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lib/libve/openpgp/opgp_sig.c

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/*-
* Copyright (c) 2018, Juniper Networks, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* RCSid:
* from: signer.c,v 1.10 2018/03/23 01:14:30 sjg
*
* @(#) Copyright (c) 2012 Simon J. Gerraty
*
* This file is provided in the hope that it will
* be of use. There is absolutely NO WARRANTY.
* Permission to copy, redistribute or otherwise
* use this file is hereby granted provided that
* the above copyright notice and this notice are
* left intact.
*
* Please send copies of changes and bug-fixes to:
* sjg@crufty.net
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "../libve-priv.h"
#define get_error_string ve_error_get
#ifdef _STANDALONE
#define warnx printf
#else
#include <sys/param.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <err.h>
#endif
#include "decode.h"
#include "packet.h"
#ifdef USE_BEARSSL
void
initialize (void)
{
#ifdef _STANDALONE
ve_trust_init();
#endif
}
#else
#include <openssl/err.h>
/**
* @brief intialize OpenSSL
*/
void
initialize(void)
{
static int once;
if (once)
return);
once = 1;
//CRYPTO_malloc_init();
ERR_load_crypto_strings();
OpenSSL_add_all_algorithms();
}
/**
* @brief
* last error from OpenSSL as a string
*/
char *
get_error_string(void)
{
initialize();
return (ERR_error_string(ERR_get_error(), NULL));
}
#endif
/**
* @brief decode a signature packet
*
* We only support RSA
*
* @sa rfc4880:5.2
*/
ssize_t
decode_sig(int tag, unsigned char **pptr, size_t len, OpenPGP_sig *sig)
{
unsigned char *ptr;
unsigned char *pgpbytes;
unsigned char *sp;
int version;
int hcount = 0;
int ucount = 0;
int stag = 0;
int n;
n = tag; /* avoid unused */
/*
* We need to keep a reference to the packet bytes
* as these form part of the signature data.
*
* @sa rfc4880:5.2.4
*/
pgpbytes = ptr = *pptr;
version = *ptr++;
if (version == 3) {
ptr++;
sig->pgpbytes = malloc(5);
if (!sig->pgpbytes)
return (-1);
memcpy(sig->pgpbytes, ptr, 5);
sig->pgpbytes_len = 5;
sig->sig_type = *ptr++;
ptr += 4;
sig->key_id = octets2hex(ptr, 8);
ptr += 8;
sig->sig_alg = *ptr++;
sig->hash_alg = *ptr++;
} else if (version == 4) {
sig->sig_type = *ptr++;
sig->sig_alg = *ptr++;
sig->hash_alg = *ptr++;
hcount = octets2i(ptr, 2);
ptr += 2;
sig->pgpbytes_len = (size_t)hcount + 6;
sig->pgpbytes = malloc(sig->pgpbytes_len + 6);
if (!sig->pgpbytes)
return (-1);
memcpy(sig->pgpbytes, pgpbytes, sig->pgpbytes_len);
sp = &sig->pgpbytes[sig->pgpbytes_len];
*sp++ = 4;
*sp++ = 255;
memcpy(sp, i2octets(4, (int)sig->pgpbytes_len), 4);
sig->pgpbytes_len += 6;
while (hcount > 0) {
sp = decode_subpacket(&ptr, &stag, &n);
hcount -= n;
/* can check stag to see if we care */
}
ucount = octets2i(ptr, 2);
ptr += 2;
while (ucount > 0) {
sp = decode_subpacket(&ptr, &stag, &n);
ucount -= n;
/* can check stag to see if we care */
if (stag == 16) {
free(sig->key_id);
sig->key_id = octets2hex(sp, 8);
}
}
} else
return (-1);
ptr += 2; /* skip hash16 */
if (sig->sig_alg == 1) { /* RSA */
sig->sig = decode_mpi(&ptr, &sig->sig_len);
}
/* we are done */
return ((ssize_t)len);
}
/**
* @brief map OpenPGP hash algorithm id's to name
*
* @sa rfc4880:9.4
*/
static struct hash_alg_map {
int halg;
const char *hname;
} hash_algs[] = {
{1, "md5"},
{2, "sha1"},
{8, "sha256"},
{9, "sha384"},
{10, "sha512"},
{11, "sha224"},
{0, NULL},
};
static const char *
get_hname(int hash_alg)
{
struct hash_alg_map *hmp;
for (hmp = hash_algs; hmp->halg > 0; hmp++) {
if (hmp->halg == hash_alg)
return (hmp->hname);
}
return (NULL);
}
/* lifted from signer.c */
/**
* @brief verify a digest
*
* The public key, digest name, file and signature data.
*
* @return 1 on success 0 on failure, -1 on error
*/
#ifndef USE_BEARSSL
static int
verify_digest (EVP_PKEY *pkey,
const char *digest,
unsigned char *mdata, size_t mlen,
unsigned char *sdata, size_t slen)
{
EVP_MD_CTX ctx;
const EVP_MD *md = NULL;
EVP_PKEY_CTX *pctx = NULL;
int rc = 0;
int i = -1;
initialize();
md = EVP_get_digestbyname(digest);
EVP_DigestInit(&ctx, md);
pctx = EVP_PKEY_CTX_new(pkey, NULL);
if (!pctx)
goto fail;
if (EVP_PKEY_verify_init(pctx) <= 0)
goto fail;
if (EVP_PKEY_CTX_set_signature_md(pctx, ctx.digest) <= 0)
goto fail;
i = EVP_PKEY_verify(pctx, sdata, slen, mdata, mlen);
if (i >= 0)
rc = i;
fail:
EVP_PKEY_CTX_free(pctx);
return (rc);
}
#endif
/**
* @brief verify OpenPGP signed file
*
*
* @param[in] filename
* used to determine the signature name
*
* @param[in] fdata
* content of filename
*
* @param[in] fbytes
* of fdata
*
* @param[in] sdata
* content of signature
*
* @param[in] sbytes
* of sdata
*
* @param[in] flags
*
* @return 0 on success
*/
int
openpgp_verify(const char *filename,
unsigned char *fdata, size_t fbytes,
unsigned char *sdata, size_t sbytes,
int flags)
{
OpenPGP_key *key;
OpenPGP_sig *sig;
#ifdef USE_BEARSSL
const br_hash_class *md;
br_hash_compat_context mctx;
const unsigned char *hash_oid;
#else
const EVP_MD *md = NULL;
EVP_MD_CTX mctx;
#endif
unsigned char mdata[64];
unsigned char *ptr;
unsigned char *ddata = NULL;
const char *hname;
size_t mlen;
int rc = -1;
initialize();
sig = NEW(OpenPGP_sig);
if (!sdata || !sig) {
warnx("cannot verify %s", filename);
goto oops;
}
if (!(sdata[0] & 0200))
sdata = ddata = dearmor((char *)sdata, sbytes, &sbytes);
ptr = sdata;
rc = decode_packet(2, &ptr, sbytes, (decoder_t)decode_sig, sig);
if (rc == 0 && sig->key_id) {
key = load_key_id(sig->key_id);
if (!key) {
warnx("cannot find key-id: %s", sig->key_id);
rc = -1;
} else if (!(hname = get_hname(sig->hash_alg))) {
warnx("unsupported hash algorithm: %d", sig->hash_alg);
rc = -1;
} else {
/*
* Hash fdata according to the OpenPGP recipe
*
* @sa rfc4880:5.2.4
*/
#ifdef USE_BEARSSL
switch (sig->hash_alg) { /* see hash_algs above */
case 2: /* sha1 */
md = &br_sha1_vtable;
mlen = br_sha1_SIZE;
hash_oid = BR_HASH_OID_SHA1;
break;
case 8: /* sha256 */
md = &br_sha256_vtable;
mlen = br_sha256_SIZE;
hash_oid = BR_HASH_OID_SHA256;
break;
default:
warnx("unsupported hash algorithm: %s", hname);
goto oops;
}
md->init(&mctx.vtable);
md->update(&mctx.vtable, fdata, fbytes);
md->update(&mctx.vtable, sig->pgpbytes,
sig->pgpbytes_len);
md->out(&mctx.vtable, mdata);
rc = verify_rsa_digest(key->key, hash_oid,
mdata, mlen, sig->sig, sig->sig_len);
#else
md = EVP_get_digestbyname(hname);
EVP_DigestInit(&mctx, md);
EVP_DigestUpdate(&mctx, fdata, fbytes);
EVP_DigestUpdate(&mctx, sig->pgpbytes,
sig->pgpbytes_len);
mlen = sizeof(mdata);
EVP_DigestFinal(&mctx,mdata,(unsigned int *)&mlen);
rc = verify_digest(key->key, hname, mdata, mlen,
sig->sig, sig->sig_len);
#endif
if (rc > 0) {
if ((flags & 1))
printf("Verified %s signed by %s\n",
filename,
key->user ? key->user->name : "someone");
rc = 0; /* success */
} else if (rc == 0) {
printf("Unverified %s: %s\n",
filename, get_error_string());
rc = 1;
} else {
printf("Unverified %s\n", filename);
}
}
} else {
warnx("cannot decode signature for %s", filename);
rc = -1;
}
oops:
free(ddata);
free(sig);
return (rc);
}
#ifndef _STANDALONE
/**
* @brief list of extensions we handle
*
* ".asc" is preferred as it works seamlessly with openpgp
*/
static const char *sig_exts[] = {
".asc",
".pgp",
".psig",
NULL,
};
/**
* @brief verify OpenPGP signed file
*
*
* @param[in] filename
* used to determine the signature name
*
* @param[in] fdata
* content of filename
*
* @param[in] nbytes
* of fdata
*
* @return
*/
int
openpgp_verify_file(const char *filename, unsigned char *fdata, size_t nbytes)
{
char pbuf[MAXPATHLEN];
unsigned char *sdata;
const char *sname = NULL;
const char **ep;
size_t sz;
int n;
for (ep = sig_exts; *ep; ep++) {
n = snprintf(pbuf, sizeof(pbuf), "%s%s", filename, *ep);
if (n >= (int)sizeof(pbuf)) {
warnx("cannot form signature name for %s", filename);
return (-1);
}
if (access(pbuf, R_OK) == 0) {
sname = pbuf;
break;
}
}
if (!sname) {
warnx("cannot find signature for %s", filename);
return (-1);
}
sdata = read_file(sname, &sz);
return (openpgp_verify(filename, fdata, nbytes, sdata, sz, 1));
}
#endif
/**
* @brief verify OpenPGP signature
*
* @return content of signed file
*/
unsigned char *
verify_asc(const char *sigfile, int flags)
{
char pbuf[MAXPATHLEN];
char *cp;
size_t n;
unsigned char *fdata, *sdata;
size_t fbytes, sbytes;
if ((sdata = read_file(sigfile, &sbytes))) {
n = strlcpy(pbuf, sigfile, sizeof(pbuf));
if ((cp = strrchr(pbuf, '.')))
*cp = '\0';
if ((fdata = read_file(pbuf, &fbytes))) {
if (openpgp_verify(pbuf, fdata, fbytes, sdata,
sbytes, flags)) {
free(fdata);
fdata = NULL;
}
}
} else
fdata = NULL;
free(sdata);
return (fdata);
}