diff options
Diffstat (limited to 'hostfile.c')
| -rw-r--r-- | hostfile.c | 937 |
1 files changed, 937 insertions, 0 deletions
diff --git a/hostfile.c b/hostfile.c new file mode 100644 index 0000000..bd49e3a --- /dev/null +++ b/hostfile.c @@ -0,0 +1,937 @@ +/* $OpenBSD: hostfile.c,v 1.93 2022/01/06 22:02:52 djm Exp $ */ +/* + * Author: Tatu Ylonen <ylo@cs.hut.fi> + * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland + * All rights reserved + * Functions for manipulating the known hosts files. + * + * As far as I am concerned, the code I have written for this software + * can be used freely for any purpose. Any derived versions of this + * software must be clearly marked as such, and if the derived work is + * incompatible with the protocol description in the RFC file, it must be + * called by a name other than "ssh" or "Secure Shell". + * + * + * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. + * Copyright (c) 1999 Niels Provos. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "includes.h" + +#include <sys/types.h> +#include <sys/stat.h> + +#include <netinet/in.h> + +#include <errno.h> +#include <resolv.h> +#include <stdarg.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include "xmalloc.h" +#include "match.h" +#include "sshkey.h" +#include "hostfile.h" +#include "log.h" +#include "misc.h" +#include "pathnames.h" +#include "ssherr.h" +#include "digest.h" +#include "hmac.h" +#include "sshbuf.h" + +/* XXX hmac is too easy to dictionary attack; use bcrypt? */ + +static int +extract_salt(const char *s, u_int l, u_char *salt, size_t salt_len) +{ + char *p, *b64salt; + u_int b64len; + int ret; + + if (l < sizeof(HASH_MAGIC) - 1) { + debug2("extract_salt: string too short"); + return (-1); + } + if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) { + debug2("extract_salt: invalid magic identifier"); + return (-1); + } + s += sizeof(HASH_MAGIC) - 1; + l -= sizeof(HASH_MAGIC) - 1; + if ((p = memchr(s, HASH_DELIM, l)) == NULL) { + debug2("extract_salt: missing salt termination character"); + return (-1); + } + + b64len = p - s; + /* Sanity check */ + if (b64len == 0 || b64len > 1024) { + debug2("extract_salt: bad encoded salt length %u", b64len); + return (-1); + } + b64salt = xmalloc(1 + b64len); + memcpy(b64salt, s, b64len); + b64salt[b64len] = '\0'; + + ret = __b64_pton(b64salt, salt, salt_len); + free(b64salt); + if (ret == -1) { + debug2("extract_salt: salt decode error"); + return (-1); + } + if (ret != (int)ssh_hmac_bytes(SSH_DIGEST_SHA1)) { + debug2("extract_salt: expected salt len %zd, got %d", + ssh_hmac_bytes(SSH_DIGEST_SHA1), ret); + return (-1); + } + + return (0); +} + +char * +host_hash(const char *host, const char *name_from_hostfile, u_int src_len) +{ + struct ssh_hmac_ctx *ctx; + u_char salt[256], result[256]; + char uu_salt[512], uu_result[512]; + char *encoded = NULL; + u_int len; + + len = ssh_digest_bytes(SSH_DIGEST_SHA1); + + if (name_from_hostfile == NULL) { + /* Create new salt */ + arc4random_buf(salt, len); + } else { + /* Extract salt from known host entry */ + if (extract_salt(name_from_hostfile, src_len, salt, + sizeof(salt)) == -1) + return (NULL); + } + + if ((ctx = ssh_hmac_start(SSH_DIGEST_SHA1)) == NULL || + ssh_hmac_init(ctx, salt, len) < 0 || + ssh_hmac_update(ctx, host, strlen(host)) < 0 || + ssh_hmac_final(ctx, result, sizeof(result))) + fatal_f("ssh_hmac failed"); + ssh_hmac_free(ctx); + + if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 || + __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1) + fatal_f("__b64_ntop failed"); + xasprintf(&encoded, "%s%s%c%s", HASH_MAGIC, uu_salt, HASH_DELIM, + uu_result); + + return (encoded); +} + +/* + * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the + * pointer over the key. Skips any whitespace at the beginning and at end. + */ + +int +hostfile_read_key(char **cpp, u_int *bitsp, struct sshkey *ret) +{ + char *cp; + + /* Skip leading whitespace. */ + for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) + ; + + if (sshkey_read(ret, &cp) != 0) + return 0; + + /* Skip trailing whitespace. */ + for (; *cp == ' ' || *cp == '\t'; cp++) + ; + + /* Return results. */ + *cpp = cp; + if (bitsp != NULL) + *bitsp = sshkey_size(ret); + return 1; +} + +static HostkeyMarker +check_markers(char **cpp) +{ + char marker[32], *sp, *cp = *cpp; + int ret = MRK_NONE; + + while (*cp == '@') { + /* Only one marker is allowed */ + if (ret != MRK_NONE) + return MRK_ERROR; + /* Markers are terminated by whitespace */ + if ((sp = strchr(cp, ' ')) == NULL && + (sp = strchr(cp, '\t')) == NULL) + return MRK_ERROR; + /* Extract marker for comparison */ + if (sp <= cp + 1 || sp >= cp + sizeof(marker)) + return MRK_ERROR; + memcpy(marker, cp, sp - cp); + marker[sp - cp] = '\0'; + if (strcmp(marker, CA_MARKER) == 0) + ret = MRK_CA; + else if (strcmp(marker, REVOKE_MARKER) == 0) + ret = MRK_REVOKE; + else + return MRK_ERROR; + + /* Skip past marker and any whitespace that follows it */ + cp = sp; + for (; *cp == ' ' || *cp == '\t'; cp++) + ; + } + *cpp = cp; + return ret; +} + +struct hostkeys * +init_hostkeys(void) +{ + struct hostkeys *ret = xcalloc(1, sizeof(*ret)); + + ret->entries = NULL; + return ret; +} + +struct load_callback_ctx { + const char *host; + u_long num_loaded; + struct hostkeys *hostkeys; +}; + +static int +record_hostkey(struct hostkey_foreach_line *l, void *_ctx) +{ + struct load_callback_ctx *ctx = (struct load_callback_ctx *)_ctx; + struct hostkeys *hostkeys = ctx->hostkeys; + struct hostkey_entry *tmp; + + if (l->status == HKF_STATUS_INVALID) { + /* XXX make this verbose() in the future */ + debug("%s:%ld: parse error in hostkeys file", + l->path, l->linenum); + return 0; + } + + debug3_f("found %skey type %s in file %s:%lu", + l->marker == MRK_NONE ? "" : + (l->marker == MRK_CA ? "ca " : "revoked "), + sshkey_type(l->key), l->path, l->linenum); + if ((tmp = recallocarray(hostkeys->entries, hostkeys->num_entries, + hostkeys->num_entries + 1, sizeof(*hostkeys->entries))) == NULL) + return SSH_ERR_ALLOC_FAIL; + hostkeys->entries = tmp; + hostkeys->entries[hostkeys->num_entries].host = xstrdup(ctx->host); + hostkeys->entries[hostkeys->num_entries].file = xstrdup(l->path); + hostkeys->entries[hostkeys->num_entries].line = l->linenum; + hostkeys->entries[hostkeys->num_entries].key = l->key; + l->key = NULL; /* steal it */ + hostkeys->entries[hostkeys->num_entries].marker = l->marker; + hostkeys->entries[hostkeys->num_entries].note = l->note; + hostkeys->num_entries++; + ctx->num_loaded++; + + return 0; +} + +void +load_hostkeys_file(struct hostkeys *hostkeys, const char *host, + const char *path, FILE *f, u_int note) +{ + int r; + struct load_callback_ctx ctx; + + ctx.host = host; + ctx.num_loaded = 0; + ctx.hostkeys = hostkeys; + + if ((r = hostkeys_foreach_file(path, f, record_hostkey, &ctx, host, + NULL, HKF_WANT_MATCH|HKF_WANT_PARSE_KEY, note)) != 0) { + if (r != SSH_ERR_SYSTEM_ERROR && errno != ENOENT) + debug_fr(r, "hostkeys_foreach failed for %s", path); + } + if (ctx.num_loaded != 0) + debug3_f("loaded %lu keys from %s", ctx.num_loaded, host); +} + +void +load_hostkeys(struct hostkeys *hostkeys, const char *host, const char *path, + u_int note) +{ + FILE *f; + + if ((f = fopen(path, "r")) == NULL) { + debug_f("fopen %s: %s", path, strerror(errno)); + return; + } + + load_hostkeys_file(hostkeys, host, path, f, note); + fclose(f); +} + +void +free_hostkeys(struct hostkeys *hostkeys) +{ + u_int i; + + for (i = 0; i < hostkeys->num_entries; i++) { + free(hostkeys->entries[i].host); + free(hostkeys->entries[i].file); + sshkey_free(hostkeys->entries[i].key); + explicit_bzero(hostkeys->entries + i, sizeof(*hostkeys->entries)); + } + free(hostkeys->entries); + freezero(hostkeys, sizeof(*hostkeys)); +} + +static int +check_key_not_revoked(struct hostkeys *hostkeys, struct sshkey *k) +{ + int is_cert = sshkey_is_cert(k); + u_int i; + + for (i = 0; i < hostkeys->num_entries; i++) { + if (hostkeys->entries[i].marker != MRK_REVOKE) + continue; + if (sshkey_equal_public(k, hostkeys->entries[i].key)) + return -1; + if (is_cert && k != NULL && + sshkey_equal_public(k->cert->signature_key, + hostkeys->entries[i].key)) + return -1; + } + return 0; +} + +/* + * Match keys against a specified key, or look one up by key type. + * + * If looking for a keytype (key == NULL) and one is found then return + * HOST_FOUND, otherwise HOST_NEW. + * + * If looking for a key (key != NULL): + * 1. If the key is a cert and a matching CA is found, return HOST_OK + * 2. If the key is not a cert and a matching key is found, return HOST_OK + * 3. If no key matches but a key with a different type is found, then + * return HOST_CHANGED + * 4. If no matching keys are found, then return HOST_NEW. + * + * Finally, check any found key is not revoked. + */ +static HostStatus +check_hostkeys_by_key_or_type(struct hostkeys *hostkeys, + struct sshkey *k, int keytype, int nid, const struct hostkey_entry **found) +{ + u_int i; + HostStatus end_return = HOST_NEW; + int want_cert = sshkey_is_cert(k); + HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE; + + if (found != NULL) + *found = NULL; + + for (i = 0; i < hostkeys->num_entries; i++) { + if (hostkeys->entries[i].marker != want_marker) + continue; + if (k == NULL) { + if (hostkeys->entries[i].key->type != keytype) + continue; + if (nid != -1 && + sshkey_type_plain(keytype) == KEY_ECDSA && + hostkeys->entries[i].key->ecdsa_nid != nid) + continue; + end_return = HOST_FOUND; + if (found != NULL) + *found = hostkeys->entries + i; + k = hostkeys->entries[i].key; + break; + } + if (want_cert) { + if (sshkey_equal_public(k->cert->signature_key, + hostkeys->entries[i].key)) { + /* A matching CA exists */ + end_return = HOST_OK; + if (found != NULL) + *found = hostkeys->entries + i; + break; + } + } else { + if (sshkey_equal(k, hostkeys->entries[i].key)) { + end_return = HOST_OK; + if (found != NULL) + *found = hostkeys->entries + i; + break; + } + /* A non-matching key exists */ + end_return = HOST_CHANGED; + if (found != NULL) + *found = hostkeys->entries + i; + } + } + if (check_key_not_revoked(hostkeys, k) != 0) { + end_return = HOST_REVOKED; + if (found != NULL) + *found = NULL; + } + return end_return; +} + +HostStatus +check_key_in_hostkeys(struct hostkeys *hostkeys, struct sshkey *key, + const struct hostkey_entry **found) +{ + if (key == NULL) + fatal("no key to look up"); + return check_hostkeys_by_key_or_type(hostkeys, key, 0, -1, found); +} + +int +lookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype, int nid, + const struct hostkey_entry **found) +{ + return (check_hostkeys_by_key_or_type(hostkeys, NULL, keytype, nid, + found) == HOST_FOUND); +} + +int +lookup_marker_in_hostkeys(struct hostkeys *hostkeys, int want_marker) +{ + u_int i; + + for (i = 0; i < hostkeys->num_entries; i++) { + if (hostkeys->entries[i].marker == (HostkeyMarker)want_marker) + return 1; + } + return 0; +} + +static int +write_host_entry(FILE *f, const char *host, const char *ip, + const struct sshkey *key, int store_hash) +{ + int r, success = 0; + char *hashed_host = NULL, *lhost; + + lhost = xstrdup(host); + lowercase(lhost); + + if (store_hash) { + if ((hashed_host = host_hash(lhost, NULL, 0)) == NULL) { + error_f("host_hash failed"); + free(lhost); + return 0; + } + fprintf(f, "%s ", hashed_host); + } else if (ip != NULL) + fprintf(f, "%s,%s ", lhost, ip); + else { + fprintf(f, "%s ", lhost); + } + free(hashed_host); + free(lhost); + if ((r = sshkey_write(key, f)) == 0) + success = 1; + else + error_fr(r, "sshkey_write"); + fputc('\n', f); + /* If hashing is enabled, the IP address needs to go on its own line */ + if (success && store_hash && ip != NULL) + success = write_host_entry(f, ip, NULL, key, 1); + return success; +} + +/* + * Create user ~/.ssh directory if it doesn't exist and we want to write to it. + * If notify is set, a message will be emitted if the directory is created. + */ +void +hostfile_create_user_ssh_dir(const char *filename, int notify) +{ + char *dotsshdir = NULL, *p; + size_t len; + struct stat st; + + if ((p = strrchr(filename, '/')) == NULL) + return; + len = p - filename; + dotsshdir = tilde_expand_filename("~/" _PATH_SSH_USER_DIR, getuid()); + if (strlen(dotsshdir) > len || strncmp(filename, dotsshdir, len) != 0) + goto out; /* not ~/.ssh prefixed */ + if (stat(dotsshdir, &st) == 0) + goto out; /* dir already exists */ + else if (errno != ENOENT) + error("Could not stat %s: %s", dotsshdir, strerror(errno)); + else { +#ifdef WITH_SELINUX + ssh_selinux_setfscreatecon(dotsshdir); +#endif + if (mkdir(dotsshdir, 0700) == -1) + error("Could not create directory '%.200s' (%s).", + dotsshdir, strerror(errno)); + else if (notify) + logit("Created directory '%s'.", dotsshdir); +#ifdef WITH_SELINUX + ssh_selinux_setfscreatecon(NULL); +#endif + } + out: + free(dotsshdir); +} + +/* + * Appends an entry to the host file. Returns false if the entry could not + * be appended. + */ +int +add_host_to_hostfile(const char *filename, const char *host, + const struct sshkey *key, int store_hash) +{ + FILE *f; + int success; + + if (key == NULL) + return 1; /* XXX ? */ + hostfile_create_user_ssh_dir(filename, 0); + f = fopen(filename, "a"); + if (!f) + return 0; + success = write_host_entry(f, host, NULL, key, store_hash); + fclose(f); + return success; +} + +struct host_delete_ctx { + FILE *out; + int quiet; + const char *host, *ip; + u_int *match_keys; /* mask of HKF_MATCH_* for this key */ + struct sshkey * const *keys; + size_t nkeys; + int modified; +}; + +static int +host_delete(struct hostkey_foreach_line *l, void *_ctx) +{ + struct host_delete_ctx *ctx = (struct host_delete_ctx *)_ctx; + int loglevel = ctx->quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE; + size_t i; + + /* Don't remove CA and revocation lines */ + if (l->status == HKF_STATUS_MATCHED && l->marker == MRK_NONE) { + /* + * If this line contains one of the keys that we will be + * adding later, then don't change it and mark the key for + * skipping. + */ + for (i = 0; i < ctx->nkeys; i++) { + if (!sshkey_equal(ctx->keys[i], l->key)) + continue; + ctx->match_keys[i] |= l->match; + fprintf(ctx->out, "%s\n", l->line); + debug3_f("%s key already at %s:%ld", + sshkey_type(l->key), l->path, l->linenum); + return 0; + } + + /* + * Hostname matches and has no CA/revoke marker, delete it + * by *not* writing the line to ctx->out. + */ + do_log2(loglevel, "%s%s%s:%ld: Removed %s key for host %s", + ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "", + l->path, l->linenum, sshkey_type(l->key), ctx->host); + ctx->modified = 1; + return 0; + } + /* Retain non-matching hosts and invalid lines when deleting */ + if (l->status == HKF_STATUS_INVALID) { + do_log2(loglevel, "%s%s%s:%ld: invalid known_hosts entry", + ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "", + l->path, l->linenum); + } + fprintf(ctx->out, "%s\n", l->line); + return 0; +} + +int +hostfile_replace_entries(const char *filename, const char *host, const char *ip, + struct sshkey **keys, size_t nkeys, int store_hash, int quiet, int hash_alg) +{ + int r, fd, oerrno = 0; + int loglevel = quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE; + struct host_delete_ctx ctx; + char *fp, *temp = NULL, *back = NULL; + const char *what; + mode_t omask; + size_t i; + u_int want; + + omask = umask(077); + + memset(&ctx, 0, sizeof(ctx)); + ctx.host = host; + ctx.ip = ip; + ctx.quiet = quiet; + + if ((ctx.match_keys = calloc(nkeys, sizeof(*ctx.match_keys))) == NULL) + return SSH_ERR_ALLOC_FAIL; + ctx.keys = keys; + ctx.nkeys = nkeys; + ctx.modified = 0; + + /* + * Prepare temporary file for in-place deletion. + */ + if ((r = asprintf(&temp, "%s.XXXXXXXXXXX", filename)) == -1 || + (r = asprintf(&back, "%s.old", filename)) == -1) { + r = SSH_ERR_ALLOC_FAIL; + goto fail; + } + + if ((fd = mkstemp(temp)) == -1) { + oerrno = errno; + error_f("mkstemp: %s", strerror(oerrno)); + r = SSH_ERR_SYSTEM_ERROR; + goto fail; + } + if ((ctx.out = fdopen(fd, "w")) == NULL) { + oerrno = errno; + close(fd); + error_f("fdopen: %s", strerror(oerrno)); + r = SSH_ERR_SYSTEM_ERROR; + goto fail; + } + + /* Remove stale/mismatching entries for the specified host */ + if ((r = hostkeys_foreach(filename, host_delete, &ctx, host, ip, + HKF_WANT_PARSE_KEY, 0)) != 0) { + oerrno = errno; + error_fr(r, "hostkeys_foreach"); + goto fail; + } + + /* Re-add the requested keys */ + want = HKF_MATCH_HOST | (ip == NULL ? 0 : HKF_MATCH_IP); + for (i = 0; i < nkeys; i++) { + if (keys[i] == NULL || (want & ctx.match_keys[i]) == want) + continue; + if ((fp = sshkey_fingerprint(keys[i], hash_alg, + SSH_FP_DEFAULT)) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto fail; + } + /* write host/ip */ + what = ""; + if (ctx.match_keys[i] == 0) { + what = "Adding new key"; + if (!write_host_entry(ctx.out, host, ip, + keys[i], store_hash)) { + r = SSH_ERR_INTERNAL_ERROR; + goto fail; + } + } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_HOST) { + what = "Fixing match (hostname)"; + if (!write_host_entry(ctx.out, host, NULL, + keys[i], store_hash)) { + r = SSH_ERR_INTERNAL_ERROR; + goto fail; + } + } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_IP) { + what = "Fixing match (address)"; + if (!write_host_entry(ctx.out, ip, NULL, + keys[i], store_hash)) { + r = SSH_ERR_INTERNAL_ERROR; + goto fail; + } + } + do_log2(loglevel, "%s%s%s for %s%s%s to %s: %s %s", + quiet ? __func__ : "", quiet ? ": " : "", what, + host, ip == NULL ? "" : ",", ip == NULL ? "" : ip, filename, + sshkey_ssh_name(keys[i]), fp); + free(fp); + ctx.modified = 1; + } + fclose(ctx.out); + ctx.out = NULL; + + if (ctx.modified) { + /* Backup the original file and replace it with the temporary */ + if (unlink(back) == -1 && errno != ENOENT) { + oerrno = errno; + error_f("unlink %.100s: %s", back, strerror(errno)); + r = SSH_ERR_SYSTEM_ERROR; + goto fail; + } + if (link(filename, back) == -1) { + oerrno = errno; + error_f("link %.100s to %.100s: %s", filename, + back, strerror(errno)); + r = SSH_ERR_SYSTEM_ERROR; + goto fail; + } + if (rename(temp, filename) == -1) { + oerrno = errno; + error_f("rename \"%s\" to \"%s\": %s", temp, + filename, strerror(errno)); + r = SSH_ERR_SYSTEM_ERROR; + goto fail; + } + } else { + /* No changes made; just delete the temporary file */ + if (unlink(temp) != 0) + error_f("unlink \"%s\": %s", temp, strerror(errno)); + } + + /* success */ + r = 0; + fail: + if (temp != NULL && r != 0) + unlink(temp); + free(temp); + free(back); + if (ctx.out != NULL) + fclose(ctx.out); + free(ctx.match_keys); + umask(omask); + if (r == SSH_ERR_SYSTEM_ERROR) + errno = oerrno; + return r; +} + +static int +match_maybe_hashed(const char *host, const char *names, int *was_hashed) +{ + int hashed = *names == HASH_DELIM, ret; + char *hashed_host = NULL; + size_t nlen = strlen(names); + + if (was_hashed != NULL) + *was_hashed = hashed; + if (hashed) { + if ((hashed_host = host_hash(host, names, nlen)) == NULL) + return -1; + ret = (nlen == strlen(hashed_host) && + strncmp(hashed_host, names, nlen) == 0); + free(hashed_host); + return ret; + } + return match_hostname(host, names) == 1; +} + +int +hostkeys_foreach_file(const char *path, FILE *f, hostkeys_foreach_fn *callback, + void *ctx, const char *host, const char *ip, u_int options, u_int note) +{ + char *line = NULL, ktype[128]; + u_long linenum = 0; + char *cp, *cp2; + u_int kbits; + int hashed; + int s, r = 0; + struct hostkey_foreach_line lineinfo; + size_t linesize = 0, l; + + memset(&lineinfo, 0, sizeof(lineinfo)); + if (host == NULL && (options & HKF_WANT_MATCH) != 0) + return SSH_ERR_INVALID_ARGUMENT; + + while (getline(&line, &linesize, f) != -1) { + linenum++; + line[strcspn(line, "\n")] = '\0'; + + free(lineinfo.line); + sshkey_free(lineinfo.key); + memset(&lineinfo, 0, sizeof(lineinfo)); + lineinfo.path = path; + lineinfo.linenum = linenum; + lineinfo.line = xstrdup(line); + lineinfo.marker = MRK_NONE; + lineinfo.status = HKF_STATUS_OK; + lineinfo.keytype = KEY_UNSPEC; + lineinfo.note = note; + + /* Skip any leading whitespace, comments and empty lines. */ + for (cp = line; *cp == ' ' || *cp == '\t'; cp++) + ; + if (!*cp || *cp == '#' || *cp == '\n') { + if ((options & HKF_WANT_MATCH) == 0) { + lineinfo.status = HKF_STATUS_COMMENT; + if ((r = callback(&lineinfo, ctx)) != 0) + break; + } + continue; + } + + if ((lineinfo.marker = check_markers(&cp)) == MRK_ERROR) { + verbose_f("invalid marker at %s:%lu", path, linenum); + if ((options & HKF_WANT_MATCH) == 0) + goto bad; + continue; + } + + /* Find the end of the host name portion. */ + for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) + ; + lineinfo.hosts = cp; + *cp2++ = '\0'; + + /* Check if the host name matches. */ + if (host != NULL) { + if ((s = match_maybe_hashed(host, lineinfo.hosts, + &hashed)) == -1) { + debug2_f("%s:%ld: bad host hash \"%.32s\"", + path, linenum, lineinfo.hosts); + goto bad; + } + if (s == 1) { + lineinfo.status = HKF_STATUS_MATCHED; + lineinfo.match |= HKF_MATCH_HOST | + (hashed ? HKF_MATCH_HOST_HASHED : 0); + } + /* Try matching IP address if supplied */ + if (ip != NULL) { + if ((s = match_maybe_hashed(ip, lineinfo.hosts, + &hashed)) == -1) { + debug2_f("%s:%ld: bad ip hash " + "\"%.32s\"", path, linenum, + lineinfo.hosts); + goto bad; + } + if (s == 1) { + lineinfo.status = HKF_STATUS_MATCHED; + lineinfo.match |= HKF_MATCH_IP | + (hashed ? HKF_MATCH_IP_HASHED : 0); + } + } + /* + * Skip this line if host matching requested and + * neither host nor address matched. + */ + if ((options & HKF_WANT_MATCH) != 0 && + lineinfo.status != HKF_STATUS_MATCHED) + continue; + } + + /* Got a match. Skip host name and any following whitespace */ + for (; *cp2 == ' ' || *cp2 == '\t'; cp2++) + ; + if (*cp2 == '\0' || *cp2 == '#') { + debug2("%s:%ld: truncated before key type", + path, linenum); + goto bad; + } + lineinfo.rawkey = cp = cp2; + + if ((options & HKF_WANT_PARSE_KEY) != 0) { + /* + * Extract the key from the line. This will skip + * any leading whitespace. Ignore badly formatted + * lines. + */ + if ((lineinfo.key = sshkey_new(KEY_UNSPEC)) == NULL) { + error_f("sshkey_new failed"); + r = SSH_ERR_ALLOC_FAIL; + break; + } + if (!hostfile_read_key(&cp, &kbits, lineinfo.key)) { + goto bad; + } + lineinfo.keytype = lineinfo.key->type; + lineinfo.comment = cp; + } else { + /* Extract and parse key type */ + l = strcspn(lineinfo.rawkey, " \t"); + if (l <= 1 || l >= sizeof(ktype) || + lineinfo.rawkey[l] == '\0') + goto bad; + memcpy(ktype, lineinfo.rawkey, l); + ktype[l] = '\0'; + lineinfo.keytype = sshkey_type_from_name(ktype); + + /* + * Assume legacy RSA1 if the first component is a short + * decimal number. + */ + if (lineinfo.keytype == KEY_UNSPEC && l < 8 && + strspn(ktype, "0123456789") == l) + goto bad; + + /* + * Check that something other than whitespace follows + * the key type. This won't catch all corruption, but + * it does catch trivial truncation. + */ + cp2 += l; /* Skip past key type */ + for (; *cp2 == ' ' || *cp2 == '\t'; cp2++) + ; + if (*cp2 == '\0' || *cp2 == '#') { + debug2("%s:%ld: truncated after key type", + path, linenum); + lineinfo.keytype = KEY_UNSPEC; + } + if (lineinfo.keytype == KEY_UNSPEC) { + bad: + sshkey_free(lineinfo.key); + lineinfo.key = NULL; + lineinfo.status = HKF_STATUS_INVALID; + if ((r = callback(&lineinfo, ctx)) != 0) + break; + continue; + } + } + if ((r = callback(&lineinfo, ctx)) != 0) + break; + } + sshkey_free(lineinfo.key); + free(lineinfo.line); + free(line); + return r; +} + +int +hostkeys_foreach(const char *path, hostkeys_foreach_fn *callback, void *ctx, + const char *host, const char *ip, u_int options, u_int note) +{ + FILE *f; + int r, oerrno; + + if ((f = fopen(path, "r")) == NULL) + return SSH_ERR_SYSTEM_ERROR; + + debug3_f("reading file \"%s\"", path); + r = hostkeys_foreach_file(path, f, callback, ctx, host, ip, + options, note); + oerrno = errno; + fclose(f); + errno = oerrno; + return r; +} |