NetBSD/usr.sbin/syslogd/sign.c

939 lines
27 KiB
C

/* $NetBSD: sign.c,v 1.6 2015/02/10 20:38:15 christos Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Martin Schütte.
*
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* sign.c
* syslog-sign related code for syslogd
*
* Martin Schütte
*/
/*
* Issues with the current internet draft:
* 1. The draft is a bit unclear on the input format for the signature,
* so this might have to be changed later. Cf. sign_string_sign()
* 2. The draft only defines DSA signatures. I hope it will be extended
* to DSS, thus allowing DSA, RSA (ANSI X9.31) and ECDSA (ANSI X9.62)
* 3. The draft does not define the data format for public keys in CBs.
* This implementation sends public keys in DER encoding.
* 4. This current implementation uses high-level OpenSSL API.
* I am not sure if these completely implement the FIPS/ANSI standards.
* Update after WG discussion in August:
* 1. check; next draft will be clearer and specify the format as implemented.
* 2. check; definitely only DSA in this version.
* 3. remains a problem, so far no statement from authors or WG.
* 4. check; used EVP_dss1 method implements FIPS.
*/
/*
* Limitations of this implementation:
* - cannot use OpenPGP keys, only PKIX or DSA due to OpenSSL capabilities
* - only works for correctly formatted messages, because incorrect messages
* are reformatted (e.g. if it receives a message with two spaces between
* fields it might even be parsed, but the output will have only one space).
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: sign.c,v 1.6 2015/02/10 20:38:15 christos Exp $");
#ifndef DISABLE_SIGN
#include "syslogd.h"
#ifndef DISABLE_TLS
#include "tls.h"
#endif /* !DISABLE_TLS */
#include "sign.h"
#include "extern.h"
/*
* init all SGs for a given algorithm
*/
bool
sign_global_init(struct filed *Files)
{
DPRINTF((D_CALL|D_SIGN), "sign_global_init()\n");
if (!(GlobalSign.sg == 0 || GlobalSign.sg == 1
|| GlobalSign.sg == 2 || GlobalSign.sg == 3)) {
logerror("sign_init(): invalid SG %d", GlobalSign.sg);
return false;
}
if (!sign_get_keys())
return false;
/* signature algorithm */
/* can probably be merged with the hash algorithm/context but
* I leave the optimization for later until the RFC is ready */
GlobalSign.sigctx = EVP_MD_CTX_create();
EVP_MD_CTX_init(GlobalSign.sigctx);
/* the signature algorithm depends on the type of key */
if (EVP_PKEY_DSA == EVP_PKEY_type(GlobalSign.pubkey->type)) {
GlobalSign.sig = EVP_dss1();
GlobalSign.sig_len_b64 = SIGN_B64SIGLEN_DSS;
/* this is the place to add non-DSA key types and algorithms
} else if (EVP_PKEY_RSA == EVP_PKEY_type(GlobalSign.pubkey->type)) {
GlobalSign.sig = EVP_sha1();
GlobalSign.sig_len_b64 = 28;
*/
} else {
logerror("key type not supported for syslog-sign");
return false;
}
assert(GlobalSign.keytype == 'C' || GlobalSign.keytype == 'K');
assert(GlobalSign.pubkey_b64 && GlobalSign.privkey &&
GlobalSign.pubkey);
assert(GlobalSign.privkey->pkey.dsa->priv_key);
GlobalSign.gbc = 0;
STAILQ_INIT(&GlobalSign.SigGroups);
/* hash algorithm */
OpenSSL_add_all_digests();
GlobalSign.mdctx = EVP_MD_CTX_create();
EVP_MD_CTX_init(GlobalSign.mdctx);
/* values for SHA-1 */
GlobalSign.md = EVP_dss1();
GlobalSign.md_len_b64 = 28;
GlobalSign.ver = "0111";
if (!sign_sg_init(Files))
return false;
sign_new_reboot_session();
DPRINTF(D_SIGN, "length values: SIGN_MAX_SD_LENGTH %d, "
"SIGN_MAX_FRAG_LENGTH %d, SIGN_MAX_SB_LENGTH %d, "
"SIGN_MAX_HASH_NUM %d\n", SIGN_MAX_SD_LENGTH,
SIGN_MAX_FRAG_LENGTH, SIGN_MAX_SB_LENGTH, SIGN_MAX_HASH_NUM);
/* set just before return, so it indicates initialization */
GlobalSign.rsid = now;
return true;
}
/*
* get keys for syslog-sign
* either from the X.509 certificate used for TLS
* or by generating a new one
*
* sets the global variables
* GlobalSign.keytype, GlobalSign.pubkey_b64,
* GlobalSign.privkey, and GlobalSign.pubkey
*/
bool
sign_get_keys(void)
{
EVP_PKEY *pubkey = NULL, *privkey = NULL;
unsigned char *der_pubkey = NULL, *ptr_der_pubkey = NULL;
char *pubkey_b64 = NULL;
int der_len;
/* try PKIX/TLS key first */
#ifndef DISABLE_TLS
SSL *ssl;
if (tls_opt.global_TLS_CTX
&& (ssl = SSL_new(tls_opt.global_TLS_CTX))) {
X509 *cert;
DPRINTF(D_SIGN, "Try to get keys from TLS X.509 cert...\n");
if (!(cert = SSL_get_certificate(ssl))) {
logerror("SSL_get_certificate() failed");
FREE_SSL(ssl);
return false;
}
if (!(privkey = SSL_get_privatekey(ssl))) {
logerror("SSL_get_privatekey() failed");
FREE_SSL(ssl);
return false;
}
if (!(pubkey = X509_get_pubkey(cert))) {
logerror("X509_get_pubkey() failed");
FREE_SSL(ssl);
return false;
}
/* note:
* - privkey is just a pointer into SSL_CTX and
* must not be changed nor be free()d
* - but pubkey has to be freed with EVP_PKEY_free()
*/
FREE_SSL(ssl);
if (EVP_PKEY_DSA != EVP_PKEY_type(pubkey->type)) {
DPRINTF(D_SIGN, "X.509 cert has no DSA key\n");
EVP_PKEY_free(pubkey);
privkey = NULL;
pubkey = NULL;
} else {
DPRINTF(D_SIGN, "Got public and private key "
"from X.509 --> use type PKIX\n");
GlobalSign.keytype = 'C';
GlobalSign.privkey = privkey;
GlobalSign.pubkey = pubkey;
/* base64 certificate encoding */
der_len = i2d_X509(cert, NULL);
if (!(ptr_der_pubkey = der_pubkey = malloc(der_len))
|| !(pubkey_b64 = malloc(der_len*2))) {
free(der_pubkey);
logerror("malloc() failed");
return false;
}
if (i2d_X509(cert, &ptr_der_pubkey) <= 0) {
logerror("i2d_X509() failed");
return false;
}
b64_ntop(der_pubkey, der_len, pubkey_b64, der_len*2);
free(der_pubkey);
/* try to resize memory object as needed */
GlobalSign.pubkey_b64 = realloc(pubkey_b64,
strlen(pubkey_b64)+1);
if (!GlobalSign.pubkey_b64)
GlobalSign.pubkey_b64 = pubkey_b64;
}
}
#endif /* !DISABLE_TLS */
if (!(privkey && pubkey)) { /* PKIX not available --> generate key */
DSA *dsa;
DPRINTF(D_SIGN, "Unable to get keys from X.509 "
"--> use DSA with type 'K'\n");
if (!(privkey = EVP_PKEY_new())) {
logerror("EVP_PKEY_new() failed");
return false;
}
dsa = DSA_generate_parameters(SIGN_GENCERT_BITS, NULL, 0,
NULL, NULL, NULL, NULL);
if (!DSA_generate_key(dsa)) {
logerror("DSA_generate_key() failed");
return false;
}
if (!EVP_PKEY_assign_DSA(privkey, dsa)) {
logerror("EVP_PKEY_assign_DSA() failed");
return false;
}
GlobalSign.keytype = 'K'; /* public/private keys used */
GlobalSign.privkey = privkey;
GlobalSign.pubkey = privkey;
/* pubkey base64 encoding */
der_len = i2d_DSA_PUBKEY(dsa, NULL);
if (!(ptr_der_pubkey = der_pubkey = malloc(der_len))
|| !(pubkey_b64 = malloc(der_len*2))) {
free(der_pubkey);
logerror("malloc() failed");
return false;
}
if (i2d_DSA_PUBKEY(dsa, &ptr_der_pubkey) <= 0) {
logerror("i2d_DSA_PUBKEY() failed");
free(der_pubkey);
free(pubkey_b64);
return false;
}
b64_ntop(der_pubkey, der_len, pubkey_b64, der_len*2);
free(der_pubkey);
/* try to resize memory object as needed */
GlobalSign.pubkey_b64 = realloc(pubkey_b64,
strlen(pubkey_b64) + 1);
if (!GlobalSign.pubkey_b64)
GlobalSign.pubkey_b64 = pubkey_b64;
}
return true;
}
/*
* init SGs
*/
bool
sign_sg_init(struct filed *Files)
{
struct signature_group_t *sg, *newsg, *last_sg;
struct filed_queue *fq;
struct string_queue *sqentry, *last_sqentry;
struct filed *f;
unsigned int i;
/* note on SG 1 and 2:
* it is assumed that redundant signature groups
* and especially signature groups without an associated
* destination are harmless.
* this currently holds true because sign_append_hash()
* is called from fprintlog(), so only actually used
* signature group get hashes and need memory for them
*/
/* possible optimization for SGs 1 and 2:
* use a struct signature_group_t *newsg[IETF_NUM_PRIVALUES]
* for direct group lookup
*/
#define ALLOC_OR_FALSE(x) do { \
if(!((x) = calloc(1, sizeof(*(x))))) { \
logerror("Unable to allocate memory"); \
return false; \
} \
} while (/*CONSTCOND*/0)
#define ALLOC_SG(x) do { \
ALLOC_OR_FALSE(x); \
(x)->last_msg_num = 1; /* cf. section 4.2.5 */ \
STAILQ_INIT(&(x)->hashes); \
STAILQ_INIT(&(x)->files); \
} while (/*CONSTCOND*/0)
/* alloc(fq) and add to SGs file queue */
#define ASSIGN_FQ() do { \
ALLOC_OR_FALSE(fq); \
fq->f = f; \
f->f_sg = newsg; \
DPRINTF(D_SIGN, "SG@%p <--> f@%p\n", newsg, f); \
STAILQ_INSERT_TAIL(&newsg->files, fq, entries); \
} while (/*CONSTCOND*/0)
switch (GlobalSign.sg) {
case 0:
/* one SG, linked to all files */
ALLOC_SG(newsg);
newsg->spri = 0;
for (f = Files; f; f = f->f_next)
ASSIGN_FQ();
STAILQ_INSERT_TAIL(&GlobalSign.SigGroups,
newsg, entries);
break;
case 1:
/* every PRI gets one SG */
for (i = 0; i < IETF_NUM_PRIVALUES; i++) {
int fac, prilev;
fac = LOG_FAC(i);
prilev = LOG_PRI(i);
ALLOC_SG(newsg);
newsg->spri = i;
/* now find all destinations associated with this SG */
for (f = Files; f; f = f->f_next)
/* check priorities */
if (MATCH_PRI(f, fac, prilev))
ASSIGN_FQ();
STAILQ_INSERT_TAIL(&GlobalSign.SigGroups,
newsg, entries);
}
break;
case 2:
/* PRI ranges get one SG, boundaries given by the
* SPRI, indicating the largest PRI in the SG
*
* either GlobalSign.sig2_delims has a list of
* user configured delimiters, or we use a default
* and set up one SG per facility
*/
if (STAILQ_EMPTY(&GlobalSign.sig2_delims)) {
DPRINTF(D_SIGN, "sign_sg_init(): set default "
"values for SG 2\n");
for (i = 0; i < (IETF_NUM_PRIVALUES>>3); i++) {
ALLOC_OR_FALSE(sqentry);
sqentry->data = NULL;
sqentry->key = (i<<3);
STAILQ_INSERT_TAIL(&GlobalSign.sig2_delims,
sqentry, entries);
}
}
assert(!STAILQ_EMPTY(&GlobalSign.sig2_delims));
/* add one more group at the end */
last_sqentry = STAILQ_LAST(&GlobalSign.sig2_delims,
string_queue, entries);
if (last_sqentry->key < IETF_NUM_PRIVALUES) {
ALLOC_OR_FALSE(sqentry);
sqentry->data = NULL;
sqentry->key = IETF_NUM_PRIVALUES-1;
STAILQ_INSERT_TAIL(&GlobalSign.sig2_delims,
sqentry, entries);
}
STAILQ_FOREACH(sqentry, &GlobalSign.sig2_delims, entries) {
unsigned int min_pri = 0;
ALLOC_SG(newsg);
newsg->spri = sqentry->key;
/* check _all_ priorities in SG */
last_sg = STAILQ_LAST(&GlobalSign.SigGroups,
signature_group_t, entries);
if (last_sg)
min_pri = last_sg->spri + 1;
DPRINTF(D_SIGN, "sign_sg_init(): add SG@%p: SG=\"2\","
" SPRI=\"%d\" -- for msgs with "
"%d <= pri <= %d\n",
newsg, newsg->spri, min_pri, newsg->spri);
/* now find all destinations associated with this SG */
for (f = Files; f; f = f->f_next) {
bool match = false;
for (i = min_pri; i <= newsg->spri; i++) {
int fac, prilev;
fac = LOG_FAC(i);
prilev = LOG_PRI(i);
if (MATCH_PRI(f, fac, prilev)) {
match = true;
break;
}
}
if (match)
ASSIGN_FQ();
}
STAILQ_INSERT_TAIL(&GlobalSign.SigGroups,
newsg, entries);
}
break;
case 3:
/* every file (with flag) gets one SG */
for (f = Files; f; f = f->f_next) {
if (!(f->f_flags & FFLAG_SIGN)) {
f->f_sg = NULL;
continue;
}
ALLOC_SG(newsg);
newsg->spri = f->f_file; /* not needed but shows SGs */
ASSIGN_FQ();
STAILQ_INSERT_TAIL(&GlobalSign.SigGroups,
newsg, entries);
}
break;
}
DPRINTF((D_PARSE|D_SIGN), "sign_sg_init() set up these "
"Signature Groups:\n");
STAILQ_FOREACH(sg, &GlobalSign.SigGroups, entries) {
DPRINTF((D_PARSE|D_SIGN), "SG@%p with SG=\"%d\", SPRI=\"%d\","
" associated files:\n", sg, GlobalSign.sg, sg->spri);
STAILQ_FOREACH(fq, &sg->files, entries) {
DPRINTF((D_PARSE|D_SIGN), " f@%p with type %d\n",
fq->f, fq->f->f_type);
}
}
return true;
}
/*
* free all SGs for a given algorithm
*/
void
sign_global_free(void)
{
struct signature_group_t *sg, *tmp_sg;
struct filed_queue *fq, *tmp_fq;
DPRINTF((D_CALL|D_SIGN), "sign_global_free()\n");
STAILQ_FOREACH_SAFE(sg, &GlobalSign.SigGroups, entries, tmp_sg) {
if (!STAILQ_EMPTY(&sg->hashes)) {
/* send CB and SB twice to get minimal redundancy
* for the last few message hashes */
sign_send_certificate_block(sg);
sign_send_certificate_block(sg);
sign_send_signature_block(sg, true);
sign_send_signature_block(sg, true);
sign_free_hashes(sg);
}
fq = STAILQ_FIRST(&sg->files);
while (fq != NULL) {
tmp_fq = STAILQ_NEXT(fq, entries);
free(fq);
fq = tmp_fq;
}
STAILQ_REMOVE(&GlobalSign.SigGroups,
sg, signature_group_t, entries);
free(sg);
}
sign_free_string_queue(&GlobalSign.sig2_delims);
if (GlobalSign.privkey) {
GlobalSign.privkey = NULL;
}
if (GlobalSign.pubkey) {
EVP_PKEY_free(GlobalSign.pubkey);
GlobalSign.pubkey = NULL;
}
if(GlobalSign.mdctx) {
EVP_MD_CTX_destroy(GlobalSign.mdctx);
GlobalSign.mdctx = NULL;
}
if(GlobalSign.sigctx) {
EVP_MD_CTX_destroy(GlobalSign.sigctx);
GlobalSign.sigctx = NULL;
}
FREEPTR(GlobalSign.pubkey_b64);
}
/*
* create and send certificate block
*/
bool
sign_send_certificate_block(struct signature_group_t *sg)
{
struct filed_queue *fq;
struct buf_msg *buffer;
char *tstamp;
char payload[SIGN_MAX_PAYLOAD_LENGTH];
char sd[SIGN_MAX_SD_LENGTH];
size_t payload_len, sd_len, fragment_len;
size_t payload_index = 0;
/* do nothing if CBs already sent or if there was no message in SG */
if (!sg->resendcount
|| ((sg->resendcount == SIGN_RESENDCOUNT_CERTBLOCK)
&& STAILQ_EMPTY(&sg->hashes)))
return false;
DPRINTF((D_CALL|D_SIGN), "sign_send_certificate_block(%p)\n", sg);
tstamp = make_timestamp(NULL, true, (size_t)-1);
payload_len = snprintf(payload, sizeof(payload), "%s %c %s", tstamp,
GlobalSign.keytype, GlobalSign.pubkey_b64);
if (payload_len >= sizeof(payload)) {
DPRINTF(D_SIGN, "Buffer too small for syslog-sign setup\n");
return false;
}
while (payload_index < payload_len) {
if (payload_len - payload_index <= SIGN_MAX_FRAG_LENGTH)
fragment_len = payload_len - payload_index;
else
fragment_len = SIGN_MAX_FRAG_LENGTH;
/* format SD */
sd_len = snprintf(sd, sizeof(sd), "[ssign-cert "
"VER=\"%s\" RSID=\"%" PRIuFAST64 "\" SG=\"%d\" "
"SPRI=\"%d\" TBPL=\"%zu\" INDEX=\"%zu\" "
"FLEN=\"%zu\" FRAG=\"%.*s\" "
"SIGN=\"\"]",
GlobalSign.ver, GlobalSign.rsid, GlobalSign.sg,
sg->spri, payload_len, payload_index+1,
fragment_len, (int)fragment_len,
&payload[payload_index]);
assert(sd_len < sizeof(sd));
assert(sd[sd_len] == '\0');
assert(sd[sd_len-1] == ']');
assert(sd[sd_len-2] == '"');
if (!sign_msg_sign(&buffer, sd, sizeof(sd)))
return 0;
DPRINTF((D_CALL|D_SIGN), "sign_send_certificate_block(): "
"calling fprintlog()\n");
STAILQ_FOREACH(fq, &sg->files, entries) {
/* we have to preserve the f_prevcount */
int tmpcnt;
tmpcnt = fq->f->f_prevcount;
fprintlog(fq->f, buffer, NULL);
fq->f->f_prevcount = tmpcnt;
}
sign_inc_gbc();
DELREF(buffer);
payload_index += fragment_len;
}
sg->resendcount--;
return true;
}
/*
* determine the SG for a message
* returns NULL if -sign not configured or no SG for this priority
*/
struct signature_group_t *
sign_get_sg(int pri, struct filed *f)
{
struct signature_group_t *sg, *rc = NULL;
if (GlobalSign.rsid && f)
switch (GlobalSign.sg) {
case 0:
rc = f->f_sg;
break;
case 1:
case 2:
STAILQ_FOREACH(sg, &GlobalSign.SigGroups, entries) {
if (sg->spri >= (unsigned int)pri) {
rc = sg;
break;
}
}
break;
case 3:
if (f->f_flags & FFLAG_SIGN)
rc = f->f_sg;
else
rc = NULL;
break;
}
DPRINTF((D_CALL|D_SIGN), "sign_get_sg(%d, %p) --> %p\n", pri, f, rc);
return rc;
}
/*
* create and send signature block
*
* uses a sliding window for redundancy
* if force==true then simply send all available hashes, e.g. on shutdown
*
* sliding window checks implicitly assume that new hashes are appended
* to the SG between two calls. if that is not the case (e.g. with repeated
* messages) the queue size will shrink.
* this has no negative consequences except generating more and shorter SBs
* than expected and confusing the operator because two consecutive SBs will
* have same FMNn
*/
unsigned
sign_send_signature_block(struct signature_group_t *sg, bool force)
{
char sd[SIGN_MAX_SD_LENGTH];
size_t sd_len;
size_t sg_num_hashes = 0; /* hashes in SG queue */
size_t hashes_in_sb = 0; /* number of hashes in current SB */
size_t hashes_sent = 0; /* count of hashes sent */
struct string_queue *qentry, *old_qentry;
struct buf_msg *buffer;
struct filed_queue *fq;
size_t i;
if (!sg) return 0;
DPRINTF((D_CALL|D_SIGN), "sign_send_signature_block(%p, %d)\n",
sg, force);
STAILQ_FOREACH(qentry, &sg->hashes, entries)
sg_num_hashes++;
/* only act if a division is full */
if (!sg_num_hashes
|| (!force && (sg_num_hashes % SIGN_HASH_DIVISION_NUM)))
return 0;
/* if no CB sent so far then do now, just before first SB */
if (sg->resendcount == SIGN_RESENDCOUNT_CERTBLOCK)
sign_send_certificate_block(sg);
/* shortly after reboot we have shorter SBs */
hashes_in_sb = MIN(sg_num_hashes, SIGN_HASH_NUM);
DPRINTF(D_SIGN, "sign_send_signature_block(): "
"sg_num_hashes = %zu, hashes_in_sb = %zu, SIGN_HASH_NUM = %d\n",
sg_num_hashes, hashes_in_sb, SIGN_HASH_NUM);
if (sg_num_hashes > SIGN_HASH_NUM) {
DPRINTF(D_SIGN, "sign_send_signature_block(): sg_num_hashes"
" > SIGN_HASH_NUM -- This should not happen!\n");
}
/* now the SD */
qentry = STAILQ_FIRST(&sg->hashes);
sd_len = snprintf(sd, sizeof(sd), "[ssign "
"VER=\"%s\" RSID=\"%" PRIuFAST64 "\" SG=\"%d\" "
"SPRI=\"%d\" GBC=\"%" PRIuFAST64 "\" FMN=\"%" PRIuFAST64 "\" "
"CNT=\"%zu\" HB=\"",
GlobalSign.ver, GlobalSign.rsid, GlobalSign.sg,
sg->spri, GlobalSign.gbc, qentry->key,
hashes_in_sb);
while (hashes_sent < hashes_in_sb) {
assert(qentry);
sd_len += snprintf(sd+sd_len, sizeof(sd)-sd_len, "%s ",
qentry->data);
hashes_sent++;
qentry = STAILQ_NEXT(qentry, entries);
}
/* overwrite last space and close SD */
assert(sd_len < sizeof(sd));
assert(sd[sd_len] == '\0');
assert(sd[sd_len-1] == ' ');
sd[sd_len-1] = '\0';
sd_len = strlcat(sd, "\" SIGN=\"\"]", sizeof(sd));
if (sign_msg_sign(&buffer, sd, sizeof(sd))) {
DPRINTF((D_CALL|D_SIGN), "sign_send_signature_block(): calling"
" fprintlog(), sending %zu out of %zu hashes\n",
MIN(SIGN_MAX_HASH_NUM, sg_num_hashes), sg_num_hashes);
STAILQ_FOREACH(fq, &sg->files, entries) {
int tmpcnt;
tmpcnt = fq->f->f_prevcount;
fprintlog(fq->f, buffer, NULL);
fq->f->f_prevcount = tmpcnt;
}
sign_inc_gbc();
DELREF(buffer);
}
/* always drop the oldest division of hashes */
if (sg_num_hashes >= SIGN_HASH_NUM) {
qentry = STAILQ_FIRST(&sg->hashes);
for (i = 0; i < SIGN_HASH_DIVISION_NUM; i++) {
old_qentry = qentry;
qentry = STAILQ_NEXT(old_qentry, entries);
STAILQ_REMOVE(&sg->hashes, old_qentry,
string_queue, entries);
FREEPTR(old_qentry->data);
FREEPTR(old_qentry);
}
}
return hashes_sent;
}
void
sign_free_hashes(struct signature_group_t *sg)
{
DPRINTF((D_CALL|D_SIGN), "sign_free_hashes(%p)\n", sg);
sign_free_string_queue(&sg->hashes);
}
void
sign_free_string_queue(struct string_queue_head *sqhead)
{
struct string_queue *qentry, *tmp_qentry;
DPRINTF((D_CALL|D_SIGN), "sign_free_string_queue(%p)\n", sqhead);
STAILQ_FOREACH_SAFE(qentry, sqhead, entries, tmp_qentry) {
STAILQ_REMOVE(sqhead, qentry, string_queue, entries);
FREEPTR(qentry->data);
free(qentry);
}
assert(STAILQ_EMPTY(sqhead));
}
/*
* hash one syslog message
*/
bool
sign_msg_hash(char *line, char **hash)
{
unsigned char md_value[EVP_MAX_MD_SIZE];
unsigned char md_b64[EVP_MAX_MD_SIZE*2];
/* TODO: exact expression for b64 length? */
unsigned md_len = 0;
DPRINTF((D_CALL|D_SIGN), "sign_msg_hash('%s')\n", line);
SSL_CHECK_ONE(EVP_DigestInit_ex(GlobalSign.mdctx, GlobalSign.md, NULL));
SSL_CHECK_ONE(EVP_DigestUpdate(GlobalSign.mdctx, line, strlen(line)));
SSL_CHECK_ONE(EVP_DigestFinal_ex(GlobalSign.mdctx, md_value, &md_len));
b64_ntop(md_value, md_len, (char *)md_b64, EVP_MAX_MD_SIZE*2);
*hash = strdup((char *)md_b64);
DPRINTF((D_CALL|D_SIGN), "sign_msg_hash() --> \"%s\"\n", *hash);
return true;
}
/*
* append hash to SG queue
*/
bool
sign_append_hash(char *hash, struct signature_group_t *sg)
{
struct string_queue *qentry;
/* if one SG is shared by several destinations
* prevent duplicate entries */
if ((qentry = STAILQ_LAST(&sg->hashes, string_queue, entries))
&& !strcmp(qentry->data, hash)) {
DPRINTF((D_CALL|D_SIGN), "sign_append_hash('%s', %p): "
"hash already in queue\n", hash, sg);
return false;
}
MALLOC(qentry, sizeof(*qentry));
qentry->key = sign_assign_msg_num(sg);
qentry->data = hash;
STAILQ_INSERT_TAIL(&sg->hashes, qentry, entries);
DPRINTF((D_CALL|D_SIGN), "sign_append_hash('%s', %p): "
"#%" PRIdFAST64 "\n", hash, sg, qentry->key);
return true;
}
/*
* sign one syslog-sign message
*
* requires a ssign or ssigt-cert SD element
* ending with ' SIGN=""]' in sd
* linesize is available memory (= sizeof(sd))
*
* function will calculate signature and return a new buffer
*/
bool
sign_msg_sign(struct buf_msg **bufferptr, char *sd, size_t linesize)
{
char *signature, *line;
size_t linelen, tlsprefixlen, endptr, newlinelen;
struct buf_msg *buffer;
DPRINTF((D_CALL|D_SIGN), "sign_msg_sign()\n");
endptr = strlen(sd);
assert(endptr < linesize);
assert(sd[endptr] == '\0');
assert(sd[endptr-1] == ']');
assert(sd[endptr-2] == '"');
/* set up buffer */
buffer = buf_msg_new(0);
buffer->timestamp = make_timestamp(NULL, !BSDOutputFormat, 0);
buffer->prog = appname;
buffer->pid = include_pid;
buffer->recvhost = buffer->host = LocalFQDN;
buffer->pri = 110;
buffer->flags = IGN_CONS|SIGN_MSG;
buffer->sd = sd;
/* SD ready, now format and sign */
if (!format_buffer(buffer, &line, &linelen, NULL,
&tlsprefixlen, NULL)) {
DPRINTF((D_CALL|D_SIGN), "sign_send_signature_block():"
" format_buffer() failed\n");
buffer->sd = NULL;
DELREF(buffer);
return false;
}
if (!sign_string_sign(line+tlsprefixlen, &signature)) {
DPRINTF((D_CALL|D_SIGN), "sign_send_signature_block():"
" sign_string_sign() failed\n");
buffer->sd = NULL;
DELREF(buffer);
FREEPTR(line);
return false;
}
FREEPTR(line);
sd[endptr-2] = '\0';
newlinelen = strlcat(sd, signature, linesize);
newlinelen = strlcat(sd, "\"]", linesize);
if (newlinelen >= linesize) {
DPRINTF(D_SIGN, "sign_send_signature_block(): "
"buffer too small\n");
buffer->sd = NULL;
DELREF(buffer);
return false;
}
assert(newlinelen < linesize);
assert(sd[newlinelen] == '\0');
assert(sd[newlinelen-1] == ']');
assert(sd[newlinelen-2] == '"');
buffer->sd = strdup(sd);
*bufferptr = buffer;
return true;
}
/*
* sign one string
*/
bool
sign_string_sign(char *line, char **signature)
{
char buf[SIGN_MAX_LENGTH+1];
unsigned char sig_value[SIGN_B64SIGLEN_DSS];
unsigned char sig_b64[SIGN_B64SIGLEN_DSS];
unsigned sig_len = 0;
char *p, *q;
/*
* The signature is calculated over the completely formatted
* syslog-message, including all of the PRI, HEADER, and hashes
* in the hash block, excluding spaces between fields, and also
* excluding the signature field (SD Parameter Name "SIGN", "=",
* and corresponding value).
*
* -- I am not quite sure which spaces are to be removed.
* Only the ones inside the "ssign" element or those between
* header fields as well?
*/
/* removes the string ' SIGN=""' */
for (p = line, q = buf;
*p && (q - buf <= SIGN_MAX_LENGTH);) {
if (strncmp(p, " SIGN=\"\"", 8) == 0)
p += 8;
*q++ = *p++;
}
*q = '\0';
SSL_CHECK_ONE(EVP_SignInit(GlobalSign.sigctx, GlobalSign.sig));
SSL_CHECK_ONE(EVP_SignUpdate(GlobalSign.sigctx, buf, q-buf));
assert(GlobalSign.privkey);
SSL_CHECK_ONE(EVP_SignFinal(GlobalSign.sigctx, sig_value, &sig_len,
GlobalSign.privkey));
b64_ntop(sig_value, sig_len, (char *)sig_b64, sizeof(sig_b64));
*signature = strdup((char *)sig_b64);
DPRINTF((D_CALL|D_SIGN), "sign_string_sign('%s') --> '%s'\n",
buf, *signature);
return *signature != NULL;
}
void
sign_new_reboot_session(void)
{
struct signature_group_t *sg;
DPRINTF((D_CALL|D_SIGN), "sign_new_reboot_session()\n");
/* global counters */
GlobalSign.gbc = 0;
/* might be useful for later analysis:
* rebooted session IDs are sequential,
* normal IDs are almost always not */
GlobalSign.rsid++;
assert(GlobalSign.sg <= 3);
/* reset SGs */
STAILQ_FOREACH(sg, &GlobalSign.SigGroups, entries) {
sg->resendcount = SIGN_RESENDCOUNT_CERTBLOCK;
sg->last_msg_num = 1;
}
}
/* get msg_num, increment counter, check overflow */
uint_fast64_t
sign_assign_msg_num(struct signature_group_t *sg)
{
uint_fast64_t old;
old = sg->last_msg_num++;
if (sg->last_msg_num > SIGN_MAX_COUNT)
sign_new_reboot_session();
return old;
}
/* increment gbc, check overflow */
void
sign_inc_gbc(void)
{
if (++GlobalSign.gbc > SIGN_MAX_COUNT)
sign_new_reboot_session();
}
#endif /* !DISABLE_SIGN */