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Diffstat (limited to 'g10/key-clean.c')
| -rw-r--r-- | g10/key-clean.c | 614 |
1 files changed, 614 insertions, 0 deletions
diff --git a/g10/key-clean.c b/g10/key-clean.c new file mode 100644 index 0000000..f66a0db --- /dev/null +++ b/g10/key-clean.c @@ -0,0 +1,614 @@ +/* key-clean.c - Functions to clean a keyblock + * Copyright (C) 1998-2008, 2010-2011 Free Software Foundation, Inc. + * Copyright (C) 2014, 2016-2018 Werner Koch + * + * 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/>. + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +#include <config.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "gpg.h" +#include "keydb.h" +#include "../common/util.h" +#include "../common/host2net.h" +#include "../common/i18n.h" +#include "options.h" +#include "packet.h" +#include "main.h" +#include "key-clean.h" + + +/* + * Mark the signature of the given UID which are used to certify it. + * To do this, we first revmove all signatures which are not valid and + * from the remain ones we look for the latest one. If this is not a + * certification revocation signature we mark the signature by setting + * node flag bit 8. Revocations are marked with flag 11, and sigs + * from unavailable keys are marked with flag 12. Note that flag bits + * 9 and 10 are used for internal purposes. + */ +void +mark_usable_uid_certs (ctrl_t ctrl, kbnode_t keyblock, kbnode_t uidnode, + u32 *main_kid, struct key_item *klist, + u32 curtime, u32 *next_expire) +{ + kbnode_t node; + PKT_signature *sig; + + /* First check all signatures. */ + for (node=uidnode->next; node; node = node->next) + { + int rc; + + node->flag &= ~(1<<8 | 1<<9 | 1<<10 | 1<<11 | 1<<12); + if (node->pkt->pkttype == PKT_USER_ID + || node->pkt->pkttype == PKT_PUBLIC_SUBKEY + || node->pkt->pkttype == PKT_SECRET_SUBKEY) + break; /* ready */ + if (node->pkt->pkttype != PKT_SIGNATURE) + continue; + sig = node->pkt->pkt.signature; + if (main_kid + && sig->keyid[0] == main_kid[0] && sig->keyid[1] == main_kid[1]) + continue; /* ignore self-signatures if we pass in a main_kid */ + if (!IS_UID_SIG(sig) && !IS_UID_REV(sig)) + continue; /* we only look at these signature classes */ + if(sig->sig_class>=0x11 && sig->sig_class<=0x13 && + sig->sig_class-0x10<opt.min_cert_level) + continue; /* treat anything under our min_cert_level as an + invalid signature */ + if (klist && !is_in_klist (klist, sig)) + continue; /* no need to check it then */ + if ((rc=check_key_signature (ctrl, keyblock, node, NULL))) + { + /* we ignore anything that won't verify, but tag the + no_pubkey case */ + if (gpg_err_code (rc) == GPG_ERR_NO_PUBKEY) + node->flag |= 1<<12; + continue; + } + node->flag |= 1<<9; + } + /* Reset the remaining flags. */ + for (; node; node = node->next) + node->flag &= ~(1<<8 | 1<<9 | 1<<10 | 1<<11 | 1<<12); + + /* kbnode flag usage: bit 9 is here set for signatures to consider, + * bit 10 will be set by the loop to keep track of keyIDs already + * processed, bit 8 will be set for the usable signatures, and bit + * 11 will be set for usable revocations. */ + + /* For each cert figure out the latest valid one. */ + for (node=uidnode->next; node; node = node->next) + { + KBNODE n, signode; + u32 kid[2]; + u32 sigdate; + + if (node->pkt->pkttype == PKT_PUBLIC_SUBKEY + || node->pkt->pkttype == PKT_SECRET_SUBKEY) + break; + if ( !(node->flag & (1<<9)) ) + continue; /* not a node to look at */ + if ( (node->flag & (1<<10)) ) + continue; /* signature with a keyID already processed */ + node->flag |= (1<<10); /* mark this node as processed */ + sig = node->pkt->pkt.signature; + signode = node; + sigdate = sig->timestamp; + kid[0] = sig->keyid[0]; kid[1] = sig->keyid[1]; + + /* Now find the latest and greatest signature */ + for (n=uidnode->next; n; n = n->next) + { + if (n->pkt->pkttype == PKT_PUBLIC_SUBKEY + || n->pkt->pkttype == PKT_SECRET_SUBKEY) + break; + if ( !(n->flag & (1<<9)) ) + continue; + if ( (n->flag & (1<<10)) ) + continue; /* shortcut already processed signatures */ + sig = n->pkt->pkt.signature; + if (kid[0] != sig->keyid[0] || kid[1] != sig->keyid[1]) + continue; + n->flag |= (1<<10); /* mark this node as processed */ + + /* If signode is nonrevocable and unexpired and n isn't, + then take signode (skip). It doesn't matter which is + older: if signode was older then we don't want to take n + as signode is nonrevocable. If n was older then we're + automatically fine. */ + + if(((IS_UID_SIG(signode->pkt->pkt.signature) && + !signode->pkt->pkt.signature->flags.revocable && + (signode->pkt->pkt.signature->expiredate==0 || + signode->pkt->pkt.signature->expiredate>curtime))) && + (!(IS_UID_SIG(n->pkt->pkt.signature) && + !n->pkt->pkt.signature->flags.revocable && + (n->pkt->pkt.signature->expiredate==0 || + n->pkt->pkt.signature->expiredate>curtime)))) + continue; + + /* If n is nonrevocable and unexpired and signode isn't, + then take n. Again, it doesn't matter which is older: if + n was older then we don't want to take signode as n is + nonrevocable. If signode was older then we're + automatically fine. */ + + if((!(IS_UID_SIG(signode->pkt->pkt.signature) && + !signode->pkt->pkt.signature->flags.revocable && + (signode->pkt->pkt.signature->expiredate==0 || + signode->pkt->pkt.signature->expiredate>curtime))) && + ((IS_UID_SIG(n->pkt->pkt.signature) && + !n->pkt->pkt.signature->flags.revocable && + (n->pkt->pkt.signature->expiredate==0 || + n->pkt->pkt.signature->expiredate>curtime)))) + { + signode = n; + sigdate = sig->timestamp; + continue; + } + + /* At this point, if it's newer, it goes in as the only + remaining possibilities are signode and n are both either + revocable or expired or both nonrevocable and unexpired. + If the timestamps are equal take the later ordered + packet, presuming that the key packets are hopefully in + their original order. */ + + if (sig->timestamp >= sigdate) + { + signode = n; + sigdate = sig->timestamp; + } + } + + sig = signode->pkt->pkt.signature; + if (IS_UID_SIG (sig)) + { /* this seems to be a usable one which is not revoked. + * Just need to check whether there is an expiration time, + * We do the expired certification after finding a suitable + * certification, the assumption is that a signator does not + * want that after the expiration of his certificate the + * system falls back to an older certification which has a + * different expiration time */ + const byte *p; + u32 expire; + + p = parse_sig_subpkt (sig->hashed, SIGSUBPKT_SIG_EXPIRE, NULL ); + expire = p? sig->timestamp + buf32_to_u32(p) : 0; + + if (expire==0 || expire > curtime ) + { + signode->flag |= (1<<8); /* yeah, found a good cert */ + if (next_expire && expire && expire < *next_expire) + *next_expire = expire; + } + } + else + signode->flag |= (1<<11); + } +} + + +static int +clean_sigs_from_uid (ctrl_t ctrl, kbnode_t keyblock, kbnode_t uidnode, + int noisy, int self_only) +{ + int deleted = 0; + kbnode_t node; + u32 keyid[2]; + + log_assert (keyblock->pkt->pkttype == PKT_PUBLIC_KEY + || keyblock->pkt->pkttype == PKT_SECRET_KEY); + + keyid_from_pk (keyblock->pkt->pkt.public_key, keyid); + + /* Passing in a 0 for current time here means that we'll never weed + out an expired sig. This is correct behavior since we want to + keep the most recent expired sig in a series. */ + mark_usable_uid_certs (ctrl, keyblock, uidnode, NULL, NULL, 0, NULL); + + /* What we want to do here is remove signatures that are not + considered as part of the trust calculations. Thus, all invalid + signatures are out, as are any signatures that aren't the last of + a series of uid sigs or revocations It breaks down like this: + coming out of mark_usable_uid_certs, if a sig is unflagged, it is + not even a candidate. If a sig has flag 9 or 10, that means it + was selected as a candidate and vetted. If a sig has flag 8 it + is a usable signature. If a sig has flag 11 it is a usable + revocation. If a sig has flag 12 it was issued by an unavailable + key. "Usable" here means the most recent valid + signature/revocation in a series from a particular signer. + + Delete everything that isn't a usable uid sig (which might be + expired), a usable revocation, or a sig from an unavailable + key. */ + + for (node=uidnode->next; + node && node->pkt->pkttype==PKT_SIGNATURE; + node=node->next) + { + int keep; + + keep = self_only? (node->pkt->pkt.signature->keyid[0] == keyid[0] + && node->pkt->pkt.signature->keyid[1] == keyid[1]) : 1; + + /* Keep usable uid sigs ... */ + if ((node->flag & (1<<8)) && keep) + continue; + + /* ... and usable revocations... */ + if ((node->flag & (1<<11)) && keep) + continue; + + /* ... and sigs from unavailable keys. */ + /* disabled for now since more people seem to want sigs from + unavailable keys removed altogether. */ + /* + if(node->flag & (1<<12)) + continue; + */ + + /* Everything else we delete */ + + /* At this point, if 12 is set, the signing key was unavailable. + If 9 or 10 is set, it's superseded. Otherwise, it's + invalid. */ + + if (noisy) + log_info ("removing signature from key %s on user ID \"%s\": %s\n", + keystr (node->pkt->pkt.signature->keyid), + uidnode->pkt->pkt.user_id->name, + node->flag&(1<<12)? "key unavailable": + node->flag&(1<<9)? "signature superseded" + /* */ :"invalid signature" ); + + delete_kbnode (node); + deleted++; + } + + return deleted; +} + + +/* This is substantially easier than clean_sigs_from_uid since we just + have to establish if the uid has a valid self-sig, is not revoked, + and is not expired. Note that this does not take into account + whether the uid has a trust path to it - just whether the keyholder + themselves has certified the uid. Returns true if the uid was + compacted. To "compact" a user ID, we simply remove ALL signatures + except the self-sig that caused the user ID to be remove-worthy. + We don't actually remove the user ID packet itself since it might + be resurrected in a later merge. Note that this function requires + that the caller has already done a merge_keys_and_selfsig(). + + TODO: change the import code to allow importing a uid with only a + revocation if the uid already exists on the keyring. */ + +static int +clean_uid_from_key (kbnode_t keyblock, kbnode_t uidnode, int noisy) +{ + kbnode_t node; + PKT_user_id *uid = uidnode->pkt->pkt.user_id; + int deleted = 0; + + log_assert (keyblock->pkt->pkttype == PKT_PUBLIC_KEY + || keyblock->pkt->pkttype == PKT_SECRET_KEY); + log_assert (uidnode->pkt->pkttype==PKT_USER_ID); + + /* Skip valid user IDs, compacted user IDs, and non-self-signed user + IDs if --allow-non-selfsigned-uid is set. */ + if (uid->created + || uid->flags.compacted + || (!uid->flags.expired && !uid->flags.revoked && opt.allow_non_selfsigned_uid)) + return 0; + + for (node=uidnode->next; + node && node->pkt->pkttype == PKT_SIGNATURE; + node=node->next) + { + if (!node->pkt->pkt.signature->flags.chosen_selfsig) + { + delete_kbnode (node); + deleted = 1; + uidnode->pkt->pkt.user_id->flags.compacted = 1; + } + } + + if (noisy) + { + const char *reason; + char *user = utf8_to_native (uid->name, uid->len, 0); + + if (uid->flags.revoked) + reason = _("revoked"); + else if (uid->flags.expired) + reason = _("expired"); + else + reason = _("invalid"); + + log_info ("compacting user ID \"%s\" on key %s: %s\n", + user, keystr_from_pk (keyblock->pkt->pkt.public_key), + reason); + + xfree (user); + } + + return deleted; +} + + +/* Needs to be called after a merge_keys_and_selfsig() */ +void +clean_one_uid (ctrl_t ctrl, kbnode_t keyblock, kbnode_t uidnode, + int noisy, int self_only, int *uids_cleaned, int *sigs_cleaned) +{ + int dummy = 0; + + log_assert (keyblock->pkt->pkttype == PKT_PUBLIC_KEY + || keyblock->pkt->pkttype == PKT_SECRET_KEY); + log_assert (uidnode->pkt->pkttype==PKT_USER_ID); + + if (!uids_cleaned) + uids_cleaned = &dummy; + + if (!sigs_cleaned) + sigs_cleaned = &dummy; + + /* Do clean_uid_from_key first since if it fires off, we don't have + to bother with the other. */ + *uids_cleaned += clean_uid_from_key (keyblock, uidnode, noisy); + if (!uidnode->pkt->pkt.user_id->flags.compacted) + *sigs_cleaned += clean_sigs_from_uid (ctrl, keyblock, uidnode, + noisy, self_only); +} + + +/* NB: This function marks the deleted nodes only and the caller is + * responsible to skip or remove them. Needs to be called after a + * merge_keys_and_selfsig(). */ +void +clean_all_uids (ctrl_t ctrl, kbnode_t keyblock, int noisy, int self_only, + int *uids_cleaned, int *sigs_cleaned) +{ + kbnode_t node; + + for (node = keyblock->next; + node && !(node->pkt->pkttype == PKT_PUBLIC_SUBKEY + || node->pkt->pkttype == PKT_SECRET_SUBKEY); + node = node->next) + { + if (node->pkt->pkttype == PKT_USER_ID) + clean_one_uid (ctrl, keyblock, node, noisy, self_only, + uids_cleaned, sigs_cleaned); + } + + /* Remove bogus subkey binding signatures: The only signatures + * allowed are of class 0x18 and 0x28. */ + log_assert (!node || (node->pkt->pkttype == PKT_PUBLIC_SUBKEY + || node->pkt->pkttype == PKT_SECRET_SUBKEY)); +} + + +/* Helper for clean_all_subkeys. */ +static int +clean_one_subkey (ctrl_t ctrl, kbnode_t subkeynode, int noisy, int clean_level) +{ + kbnode_t node; + PKT_public_key *pk = subkeynode->pkt->pkt.public_key; + unsigned int use = pk->pubkey_usage; + int do_clean = 0; + + (void)ctrl; + (void)noisy; + + log_assert (subkeynode->pkt->pkttype == PKT_PUBLIC_SUBKEY + || subkeynode->pkt->pkttype == PKT_SECRET_SUBKEY); + + if (DBG_LOOKUP) + log_debug ("\tchecking subkey %08lX [%c%c%c%c%c]\n", + (ulong) keyid_from_pk (pk, NULL), + (use & PUBKEY_USAGE_ENC)? 'e':'-', + (use & PUBKEY_USAGE_SIG)? 's':'-', + (use & PUBKEY_USAGE_CERT)? 'c':'-', + (use & PUBKEY_USAGE_AUTH)? 'a':'-', + (use & PUBKEY_USAGE_UNKNOWN)? '?':'-'); + + if (!pk->flags.valid) + { + if (DBG_LOOKUP) + log_debug ("\tsubkey not valid\n"); + if (clean_level == KEY_CLEAN_INVALID) + do_clean = 1; + } + if (pk->has_expired) + { + if (DBG_LOOKUP) + log_debug ("\tsubkey has expired\n"); + if (clean_level == KEY_CLEAN_ALL) + do_clean = 1; + else if (clean_level == KEY_CLEAN_AUTHENCR + && (use & (PUBKEY_USAGE_ENC | PUBKEY_USAGE_AUTH)) + && !(use & (PUBKEY_USAGE_SIG | PUBKEY_USAGE_CERT))) + do_clean = 1; + else if (clean_level == KEY_CLEAN_ENCR + && (use & PUBKEY_USAGE_ENC) + && !(use & (PUBKEY_USAGE_SIG | PUBKEY_USAGE_CERT + | PUBKEY_USAGE_AUTH))) + do_clean = 1; + } + if (pk->flags.revoked) + { + if (DBG_LOOKUP) + log_debug ("\tsubkey has been revoked (keeping)\n"); + /* Avoid any cleaning because revocations are important. */ + do_clean = 0; + } + if (!do_clean) + return 0; + + if (DBG_LOOKUP) + log_debug ("\t=> removing this subkey\n"); + + delete_kbnode (subkeynode); + for (node = subkeynode->next; + node && !(node->pkt->pkttype == PKT_PUBLIC_SUBKEY + || node->pkt->pkttype == PKT_SECRET_SUBKEY); + node = node->next) + delete_kbnode (node); + + return 1; +} + + +/* Helper for clean_all_subkeys. Here duplicate signatures from a + * subkey are removed. This should in general not happen because + * import takes care of that. However, sometimes other tools are used + * to manage a keyring or key has been imported a long time ago. */ +static int +clean_one_subkey_dupsigs (ctrl_t ctrl, kbnode_t subkeynode) +{ + kbnode_t node; + PKT_public_key *pk = subkeynode->pkt->pkt.public_key; + int any_choosen = 0; + int count = 0; + + (void)ctrl; + + log_assert (subkeynode->pkt->pkttype == PKT_PUBLIC_SUBKEY + || subkeynode->pkt->pkttype == PKT_SECRET_SUBKEY); + + if (DBG_LOOKUP) + log_debug ("\tchecking subkey %08lX for dupsigs\n", + (ulong) keyid_from_pk (pk, NULL)); + + /* First check that the choosen flag has been set. Note that we + * only look at plain signatures so to keep all revocation + * signatures which may carry important information. */ + for (node = subkeynode->next; + node && !(node->pkt->pkttype == PKT_PUBLIC_SUBKEY + || node->pkt->pkttype == PKT_SECRET_SUBKEY); + node = node->next) + { + if (!is_deleted_kbnode (node) + && node->pkt->pkttype == PKT_SIGNATURE + && IS_SUBKEY_SIG (node->pkt->pkt.signature) + && node->pkt->pkt.signature->flags.chosen_selfsig) + { + any_choosen = 1; + break; + } + } + + if (!any_choosen) + return 0; /* Ooops no choosen flag set - we can't decide. */ + + for (node = subkeynode->next; + node && !(node->pkt->pkttype == PKT_PUBLIC_SUBKEY + || node->pkt->pkttype == PKT_SECRET_SUBKEY); + node = node->next) + { + if (!is_deleted_kbnode (node) + && node->pkt->pkttype == PKT_SIGNATURE + && IS_SUBKEY_SIG (node->pkt->pkt.signature) + && !node->pkt->pkt.signature->flags.chosen_selfsig) + { + delete_kbnode (node); + count++; + } + } + + return count; +} + + +/* This function only marks the deleted nodes and the caller is + * responsible to skip or remove them. Needs to be called after a + * merge_keys_and_selfsig. CLEAN_LEVEL is one of the KEY_CLEAN_* + * values. */ +void +clean_all_subkeys (ctrl_t ctrl, kbnode_t keyblock, int noisy, int clean_level, + int *subkeys_cleaned, int *sigs_cleaned) +{ + kbnode_t first_subkey, node; + int n; + + if (DBG_LOOKUP) + log_debug ("clean_all_subkeys: checking key %08lX\n", + (ulong) keyid_from_pk (keyblock->pkt->pkt.public_key, NULL)); + + for (node = keyblock->next; node; node = node->next) + if (!is_deleted_kbnode (node) + && (node->pkt->pkttype == PKT_PUBLIC_SUBKEY + || node->pkt->pkttype == PKT_SECRET_SUBKEY)) + break; + first_subkey = node; + + /* Remove bogus subkey binding signatures: The only signatures + * allowed are of class 0x18 and 0x28. */ + for (node = first_subkey; node; node = node->next) + { + if (is_deleted_kbnode (node)) + continue; + if (node->pkt->pkttype == PKT_SIGNATURE + && !(IS_SUBKEY_SIG (node->pkt->pkt.signature) + || IS_SUBKEY_REV (node->pkt->pkt.signature))) + { + delete_kbnode (node); + if (sigs_cleaned) + ++*sigs_cleaned; + } + } + + /* Do the selected cleaning. */ + if (clean_level > KEY_CLEAN_NONE) + { + /* Clean enitre subkeys. */ + for (node = first_subkey; node; node = node->next) + { + if (is_deleted_kbnode (node)) + continue; + if (node->pkt->pkttype == PKT_PUBLIC_SUBKEY + || node->pkt->pkttype == PKT_SECRET_SUBKEY) + { + if (clean_one_subkey (ctrl, node, noisy, clean_level)) + { + if (subkeys_cleaned) + ++*subkeys_cleaned; + } + } + } + + /* Clean duplicate signatures from a subkey. */ + for (node = first_subkey; node; node = node->next) + { + if (is_deleted_kbnode (node)) + continue; + if (node->pkt->pkttype == PKT_PUBLIC_SUBKEY + || node->pkt->pkttype == PKT_SECRET_SUBKEY) + { + n = clean_one_subkey_dupsigs (ctrl, node); + if (sigs_cleaned) + *sigs_cleaned += n; + } + } + } +} |