)
{
log_debug ("%s", pending_desc);
log_debug (" Bad signature.\n");
}
if (DBG_PACKET)
dump_sig_params = 1;
bad_signature ++;
rc = GPG_ERR_BAD_SIGNATURE;
}
/* We don't cache the result here, because we haven't
completely checked that the signature is legitimate. For
instance, if we have a revocation certificate on Alice's
key signed by Bob, the signature may be good, but we
haven't checked that Bob is a designated revoker. */
/* cache_sig_result (sig, rc); */
{
int has_selfsig = 0;
if (! rc && issuer == pk)
{
if (n2->pkt->pkttype == PKT_PUBLIC_KEY
&& (/* Direct key signature. */
sig->sig_class == 0x1f
/* Key revocation signature. */
|| sig->sig_class == 0x20))
has_selfsig = 1;
if (n2->pkt->pkttype == PKT_PUBLIC_SUBKEY
&& (/* Subkey binding sig. */
sig->sig_class == 0x18
/* Subkey revocation sig. */
|| sig->sig_class == 0x28))
has_selfsig = 1;
if (n2->pkt->pkttype == PKT_USER_ID
&& (/* Certification sigs. */
sig->sig_class == 0x10
|| sig->sig_class == 0x11
|| sig->sig_class == 0x12
|| sig->sig_class == 0x13
/* Certification revocation sig. */
|| sig->sig_class == 0x30))
has_selfsig = 1;
}
if (DBG_PACKET
&& ((n2 && n2 != last_printed_component)
|| (! n2 && last_printed_component != current_component)))
{
int is_reordered = n2 && n2 != current_component;
if (n2)
last_printed_component = n2;
else
last_printed_component = current_component;
if (!modified)
;
else if (last_printed_component->pkt->pkttype == PKT_USER_ID)
{
log_debug ("uid ");
print_utf8_buffer (log_get_stream (),
last_printed_component
->pkt->pkt.user_id->name,
last_printed_component
->pkt->pkt.user_id->len);
log_flush ();
}
else if (last_printed_component->pkt->pkttype
== PKT_PUBLIC_KEY)
log_debug ("pub %s\n",
pk_keyid_str (last_printed_component
->pkt->pkt.public_key));
else
log_debug ("sub %s\n",
pk_keyid_str (last_printed_component
->pkt->pkt.public_key));
if (modified)
{
if (is_reordered)
log_debug ("%s\n", _(" (reordered signatures follow)"));
}
}
if (DBG_PACKET && modified)
keyedit_print_one_sig (ctrl, log_get_stream (),
rc, kb, n, NULL, NULL, NULL,
has_selfsig, 0, only_selfsigs);
}
if (dump_sig_params)
{
int i;
for (i = 0; i < pubkey_get_nsig (sig->pubkey_algo); i ++)
{
char buffer[1024];
size_t len;
char *printable;
if (gcry_mpi_get_flag (sig->data[i], GCRYMPI_FLAG_OPAQUE))
{
const byte *sigdata;
unsigned int nbits;
sigdata = gcry_mpi_get_opaque (sig->data[i], &nbits);
len = (nbits+7)/8;
memcpy (buffer, sigdata, len);
}
else
gcry_mpi_print (GCRYMPI_FMT_USG,
buffer, sizeof (buffer), &len,
sig->data[i]);
printable = bin2hex (buffer, len, NULL);
log_debug (" %d: %s\n", i, printable);
xfree (printable);
}
}
break;
default:
if (DBG_PACKET)
log_debug ("unhandled packet: %d\n", p->pkttype);
break;
}
}
xfree (pending_desc);
pending_desc = NULL;
if (issuer != pk)
free_public_key (issuer);
issuer = NULL;
/* If we reordered signatures we need to de-duplicate again because
* a signature can now be a duplicate in another block. */
if (reordered)
{
if (remove_duplicate_sigs (kb, &dups, &modified))
goto leave;
}
/* Identify keys / uids that don't have a self-sig. */
{
int has_selfsig = 0;
PACKET *p;
current_component = NULL;
for (n = kb; n; n = n->next)
{
if (is_deleted_kbnode (n))
continue;
p = n->pkt;
switch (p->pkttype)
{
case PKT_PUBLIC_KEY:
case PKT_PUBLIC_SUBKEY:
case PKT_USER_ID:
if (current_component && ! has_selfsig)
missing_selfsig ++;
current_component = n;
has_selfsig = 0;
break;
case PKT_SIGNATURE:
if (! current_component || has_selfsig)
break;
sig = n->pkt->pkt.signature;
if (! (sig->flags.checked && sig->flags.valid))
break;
if (keyid_cmp (pk_keyid (pk), sig->keyid) != 0)
/* Different issuer, couldn't be a self-sig. */
break;
if (current_component->pkt->pkttype == PKT_PUBLIC_KEY
&& (/* Direct key signature. */
sig->sig_class == 0x1f
/* Key revocation signature. */
|| sig->sig_class == 0x20))
has_selfsig = 1;
if (current_component->pkt->pkttype == PKT_PUBLIC_SUBKEY
&& (/* Subkey binding sig. */
sig->sig_class == 0x18
/* Subkey revocation sig. */
|| sig->sig_class == 0x28))
has_selfsig = 1;
if (current_component->pkt->pkttype == PKT_USER_ID
&& (/* Certification sigs. */
sig->sig_class == 0x10
|| sig->sig_class == 0x11
|| sig->sig_class == 0x12
|| sig->sig_class == 0x13
/* Certification revocation sig. */
|| sig->sig_class == 0x30))
has_selfsig = 1;
break;
default:
if (current_component && ! has_selfsig)
missing_selfsig ++;
current_component = NULL;
}
}
}
leave:
if (!opt.quiet)
{
char prefix[100];
char *p;
/* To avoid string changes in 2.2 we strip the LF here. */
snprintf (prefix, sizeof prefix, _("key %s:\n"), pk_keyid_str (pk));
p = strrchr (prefix, '\n');
if (p)
*p = 0;
if (dups)
{
p = xtryasprintf
(ngettext ("%d duplicate signature removed\n",
"%d duplicate signatures removed\n", dups), dups);
print_info (mode, prefix, p);
xfree (p);
}
if (missing_issuer)
{
p = xtryasprintf
(ngettext ("%d signature not checked due to a missing key\n",
"%d signatures not checked due to missing keys\n",
missing_issuer), missing_issuer);
print_info (mode, prefix, p);
xfree (p);
}
if (bad_signature)
{
p = xtryasprintf (ngettext ("%d bad signature\n",
"%d bad signatures\n",
bad_signature), bad_signature);
print_info (mode, prefix, p);
xfree (p);
}
if (reordered)
{
p = xtryasprintf (ngettext ("%d signature reordered\n",
"%d signatures reordered\n",
reordered), reordered);
print_info (mode, prefix, p);
xfree (p);
}
if (only_selfsigs && (bad_signature || reordered))
{
p = xtryasprintf
(_("Warning: errors found and only checked self-signatures,"
" run '%s' to check all signatures.\n"), "check");
print_info (mode, prefix, p);
xfree (p);
}
}
return modified;
}
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