803 lines
21 KiB
C
803 lines
21 KiB
C
/*
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* Copyright (c) 2019 Google LLC
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "includes.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <errno.h>
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#include <string.h>
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#include <unistd.h>
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#include "authfd.h"
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#include "authfile.h"
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#include "log.h"
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#include "misc.h"
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#include "sshbuf.h"
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#include "sshsig.h"
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#include "ssherr.h"
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#include "sshkey.h"
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#include "match.h"
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#include "digest.h"
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#define SIG_VERSION 0x01
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#define MAGIC_PREAMBLE "SSHSIG"
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#define MAGIC_PREAMBLE_LEN (sizeof(MAGIC_PREAMBLE) - 1)
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#define BEGIN_SIGNATURE "-----BEGIN SSH SIGNATURE-----\n"
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#define END_SIGNATURE "-----END SSH SIGNATURE-----"
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#define RSA_SIGN_ALG "rsa-sha2-512" /* XXX maybe make configurable */
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#define RSA_SIGN_ALLOWED "rsa-sha2-512,rsa-sha2-256"
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#define HASHALG_DEFAULT "sha512" /* XXX maybe make configurable */
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#define HASHALG_ALLOWED "sha256,sha512"
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int
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sshsig_armor(const struct sshbuf *blob, struct sshbuf **out)
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{
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struct sshbuf *buf = NULL;
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int r = SSH_ERR_INTERNAL_ERROR;
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*out = NULL;
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if ((buf = sshbuf_new()) == NULL) {
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error("%s: sshbuf_new failed", __func__);
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r = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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if ((r = sshbuf_put(buf, BEGIN_SIGNATURE,
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sizeof(BEGIN_SIGNATURE)-1)) != 0) {
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error("%s: sshbuf_putf failed: %s", __func__, ssh_err(r));
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goto out;
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}
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if ((r = sshbuf_dtob64(blob, buf, 1)) != 0) {
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error("%s: Couldn't base64 encode signature blob: %s",
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__func__, ssh_err(r));
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goto out;
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}
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if ((r = sshbuf_put(buf, END_SIGNATURE,
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sizeof(END_SIGNATURE)-1)) != 0 ||
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(r = sshbuf_put_u8(buf, '\n')) != 0) {
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error("%s: sshbuf_put failed: %s", __func__, ssh_err(r));
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goto out;
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}
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/* success */
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*out = buf;
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buf = NULL; /* transferred */
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r = 0;
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out:
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sshbuf_free(buf);
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return r;
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}
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int
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sshsig_dearmor(struct sshbuf *sig, struct sshbuf **out)
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{
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int r;
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size_t eoffset = 0;
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struct sshbuf *buf = NULL;
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struct sshbuf *sbuf = NULL;
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char *b64 = NULL;
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if ((sbuf = sshbuf_fromb(sig)) == NULL) {
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error("%s: sshbuf_fromb failed", __func__);
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return SSH_ERR_ALLOC_FAIL;
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}
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if ((r = sshbuf_cmp(sbuf, 0,
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BEGIN_SIGNATURE, sizeof(BEGIN_SIGNATURE)-1)) != 0) {
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error("Couldn't parse signature: missing header");
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goto done;
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}
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if ((r = sshbuf_consume(sbuf, sizeof(BEGIN_SIGNATURE)-1)) != 0) {
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error("%s: sshbuf_consume failed: %s", __func__, ssh_err(r));
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goto done;
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}
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if ((r = sshbuf_find(sbuf, 0, "\n" END_SIGNATURE,
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sizeof("\n" END_SIGNATURE)-1, &eoffset)) != 0) {
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error("Couldn't parse signature: missing footer");
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goto done;
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}
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if ((r = sshbuf_consume_end(sbuf, sshbuf_len(sbuf)-eoffset)) != 0) {
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error("%s: sshbuf_consume failed: %s", __func__, ssh_err(r));
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goto done;
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}
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if ((b64 = sshbuf_dup_string(sbuf)) == NULL) {
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error("%s: sshbuf_dup_string failed", __func__);
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r = SSH_ERR_ALLOC_FAIL;
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goto done;
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}
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if ((buf = sshbuf_new()) == NULL) {
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error("%s: sshbuf_new() failed", __func__);
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r = SSH_ERR_ALLOC_FAIL;
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goto done;
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}
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if ((r = sshbuf_b64tod(buf, b64)) != 0) {
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error("Couldn't decode signature: %s", ssh_err(r));
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goto done;
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}
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/* success */
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*out = buf;
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r = 0;
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buf = NULL; /* transferred */
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done:
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sshbuf_free(buf);
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sshbuf_free(sbuf);
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free(b64);
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return r;
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}
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static int
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sshsig_wrap_sign(struct sshkey *key, const char *hashalg,
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const char *sk_provider, const struct sshbuf *h_message,
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const char *sig_namespace, struct sshbuf **out,
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sshsig_signer *signer, void *signer_ctx)
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{
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int r;
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size_t slen = 0;
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u_char *sig = NULL;
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struct sshbuf *blob = NULL;
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struct sshbuf *tosign = NULL;
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const char *sign_alg = NULL;
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if ((tosign = sshbuf_new()) == NULL ||
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(blob = sshbuf_new()) == NULL) {
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error("%s: sshbuf_new failed", __func__);
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r = SSH_ERR_ALLOC_FAIL;
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goto done;
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}
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if ((r = sshbuf_put(tosign, MAGIC_PREAMBLE, MAGIC_PREAMBLE_LEN)) != 0 ||
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(r = sshbuf_put_cstring(tosign, sig_namespace)) != 0 ||
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(r = sshbuf_put_string(tosign, NULL, 0)) != 0 || /* reserved */
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(r = sshbuf_put_cstring(tosign, hashalg)) != 0 ||
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(r = sshbuf_put_stringb(tosign, h_message)) != 0) {
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error("Couldn't construct message to sign: %s", ssh_err(r));
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goto done;
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}
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/* If using RSA keys then default to a good signature algorithm */
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if (sshkey_type_plain(key->type) == KEY_RSA)
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sign_alg = RSA_SIGN_ALG;
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if (signer != NULL) {
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if ((r = signer(key, &sig, &slen,
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sshbuf_ptr(tosign), sshbuf_len(tosign),
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sign_alg, sk_provider, 0, signer_ctx)) != 0) {
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error("Couldn't sign message: %s", ssh_err(r));
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goto done;
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}
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} else {
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if ((r = sshkey_sign(key, &sig, &slen,
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sshbuf_ptr(tosign), sshbuf_len(tosign),
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sign_alg, sk_provider, 0)) != 0) {
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error("Couldn't sign message: %s", ssh_err(r));
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goto done;
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}
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}
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if ((r = sshbuf_put(blob, MAGIC_PREAMBLE, MAGIC_PREAMBLE_LEN)) != 0 ||
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(r = sshbuf_put_u32(blob, SIG_VERSION)) != 0 ||
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(r = sshkey_puts(key, blob)) != 0 ||
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(r = sshbuf_put_cstring(blob, sig_namespace)) != 0 ||
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(r = sshbuf_put_string(blob, NULL, 0)) != 0 || /* reserved */
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(r = sshbuf_put_cstring(blob, hashalg)) != 0 ||
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(r = sshbuf_put_string(blob, sig, slen)) != 0) {
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error("Couldn't populate blob: %s", ssh_err(r));
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goto done;
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}
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*out = blob;
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blob = NULL;
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r = 0;
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done:
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free(sig);
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sshbuf_free(blob);
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sshbuf_free(tosign);
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return r;
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}
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/* Check preamble and version. */
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static int
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sshsig_parse_preamble(struct sshbuf *buf)
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{
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int r = SSH_ERR_INTERNAL_ERROR;
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uint32_t sversion;
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if ((r = sshbuf_cmp(buf, 0, MAGIC_PREAMBLE, MAGIC_PREAMBLE_LEN)) != 0 ||
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(r = sshbuf_consume(buf, (sizeof(MAGIC_PREAMBLE)-1))) != 0 ||
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(r = sshbuf_get_u32(buf, &sversion)) != 0) {
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error("Couldn't verify signature: invalid format");
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return r;
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}
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if (sversion > SIG_VERSION) {
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error("Signature version %lu is larger than supported "
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"version %u", (unsigned long)sversion, SIG_VERSION);
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return SSH_ERR_INVALID_FORMAT;
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}
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return 0;
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}
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static int
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sshsig_check_hashalg(const char *hashalg)
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{
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if (hashalg == NULL ||
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match_pattern_list(hashalg, HASHALG_ALLOWED, 0) == 1)
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return 0;
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error("%s: unsupported hash algorithm \"%.100s\"", __func__, hashalg);
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return SSH_ERR_SIGN_ALG_UNSUPPORTED;
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}
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static int
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sshsig_peek_hashalg(struct sshbuf *signature, char **hashalgp)
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{
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struct sshbuf *buf = NULL;
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char *hashalg = NULL;
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int r = SSH_ERR_INTERNAL_ERROR;
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if (hashalgp != NULL)
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*hashalgp = NULL;
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if ((buf = sshbuf_fromb(signature)) == NULL)
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return SSH_ERR_ALLOC_FAIL;
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if ((r = sshsig_parse_preamble(buf)) != 0)
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goto done;
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if ((r = sshbuf_get_string_direct(buf, NULL, NULL)) != 0 ||
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(r = sshbuf_get_string_direct(buf, NULL, NULL)) != 0 ||
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(r = sshbuf_get_string(buf, NULL, NULL)) != 0 ||
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(r = sshbuf_get_cstring(buf, &hashalg, NULL)) != 0 ||
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(r = sshbuf_get_string_direct(buf, NULL, NULL)) != 0) {
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error("Couldn't parse signature blob: %s", ssh_err(r));
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goto done;
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}
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/* success */
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r = 0;
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*hashalgp = hashalg;
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hashalg = NULL;
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done:
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free(hashalg);
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sshbuf_free(buf);
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return r;
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}
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static int
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sshsig_wrap_verify(struct sshbuf *signature, const char *hashalg,
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const struct sshbuf *h_message, const char *expect_namespace,
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struct sshkey **sign_keyp)
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{
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int r = SSH_ERR_INTERNAL_ERROR;
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struct sshbuf *buf = NULL, *toverify = NULL;
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struct sshkey *key = NULL;
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const u_char *sig;
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char *got_namespace = NULL, *sigtype = NULL, *sig_hashalg = NULL;
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size_t siglen;
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debug("%s: verify message length %zu", __func__, sshbuf_len(h_message));
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if (sign_keyp != NULL)
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*sign_keyp = NULL;
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if ((toverify = sshbuf_new()) == NULL) {
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error("%s: sshbuf_new failed", __func__);
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r = SSH_ERR_ALLOC_FAIL;
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goto done;
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}
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if ((r = sshbuf_put(toverify, MAGIC_PREAMBLE,
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MAGIC_PREAMBLE_LEN)) != 0 ||
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(r = sshbuf_put_cstring(toverify, expect_namespace)) != 0 ||
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(r = sshbuf_put_string(toverify, NULL, 0)) != 0 || /* reserved */
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(r = sshbuf_put_cstring(toverify, hashalg)) != 0 ||
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(r = sshbuf_put_stringb(toverify, h_message)) != 0) {
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error("Couldn't construct message to verify: %s", ssh_err(r));
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goto done;
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}
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if ((r = sshsig_parse_preamble(signature)) != 0)
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goto done;
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if ((r = sshkey_froms(signature, &key)) != 0 ||
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(r = sshbuf_get_cstring(signature, &got_namespace, NULL)) != 0 ||
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(r = sshbuf_get_string(signature, NULL, NULL)) != 0 ||
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(r = sshbuf_get_cstring(signature, &sig_hashalg, NULL)) != 0 ||
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(r = sshbuf_get_string_direct(signature, &sig, &siglen)) != 0) {
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error("Couldn't parse signature blob: %s", ssh_err(r));
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goto done;
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}
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if (sshbuf_len(signature) != 0) {
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error("Signature contains trailing data");
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r = SSH_ERR_INVALID_FORMAT;
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goto done;
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}
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if (strcmp(expect_namespace, got_namespace) != 0) {
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error("Couldn't verify signature: namespace does not match");
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debug("%s: expected namespace \"%s\" received \"%s\"",
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__func__, expect_namespace, got_namespace);
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r = SSH_ERR_SIGNATURE_INVALID;
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goto done;
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}
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if (strcmp(hashalg, sig_hashalg) != 0) {
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error("Couldn't verify signature: hash algorithm mismatch");
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debug("%s: expected algorithm \"%s\" received \"%s\"",
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__func__, hashalg, sig_hashalg);
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r = SSH_ERR_SIGNATURE_INVALID;
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goto done;
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}
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/* Ensure that RSA keys use an acceptable signature algorithm */
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if (sshkey_type_plain(key->type) == KEY_RSA) {
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if ((r = sshkey_get_sigtype(sig, siglen, &sigtype)) != 0) {
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error("Couldn't verify signature: unable to get "
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"signature type: %s", ssh_err(r));
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goto done;
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}
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if (match_pattern_list(sigtype, RSA_SIGN_ALLOWED, 0) != 1) {
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error("Couldn't verify signature: unsupported RSA "
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"signature algorithm %s", sigtype);
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r = SSH_ERR_SIGN_ALG_UNSUPPORTED;
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goto done;
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}
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}
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if ((r = sshkey_verify(key, sig, siglen, sshbuf_ptr(toverify),
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sshbuf_len(toverify), NULL, 0)) != 0) {
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error("Signature verification failed: %s", ssh_err(r));
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goto done;
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}
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/* success */
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r = 0;
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if (sign_keyp != NULL) {
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*sign_keyp = key;
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key = NULL; /* transferred */
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}
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done:
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free(got_namespace);
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free(sigtype);
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free(sig_hashalg);
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sshbuf_free(buf);
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sshbuf_free(toverify);
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sshkey_free(key);
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return r;
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}
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static int
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hash_buffer(const struct sshbuf *m, const char *hashalg, struct sshbuf **bp)
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{
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char *hex, hash[SSH_DIGEST_MAX_LENGTH];
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int alg, r = SSH_ERR_INTERNAL_ERROR;
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struct sshbuf *b = NULL;
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*bp = NULL;
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memset(hash, 0, sizeof(hash));
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if ((r = sshsig_check_hashalg(hashalg)) != 0)
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return r;
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if ((alg = ssh_digest_alg_by_name(hashalg)) == -1) {
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error("%s: can't look up hash algorithm %s",
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__func__, hashalg);
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return SSH_ERR_INTERNAL_ERROR;
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}
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if ((r = ssh_digest_buffer(alg, m, hash, sizeof(hash))) != 0) {
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error("%s: ssh_digest_buffer failed: %s", __func__, ssh_err(r));
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return r;
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}
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if ((hex = tohex(hash, ssh_digest_bytes(alg))) != NULL) {
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debug3("%s: final hash: %s", __func__, hex);
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freezero(hex, strlen(hex));
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}
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if ((b = sshbuf_new()) == NULL) {
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r = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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if ((r = sshbuf_put(b, hash, ssh_digest_bytes(alg))) != 0) {
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error("%s: sshbuf_put: %s", __func__, ssh_err(r));
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goto out;
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}
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*bp = b;
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b = NULL; /* transferred */
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/* success */
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r = 0;
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out:
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sshbuf_free(b);
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explicit_bzero(hash, sizeof(hash));
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return 0;
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}
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int
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sshsig_signb(struct sshkey *key, const char *hashalg, const char *sk_provider,
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const struct sshbuf *message, const char *sig_namespace,
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struct sshbuf **out, sshsig_signer *signer, void *signer_ctx)
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{
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struct sshbuf *b = NULL;
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int r = SSH_ERR_INTERNAL_ERROR;
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if (hashalg == NULL)
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hashalg = HASHALG_DEFAULT;
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if (out != NULL)
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*out = NULL;
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if ((r = hash_buffer(message, hashalg, &b)) != 0) {
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error("%s: hash_buffer failed: %s", __func__, ssh_err(r));
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goto out;
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}
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if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, b,
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sig_namespace, out, signer, signer_ctx)) != 0)
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goto out;
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/* success */
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r = 0;
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out:
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sshbuf_free(b);
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return r;
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}
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int
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sshsig_verifyb(struct sshbuf *signature, const struct sshbuf *message,
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const char *expect_namespace, struct sshkey **sign_keyp)
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{
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struct sshbuf *b = NULL;
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int r = SSH_ERR_INTERNAL_ERROR;
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char *hashalg = NULL;
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if (sign_keyp != NULL)
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*sign_keyp = NULL;
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if ((r = sshsig_peek_hashalg(signature, &hashalg)) != 0)
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return r;
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debug("%s: signature made with hash \"%s\"", __func__, hashalg);
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if ((r = hash_buffer(message, hashalg, &b)) != 0) {
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error("%s: hash_buffer failed: %s", __func__, ssh_err(r));
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goto out;
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}
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if ((r = sshsig_wrap_verify(signature, hashalg, b, expect_namespace,
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sign_keyp)) != 0)
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goto out;
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/* success */
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r = 0;
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out:
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sshbuf_free(b);
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free(hashalg);
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return r;
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}
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static int
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hash_file(int fd, const char *hashalg, struct sshbuf **bp)
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{
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char *hex, rbuf[8192], hash[SSH_DIGEST_MAX_LENGTH];
|
|
ssize_t n, total = 0;
|
|
struct ssh_digest_ctx *ctx;
|
|
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("%s: can't look up hash algorithm %s",
|
|
__func__, hashalg);
|
|
return SSH_ERR_INTERNAL_ERROR;
|
|
}
|
|
if ((ctx = ssh_digest_start(alg)) == NULL) {
|
|
error("%s: ssh_digest_start failed", __func__);
|
|
return SSH_ERR_INTERNAL_ERROR;
|
|
}
|
|
for (;;) {
|
|
if ((n = read(fd, rbuf, sizeof(rbuf))) == -1) {
|
|
if (errno == EINTR || errno == EAGAIN)
|
|
continue;
|
|
oerrno = errno;
|
|
error("%s: read: %s", __func__, strerror(errno));
|
|
ssh_digest_free(ctx);
|
|
errno = oerrno;
|
|
r = SSH_ERR_SYSTEM_ERROR;
|
|
goto out;
|
|
} else if (n == 0) {
|
|
debug2("%s: hashed %zu bytes", __func__, total);
|
|
break; /* EOF */
|
|
}
|
|
total += (size_t)n;
|
|
if ((r = ssh_digest_update(ctx, rbuf, (size_t)n)) != 0) {
|
|
error("%s: ssh_digest_update: %s",
|
|
__func__, ssh_err(r));
|
|
goto out;
|
|
}
|
|
}
|
|
if ((r = ssh_digest_final(ctx, hash, sizeof(hash))) != 0) {
|
|
error("%s: ssh_digest_final: %s", __func__, ssh_err(r));
|
|
goto out;
|
|
}
|
|
if ((hex = tohex(hash, ssh_digest_bytes(alg))) != NULL) {
|
|
debug3("%s: final hash: %s", __func__, 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("%s: sshbuf_put: %s", __func__, ssh_err(r));
|
|
goto out;
|
|
}
|
|
*bp = b;
|
|
b = NULL; /* transferred */
|
|
/* success */
|
|
r = 0;
|
|
out:
|
|
sshbuf_free(b);
|
|
ssh_digest_free(ctx);
|
|
explicit_bzero(hash, sizeof(hash));
|
|
return 0;
|
|
}
|
|
|
|
int
|
|
sshsig_sign_fd(struct sshkey *key, const char *hashalg, const char *sk_provider,
|
|
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("%s: hash_file failed: %s", __func__, ssh_err(r));
|
|
return r;
|
|
}
|
|
if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, 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 sshbuf *b = NULL;
|
|
int r = SSH_ERR_INTERNAL_ERROR;
|
|
char *hashalg = NULL;
|
|
|
|
if (sign_keyp != NULL)
|
|
*sign_keyp = NULL;
|
|
|
|
if ((r = sshsig_peek_hashalg(signature, &hashalg)) != 0)
|
|
return r;
|
|
debug("%s: signature made with hash \"%s\"", __func__, hashalg);
|
|
if ((r = hash_file(fd, hashalg, &b)) != 0) {
|
|
error("%s: hash_file failed: %s", __func__, ssh_err(r));
|
|
goto out;
|
|
}
|
|
if ((r = sshsig_wrap_verify(signature, hashalg, b, expect_namespace,
|
|
sign_keyp)) != 0)
|
|
goto out;
|
|
/* success */
|
|
r = 0;
|
|
out:
|
|
sshbuf_free(b);
|
|
free(hashalg);
|
|
return r;
|
|
}
|
|
|
|
struct sshsigopt {
|
|
int ca;
|
|
char *namespaces;
|
|
};
|
|
|
|
struct sshsigopt *
|
|
sshsigopt_parse(const char *opts, const char *path, u_long linenum,
|
|
const char **errstrp)
|
|
{
|
|
struct sshsigopt *ret;
|
|
int r;
|
|
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;
|
|
}
|
|
/*
|
|
* 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;
|
|
}
|
|
}
|
|
/* 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
|
|
check_allowed_keys_line(const char *path, u_long linenum, char *line,
|
|
const struct sshkey *sign_key, const char *principal,
|
|
const char *sig_namespace)
|
|
{
|
|
struct sshkey *found_key = NULL;
|
|
char *cp, *opts = NULL, *identities = NULL;
|
|
int r, found = 0;
|
|
const char *reason = NULL;
|
|
struct sshsigopt *sigopts = NULL;
|
|
|
|
if ((found_key = sshkey_new(KEY_UNSPEC)) == NULL) {
|
|
error("%s: sshkey_new failed", __func__);
|
|
return SSH_ERR_ALLOC_FAIL;
|
|
}
|
|
|
|
/* format: identity[,identity...] [option[,option...]] key */
|
|
cp = line;
|
|
cp = cp + strspn(cp, " \t"); /* skip leading whitespace */
|
|
if (*cp == '#' || *cp == '\0')
|
|
goto done;
|
|
if ((identities = strdelimw(&cp)) == NULL) {
|
|
error("%s:%lu: invalid line", path, linenum);
|
|
goto done;
|
|
}
|
|
if (match_pattern_list(principal, identities, 0) != 1) {
|
|
/* principal didn't match */
|
|
goto done;
|
|
}
|
|
debug("%s: %s:%lu: matched principal \"%s\"",
|
|
__func__, path, linenum, principal);
|
|
|
|
if (sshkey_read(found_key, &cp) != 0) {
|
|
/* no key? Check for options */
|
|
opts = cp;
|
|
if (sshkey_advance_past_options(&cp) != 0) {
|
|
error("%s:%lu: invalid options",
|
|
path, linenum);
|
|
goto done;
|
|
}
|
|
*cp++ = '\0';
|
|
skip_space(&cp);
|
|
if (sshkey_read(found_key, &cp) != 0) {
|
|
error("%s:%lu: invalid key", path,
|
|
linenum);
|
|
goto done;
|
|
}
|
|
}
|
|
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);
|
|
goto done;
|
|
}
|
|
|
|
/* Check whether options preclude the use of this key */
|
|
if (sigopts->namespaces != 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;
|
|
}
|
|
|
|
if (!sigopts->ca && sshkey_equal(found_key, sign_key)) {
|
|
/* Exact match of key */
|
|
debug("%s:%lu: matched key and principal", path, linenum);
|
|
/* success */
|
|
found = 1;
|
|
} else if (sigopts->ca && sshkey_is_cert(sign_key) &&
|
|
sshkey_equal_public(sign_key->cert->signature_key, found_key)) {
|
|
/* Match of certificate's CA key */
|
|
if ((r = sshkey_cert_check_authority(sign_key, 0, 1,
|
|
principal, &reason)) != 0) {
|
|
error("%s:%lu: certificate not authorized: %s",
|
|
path, linenum, reason);
|
|
goto done;
|
|
}
|
|
debug("%s:%lu: matched certificate CA key", path, linenum);
|
|
/* success */
|
|
found = 1;
|
|
} else {
|
|
/* Principal matched but key didn't */
|
|
goto done;
|
|
}
|
|
done:
|
|
sshkey_free(found_key);
|
|
sshsigopt_free(sigopts);
|
|
return found ? 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)
|
|
{
|
|
FILE *f = NULL;
|
|
char *line = NULL;
|
|
size_t linesize = 0;
|
|
u_long linenum = 0;
|
|
int r, 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);
|
|
free(line);
|
|
line = NULL;
|
|
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 == 0 ? SSH_ERR_KEY_NOT_FOUND : r;
|
|
}
|