diff options
Diffstat (limited to 'authfile.c')
| -rw-r--r-- | authfile.c | 526 |
1 files changed, 526 insertions, 0 deletions
diff --git a/authfile.c b/authfile.c new file mode 100644 index 0000000..9ed4f4c --- /dev/null +++ b/authfile.c @@ -0,0 +1,526 @@ +/* $OpenBSD: authfile.c,v 1.143 2022/06/21 14:52:13 tobhe Exp $ */ +/* + * Copyright (c) 2000, 2013 Markus Friedl. 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 <sys/uio.h> + +#include <errno.h> +#include <fcntl.h> +#include <stdio.h> +#include <stdarg.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <limits.h> + +#include "cipher.h" +#include "ssh.h" +#include "log.h" +#include "authfile.h" +#include "misc.h" +#include "atomicio.h" +#include "sshkey.h" +#include "sshbuf.h" +#include "ssherr.h" +#include "krl.h" + +#define MAX_KEY_FILE_SIZE (1024 * 1024) + +/* Save a key blob to a file */ +static int +sshkey_save_private_blob(struct sshbuf *keybuf, const char *filename) +{ + int r; + mode_t omask; + + omask = umask(077); + r = sshbuf_write_file(filename, keybuf); + umask(omask); + return r; +} + +int +sshkey_save_private(struct sshkey *key, const char *filename, + const char *passphrase, const char *comment, + int format, const char *openssh_format_cipher, int openssh_format_rounds) +{ + struct sshbuf *keyblob = NULL; + int r; + + if ((keyblob = sshbuf_new()) == NULL) + return SSH_ERR_ALLOC_FAIL; + if ((r = sshkey_private_to_fileblob(key, keyblob, passphrase, comment, + format, openssh_format_cipher, openssh_format_rounds)) != 0) + goto out; + if ((r = sshkey_save_private_blob(keyblob, filename)) != 0) + goto out; + r = 0; + out: + sshbuf_free(keyblob); + return r; +} + +/* XXX remove error() calls from here? */ +int +sshkey_perm_ok(int fd, const char *filename) +{ + struct stat st; + + if (fstat(fd, &st) == -1) + return SSH_ERR_SYSTEM_ERROR; + /* + * if a key owned by the user is accessed, then we check the + * permissions of the file. if the key owned by a different user, + * then we don't care. + */ +#ifdef HAVE_CYGWIN + if (check_ntsec(filename)) +#endif + if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) { + error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); + error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @"); + error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); + error("Permissions 0%3.3o for '%s' are too open.", + (u_int)st.st_mode & 0777, filename); + error("It is required that your private key files are NOT accessible by others."); + error("This private key will be ignored."); + return SSH_ERR_KEY_BAD_PERMISSIONS; + } + return 0; +} + +int +sshkey_load_private_type(int type, const char *filename, const char *passphrase, + struct sshkey **keyp, char **commentp) +{ + int fd, r; + + if (keyp != NULL) + *keyp = NULL; + if (commentp != NULL) + *commentp = NULL; + + if ((fd = open(filename, O_RDONLY)) == -1) + return SSH_ERR_SYSTEM_ERROR; + + r = sshkey_perm_ok(fd, filename); + if (r != 0) + goto out; + + r = sshkey_load_private_type_fd(fd, type, passphrase, keyp, commentp); + if (r == 0 && keyp && *keyp) + r = sshkey_set_filename(*keyp, filename); + out: + close(fd); + return r; +} + +int +sshkey_load_private(const char *filename, const char *passphrase, + struct sshkey **keyp, char **commentp) +{ + return sshkey_load_private_type(KEY_UNSPEC, filename, passphrase, + keyp, commentp); +} + +int +sshkey_load_private_type_fd(int fd, int type, const char *passphrase, + struct sshkey **keyp, char **commentp) +{ + struct sshbuf *buffer = NULL; + int r; + + if (keyp != NULL) + *keyp = NULL; + if ((r = sshbuf_load_fd(fd, &buffer)) != 0 || + (r = sshkey_parse_private_fileblob_type(buffer, type, + passphrase, keyp, commentp)) != 0) + goto out; + + /* success */ + r = 0; + out: + sshbuf_free(buffer); + return r; +} + +/* Load a pubkey from the unencrypted envelope of a new-format private key */ +static int +sshkey_load_pubkey_from_private(const char *filename, struct sshkey **pubkeyp) +{ + struct sshbuf *buffer = NULL; + struct sshkey *pubkey = NULL; + int r, fd; + + if (pubkeyp != NULL) + *pubkeyp = NULL; + + if ((fd = open(filename, O_RDONLY)) == -1) + return SSH_ERR_SYSTEM_ERROR; + if ((r = sshbuf_load_fd(fd, &buffer)) != 0 || + (r = sshkey_parse_pubkey_from_private_fileblob_type(buffer, + KEY_UNSPEC, &pubkey)) != 0) + goto out; + if ((r = sshkey_set_filename(pubkey, filename)) != 0) + goto out; + /* success */ + if (pubkeyp != NULL) { + *pubkeyp = pubkey; + pubkey = NULL; + } + r = 0; + out: + close(fd); + sshbuf_free(buffer); + sshkey_free(pubkey); + return r; +} + +static int +sshkey_try_load_public(struct sshkey **kp, const char *filename, + char **commentp) +{ + FILE *f; + char *line = NULL, *cp; + size_t linesize = 0; + int r; + struct sshkey *k = NULL; + + *kp = NULL; + if (commentp != NULL) + *commentp = NULL; + if ((f = fopen(filename, "r")) == NULL) + return SSH_ERR_SYSTEM_ERROR; + if ((k = sshkey_new(KEY_UNSPEC)) == NULL) { + fclose(f); + return SSH_ERR_ALLOC_FAIL; + } + while (getline(&line, &linesize, f) != -1) { + cp = line; + switch (*cp) { + case '#': + case '\n': + case '\0': + continue; + } + /* Abort loading if this looks like a private key */ + if (strncmp(cp, "-----BEGIN", 10) == 0 || + strcmp(cp, "SSH PRIVATE KEY FILE") == 0) + break; + /* Skip leading whitespace. */ + for (; *cp && (*cp == ' ' || *cp == '\t'); cp++) + ; + if (*cp) { + if ((r = sshkey_read(k, &cp)) == 0) { + cp[strcspn(cp, "\r\n")] = '\0'; + if (commentp) { + *commentp = strdup(*cp ? + cp : filename); + if (*commentp == NULL) + r = SSH_ERR_ALLOC_FAIL; + } + /* success */ + *kp = k; + free(line); + fclose(f); + return r; + } + } + } + free(k); + free(line); + fclose(f); + return SSH_ERR_INVALID_FORMAT; +} + +/* load public key from any pubkey file */ +int +sshkey_load_public(const char *filename, struct sshkey **keyp, char **commentp) +{ + char *pubfile = NULL; + int r, oerrno; + + if (keyp != NULL) + *keyp = NULL; + if (commentp != NULL) + *commentp = NULL; + + if ((r = sshkey_try_load_public(keyp, filename, commentp)) == 0) + goto out; + + /* try .pub suffix */ + if (asprintf(&pubfile, "%s.pub", filename) == -1) + return SSH_ERR_ALLOC_FAIL; + if ((r = sshkey_try_load_public(keyp, pubfile, commentp)) == 0) + goto out; + + /* finally, try to extract public key from private key file */ + if ((r = sshkey_load_pubkey_from_private(filename, keyp)) == 0) + goto out; + + /* Pretend we couldn't find the key */ + r = SSH_ERR_SYSTEM_ERROR; + errno = ENOENT; + + out: + oerrno = errno; + free(pubfile); + errno = oerrno; + return r; +} + +/* Load the certificate associated with the named private key */ +int +sshkey_load_cert(const char *filename, struct sshkey **keyp) +{ + struct sshkey *pub = NULL; + char *file = NULL; + int r = SSH_ERR_INTERNAL_ERROR; + + if (keyp != NULL) + *keyp = NULL; + + if (asprintf(&file, "%s-cert.pub", filename) == -1) + return SSH_ERR_ALLOC_FAIL; + + r = sshkey_try_load_public(keyp, file, NULL); + free(file); + sshkey_free(pub); + return r; +} + +/* Load private key and certificate */ +int +sshkey_load_private_cert(int type, const char *filename, const char *passphrase, + struct sshkey **keyp) +{ + struct sshkey *key = NULL, *cert = NULL; + int r; + + if (keyp != NULL) + *keyp = NULL; + + switch (type) { +#ifdef WITH_OPENSSL + case KEY_RSA: + case KEY_DSA: + case KEY_ECDSA: +#endif /* WITH_OPENSSL */ + case KEY_ED25519: + case KEY_XMSS: + case KEY_UNSPEC: + break; + default: + return SSH_ERR_KEY_TYPE_UNKNOWN; + } + + if ((r = sshkey_load_private_type(type, filename, + passphrase, &key, NULL)) != 0 || + (r = sshkey_load_cert(filename, &cert)) != 0) + goto out; + + /* Make sure the private key matches the certificate */ + if (sshkey_equal_public(key, cert) == 0) { + r = SSH_ERR_KEY_CERT_MISMATCH; + goto out; + } + + if ((r = sshkey_to_certified(key)) != 0 || + (r = sshkey_cert_copy(cert, key)) != 0) + goto out; + r = 0; + if (keyp != NULL) { + *keyp = key; + key = NULL; + } + out: + sshkey_free(key); + sshkey_free(cert); + return r; +} + +/* + * Returns success if the specified "key" is listed in the file "filename", + * SSH_ERR_KEY_NOT_FOUND: if the key is not listed or another error. + * If "strict_type" is set then the key type must match exactly, + * otherwise a comparison that ignores certificate data is performed. + * If "check_ca" is set and "key" is a certificate, then its CA key is + * also checked and sshkey_in_file() will return success if either is found. + */ +int +sshkey_in_file(struct sshkey *key, const char *filename, int strict_type, + int check_ca) +{ + FILE *f; + char *line = NULL, *cp; + size_t linesize = 0; + int r = 0; + struct sshkey *pub = NULL; + + int (*sshkey_compare)(const struct sshkey *, const struct sshkey *) = + strict_type ? sshkey_equal : sshkey_equal_public; + + if ((f = fopen(filename, "r")) == NULL) + return SSH_ERR_SYSTEM_ERROR; + + while (getline(&line, &linesize, f) != -1) { + sshkey_free(pub); + pub = NULL; + cp = line; + + /* Skip leading whitespace. */ + for (; *cp && (*cp == ' ' || *cp == '\t'); cp++) + ; + + /* Skip comments and empty lines */ + switch (*cp) { + case '#': + case '\n': + case '\0': + continue; + } + + if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + switch (r = sshkey_read(pub, &cp)) { + case 0: + break; + case SSH_ERR_KEY_LENGTH: + continue; + default: + goto out; + } + if (sshkey_compare(key, pub) || + (check_ca && sshkey_is_cert(key) && + sshkey_compare(key->cert->signature_key, pub))) { + r = 0; + goto out; + } + } + r = SSH_ERR_KEY_NOT_FOUND; + out: + free(line); + sshkey_free(pub); + fclose(f); + return r; +} + +/* + * Checks whether the specified key is revoked, returning 0 if not, + * SSH_ERR_KEY_REVOKED if it is or another error code if something + * unexpected happened. + * This will check both the key and, if it is a certificate, its CA key too. + * "revoked_keys_file" may be a KRL or a one-per-line list of public keys. + */ +int +sshkey_check_revoked(struct sshkey *key, const char *revoked_keys_file) +{ + int r; + + r = ssh_krl_file_contains_key(revoked_keys_file, key); + /* If this was not a KRL to begin with then continue below */ + if (r != SSH_ERR_KRL_BAD_MAGIC) + return r; + + /* + * If the file is not a KRL or we can't handle KRLs then attempt to + * parse the file as a flat list of keys. + */ + switch ((r = sshkey_in_file(key, revoked_keys_file, 0, 1))) { + case 0: + /* Key found => revoked */ + return SSH_ERR_KEY_REVOKED; + case SSH_ERR_KEY_NOT_FOUND: + /* Key not found => not revoked */ + return 0; + default: + /* Some other error occurred */ + return r; + } +} + +/* + * Advanced *cpp past the end of key options, defined as the first unquoted + * whitespace character. Returns 0 on success or -1 on failure (e.g. + * unterminated quotes). + */ +int +sshkey_advance_past_options(char **cpp) +{ + char *cp = *cpp; + int quoted = 0; + + for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) { + if (*cp == '\\' && cp[1] == '"') + cp++; /* Skip both */ + else if (*cp == '"') + quoted = !quoted; + } + *cpp = cp; + /* return failure for unterminated quotes */ + return (*cp == '\0' && quoted) ? -1 : 0; +} + +/* Save a public key */ +int +sshkey_save_public(const struct sshkey *key, const char *path, + const char *comment) +{ + int fd, oerrno; + FILE *f = NULL; + int r = SSH_ERR_INTERNAL_ERROR; + + if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, 0644)) == -1) + return SSH_ERR_SYSTEM_ERROR; + if ((f = fdopen(fd, "w")) == NULL) { + r = SSH_ERR_SYSTEM_ERROR; + close(fd); + goto fail; + } + if ((r = sshkey_write(key, f)) != 0) + goto fail; + fprintf(f, " %s\n", comment); + if (ferror(f)) { + r = SSH_ERR_SYSTEM_ERROR; + goto fail; + } + if (fclose(f) != 0) { + r = SSH_ERR_SYSTEM_ERROR; + f = NULL; + fail: + if (f != NULL) { + oerrno = errno; + fclose(f); + errno = oerrno; + } + return r; + } + return 0; +} |