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/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* Host functions for signature generation.
*/
/* TODO: change all 'return 0', 'return 1' into meaningful return codes */
#include <openssl/rsa.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include "2sysincludes.h"
#include "2common.h"
#include "2sha.h"
#include "cryptolib.h"
#include "file_keys.h"
#include "host_common.h"
#include "vboot_common.h"
VbSignature* SignatureAlloc(uint64_t sig_size, uint64_t data_size) {
VbSignature* sig = (VbSignature*)malloc(sizeof(VbSignature) + sig_size);
if (!sig)
return NULL;
sig->sig_offset = sizeof(VbSignature);
sig->sig_size = sig_size;
sig->data_size = data_size;
return sig;
}
void SignatureInit(VbSignature* sig, uint8_t* sig_data,
uint64_t sig_size, uint64_t data_size) {
sig->sig_offset = OffsetOf(sig, sig_data);
sig->sig_size = sig_size;
sig->data_size = data_size;
}
int SignatureCopy(VbSignature* dest, const VbSignature* src) {
if (dest->sig_size < src->sig_size)
return 1;
dest->sig_size = src->sig_size;
dest->data_size = src->data_size;
Memcpy(GetSignatureData(dest), GetSignatureDataC(src), src->sig_size);
return 0;
}
/* Invoke [external_signer] command with [pem_file] as
* an argument, contents of [inbuf] passed redirected to stdin,
* and the stdout of the command is put back into [outbuf].
* Returns -1 on error, 0 on success.
*/
int InvokeExternalSigner(uint64_t size,
const uint8_t* inbuf,
uint8_t* outbuf,
uint64_t outbufsize,
const char* pem_file,
const char* external_signer) {
int rv = 0, n;
int p_to_c[2], c_to_p[2]; /* pipe descriptors */
pid_t pid;
VBDEBUG(("Will invoke \"%s %s\" to perform signing.\n"
"Input to the signer will be provided on standard in.\n"
"Output of the signer will be read from standard out.\n",
external_signer, pem_file));
/* Need two pipes since we want to invoke the external_signer as
* a co-process writing to its stdin and reading from its stdout. */
if (pipe(p_to_c) < 0 || pipe(c_to_p) < 0) {
VBDEBUG(("pipe() error\n"));
return -1;
}
if ((pid = fork()) < 0) {
VBDEBUG(("fork() error"));
return -1;
}
else if (pid > 0) { /* Parent. */
close(p_to_c[STDIN_FILENO]);
close(c_to_p[STDOUT_FILENO]);
/* We provide input to the child process (external signer). */
if (write(p_to_c[STDOUT_FILENO], inbuf, size) != size) {
VBDEBUG(("write() error while providing input to external signer\n"));
rv = -1;
} else {
close(p_to_c[STDOUT_FILENO]); /* Send EOF to child (signer process). */
do {
n = read(c_to_p[STDIN_FILENO], outbuf, outbufsize);
outbuf += n;
outbufsize -= n;
} while (n > 0 && outbufsize);
if (n < 0) {
VBDEBUG(("read() error while reading output from external signer\n"));
rv = -1;
}
}
if (waitpid(pid, NULL, 0) < 0) {
VBDEBUG(("waitpid() error\n"));
rv = -1;
}
} else { /* Child. */
close (p_to_c[STDOUT_FILENO]);
close (c_to_p[STDIN_FILENO]);
/* Map the stdin to the first pipe (this pipe gets input
* from the parent) */
if (STDIN_FILENO != p_to_c[STDIN_FILENO]) {
if (dup2(p_to_c[STDIN_FILENO], STDIN_FILENO) != STDIN_FILENO) {
VBDEBUG(("stdin dup2() failed (external signer)\n"));
close(p_to_c[0]);
return -1;
}
}
/* Map the stdout to the second pipe (this pipe sends back
* signer output to the parent) */
if (STDOUT_FILENO != c_to_p[STDOUT_FILENO]) {
if (dup2(c_to_p[STDOUT_FILENO], STDOUT_FILENO) != STDOUT_FILENO) {
VBDEBUG(("stdout dup2() failed (external signer)\n"));
close(c_to_p[STDOUT_FILENO]);
return -1;
}
}
/* External signer is invoked here. */
if (execl(external_signer, external_signer, pem_file, (char *) 0) < 0) {
VBDEBUG(("execl() of external signer failed\n"));
}
}
return rv;
}
VbSignature* CalculateSignature_external(const uint8_t* data, uint64_t size,
const char* key_file,
uint64_t key_algorithm,
const char* external_signer) {
int vb2_alg = vb2_crypto_to_hash(key_algorithm);
uint8_t digest[VB2_MAX_DIGEST_SIZE];
int digest_size = vb2_digest_size(vb2_alg);
const uint8_t* digestinfo = hash_digestinfo_map[key_algorithm];
uint64_t digestinfo_size = digestinfo_size_map[key_algorithm];
uint8_t* signature_digest;
uint64_t signature_digest_len = digest_size + digestinfo_size;
VbSignature* sig;
int rv;
/* Calculate the digest */
if (VB2_SUCCESS != vb2_digest_buffer(data, size, vb2_alg,
digest, sizeof(digest)))
return NULL;
/* Prepend the digest info to the digest */
signature_digest = malloc(signature_digest_len);
if (!signature_digest)
return NULL;
Memcpy(signature_digest, digestinfo, digestinfo_size);
Memcpy(signature_digest + digestinfo_size, digest, digest_size);
/* Allocate output signature */
sig = SignatureAlloc(siglen_map[key_algorithm], size);
if (!sig) {
free(signature_digest);
return NULL;
}
/* Sign the signature_digest into our output buffer */
rv = InvokeExternalSigner(signature_digest_len, /* Input length */
signature_digest, /* Input data */
GetSignatureData(sig), /* Output sig */
siglen_map[key_algorithm], /* Max Output sig size */
key_file, /* Key file to use */
external_signer); /* External cmd to invoke */
free(signature_digest);
if (-1 == rv) {
VBDEBUG(("SignatureBuf(): RSA_private_encrypt() failed.\n"));
free(sig);
return NULL;
}
/* Return the signature */
return sig;
}
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