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- /* $OpenBSD: sshsig.c,v 1.35 2024/03/08 22:16:32 djm Exp $ */
- /*
- * Copyright (c) 2019 Google LLC
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-
- #include "includes.h"
-
- #include <stdio.h>
- #include <stdlib.h>
- #include <stdarg.h>
- #include <errno.h>
- #include <string.h>
- #include <unistd.h>
-
- #include "authfd.h"
- #include "authfile.h"
- #include "log.h"
- #include "misc.h"
- #include "sshbuf.h"
- #include "sshsig.h"
- #include "ssherr.h"
- #include "sshkey.h"
- #include "match.h"
- #include "digest.h"
-
- #define SIG_VERSION 0x01
- #define MAGIC_PREAMBLE "SSHSIG"
- #define MAGIC_PREAMBLE_LEN (sizeof(MAGIC_PREAMBLE) - 1)
- #define BEGIN_SIGNATURE "-----BEGIN SSH SIGNATURE-----"
- #define END_SIGNATURE "-----END SSH SIGNATURE-----"
- #define RSA_SIGN_ALG "rsa-sha2-512" /* XXX maybe make configurable */
- #define RSA_SIGN_ALLOWED "rsa-sha2-512,rsa-sha2-256"
- #define HASHALG_DEFAULT "sha512" /* XXX maybe make configurable */
- #define HASHALG_ALLOWED "sha256,sha512"
-
- int
- sshsig_armor(const struct sshbuf *blob, struct sshbuf **out)
- {
- struct sshbuf *buf = NULL;
- int r = SSH_ERR_INTERNAL_ERROR;
-
- *out = NULL;
-
- if ((buf = sshbuf_new()) == NULL) {
- error_f("sshbuf_new failed");
- r = SSH_ERR_ALLOC_FAIL;
- goto out;
- }
-
- if ((r = sshbuf_putf(buf, "%s\n", BEGIN_SIGNATURE)) != 0) {
- error_fr(r, "sshbuf_putf");
- goto out;
- }
-
- if ((r = sshbuf_dtob64(blob, buf, 1)) != 0) {
- error_fr(r, "base64 encode signature");
- goto out;
- }
-
- if ((r = sshbuf_put(buf, END_SIGNATURE,
- sizeof(END_SIGNATURE)-1)) != 0 ||
- (r = sshbuf_put_u8(buf, '\n')) != 0) {
- error_fr(r, "sshbuf_put");
- goto out;
- }
- /* success */
- *out = buf;
- buf = NULL; /* transferred */
- r = 0;
- out:
- sshbuf_free(buf);
- return r;
- }
-
- int
- sshsig_dearmor(struct sshbuf *sig, struct sshbuf **out)
- {
- int r;
- size_t eoffset = 0;
- struct sshbuf *buf = NULL;
- struct sshbuf *sbuf = NULL;
- char *b64 = NULL;
-
- if ((sbuf = sshbuf_fromb(sig)) == NULL) {
- error_f("sshbuf_fromb failed");
- return SSH_ERR_ALLOC_FAIL;
- }
-
- /* Expect and consume preamble + lf/crlf */
- if ((r = sshbuf_cmp(sbuf, 0,
- BEGIN_SIGNATURE, sizeof(BEGIN_SIGNATURE)-1)) != 0) {
- error("Couldn't parse signature: missing header");
- goto done;
- }
- if ((r = sshbuf_consume(sbuf, sizeof(BEGIN_SIGNATURE)-1)) != 0) {
- error_fr(r, "consume");
- goto done;
- }
- if ((r = sshbuf_cmp(sbuf, 0, "\r\n", 2)) == 0)
- eoffset = 2;
- else if ((r = sshbuf_cmp(sbuf, 0, "\n", 1)) == 0)
- eoffset = 1;
- else {
- r = SSH_ERR_INVALID_FORMAT;
- error_f("no header eol");
- goto done;
- }
- if ((r = sshbuf_consume(sbuf, eoffset)) != 0) {
- error_fr(r, "consume eol");
- goto done;
- }
- /* Find and consume lf + suffix (any prior cr would be ignored) */
- if ((r = sshbuf_find(sbuf, 0, "\n" END_SIGNATURE,
- sizeof(END_SIGNATURE), &eoffset)) != 0) {
- error("Couldn't parse signature: missing footer");
- goto done;
- }
- if ((r = sshbuf_consume_end(sbuf, sshbuf_len(sbuf)-eoffset)) != 0) {
- error_fr(r, "consume");
- goto done;
- }
-
- if ((b64 = sshbuf_dup_string(sbuf)) == NULL) {
- error_f("sshbuf_dup_string failed");
- r = SSH_ERR_ALLOC_FAIL;
- goto done;
- }
-
- if ((buf = sshbuf_new()) == NULL) {
- error_f("sshbuf_new() failed");
- r = SSH_ERR_ALLOC_FAIL;
- goto done;
- }
-
- if ((r = sshbuf_b64tod(buf, b64)) != 0) {
- error_fr(r, "decode base64");
- goto done;
- }
-
- /* success */
- *out = buf;
- r = 0;
- buf = NULL; /* transferred */
- done:
- sshbuf_free(buf);
- sshbuf_free(sbuf);
- free(b64);
- return r;
- }
-
- static int
- sshsig_wrap_sign(struct sshkey *key, const char *hashalg,
- const char *sk_provider, const char *sk_pin, const struct sshbuf *h_message,
- const char *sig_namespace, struct sshbuf **out,
- sshsig_signer *signer, void *signer_ctx)
- {
- int r;
- size_t slen = 0;
- u_char *sig = NULL;
- struct sshbuf *blob = NULL;
- struct sshbuf *tosign = NULL;
- const char *sign_alg = NULL;
-
- if ((tosign = sshbuf_new()) == NULL ||
- (blob = sshbuf_new()) == NULL) {
- error_f("sshbuf_new failed");
- r = SSH_ERR_ALLOC_FAIL;
- goto done;
- }
-
- if ((r = sshbuf_put(tosign, MAGIC_PREAMBLE, MAGIC_PREAMBLE_LEN)) != 0 ||
- (r = sshbuf_put_cstring(tosign, sig_namespace)) != 0 ||
- (r = sshbuf_put_string(tosign, NULL, 0)) != 0 || /* reserved */
- (r = sshbuf_put_cstring(tosign, hashalg)) != 0 ||
- (r = sshbuf_put_stringb(tosign, h_message)) != 0) {
- error_fr(r, "assemble message to sign");
- goto done;
- }
-
- /* If using RSA keys then default to a good signature algorithm */
- if (sshkey_type_plain(key->type) == KEY_RSA)
- sign_alg = RSA_SIGN_ALG;
-
- if (signer != NULL) {
- if ((r = signer(key, &sig, &slen,
- sshbuf_ptr(tosign), sshbuf_len(tosign),
- sign_alg, sk_provider, sk_pin, 0, signer_ctx)) != 0) {
- error_r(r, "Couldn't sign message (signer)");
- goto done;
- }
- } else {
- if ((r = sshkey_sign(key, &sig, &slen,
- sshbuf_ptr(tosign), sshbuf_len(tosign),
- sign_alg, sk_provider, sk_pin, 0)) != 0) {
- error_r(r, "Couldn't sign message");
- goto done;
- }
- }
-
- if ((r = sshbuf_put(blob, MAGIC_PREAMBLE, MAGIC_PREAMBLE_LEN)) != 0 ||
- (r = sshbuf_put_u32(blob, SIG_VERSION)) != 0 ||
- (r = sshkey_puts(key, blob)) != 0 ||
- (r = sshbuf_put_cstring(blob, sig_namespace)) != 0 ||
- (r = sshbuf_put_string(blob, NULL, 0)) != 0 || /* reserved */
- (r = sshbuf_put_cstring(blob, hashalg)) != 0 ||
- (r = sshbuf_put_string(blob, sig, slen)) != 0) {
- error_fr(r, "assemble signature object");
- goto done;
- }
-
- if (out != NULL) {
- *out = blob;
- blob = NULL;
- }
- r = 0;
- done:
- free(sig);
- sshbuf_free(blob);
- sshbuf_free(tosign);
- return r;
- }
-
- /* Check preamble and version. */
- static int
- sshsig_parse_preamble(struct sshbuf *buf)
- {
- int r = SSH_ERR_INTERNAL_ERROR;
- uint32_t sversion;
-
- if ((r = sshbuf_cmp(buf, 0, MAGIC_PREAMBLE, MAGIC_PREAMBLE_LEN)) != 0 ||
- (r = sshbuf_consume(buf, (sizeof(MAGIC_PREAMBLE)-1))) != 0 ||
- (r = sshbuf_get_u32(buf, &sversion)) != 0) {
- error("Couldn't verify signature: invalid format");
- return r;
- }
-
- if (sversion > SIG_VERSION) {
- error("Signature version %lu is larger than supported "
- "version %u", (unsigned long)sversion, SIG_VERSION);
- return SSH_ERR_INVALID_FORMAT;
- }
- return 0;
- }
-
- static int
- sshsig_check_hashalg(const char *hashalg)
- {
- if (hashalg == NULL ||
- match_pattern_list(hashalg, HASHALG_ALLOWED, 0) == 1)
- return 0;
- error_f("unsupported hash algorithm \"%.100s\"", hashalg);
- return SSH_ERR_SIGN_ALG_UNSUPPORTED;
- }
-
- static int
- sshsig_peek_hashalg(struct sshbuf *signature, char **hashalgp)
- {
- struct sshbuf *buf = NULL;
- char *hashalg = NULL;
- int r = SSH_ERR_INTERNAL_ERROR;
-
- if (hashalgp != NULL)
- *hashalgp = NULL;
- if ((buf = sshbuf_fromb(signature)) == NULL)
- return SSH_ERR_ALLOC_FAIL;
- if ((r = sshsig_parse_preamble(buf)) != 0)
- goto done;
- if ((r = sshbuf_get_string_direct(buf, NULL, NULL)) != 0 ||
- (r = sshbuf_get_string_direct(buf, NULL, NULL)) != 0 ||
- (r = sshbuf_get_string(buf, NULL, NULL)) != 0 ||
- (r = sshbuf_get_cstring(buf, &hashalg, NULL)) != 0 ||
- (r = sshbuf_get_string_direct(buf, NULL, NULL)) != 0) {
- error_fr(r, "parse signature object");
- goto done;
- }
-
- /* success */
- r = 0;
- *hashalgp = hashalg;
- hashalg = NULL;
- done:
- free(hashalg);
- sshbuf_free(buf);
- return r;
- }
-
- static int
- sshsig_wrap_verify(struct sshbuf *signature, const char *hashalg,
- const struct sshbuf *h_message, const char *expect_namespace,
- struct sshkey **sign_keyp, struct sshkey_sig_details **sig_details)
- {
- int r = SSH_ERR_INTERNAL_ERROR;
- struct sshbuf *buf = NULL, *toverify = NULL;
- struct sshkey *key = NULL;
- const u_char *sig;
- char *got_namespace = NULL, *sigtype = NULL, *sig_hashalg = NULL;
- size_t siglen;
-
- debug_f("verify message length %zu", sshbuf_len(h_message));
- if (sig_details != NULL)
- *sig_details = NULL;
- if (sign_keyp != NULL)
- *sign_keyp = NULL;
-
- if ((toverify = sshbuf_new()) == NULL) {
- error_f("sshbuf_new failed");
- r = SSH_ERR_ALLOC_FAIL;
- goto done;
- }
- if ((r = sshbuf_put(toverify, MAGIC_PREAMBLE,
- MAGIC_PREAMBLE_LEN)) != 0 ||
- (r = sshbuf_put_cstring(toverify, expect_namespace)) != 0 ||
- (r = sshbuf_put_string(toverify, NULL, 0)) != 0 || /* reserved */
- (r = sshbuf_put_cstring(toverify, hashalg)) != 0 ||
- (r = sshbuf_put_stringb(toverify, h_message)) != 0) {
- error_fr(r, "assemble message to verify");
- goto done;
- }
-
- if ((r = sshsig_parse_preamble(signature)) != 0)
- goto done;
-
- if ((r = sshkey_froms(signature, &key)) != 0 ||
- (r = sshbuf_get_cstring(signature, &got_namespace, NULL)) != 0 ||
- (r = sshbuf_get_string(signature, NULL, NULL)) != 0 ||
- (r = sshbuf_get_cstring(signature, &sig_hashalg, NULL)) != 0 ||
- (r = sshbuf_get_string_direct(signature, &sig, &siglen)) != 0) {
- error_fr(r, "parse signature object");
- goto done;
- }
-
- if (sshbuf_len(signature) != 0) {
- error("Signature contains trailing data");
- r = SSH_ERR_INVALID_FORMAT;
- goto done;
- }
-
- if (strcmp(expect_namespace, got_namespace) != 0) {
- error("Couldn't verify signature: namespace does not match");
- debug_f("expected namespace \"%s\" received \"%s\"",
- expect_namespace, got_namespace);
- r = SSH_ERR_SIGNATURE_INVALID;
- goto done;
- }
- if (strcmp(hashalg, sig_hashalg) != 0) {
- error("Couldn't verify signature: hash algorithm mismatch");
- debug_f("expected algorithm \"%s\" received \"%s\"",
- hashalg, sig_hashalg);
- r = SSH_ERR_SIGNATURE_INVALID;
- goto done;
- }
- /* Ensure that RSA keys use an acceptable signature algorithm */
- if (sshkey_type_plain(key->type) == KEY_RSA) {
- if ((r = sshkey_get_sigtype(sig, siglen, &sigtype)) != 0) {
- error_r(r, "Couldn't verify signature: unable to get "
- "signature type");
- goto done;
- }
- if (match_pattern_list(sigtype, RSA_SIGN_ALLOWED, 0) != 1) {
- error("Couldn't verify signature: unsupported RSA "
- "signature algorithm %s", sigtype);
- r = SSH_ERR_SIGN_ALG_UNSUPPORTED;
- goto done;
- }
- }
- if ((r = sshkey_verify(key, sig, siglen, sshbuf_ptr(toverify),
- sshbuf_len(toverify), NULL, 0, sig_details)) != 0) {
- error_r(r, "Signature verification failed");
- goto done;
- }
-
- /* success */
- r = 0;
- if (sign_keyp != NULL) {
- *sign_keyp = key;
- key = NULL; /* transferred */
- }
- done:
- free(got_namespace);
- free(sigtype);
- free(sig_hashalg);
- sshbuf_free(buf);
- sshbuf_free(toverify);
- sshkey_free(key);
- return r;
- }
-
- static int
- hash_buffer(const struct sshbuf *m, const char *hashalg, struct sshbuf **bp)
- {
- char *hex, hash[SSH_DIGEST_MAX_LENGTH];
- int alg, r = SSH_ERR_INTERNAL_ERROR;
- struct sshbuf *b = NULL;
-
- *bp = NULL;
- memset(hash, 0, sizeof(hash));
-
- if ((r = sshsig_check_hashalg(hashalg)) != 0)
- return r;
- if ((alg = ssh_digest_alg_by_name(hashalg)) == -1) {
- error_f("can't look up hash algorithm %s", hashalg);
- return SSH_ERR_INTERNAL_ERROR;
- }
- if ((r = ssh_digest_buffer(alg, m, hash, sizeof(hash))) != 0) {
- error_fr(r, "ssh_digest_buffer");
- return r;
- }
- if ((hex = tohex(hash, ssh_digest_bytes(alg))) != NULL) {
- debug3_f("final hash: %s", hex);
- freezero(hex, strlen(hex));
- }
- if ((b = sshbuf_new()) == NULL) {
- r = SSH_ERR_ALLOC_FAIL;
- goto out;
- }
- if ((r = sshbuf_put(b, hash, ssh_digest_bytes(alg))) != 0) {
- error_fr(r, "sshbuf_put");
- goto out;
- }
- *bp = b;
- b = NULL; /* transferred */
- /* success */
- r = 0;
- out:
- sshbuf_free(b);
- explicit_bzero(hash, sizeof(hash));
- return r;
- }
-
- int
- sshsig_signb(struct sshkey *key, const char *hashalg,
- const char *sk_provider, const char *sk_pin,
- const struct sshbuf *message, const char *sig_namespace,
- struct sshbuf **out, sshsig_signer *signer, void *signer_ctx)
- {
- struct sshbuf *b = NULL;
- int r = SSH_ERR_INTERNAL_ERROR;
-
- if (hashalg == NULL)
- hashalg = HASHALG_DEFAULT;
- if (out != NULL)
- *out = NULL;
- if ((r = hash_buffer(message, hashalg, &b)) != 0) {
- error_fr(r, "hash buffer");
- goto out;
- }
- if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, sk_pin, b,
- sig_namespace, out, signer, signer_ctx)) != 0)
- goto out;
- /* success */
- r = 0;
- out:
- sshbuf_free(b);
- return r;
- }
-
- int
- sshsig_verifyb(struct sshbuf *signature, const struct sshbuf *message,
- const char *expect_namespace, struct sshkey **sign_keyp,
- struct sshkey_sig_details **sig_details)
- {
- struct sshbuf *b = NULL;
- int r = SSH_ERR_INTERNAL_ERROR;
- char *hashalg = NULL;
-
- if (sig_details != NULL)
- *sig_details = NULL;
- if (sign_keyp != NULL)
- *sign_keyp = NULL;
- if ((r = sshsig_peek_hashalg(signature, &hashalg)) != 0)
- return r;
- debug_f("signature made with hash \"%s\"", hashalg);
- if ((r = hash_buffer(message, hashalg, &b)) != 0) {
- error_fr(r, "hash buffer");
- goto out;
- }
- if ((r = sshsig_wrap_verify(signature, hashalg, b, expect_namespace,
- sign_keyp, sig_details)) != 0)
- goto out;
- /* success */
- r = 0;
- out:
- sshbuf_free(b);
- free(hashalg);
- return r;
- }
-
- static int
- hash_file(int fd, const char *hashalg, struct sshbuf **bp)
- {
- char *hex, rbuf[8192], hash[SSH_DIGEST_MAX_LENGTH];
- ssize_t n, total = 0;
- struct ssh_digest_ctx *ctx = NULL;
- int alg, oerrno, r = SSH_ERR_INTERNAL_ERROR;
- struct sshbuf *b = NULL;
-
- *bp = NULL;
- memset(hash, 0, sizeof(hash));
-
- if ((r = sshsig_check_hashalg(hashalg)) != 0)
- return r;
- if ((alg = ssh_digest_alg_by_name(hashalg)) == -1) {
- error_f("can't look up hash algorithm %s", hashalg);
- return SSH_ERR_INTERNAL_ERROR;
- }
- if ((ctx = ssh_digest_start(alg)) == NULL) {
- error_f("ssh_digest_start failed");
- return SSH_ERR_INTERNAL_ERROR;
- }
- for (;;) {
- if ((n = read(fd, rbuf, sizeof(rbuf))) == -1) {
- if (errno == EINTR || errno == EAGAIN)
- continue;
- oerrno = errno;
- error_f("read: %s", strerror(errno));
- errno = oerrno;
- r = SSH_ERR_SYSTEM_ERROR;
- goto out;
- } else if (n == 0) {
- debug2_f("hashed %zu bytes", total);
- break; /* EOF */
- }
- total += (size_t)n;
- if ((r = ssh_digest_update(ctx, rbuf, (size_t)n)) != 0) {
- error_fr(r, "ssh_digest_update");
- goto out;
- }
- }
- if ((r = ssh_digest_final(ctx, hash, sizeof(hash))) != 0) {
- error_fr(r, "ssh_digest_final");
- goto out;
- }
- if ((hex = tohex(hash, ssh_digest_bytes(alg))) != NULL) {
- debug3_f("final hash: %s", hex);
- freezero(hex, strlen(hex));
- }
- if ((b = sshbuf_new()) == NULL) {
- r = SSH_ERR_ALLOC_FAIL;
- goto out;
- }
- if ((r = sshbuf_put(b, hash, ssh_digest_bytes(alg))) != 0) {
- error_fr(r, "sshbuf_put");
- goto out;
- }
- *bp = b;
- b = NULL; /* transferred */
- /* success */
- r = 0;
- out:
- oerrno = errno;
- sshbuf_free(b);
- ssh_digest_free(ctx);
- explicit_bzero(hash, sizeof(hash));
- errno = oerrno;
- return r;
- }
-
- int
- sshsig_sign_fd(struct sshkey *key, const char *hashalg,
- const char *sk_provider, const char *sk_pin,
- int fd, const char *sig_namespace, struct sshbuf **out,
- sshsig_signer *signer, void *signer_ctx)
- {
- struct sshbuf *b = NULL;
- int r = SSH_ERR_INTERNAL_ERROR;
-
- if (hashalg == NULL)
- hashalg = HASHALG_DEFAULT;
- if (out != NULL)
- *out = NULL;
- if ((r = hash_file(fd, hashalg, &b)) != 0) {
- error_fr(r, "hash_file");
- return r;
- }
- if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, sk_pin, b,
- sig_namespace, out, signer, signer_ctx)) != 0)
- goto out;
- /* success */
- r = 0;
- out:
- sshbuf_free(b);
- return r;
- }
-
- int
- sshsig_verify_fd(struct sshbuf *signature, int fd,
- const char *expect_namespace, struct sshkey **sign_keyp,
- struct sshkey_sig_details **sig_details)
- {
- struct sshbuf *b = NULL;
- int r = SSH_ERR_INTERNAL_ERROR;
- char *hashalg = NULL;
-
- if (sig_details != NULL)
- *sig_details = NULL;
- if (sign_keyp != NULL)
- *sign_keyp = NULL;
- if ((r = sshsig_peek_hashalg(signature, &hashalg)) != 0)
- return r;
- debug_f("signature made with hash \"%s\"", hashalg);
- if ((r = hash_file(fd, hashalg, &b)) != 0) {
- error_fr(r, "hash_file");
- goto out;
- }
- if ((r = sshsig_wrap_verify(signature, hashalg, b, expect_namespace,
- sign_keyp, sig_details)) != 0)
- goto out;
- /* success */
- r = 0;
- out:
- sshbuf_free(b);
- free(hashalg);
- return r;
- }
-
- struct sshsigopt {
- int ca;
- char *namespaces;
- uint64_t valid_after, valid_before;
- };
-
- struct sshsigopt *
- sshsigopt_parse(const char *opts, const char *path, u_long linenum,
- const char **errstrp)
- {
- struct sshsigopt *ret;
- int r;
- char *opt;
- const char *errstr = NULL;
-
- if ((ret = calloc(1, sizeof(*ret))) == NULL)
- return NULL;
- if (opts == NULL || *opts == '\0')
- return ret; /* Empty options yields empty options :) */
-
- while (*opts && *opts != ' ' && *opts != '\t') {
- /* flag options */
- if ((r = opt_flag("cert-authority", 0, &opts)) != -1) {
- ret->ca = 1;
- } else if (opt_match(&opts, "namespaces")) {
- if (ret->namespaces != NULL) {
- errstr = "multiple \"namespaces\" clauses";
- goto fail;
- }
- ret->namespaces = opt_dequote(&opts, &errstr);
- if (ret->namespaces == NULL)
- goto fail;
- } else if (opt_match(&opts, "valid-after")) {
- if (ret->valid_after != 0) {
- errstr = "multiple \"valid-after\" clauses";
- goto fail;
- }
- if ((opt = opt_dequote(&opts, &errstr)) == NULL)
- goto fail;
- if (parse_absolute_time(opt, &ret->valid_after) != 0 ||
- ret->valid_after == 0) {
- free(opt);
- errstr = "invalid \"valid-after\" time";
- goto fail;
- }
- free(opt);
- } else if (opt_match(&opts, "valid-before")) {
- if (ret->valid_before != 0) {
- errstr = "multiple \"valid-before\" clauses";
- goto fail;
- }
- if ((opt = opt_dequote(&opts, &errstr)) == NULL)
- goto fail;
- if (parse_absolute_time(opt, &ret->valid_before) != 0 ||
- ret->valid_before == 0) {
- free(opt);
- errstr = "invalid \"valid-before\" time";
- goto fail;
- }
- free(opt);
- }
- /*
- * Skip the comma, and move to the next option
- * (or break out if there are no more).
- */
- if (*opts == '\0' || *opts == ' ' || *opts == '\t')
- break; /* End of options. */
- /* Anything other than a comma is an unknown option */
- if (*opts != ',') {
- errstr = "unknown key option";
- goto fail;
- }
- opts++;
- if (*opts == '\0') {
- errstr = "unexpected end-of-options";
- goto fail;
- }
- }
- /* final consistency check */
- if (ret->valid_after != 0 && ret->valid_before != 0 &&
- ret->valid_before <= ret->valid_after) {
- errstr = "\"valid-before\" time is before \"valid-after\"";
- goto fail;
- }
- /* success */
- return ret;
- fail:
- if (errstrp != NULL)
- *errstrp = errstr;
- sshsigopt_free(ret);
- return NULL;
- }
-
- void
- sshsigopt_free(struct sshsigopt *opts)
- {
- if (opts == NULL)
- return;
- free(opts->namespaces);
- free(opts);
- }
-
- static int
- parse_principals_key_and_options(const char *path, u_long linenum, char *line,
- const char *required_principal, char **principalsp, struct sshkey **keyp,
- struct sshsigopt **sigoptsp)
- {
- char *opts = NULL, *tmp, *cp, *principals = NULL;
- const char *reason = NULL;
- struct sshsigopt *sigopts = NULL;
- struct sshkey *key = NULL;
- int r = SSH_ERR_INTERNAL_ERROR;
-
- if (principalsp != NULL)
- *principalsp = NULL;
- if (sigoptsp != NULL)
- *sigoptsp = NULL;
- if (keyp != NULL)
- *keyp = NULL;
-
- cp = line;
- cp = cp + strspn(cp, " \t\n\r"); /* skip leading whitespace */
- if (*cp == '#' || *cp == '\0')
- return SSH_ERR_KEY_NOT_FOUND; /* blank or all-comment line */
-
- /* format: identity[,identity...] [option[,option...]] key */
- if ((tmp = strdelimw(&cp)) == NULL || cp == NULL) {
- error("%s:%lu: invalid line", path, linenum);
- r = SSH_ERR_INVALID_FORMAT;
- goto out;
- }
- if ((principals = strdup(tmp)) == NULL) {
- error_f("strdup failed");
- r = SSH_ERR_ALLOC_FAIL;
- goto out;
- }
- /*
- * Bail out early if we're looking for a particular principal and this
- * line does not list it.
- */
- if (required_principal != NULL) {
- if (match_pattern_list(required_principal,
- principals, 0) != 1) {
- /* principal didn't match */
- r = SSH_ERR_KEY_NOT_FOUND;
- goto out;
- }
- debug_f("%s:%lu: matched principal \"%s\"",
- path, linenum, required_principal);
- }
-
- if ((key = sshkey_new(KEY_UNSPEC)) == NULL) {
- error_f("sshkey_new failed");
- r = SSH_ERR_ALLOC_FAIL;
- goto out;
- }
- if (sshkey_read(key, &cp) != 0) {
- /* no key? Check for options */
- opts = cp;
- if (sshkey_advance_past_options(&cp) != 0) {
- error("%s:%lu: invalid options", path, linenum);
- r = SSH_ERR_INVALID_FORMAT;
- goto out;
- }
- if (cp == NULL || *cp == '\0') {
- error("%s:%lu: missing key", path, linenum);
- r = SSH_ERR_INVALID_FORMAT;
- goto out;
- }
- *cp++ = '\0';
- skip_space(&cp);
- if (sshkey_read(key, &cp) != 0) {
- error("%s:%lu: invalid key", path, linenum);
- r = SSH_ERR_INVALID_FORMAT;
- goto out;
- }
- }
- debug3("%s:%lu: options %s", path, linenum, opts == NULL ? "" : opts);
- if ((sigopts = sshsigopt_parse(opts, path, linenum, &reason)) == NULL) {
- error("%s:%lu: bad options: %s", path, linenum, reason);
- r = SSH_ERR_INVALID_FORMAT;
- goto out;
- }
- /* success */
- if (principalsp != NULL) {
- *principalsp = principals;
- principals = NULL; /* transferred */
- }
- if (sigoptsp != NULL) {
- *sigoptsp = sigopts;
- sigopts = NULL; /* transferred */
- }
- if (keyp != NULL) {
- *keyp = key;
- key = NULL; /* transferred */
- }
- r = 0;
- out:
- free(principals);
- sshsigopt_free(sigopts);
- sshkey_free(key);
- return r;
- }
-
- static int
- cert_filter_principals(const char *path, u_long linenum,
- char **principalsp, const struct sshkey *cert, uint64_t verify_time)
- {
- char *cp, *oprincipals, *principals;
- const char *reason;
- struct sshbuf *nprincipals;
- int r = SSH_ERR_INTERNAL_ERROR, success = 0;
- u_int i;
-
- oprincipals = principals = *principalsp;
- *principalsp = NULL;
-
- if ((nprincipals = sshbuf_new()) == NULL) {
- r = SSH_ERR_ALLOC_FAIL;
- goto out;
- }
-
- while ((cp = strsep(&principals, ",")) != NULL && *cp != '\0') {
- /* Check certificate validity */
- if ((r = sshkey_cert_check_authority(cert, 0, 1, 0,
- verify_time, NULL, &reason)) != 0) {
- debug("%s:%lu: principal \"%s\" not authorized: %s",
- path, linenum, cp, reason);
- continue;
- }
- /* Return all matching principal names from the cert */
- for (i = 0; i < cert->cert->nprincipals; i++) {
- if (match_pattern(cert->cert->principals[i], cp)) {
- if ((r = sshbuf_putf(nprincipals, "%s%s",
- sshbuf_len(nprincipals) != 0 ? "," : "",
- cert->cert->principals[i])) != 0) {
- error_f("buffer error");
- goto out;
- }
- }
- }
- }
- if (sshbuf_len(nprincipals) == 0) {
- error("%s:%lu: no valid principals found", path, linenum);
- r = SSH_ERR_KEY_CERT_INVALID;
- goto out;
- }
- if ((principals = sshbuf_dup_string(nprincipals)) == NULL) {
- error_f("buffer error");
- goto out;
- }
- /* success */
- success = 1;
- *principalsp = principals;
- out:
- sshbuf_free(nprincipals);
- free(oprincipals);
- return success ? 0 : r;
- }
-
- static int
- check_allowed_keys_line(const char *path, u_long linenum, char *line,
- const struct sshkey *sign_key, const char *principal,
- const char *sig_namespace, uint64_t verify_time, char **principalsp)
- {
- struct sshkey *found_key = NULL;
- char *principals = NULL;
- int r, success = 0;
- const char *reason = NULL;
- struct sshsigopt *sigopts = NULL;
- char tvalid[64], tverify[64];
-
- if (principalsp != NULL)
- *principalsp = NULL;
-
- /* Parse the line */
- if ((r = parse_principals_key_and_options(path, linenum, line,
- principal, &principals, &found_key, &sigopts)) != 0) {
- /* error already logged */
- goto done;
- }
-
- if (!sigopts->ca && sshkey_equal(found_key, sign_key)) {
- /* Exact match of key */
- debug("%s:%lu: matched key", path, linenum);
- } else if (sigopts->ca && sshkey_is_cert(sign_key) &&
- sshkey_equal_public(sign_key->cert->signature_key, found_key)) {
- if (principal) {
- /* Match certificate CA key with specified principal */
- if ((r = sshkey_cert_check_authority(sign_key, 0, 1, 0,
- verify_time, principal, &reason)) != 0) {
- error("%s:%lu: certificate not authorized: %s",
- path, linenum, reason);
- goto done;
- }
- debug("%s:%lu: matched certificate CA key",
- path, linenum);
- } else {
- /* No principal specified - find all matching ones */
- if ((r = cert_filter_principals(path, linenum,
- &principals, sign_key, verify_time)) != 0) {
- /* error already displayed */
- debug_r(r, "%s:%lu: cert_filter_principals",
- path, linenum);
- goto done;
- }
- debug("%s:%lu: matched certificate CA key",
- path, linenum);
- }
- } else {
- /* Didn't match key */
- goto done;
- }
-
- /* Check whether options preclude the use of this key */
- if (sigopts->namespaces != NULL && sig_namespace != NULL &&
- match_pattern_list(sig_namespace, sigopts->namespaces, 0) != 1) {
- error("%s:%lu: key is not permitted for use in signature "
- "namespace \"%s\"", path, linenum, sig_namespace);
- goto done;
- }
-
- /* check key time validity */
- format_absolute_time((uint64_t)verify_time, tverify, sizeof(tverify));
- if (sigopts->valid_after != 0 &&
- (uint64_t)verify_time < sigopts->valid_after) {
- format_absolute_time(sigopts->valid_after,
- tvalid, sizeof(tvalid));
- error("%s:%lu: key is not yet valid: "
- "verify time %s < valid-after %s", path, linenum,
- tverify, tvalid);
- goto done;
- }
- if (sigopts->valid_before != 0 &&
- (uint64_t)verify_time > sigopts->valid_before) {
- format_absolute_time(sigopts->valid_before,
- tvalid, sizeof(tvalid));
- error("%s:%lu: key has expired: "
- "verify time %s > valid-before %s", path, linenum,
- tverify, tvalid);
- goto done;
- }
- success = 1;
-
- done:
- if (success && principalsp != NULL) {
- *principalsp = principals;
- principals = NULL; /* transferred */
- }
- free(principals);
- sshkey_free(found_key);
- sshsigopt_free(sigopts);
- return success ? 0 : SSH_ERR_KEY_NOT_FOUND;
- }
-
- int
- sshsig_check_allowed_keys(const char *path, const struct sshkey *sign_key,
- const char *principal, const char *sig_namespace, uint64_t verify_time)
- {
- FILE *f = NULL;
- char *line = NULL;
- size_t linesize = 0;
- u_long linenum = 0;
- int r = SSH_ERR_KEY_NOT_FOUND, oerrno;
-
- /* Check key and principal against file */
- if ((f = fopen(path, "r")) == NULL) {
- oerrno = errno;
- error("Unable to open allowed keys file \"%s\": %s",
- path, strerror(errno));
- errno = oerrno;
- return SSH_ERR_SYSTEM_ERROR;
- }
-
- while (getline(&line, &linesize, f) != -1) {
- linenum++;
- r = check_allowed_keys_line(path, linenum, line, sign_key,
- principal, sig_namespace, verify_time, NULL);
- free(line);
- line = NULL;
- linesize = 0;
- if (r == SSH_ERR_KEY_NOT_FOUND)
- continue;
- else if (r == 0) {
- /* success */
- fclose(f);
- return 0;
- } else
- break;
- }
- /* Either we hit an error parsing or we simply didn't find the key */
- fclose(f);
- free(line);
- return r;
- }
-
- int
- sshsig_find_principals(const char *path, const struct sshkey *sign_key,
- uint64_t verify_time, char **principals)
- {
- FILE *f = NULL;
- char *line = NULL;
- size_t linesize = 0;
- u_long linenum = 0;
- int r = SSH_ERR_KEY_NOT_FOUND, oerrno;
-
- if ((f = fopen(path, "r")) == NULL) {
- oerrno = errno;
- error("Unable to open allowed keys file \"%s\": %s",
- path, strerror(errno));
- errno = oerrno;
- return SSH_ERR_SYSTEM_ERROR;
- }
-
- while (getline(&line, &linesize, f) != -1) {
- linenum++;
- r = check_allowed_keys_line(path, linenum, line,
- sign_key, NULL, NULL, verify_time, principals);
- free(line);
- line = NULL;
- linesize = 0;
- if (r == SSH_ERR_KEY_NOT_FOUND)
- continue;
- else if (r == 0) {
- /* success */
- fclose(f);
- return 0;
- } else
- break;
- }
- free(line);
- /* Either we hit an error parsing or we simply didn't find the key */
- if (ferror(f) != 0) {
- oerrno = errno;
- fclose(f);
- error("Unable to read allowed keys file \"%s\": %s",
- path, strerror(errno));
- errno = oerrno;
- return SSH_ERR_SYSTEM_ERROR;
- }
- fclose(f);
- return r;
- }
-
- int
- sshsig_match_principals(const char *path, const char *principal,
- char ***principalsp, size_t *nprincipalsp)
- {
- FILE *f = NULL;
- char *found, *line = NULL, **principals = NULL, **tmp;
- size_t i, nprincipals = 0, linesize = 0;
- u_long linenum = 0;
- int oerrno = 0, r, ret = 0;
-
- if (principalsp != NULL)
- *principalsp = NULL;
- if (nprincipalsp != NULL)
- *nprincipalsp = 0;
-
- /* Check key and principal against file */
- if ((f = fopen(path, "r")) == NULL) {
- oerrno = errno;
- error("Unable to open allowed keys file \"%s\": %s",
- path, strerror(errno));
- errno = oerrno;
- return SSH_ERR_SYSTEM_ERROR;
- }
-
- while (getline(&line, &linesize, f) != -1) {
- linenum++;
- /* Parse the line */
- if ((r = parse_principals_key_and_options(path, linenum, line,
- principal, &found, NULL, NULL)) != 0) {
- if (r == SSH_ERR_KEY_NOT_FOUND)
- continue;
- ret = r;
- oerrno = errno;
- break; /* unexpected error */
- }
- if ((tmp = recallocarray(principals, nprincipals,
- nprincipals + 1, sizeof(*principals))) == NULL) {
- ret = SSH_ERR_ALLOC_FAIL;
- free(found);
- break;
- }
- principals = tmp;
- principals[nprincipals++] = found; /* transferred */
- free(line);
- line = NULL;
- linesize = 0;
- }
- fclose(f);
-
- if (ret == 0) {
- if (nprincipals == 0)
- ret = SSH_ERR_KEY_NOT_FOUND;
- if (nprincipalsp != 0)
- *nprincipalsp = nprincipals;
- if (principalsp != NULL) {
- *principalsp = principals;
- principals = NULL; /* transferred */
- nprincipals = 0;
- }
- }
-
- for (i = 0; i < nprincipals; i++)
- free(principals[i]);
- free(principals);
-
- errno = oerrno;
- return ret;
- }
-
- int
- sshsig_get_pubkey(struct sshbuf *signature, struct sshkey **pubkey)
- {
- struct sshkey *pk = NULL;
- int r = SSH_ERR_SIGNATURE_INVALID;
-
- if (pubkey == NULL)
- return SSH_ERR_INTERNAL_ERROR;
- if ((r = sshsig_parse_preamble(signature)) != 0)
- return r;
- if ((r = sshkey_froms(signature, &pk)) != 0)
- return r;
-
- *pubkey = pk;
- pk = NULL;
- return 0;
- }
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