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-rw-r--r--g10/key-check.c750
1 files changed, 750 insertions, 0 deletions
diff --git a/g10/key-check.c b/g10/key-check.c
new file mode 100644
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--- /dev/null
+++ b/g10/key-check.c
@@ -0,0 +1,750 @@
+/* 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;
+
+ 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;
+ 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;
+}