/* $NetBSD: sshsig.c,v 1.10.2.2 2023/12/25 12:22:56 martin Exp $ */ /* $OpenBSD: sshsig.c,v 1.34 2023/12/08 09:18:39 markus 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" __RCSID("$NetBSD: sshsig.c,v 1.10.2.2 2023/12/25 12:22:56 martin Exp $"); #include #include #include #include #include #include #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, (unsigned char *)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, (unsigned char *)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"); /* 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; }