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author | Andreas Schneider <asn@cryptomilk.org> | 2017-02-05 20:30:04 +0100 |
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committer | Andreas Schneider <asn@cryptomilk.org> | 2018-06-04 11:20:28 +0200 |
commit | 702e9e8ad56491e3dda7fc215c8e2f4f139e2d2e (patch) | |
tree | eda56b6a0137b269d0c7ab9a1e6c1e64036860dd /src | |
parent | 250bf37a28ab3e320db1c9fc93971ddfc9a5e88c (diff) | |
download | libssh-702e9e8ad56491e3dda7fc215c8e2f4f139e2d2e.tar.gz libssh-702e9e8ad56491e3dda7fc215c8e2f4f139e2d2e.tar.xz libssh-702e9e8ad56491e3dda7fc215c8e2f4f139e2d2e.zip |
knownhosts: Introduce new known hosts managing functions
Signed-off-by: Andreas Schneider <asn@cryptomilk.org>
Diffstat (limited to 'src')
-rw-r--r-- | src/CMakeLists.txt | 1 | ||||
-rw-r--r-- | src/knownhosts.c | 295 |
2 files changed, 296 insertions, 0 deletions
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt index da87313e..7ecee06c 100644 --- a/src/CMakeLists.txt +++ b/src/CMakeLists.txt @@ -135,6 +135,7 @@ set(libssh_SRCS init.c kex.c known_hosts.c + knownhosts.c legacy.c log.c match.c diff --git a/src/knownhosts.c b/src/knownhosts.c new file mode 100644 index 00000000..6557f89f --- /dev/null +++ b/src/knownhosts.c @@ -0,0 +1,295 @@ +/* + * known_hosts: Host and public key verification. + * + * This file is part of the SSH Library + * + * Copyright (c) 2003-2009 by Aris Adamantiadis + * Copyright (c) 2009-2017 by Andreas Schneider <asn@cryptomilk.org> + * + * The SSH Library is free software; you can redistribute it and/or modify + * it under the terms of the GNU Lesser General Public License as published by + * the Free Software Foundation; either version 2.1 of the License, or (at your + * option) any later version. + * + * The SSH Library 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 Lesser General Public + * License for more details. + * + * You should have received a copy of the GNU Lesser General Public License + * along with the SSH Library; see the file COPYING. If not, write to + * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, + * MA 02111-1307, USA. + */ + +#include "config.h" + +#include <ctype.h> +#include <errno.h> +#include <stdio.h> +#include <stdlib.h> +#include <arpa/inet.h> +#include <netinet/in.h> + +#include "libssh/priv.h" +#include "libssh/session.h" +#include "libssh/options.h" +#include "libssh/misc.h" +#include "libssh/pki.h" + +static int hash_hostname(const char *name, + unsigned char *salt, + unsigned int salt_size, + unsigned char **hash, + unsigned int *hash_size) +{ + HMACCTX mac_ctx; + + mac_ctx = hmac_init(salt, salt_size, SSH_HMAC_SHA1); + if (mac_ctx == NULL) { + return SSH_ERROR; + } + + hmac_update(mac_ctx, name, strlen(name)); + hmac_final(mac_ctx, *hash, hash_size); + + return SSH_OK; +} + +static int match_hashed_hostname(const char *host, const char *hashed_host) +{ + char *hashed; + char *b64_hash; + ssh_buffer salt = NULL; + ssh_buffer hash = NULL; + unsigned char hashed_buf[256] = {0}; + unsigned char *hashed_buf_ptr = hashed_buf; + unsigned int hashed_buf_size = sizeof(hashed_buf); + int cmp; + int rc; + int match = 0; + + cmp = strncmp(hashed_host, "|1|", 3); + if (cmp != 0) { + return 0; + } + + hashed = strdup(hashed_host + 3); + if (hashed == NULL) { + return 0; + } + + b64_hash = strchr(hashed, '|'); + if (b64_hash == NULL) { + goto error; + } + *b64_hash = '\0'; + b64_hash++; + + salt = base64_to_bin(hashed); + if (salt == NULL) { + goto error; + } + + hash = base64_to_bin(b64_hash); + if (hash == NULL) { + goto error; + } + + rc = hash_hostname(host, + ssh_buffer_get(salt), + ssh_buffer_get_len(salt), + &hashed_buf_ptr, + &hashed_buf_size); + if (rc != SSH_OK) { + goto error; + } + + if (hashed_buf_size != ssh_buffer_get_len(hash)) { + goto error; + } + + cmp = memcmp(hashed_buf, ssh_buffer_get(hash), hashed_buf_size); + if (cmp == 0) { + match = 1; + } + +error: + free(hashed); + ssh_buffer_free(salt); + ssh_buffer_free(hash); + + return match; +} + +/** + * @brief Free an allocated ssh_knownhosts_entry. + * + * Use SSH_KNOWNHOSTS_ENTRY_FREE() to set the pointer to NULL. + * + * @param[in] entry The entry to free. + */ +void ssh_knownhosts_entry_free(struct ssh_knownhosts_entry *entry) +{ + if (entry == NULL) { + return; + } + + SAFE_FREE(entry->hostname); + SAFE_FREE(entry->unparsed); + ssh_key_free(entry->publickey); + SAFE_FREE(entry->comment); + SAFE_FREE(entry); +} + +/** + * @brief Parse a line from a known_hosts entry into a structure + * + * This parses an known_hosts entry into a structure with the key in a libssh + * consumeable form. You can use the PKI key function to further work with it. + * + * @param[in] hostname The hostname to match the line to + * + * @param[in] line The line to compare and parse if we have a hostname + * match. + * + * @param[in] entry A pointer to store the the allocated known_hosts + * entry structure. The user needs to free the memory + * using SSH_KNOWNHOSTS_ENTRY_FREE(). + * + * @return SSH_OK on success, SSH_ERROR otherwise. + */ +int ssh_known_hosts_parse_line(const char *hostname, + const char *line, + struct ssh_knownhosts_entry **entry) +{ + struct ssh_knownhosts_entry *e = NULL; + char *known_host = NULL; + char *p; + enum ssh_keytypes_e key_type; + int match = 0; + int rc = SSH_OK; + + known_host = strdup(line); + if (known_host == NULL) { + return SSH_ERROR; + } + + /* match pattern for hostname or hashed hostname */ + p = strtok(known_host, " "); + if (p == NULL ) { + free(known_host); + return SSH_ERROR; + } + + e = calloc(1, sizeof(struct ssh_knownhosts_entry)); + if (e == NULL) { + free(known_host); + return SSH_ERROR; + } + + if (hostname != NULL) { + char *match_pattern = NULL; + char *q; + + /* Hashed */ + if (p[0] == '|') { + match = match_hashed_hostname(hostname, p); + } + + for (q = strtok(p, ","); + q != NULL; + q = strtok(NULL, ",")) { + int cmp; + + cmp = match_hostname(hostname, q, strlen(q)); + if (cmp == 1) { + match = 1; + break; + } + } + SAFE_FREE(match_pattern); + + if (match == 0) { + rc = SSH_AGAIN; + goto out; + } + + e->hostname = strdup(hostname); + if (e->hostname == NULL) { + rc = SSH_ERROR; + goto out; + } + } + + /* Restart parsing */ + SAFE_FREE(known_host); + known_host = strdup(line); + if (known_host == NULL) { + return SSH_ERROR; + } + + p = strtok(known_host, " "); + if (p == NULL ) { + free(known_host); + return SSH_ERROR; + } + + e->unparsed = strdup(p); + if (e->unparsed == NULL) { + rc = SSH_ERROR; + goto out; + } + + /* pubkey type */ + p = strtok(NULL, " "); + if (p == NULL) { + rc = SSH_ERROR; + goto out; + } + + key_type = ssh_key_type_from_name(p); + if (key_type == SSH_KEYTYPE_UNKNOWN) { + SSH_LOG(SSH_LOG_WARN, "key type '%s' unknown!", p); + rc = SSH_ERROR; + goto out; + } + + /* public key */ + p = strtok(NULL, " "); + if (p == NULL) { + rc = SSH_ERROR; + goto out; + } + + rc = ssh_pki_import_pubkey_base64(p, + key_type, + &e->publickey); + if (rc != SSH_OK) { + SSH_LOG(SSH_LOG_WARN, + "Failed to parse %s key for entry: %s!", + ssh_key_type_to_char(key_type), + e->unparsed); + goto out; + } + + /* comment */ + p = strtok(NULL, " "); + if (p != NULL) { + p = strstr(line, p); + e->comment = strdup(p); + if (e->comment == NULL) { + rc = SSH_ERROR; + goto out; + } + } + + *entry = e; + SAFE_FREE(known_host); + + return SSH_OK; +out: + SAFE_FREE(known_host); + ssh_knownhosts_entry_free(e); + return rc; +} |