File: [local] / src / usr.bin / signify / signify.c (download)
Revision 1.77, Tue May 6 23:33:04 2014 UTC (10 years, 1 month ago) by tedu
Branch: MAIN
Changes since 1.76: +2 -4 lines
remove unneeded variable
|
/* $OpenBSD: signify.c,v 1.77 2014/05/06 23:33:04 tedu Exp $ */
/*
* Copyright (c) 2013 Ted Unangst <tedu@openbsd.org>
*
* 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 <sys/stat.h>
#include <netinet/in.h>
#include <resolv.h>
#include <stdint.h>
#include <fcntl.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <err.h>
#include <unistd.h>
#include <readpassphrase.h>
#include <util.h>
#include <sha2.h>
#include "crypto_api.h"
#define SIGBYTES crypto_sign_ed25519_BYTES
#define SECRETBYTES crypto_sign_ed25519_SECRETKEYBYTES
#define PUBLICBYTES crypto_sign_ed25519_PUBLICKEYBYTES
#define PKALG "Ed"
#define KDFALG "BK"
#define FPLEN 8
#define COMMENTHDR "untrusted comment: "
#define COMMENTHDRLEN 19
#define COMMENTMAXLEN 1024
#define VERIFYWITH "verify with "
struct enckey {
uint8_t pkalg[2];
uint8_t kdfalg[2];
uint32_t kdfrounds;
uint8_t salt[16];
uint8_t checksum[8];
uint8_t fingerprint[FPLEN];
uint8_t seckey[SECRETBYTES];
};
struct pubkey {
uint8_t pkalg[2];
uint8_t fingerprint[FPLEN];
uint8_t pubkey[PUBLICBYTES];
};
struct sig {
uint8_t pkalg[2];
uint8_t fingerprint[FPLEN];
uint8_t sig[SIGBYTES];
};
extern char *__progname;
static void
usage(const char *error)
{
if (error)
fprintf(stderr, "%s\n", error);
fprintf(stderr, "usage:"
#ifndef VERIFYONLY
"\t%1$s -C [-q] -p pubkey -x sigfile [file ...]\n"
"\t%1$s -G [-n] [-c comment] -p pubkey -s seckey\n"
"\t%1$s -I [-p pubkey] [-s seckey] [-x sigfile]\n"
"\t%1$s -S [-e] [-x sigfile] -s seckey -m message\n"
#endif
"\t%1$s -V [-eq] [-x sigfile] -p pubkey -m message\n",
__progname);
exit(1);
}
static int
xopen(const char *fname, int oflags, mode_t mode)
{
struct stat sb;
int fd;
if (strcmp(fname, "-") == 0) {
if ((oflags & O_WRONLY))
fd = dup(STDOUT_FILENO);
else
fd = dup(STDIN_FILENO);
if (fd == -1)
err(1, "dup failed");
} else {
fd = open(fname, oflags, mode);
if (fd == -1)
err(1, "can't open %s for %s", fname,
(oflags & O_WRONLY) ? "writing" : "reading");
}
if (fstat(fd, &sb) == -1 || S_ISDIR(sb.st_mode))
errx(1, "not a valid file: %s", fname);
return fd;
}
static void *
xmalloc(size_t len)
{
void *p;
p = malloc(len);
if (!p)
err(1, "malloc %zu", len);
return p;
}
static size_t
parseb64file(const char *filename, char *b64, void *buf, size_t buflen,
char *comment)
{
char *commentend, *b64end;
commentend = strchr(b64, '\n');
if (!commentend || commentend - b64 <= COMMENTHDRLEN ||
memcmp(b64, COMMENTHDR, COMMENTHDRLEN) != 0)
errx(1, "invalid comment in %s; must start with '%s'",
filename, COMMENTHDR);
*commentend = '\0';
if (comment) {
if (strlcpy(comment, b64 + COMMENTHDRLEN,
COMMENTMAXLEN) >= COMMENTMAXLEN)
errx(1, "comment too long");
}
b64end = strchr(commentend + 1, '\n');
if (!b64end)
errx(1, "missing new line after b64 in %s", filename);
*b64end = '\0';
if (b64_pton(commentend + 1, buf, buflen) != buflen)
errx(1, "invalid b64 encoding in %s", filename);
if (memcmp(buf, PKALG, 2) != 0)
errx(1, "unsupported file %s", filename);
return b64end - b64 + 1;
}
static void
readb64file(const char *filename, void *buf, size_t buflen, char *comment)
{
char b64[2048];
int rv, fd;
fd = xopen(filename, O_RDONLY | O_NOFOLLOW, 0);
rv = read(fd, b64, sizeof(b64) - 1);
if (rv == -1)
err(1, "read from %s", filename);
b64[rv] = '\0';
parseb64file(filename, b64, buf, buflen, comment);
explicit_bzero(b64, sizeof(b64));
close(fd);
}
static uint8_t *
readmsg(const char *filename, unsigned long long *msglenp)
{
unsigned long long msglen = 0;
uint8_t *msg = NULL;
struct stat sb;
ssize_t x, space;
int fd;
const unsigned long long maxmsgsize = 1UL << 30;
fd = xopen(filename, O_RDONLY | O_NOFOLLOW, 0);
if (fstat(fd, &sb) == 0 && S_ISREG(sb.st_mode)) {
if (sb.st_size > maxmsgsize)
errx(1, "msg too large in %s", filename);
space = sb.st_size + 1;
} else {
space = 64 * 1024;
}
msg = xmalloc(space + 1);
while (1) {
if (space == 0) {
if (msglen * 2 > maxmsgsize)
errx(1, "msg too large in %s", filename);
space = msglen;
if (!(msg = realloc(msg, msglen + space + 1)))
errx(1, "realloc");
}
if ((x = read(fd, msg + msglen, space)) == -1)
err(1, "read from %s", filename);
if (x == 0)
break;
space -= x;
msglen += x;
}
msg[msglen] = '\0';
close(fd);
*msglenp = msglen;
return msg;
}
static void
writeall(int fd, const void *buf, size_t buflen, const char *filename)
{
ssize_t x;
while (buflen != 0) {
x = write(fd, buf, buflen);
if (x == -1)
err(1, "write to %s", filename);
buflen -= x;
buf = (char *)buf + x;
}
}
#ifndef VERIFYONLY
static void
writeb64file(const char *filename, const char *comment, const void *buf,
size_t buflen, const void *msg, size_t msglen, int oflags, mode_t mode)
{
char header[1024];
char b64[1024];
int fd, rv;
fd = xopen(filename, O_CREAT|oflags|O_NOFOLLOW|O_WRONLY, mode);
if (snprintf(header, sizeof(header), "%s%s\n",
COMMENTHDR, comment) >= sizeof(header))
errx(1, "comment too long");
writeall(fd, header, strlen(header), filename);
if ((rv = b64_ntop(buf, buflen, b64, sizeof(b64)-1)) == -1)
errx(1, "b64 encode failed");
b64[rv++] = '\n';
writeall(fd, b64, rv, filename);
explicit_bzero(b64, sizeof(b64));
if (msg)
writeall(fd, msg, msglen, filename);
close(fd);
}
static void
kdf(uint8_t *salt, size_t saltlen, int rounds, int allowstdin, int confirm,
uint8_t *key, size_t keylen)
{
char pass[1024];
int rppflags = RPP_ECHO_OFF;
if (rounds == 0) {
memset(key, 0, keylen);
return;
}
if (allowstdin && !isatty(STDIN_FILENO))
rppflags |= RPP_STDIN;
if (!readpassphrase("passphrase: ", pass, sizeof(pass), rppflags))
errx(1, "unable to read passphrase");
if (strlen(pass) == 0)
errx(1, "please provide a password");
if (confirm && !(rppflags & RPP_STDIN)) {
char pass2[1024];
if (!readpassphrase("confirm passphrase: ", pass2,
sizeof(pass2), rppflags))
errx(1, "unable to read passphrase");
if (strcmp(pass, pass2) != 0)
errx(1, "passwords don't match");
explicit_bzero(pass2, sizeof(pass2));
}
if (bcrypt_pbkdf(pass, strlen(pass), salt, saltlen, key,
keylen, rounds) == -1)
errx(1, "bcrypt pbkdf");
explicit_bzero(pass, sizeof(pass));
}
static void
signmsg(uint8_t *seckey, uint8_t *msg, unsigned long long msglen,
uint8_t *sig)
{
unsigned long long siglen;
uint8_t *sigbuf;
sigbuf = xmalloc(msglen + SIGBYTES);
crypto_sign_ed25519(sigbuf, &siglen, msg, msglen, seckey);
memcpy(sig, sigbuf, SIGBYTES);
free(sigbuf);
}
static void
generate(const char *pubkeyfile, const char *seckeyfile, int rounds,
const char *comment)
{
uint8_t digest[SHA512_DIGEST_LENGTH];
struct pubkey pubkey;
struct enckey enckey;
uint8_t xorkey[sizeof(enckey.seckey)];
uint8_t fingerprint[FPLEN];
char commentbuf[COMMENTMAXLEN];
SHA2_CTX ctx;
int i;
crypto_sign_ed25519_keypair(pubkey.pubkey, enckey.seckey);
arc4random_buf(fingerprint, sizeof(fingerprint));
SHA512Init(&ctx);
SHA512Update(&ctx, enckey.seckey, sizeof(enckey.seckey));
SHA512Final(digest, &ctx);
memcpy(enckey.pkalg, PKALG, 2);
memcpy(enckey.kdfalg, KDFALG, 2);
enckey.kdfrounds = htonl(rounds);
memcpy(enckey.fingerprint, fingerprint, FPLEN);
arc4random_buf(enckey.salt, sizeof(enckey.salt));
kdf(enckey.salt, sizeof(enckey.salt), rounds, 1, 1, xorkey, sizeof(xorkey));
memcpy(enckey.checksum, digest, sizeof(enckey.checksum));
for (i = 0; i < sizeof(enckey.seckey); i++)
enckey.seckey[i] ^= xorkey[i];
explicit_bzero(digest, sizeof(digest));
explicit_bzero(xorkey, sizeof(xorkey));
if (snprintf(commentbuf, sizeof(commentbuf), "%s secret key",
comment) >= sizeof(commentbuf))
errx(1, "comment too long");
writeb64file(seckeyfile, commentbuf, &enckey,
sizeof(enckey), NULL, 0, O_EXCL, 0600);
explicit_bzero(&enckey, sizeof(enckey));
memcpy(pubkey.pkalg, PKALG, 2);
memcpy(pubkey.fingerprint, fingerprint, FPLEN);
if (snprintf(commentbuf, sizeof(commentbuf), "%s public key",
comment) >= sizeof(commentbuf))
errx(1, "comment too long");
writeb64file(pubkeyfile, commentbuf, &pubkey,
sizeof(pubkey), NULL, 0, O_EXCL, 0666);
}
static void
sign(const char *seckeyfile, const char *msgfile, const char *sigfile,
int embedded)
{
struct sig sig;
uint8_t digest[SHA512_DIGEST_LENGTH];
struct enckey enckey;
uint8_t xorkey[sizeof(enckey.seckey)];
uint8_t *msg;
char comment[COMMENTMAXLEN], sigcomment[COMMENTMAXLEN];
char *secname;
unsigned long long msglen;
int i, rounds;
SHA2_CTX ctx;
readb64file(seckeyfile, &enckey, sizeof(enckey), comment);
if (memcmp(enckey.kdfalg, KDFALG, 2) != 0)
errx(1, "unsupported KDF");
rounds = ntohl(enckey.kdfrounds);
kdf(enckey.salt, sizeof(enckey.salt), rounds, strcmp(msgfile, "-") != 0,
0, xorkey, sizeof(xorkey));
for (i = 0; i < sizeof(enckey.seckey); i++)
enckey.seckey[i] ^= xorkey[i];
explicit_bzero(xorkey, sizeof(xorkey));
SHA512Init(&ctx);
SHA512Update(&ctx, enckey.seckey, sizeof(enckey.seckey));
SHA512Final(digest, &ctx);
if (memcmp(enckey.checksum, digest, sizeof(enckey.checksum)) != 0)
errx(1, "incorrect passphrase");
explicit_bzero(digest, sizeof(digest));
msg = readmsg(msgfile, &msglen);
signmsg(enckey.seckey, msg, msglen, sig.sig);
memcpy(sig.fingerprint, enckey.fingerprint, FPLEN);
explicit_bzero(&enckey, sizeof(enckey));
memcpy(sig.pkalg, PKALG, 2);
if ((secname = strstr(seckeyfile, ".sec")) && strlen(secname) == 4) {
if (snprintf(sigcomment, sizeof(sigcomment), VERIFYWITH "%.*s.pub",
(int)strlen(seckeyfile) - 4, seckeyfile) >= sizeof(sigcomment))
errx(1, "comment too long");
} else {
if (snprintf(sigcomment, sizeof(sigcomment), "signature from %s",
comment) >= sizeof(sigcomment))
errx(1, "comment too long");
}
if (embedded)
writeb64file(sigfile, sigcomment, &sig, sizeof(sig), msg,
msglen, O_TRUNC, 0666);
else
writeb64file(sigfile, sigcomment, &sig, sizeof(sig), NULL,
0, O_TRUNC, 0666);
free(msg);
}
static void
inspect(const char *seckeyfile, const char *pubkeyfile, const char *sigfile)
{
struct sig sig;
struct enckey enckey;
struct pubkey pubkey;
char fp[(FPLEN + 2) / 3 * 4 + 1];
if (seckeyfile) {
readb64file(seckeyfile, &enckey, sizeof(enckey), NULL);
b64_ntop(enckey.fingerprint, FPLEN, fp, sizeof(fp));
printf("sec fp: %s\n", fp);
}
if (pubkeyfile) {
readb64file(pubkeyfile, &pubkey, sizeof(pubkey), NULL);
b64_ntop(pubkey.fingerprint, FPLEN, fp, sizeof(fp));
printf("pub fp: %s\n", fp);
}
if (sigfile) {
readb64file(sigfile, &sig, sizeof(sig), NULL);
b64_ntop(sig.fingerprint, FPLEN, fp, sizeof(fp));
printf("sig fp: %s\n", fp);
}
}
#endif
static void
verifymsg(struct pubkey *pubkey, uint8_t *msg, unsigned long long msglen,
struct sig *sig, int quiet)
{
uint8_t *sigbuf, *dummybuf;
unsigned long long siglen, dummylen;
if (memcmp(pubkey->fingerprint, sig->fingerprint, FPLEN) != 0)
errx(1, "verification failed: checked against wrong key");
siglen = SIGBYTES + msglen;
sigbuf = xmalloc(siglen);
dummybuf = xmalloc(siglen);
memcpy(sigbuf, sig->sig, SIGBYTES);
memcpy(sigbuf + SIGBYTES, msg, msglen);
if (crypto_sign_ed25519_open(dummybuf, &dummylen, sigbuf, siglen,
pubkey->pubkey) == -1)
errx(1, "signature verification failed");
if (!quiet)
printf("Signature Verified\n");
free(sigbuf);
free(dummybuf);
}
static void
readpubkey(const char *pubkeyfile, struct pubkey *pubkey,
const char *sigcomment)
{
const char *safepath = "/etc/signify/";
if (!pubkeyfile) {
if ((pubkeyfile = strstr(sigcomment, VERIFYWITH))) {
pubkeyfile += strlen(VERIFYWITH);
if (strncmp(pubkeyfile, safepath, strlen(safepath)) != 0 ||
strstr(pubkeyfile, "/../") != NULL)
errx(1, "untrusted path %s", pubkeyfile);
} else
usage("must specify pubkey");
}
readb64file(pubkeyfile, pubkey, sizeof(*pubkey), NULL);
}
static void
verifysimple(const char *pubkeyfile, const char *msgfile, const char *sigfile,
int quiet)
{
char sigcomment[COMMENTMAXLEN];
struct sig sig;
struct pubkey pubkey;
unsigned long long msglen;
uint8_t *msg;
msg = readmsg(msgfile, &msglen);
readb64file(sigfile, &sig, sizeof(sig), sigcomment);
readpubkey(pubkeyfile, &pubkey, sigcomment);
verifymsg(&pubkey, msg, msglen, &sig, quiet);
free(msg);
}
static uint8_t *
verifyembedded(const char *pubkeyfile, const char *sigfile,
int quiet, unsigned long long *msglenp)
{
char sigcomment[COMMENTMAXLEN];
struct sig sig;
struct pubkey pubkey;
unsigned long long msglen, siglen;
uint8_t *msg;
msg = readmsg(sigfile, &msglen);
siglen = parseb64file(sigfile, msg, &sig, sizeof(sig), sigcomment);
readpubkey(pubkeyfile, &pubkey, sigcomment);
msglen -= siglen;
memmove(msg, msg + siglen, msglen);
msg[msglen] = 0;
verifymsg(&pubkey, msg, msglen, &sig, quiet);
*msglenp = msglen;
return msg;
}
static void
verify(const char *pubkeyfile, const char *msgfile, const char *sigfile,
int embedded, int quiet)
{
unsigned long long msglen;
uint8_t *msg;
int fd;
if (embedded) {
msg = verifyembedded(pubkeyfile, sigfile, quiet, &msglen);
fd = xopen(msgfile, O_CREAT|O_TRUNC|O_NOFOLLOW|O_WRONLY, 0666);
writeall(fd, msg, msglen, msgfile);
free(msg);
close(fd);
} else {
verifysimple(pubkeyfile, msgfile, sigfile, quiet);
}
}
#ifndef VERIFYONLY
struct checksum {
char file[1024];
char hash[1024];
char algo[256];
};
static void
verifychecksums(char *msg, int argc, char **argv, int quiet)
{
char buf[1024];
char *line, *endline;
struct checksum *checksums = NULL, *c = NULL;
int nchecksums = 0;
int i, j, uselist, count, hasfailed;
int *failures;
line = msg;
while (line && *line) {
if (!(checksums = reallocarray(checksums,
nchecksums + 1, sizeof(*checksums))))
err(1, "realloc");
c = &checksums[nchecksums++];
if ((endline = strchr(line, '\n')))
*endline++ = 0;
if (sscanf(line, "%255s %1023s = %1023s",
c->algo, buf, c->hash) != 3 ||
buf[0] != '(' || buf[strlen(buf) - 1] != ')')
errx(1, "unable to parse checksum line %s", line);
buf[strlen(buf) - 1] = 0;
strlcpy(c->file, buf + 1, sizeof(c->file));
line = endline;
}
if (argc) {
uselist = 0;
count = argc;
} else {
uselist = 1;
count = nchecksums;
}
if (!(failures = calloc(count, sizeof(*failures))))
err(1, "calloc");
for (i = 0; i < count; i++) {
if (uselist) {
c = &checksums[i];
} else {
for (j = 0; j < nchecksums; j++) {
c = &checksums[j];
if (strcmp(c->file, argv[i]) == 0)
break;
}
if (j == nchecksums) {
failures[i] = 1;
continue;
}
}
if (strcmp(c->algo, "SHA256") == 0) {
if (!SHA256File(c->file, buf)) {
failures[i] = 1;
continue;
}
} else if (strcmp(c->algo, "SHA512") == 0) {
if (!SHA512File(c->file, buf)) {
failures[i] = 1;
continue;
}
} else {
errx(1, "can't handle algorithm %s", c->algo);
}
if (strcmp(c->hash, buf) != 0) {
failures[i] = 1;
continue;
}
if (!quiet)
printf("%s: OK\n", c->file);
}
hasfailed = 0;
for (i = 0; i < count; i++) {
if (failures[i]) {
fprintf(stderr, "%s: FAIL\n",
uselist ? checksums[i].file : argv[i]);
hasfailed = 1;
}
}
if (hasfailed)
exit(1);
free(checksums);
free(failures);
}
static void
check(const char *pubkeyfile, const char *sigfile, int quiet, int argc,
char **argv)
{
unsigned long long msglen;
uint8_t *msg;
msg = verifyembedded(pubkeyfile, sigfile, quiet, &msglen);
verifychecksums((char *)msg, argc, argv, quiet);
free(msg);
}
#endif
int
main(int argc, char **argv)
{
const char *pubkeyfile = NULL, *seckeyfile = NULL, *msgfile = NULL,
*sigfile = NULL;
char sigfilebuf[1024];
const char *comment = "signify";
int ch, rounds;
int embedded = 0;
int quiet = 0;
enum {
NONE,
CHECK,
GENERATE,
INSPECT,
SIGN,
VERIFY
} verb = NONE;
rounds = 42;
while ((ch = getopt(argc, argv, "CGISVc:em:np:qs:x:")) != -1) {
switch (ch) {
#ifndef VERIFYONLY
case 'C':
if (verb)
usage(NULL);
verb = CHECK;
break;
case 'G':
if (verb)
usage(NULL);
verb = GENERATE;
break;
case 'I':
if (verb)
usage(NULL);
verb = INSPECT;
break;
case 'S':
if (verb)
usage(NULL);
verb = SIGN;
break;
#endif
case 'V':
if (verb)
usage(NULL);
verb = VERIFY;
break;
case 'c':
comment = optarg;
break;
case 'e':
embedded = 1;
break;
case 'm':
msgfile = optarg;
break;
case 'n':
rounds = 0;
break;
case 'p':
pubkeyfile = optarg;
break;
case 'q':
quiet = 1;
break;
case 's':
seckeyfile = optarg;
break;
case 'x':
sigfile = optarg;
break;
default:
usage(NULL);
break;
}
}
argc -= optind;
argv += optind;
#ifndef VERIFYONLY
if (verb == CHECK) {
if (!pubkeyfile || !sigfile)
usage("must specify pubkey and sigfile");
check(pubkeyfile, sigfile, quiet, argc, argv);
return 0;
}
#endif
if (argc != 0)
usage(NULL);
if (!sigfile && msgfile) {
if (strcmp(msgfile, "-") == 0)
usage("must specify sigfile with - message");
if (snprintf(sigfilebuf, sizeof(sigfilebuf), "%s.sig",
msgfile) >= sizeof(sigfilebuf))
errx(1, "path too long");
sigfile = sigfilebuf;
}
switch (verb) {
#ifndef VERIFYONLY
case GENERATE:
if (!pubkeyfile || !seckeyfile)
usage("must specify pubkey and seckey");
generate(pubkeyfile, seckeyfile, rounds, comment);
break;
case INSPECT:
inspect(seckeyfile, pubkeyfile, sigfile);
break;
case SIGN:
if (!msgfile || !seckeyfile)
usage("must specify message and seckey");
sign(seckeyfile, msgfile, sigfile, embedded);
break;
#endif
case VERIFY:
if (!msgfile)
usage("must specify message");
verify(pubkeyfile, msgfile, sigfile, embedded, quiet);
break;
default:
usage(NULL);
break;
}
return 0;
}