gpg: New command --quick-revoke-sig

* g10/gpg.c (enum cmd_and_opt_values): Add aQuickRevSig.
(opts): Add --quick-revoke-sig.
(main): Implement.
* g10/keyedit.c (quick_find_keyblock): Add arg 'want_secret' and
adjust all callers.
(keyedit_quick_revsig): new.
* g10/revoke.c (get_default_sig_revocation_reason): New.
* g10/keylist.c (cmp_signodes): Make global.
--

GnuPG-bug-id: 5093

7 files changed, 288 insertions, 9 deletions

diff --git a/doc/gpg.texi b/doc/gpg.texi
index ccb0689f6..48e52e98f 100644
--- a/doc/gpg.texi
+++ b/doc/gpg.texi
@@ -1147,6 +1147,17 @@ you want to specify a different revocation reason, or to supply
 supplementary revocation text, you should use the interactive
 sub-command @code{revuid} of @option{--edit-key}.
 
+@item --quick-revoke-sig  @var{fpr} @var{signing-fpr} [@var{names}]
+@opindex quick-revoke-sig
+This command revokes the key signatures made by @var{signing-fpr} from
+the key specified by the fingerprint @var{fpr}.  With @var{names}
+given only the signatures on user ids of the key matching any of the
+given names are affected (see @option{--quick-sign-key}).  If a
+revocation already exists a notice is printed instead of creating a
+new revocation; no error is returned in this case.  Note that key
+signature revocations may be superseded by a newer key signature and
+in turn again revoked.
+
 @item --quick-set-primary-uid  @var{user-id} @var{primary-user-id}
 @opindex quick-set-primary-uid
 This command sets or updates the primary user ID flag on an existing
diff --git a/g10/gpg.c b/g10/gpg.c
index 910977a6c..ae890ca9e 100644
--- a/g10/gpg.c
+++ b/g10/gpg.c
@@ -129,6 +129,7 @@ enum cmd_and_opt_values
     aLSignKey,
     aQuickSignKey,
     aQuickLSignKey,
+    aQuickRevSig,
     aQuickAddUid,
     aQuickAddKey,
     aQuickRevUid,
@@ -499,6 +500,8 @@ static gpgrt_opt_t opts[] = {
               N_("quickly sign a key")),
   ARGPARSE_c (aQuickLSignKey, "quick-lsign-key",
               N_("quickly sign a key locally")),
+  ARGPARSE_c (aQuickRevSig,   "quick-revoke-sig" ,
+              N_("quickly revoke a key signature")),
   ARGPARSE_c (aSignKey,  "sign-key"   ,N_("sign a key")),
   ARGPARSE_c (aLSignKey, "lsign-key"  ,N_("sign a key locally")),
   ARGPARSE_c (aEditKey,  "edit-key"   ,N_("sign or edit a key")),
@@ -2631,6 +2634,7 @@ main (int argc, char **argv)
 	  case aSign:
 	  case aQuickSignKey:
 	  case aQuickLSignKey:
+	  case aQuickRevSig:
 	  case aSignKey:
 	  case aLSignKey:
 	  case aStore:
@@ -4446,6 +4450,22 @@ main (int argc, char **argv)
         }
 	break;
 
+      case aQuickRevSig:
+        {
+          const char *userid, *siguserid;
+
+          if (argc < 2)
+            wrong_args ("--quick-revoke-sig USER-ID SIG-USER-ID [userids]");
+          userid = *argv++; argc--;
+          siguserid = *argv++; argc--;
+          sl = NULL;
+          for( ; argc; argc--, argv++)
+	    append_to_strlist2 (&sl, *argv, utf8_strings);
+          keyedit_quick_revsig (ctrl, userid, siguserid, sl);
+          free_strlist (sl);
+        }
+	break;
+
       case aSignKey:
 	if( argc != 1 )
 	  wrong_args("--sign-key user-id");
diff --git a/g10/keyedit.c b/g10/keyedit.c
index 19fd0a1fc..9f4aad24a 100644
--- a/g10/keyedit.c
+++ b/g10/keyedit.c
@@ -2278,7 +2278,7 @@ leave:
  * Returns on success the key database handle at R_KDBHD and the
  * keyblock at R_KEYBLOCK.  */
 static gpg_error_t
-quick_find_keyblock (ctrl_t ctrl, const char *username,
+quick_find_keyblock (ctrl_t ctrl, const char *username, int want_secret,
                      KEYDB_HANDLE *r_kdbhd, kbnode_t *r_keyblock)
 {
   gpg_error_t err;
@@ -2321,7 +2321,7 @@ quick_find_keyblock (ctrl_t ctrl, const char *username,
         err = 0;
       keydb_pop_found_state (kdbhd);
 
-      if (!err)
+      if (!err && want_secret)
         {
           /* We require the secret primary key to set the primary UID.  */
           node = find_kbnode (keyblock, PKT_PUBLIC_KEY);
@@ -2379,7 +2379,7 @@ keyedit_quick_adduid (ctrl_t ctrl, const char *username, const char *newuid)
 #endif
 
   /* Search the key; we don't want the whole getkey stuff here.  */
-  err = quick_find_keyblock (ctrl, username, &kdbhd, &keyblock);
+  err = quick_find_keyblock (ctrl, username, 1, &kdbhd, &keyblock);
   if (err)
     goto leave;
 
@@ -2422,7 +2422,7 @@ keyedit_quick_revuid (ctrl_t ctrl, const char *username, const char *uidtorev)
 #endif
 
   /* Search the key; we don't want the whole getkey stuff here.  */
-  err = quick_find_keyblock (ctrl, username, &kdbhd, &keyblock);
+  err = quick_find_keyblock (ctrl, username, 1, &kdbhd, &keyblock);
   if (err)
     goto leave;
 
@@ -2502,7 +2502,7 @@ keyedit_quick_set_primary (ctrl_t ctrl, const char *username,
   check_trustdb_stale (ctrl);
 #endif
 
-  err = quick_find_keyblock (ctrl, username, &kdbhd, &keyblock);
+  err = quick_find_keyblock (ctrl, username, 1, &kdbhd, &keyblock);
   if (err)
     goto leave;
 
@@ -2763,6 +2763,240 @@ keyedit_quick_sign (ctrl_t ctrl, const char *fpr, strlist_t uids,
 }
 
 
+/* Unattended revocation of a key signatures.  USERNAME specifies the
+ * key; this should best be a fingerprint. SIGTOREV is the user-id of
+ * the key for which the key signature shall be removed.  Only
+ * non-self-signatures can be removed with this functions.  If
+ * AFFECTED_UIDS is not NULL only the key signatures on these user-ids
+ * are revoked. */
+void
+keyedit_quick_revsig (ctrl_t ctrl, const char *username, const char *sigtorev,
+                      strlist_t affected_uids)
+{
+  gpg_error_t err;
+  int no_signing_key = 0;
+  KEYDB_HANDLE kdbhd = NULL;
+  kbnode_t keyblock = NULL;
+  PKT_public_key *primarypk;  /* Points into KEYBLOCK.  */
+  u32 *primarykid;
+  PKT_public_key *pksigtorev = NULL;
+  u32 *pksigtorevkid;
+  kbnode_t node, n;
+  int skip_remaining;
+  int consider_sig;
+  strlist_t sl;
+  struct sign_attrib attrib = { 0 };
+
+#ifdef HAVE_W32_SYSTEM
+  /* See keyedit_menu for why we need this.  */
+  check_trustdb_stale (ctrl);
+#endif
+
+  /* Search the key; we don't want the whole getkey stuff here.  Noet
+   * that we are looking for the public key here.  */
+  err = quick_find_keyblock (ctrl, username, 0, &kdbhd, &keyblock);
+  if (err)
+    goto leave;
+  log_assert (keyblock->pkt->pkttype == PKT_PUBLIC_KEY
+              || keyblock->pkt->pkttype == PKT_SECRET_KEY);
+  primarypk = keyblock->pkt->pkt.public_key;
+  primarykid = pk_keyid (primarypk);
+
+  /* Get the signing key we want to revoke.  This must be one of our
+   * signing keys.  We will compare only the keyid because we don't
+   * assume that we have duplicated keyids on our own secret keys.  If
+   * a there is a duplicated one we will notice this when creating the
+   * revocation.  */
+  pksigtorev = xtrycalloc (1, sizeof *pksigtorev);
+  if (!pksigtorev)
+    {
+      err = gpg_error_from_syserror ();
+      goto leave;
+    }
+  pksigtorev->req_usage = PUBKEY_USAGE_CERT;
+  err = getkey_byname (ctrl, NULL, pksigtorev, sigtorev, 1, NULL);
+  if (err)
+    {
+      no_signing_key = 1;
+      goto leave;
+    }
+  pksigtorevkid = pk_keyid (pksigtorev);
+
+  /* Find the signatures we want to revoke and set a mark.  */
+  skip_remaining = consider_sig = 0;
+  for (node = keyblock; node; node = node->next)
+    {
+      node->flag &= ~NODFLG_MARK_A;
+      if (skip_remaining)
+        ;
+      else if (node->pkt->pkttype == PKT_PUBLIC_SUBKEY)
+        skip_remaining = 1;
+      else if (node->pkt->pkttype == PKT_USER_ID)
+	{
+          PKT_user_id *uid = node->pkt->pkt.user_id;
+
+          consider_sig = !affected_uids;
+          for (sl = affected_uids; !consider_sig && sl; sl = sl->next)
+            {
+              const char *name = sl->d;
+
+              if (uid->attrib_data)
+                ;
+              else if (*name == '='
+                       && strlen (name+1) == uid->len
+                       && !memcmp (uid->name, name + 1, uid->len))
+                { /* Exact match.  */
+                  consider_sig = 1;
+                }
+              else if (ascii_memistr (uid->name, uid->len,
+                                      *name == '*'? name+1:name))
+                { /* Case-insensitive substring match.  */
+                  consider_sig = 1;
+                }
+            }
+	}
+      else if (node->pkt->pkttype == PKT_SIGNATURE)
+	{
+          /* We need to sort the signatures so that we can figure out
+           * whether the key signature has been revoked or the
+           * revocation has been superseded by a new key
+           * signature.  */
+          PKT_signature *sig;
+          unsigned int sigcount = 0;
+          kbnode_t *sigarray;
+
+          /* Allocate an array large enogh for all signatures.  */
+          for (n=node; n && n->pkt->pkttype == PKT_SIGNATURE; n = n->next)
+            sigcount++;
+          sigarray = xtrycalloc (sigcount, sizeof *sigarray);
+          if (!sigarray)
+            {
+              err = gpg_error_from_syserror ();
+              goto leave;
+            }
+
+          /* Now fill the array with signatures we are interested in.
+           * We also move NODE forward to the end.  */
+          sigcount = 0;
+          for (n=node; n && n->pkt->pkttype == PKT_SIGNATURE; node=n, n=n->next)
+            {
+              sig = node->pkt->pkt.signature;
+              if (!keyid_cmp (primarykid, sig->keyid))
+                continue;  /* Ignore self-signatures.  */
+
+              if (keyid_cmp (pksigtorevkid, sig->keyid))
+                continue; /* Ignore non-matching signatures.  */
+
+              n->flag &= ~NODFLG_MARK_B; /* Clear flag used by cm_signode. */
+              sigarray[sigcount++] = n;
+            }
+
+          if (sigcount)
+            {
+              qsort (sigarray, sigcount, sizeof *sigarray, cmp_signodes);
+
+              /* log_debug ("Sorted signatures:\n"); */
+              /* for (idx=0; idx < sigcount; idx++) */
+              /*   { */
+              /*     sig = sigarray[idx]->pkt->pkt.signature; */
+              /*     log_debug ("%s 0x%02x %s\n", keystr (sig->keyid), */
+              /*                sig->sig_class, datestr_from_sig (sig)); */
+              /*   } */
+              sig = sigarray[sigcount-1]->pkt->pkt.signature;
+              if ((consider_sig || !affected_uids) && IS_UID_REV (sig))
+                {
+                  if (!opt.quiet)
+                    log_info ("sig by %s already revoked at %s\n",
+                              keystr (sig->keyid), datestr_from_sig (sig));
+                }
+              else if ((consider_sig && IS_UID_SIG (sig))
+                       || (!affected_uids && IS_KEY_SIG (sig)))
+                node->flag |= NODFLG_MARK_A;  /* Select signature.  */
+            }
+
+          xfree (sigarray);
+	}
+    }
+
+  /* Check whether any signatures were done by the given key.  We do
+   * not return an error if none were found.  */
+  for (node = keyblock; node; node = node->next)
+    if ((node->flag & NODFLG_MARK_A))
+      break;
+  if (!node)
+    {
+      if (opt.verbose)
+        log_info (_("Not signed by you.\n"));
+      err = 0;
+      goto leave;
+    }
+
+  /* Revoke all marked signatures.  */
+  attrib.reason = get_default_sig_revocation_reason ();
+
+ reloop: /* (we must repeat because we are modifying the list) */
+  for (node = keyblock; node; node = node->next)
+    {
+      kbnode_t unode;
+      PKT_signature *sig;
+      PACKET *pkt;
+
+      if (!(node->flag & NODFLG_MARK_A))
+	continue;
+      node->flag &= ~NODFLG_MARK_A;
+
+      if (IS_KEY_SIG (node->pkt->pkt.signature))
+        unode = NULL;
+      else
+        {
+          unode = find_prev_kbnode (keyblock, node, PKT_USER_ID);
+          log_assert (unode);
+        }
+
+      attrib.non_exportable = !node->pkt->pkt.signature->flags.exportable;
+
+      err = make_keysig_packet (ctrl, &sig, primarypk,
+                                unode? unode->pkt->pkt.user_id : NULL,
+                                NULL, pksigtorev, 0x30, 0, 0,
+                                sign_mk_attrib, &attrib, NULL);
+      if (err)
+        {
+          log_error ("signing failed: %s\n", gpg_strerror (err));
+          goto leave;
+        }
+
+      pkt = xmalloc_clear (sizeof *pkt);
+      pkt->pkttype = PKT_SIGNATURE;
+      pkt->pkt.signature = sig;
+      if (unode)
+        insert_kbnode (unode, new_kbnode (pkt), 0);
+      goto reloop;
+    }
+
+  err = keydb_update_keyblock (ctrl, kdbhd, keyblock);
+  if (err)
+    {
+      log_error (_("update failed: %s\n"), gpg_strerror (err));
+      goto leave;
+    }
+  revalidation_mark (ctrl);
+
+ leave:
+  if (err)
+    {
+      log_error (_("revoking the key signature failed: %s\n"),
+                 gpg_strerror (err));
+      if (no_signing_key)
+        print_further_info ("error getting key used to make the key signature");
+      write_status_error ("keyedit.revoke.sig", err);
+    }
+  release_revocation_reason_info (attrib.reason);
+  free_public_key (pksigtorev);
+  release_kbnode (keyblock);
+  keydb_release (kdbhd);
+}
+
+
 /* Unattended subkey creation function.
  *
  */
@@ -5984,7 +6218,7 @@ core_revuid (ctrl_t ctrl, kbnode_t keyblock, KBNODE node,
           memset (&attrib, 0, sizeof attrib);
           /* should not need to cast away const here; but
              revocation_reason_build_cb needs to take a non-const
-             void* in order to meet the function signutare for the
+             void* in order to meet the function signature for the
              mksubpkt argument to make_keysig_packet */
           attrib.reason = (struct revocation_reason_info *)reason;
 
diff --git a/g10/keyedit.h b/g10/keyedit.h
index 89c408b63..b6e5b58b9 100644
--- a/g10/keyedit.h
+++ b/g10/keyedit.h
@@ -48,6 +48,8 @@ void keyedit_quick_revuid (ctrl_t ctrl, const char *username,
                            const char *uidtorev);
 void keyedit_quick_sign (ctrl_t ctrl, const char *fpr,
                          strlist_t uids, strlist_t locusr, int local);
+void keyedit_quick_revsig (ctrl_t ctrl, const char *username,
+                           const char *sigtorev, strlist_t affected_uids);
 void keyedit_quick_set_expire (ctrl_t ctrl,
                                const char *fpr, const char *expirestr,
                                char **subkeyfprs);
diff --git a/g10/keylist.c b/g10/keylist.c
index cb3b61e03..e222259ac 100644
--- a/g10/keylist.c
+++ b/g10/keylist.c
@@ -940,7 +940,7 @@ dump_attribs (const PKT_user_id *uid, PKT_public_key *pk)
 
 /* Order two signatures.  We first order by keyid and then by creation
  * time.  */
-static int
+int
 cmp_signodes (const void *av, const void *bv)
 {
   const kbnode_t an = *(const kbnode_t *)av;
diff --git a/g10/main.h b/g10/main.h
index 7b5754648..7f3752aac 100644
--- a/g10/main.h
+++ b/g10/main.h
@@ -457,8 +457,9 @@ int gen_desig_revoke (ctrl_t ctrl, const char *uname, strlist_t locusr);
 int revocation_reason_build_cb( PKT_signature *sig, void *opaque );
 struct revocation_reason_info *
 		ask_revocation_reason( int key_rev, int cert_rev, int hint );
-struct revocation_reason_info * get_default_uid_revocation_reason(void);
-void release_revocation_reason_info( struct revocation_reason_info *reason );
+struct revocation_reason_info * get_default_uid_revocation_reason (void);
+struct revocation_reason_info * get_default_sig_revocation_reason (void);
+void release_revocation_reason_info (struct revocation_reason_info *reason);
 
 /*-- keylist.c --*/
 void public_key_list (ctrl_t ctrl, strlist_t list,
@@ -468,6 +469,7 @@ void print_subpackets_colon(PKT_signature *sig);
 void reorder_keyblock (KBNODE keyblock);
 void list_keyblock_direct (ctrl_t ctrl, kbnode_t keyblock, int secret,
                            int has_secret, int fpr, int no_validity);
+int  cmp_signodes (const void *av, const void *bv);
 void print_fingerprint (ctrl_t ctrl, estream_t fp,
                         PKT_public_key *pk, int mode);
 void print_revokers (estream_t fp, PKT_public_key *pk);
diff --git a/g10/revoke.c b/g10/revoke.c
index 5262c17bf..c0a003b6f 100644
--- a/g10/revoke.c
+++ b/g10/revoke.c
@@ -889,6 +889,16 @@ get_default_uid_revocation_reason(void)
   return reason;
 }
 
+struct revocation_reason_info *
+get_default_sig_revocation_reason(void)
+{
+  struct revocation_reason_info *reason;
+  reason = xmalloc( sizeof *reason );
+  reason->code = 0; /* No specific reason given. */
+  reason->desc = strdup(""); /* no text */
+  return reason;
+}
+
 void
 release_revocation_reason_info( struct revocation_reason_info *reason )
 {