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/* libgcry_common.c
* This file hosts functions both being used by the rsyslog runtime as
* well as tools who do not use the runtime (so we can maintain the
* code at a single place).
*
* Copyright 2013 Adiscon GmbH.
*
* This file is part of rsyslog.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
* -or-
* see COPYING.ASL20 in the source distribution
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdio.h>
#include <gcrypt.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include "rsyslog.h" /* we need data typedefs */
#include "libgcry.h"
/* read a key from a key file
* @param[out] key - key buffer, must be freed by caller
* @param[out] keylen - length of buffer
* @returns 0 if OK, something else otherwise (we do not use
* iRet as this is also called from non-rsyslog w/o runtime)
* on error, errno is set and can be queried
* The key length is limited to 64KiB to prevent DoS.
* Note well: key is a blob, not a C string (NUL may be present!)
*/
int
gcryGetKeyFromFile(const char *const fn, char **const key, unsigned *const keylen)
{
struct stat sb;
int r = -1;
const int fd = open(fn, O_RDONLY);
if(fd < 0) goto done;
if(fstat(fd, &sb) == -1) goto done;
if(sb.st_size > 64*1024) {
errno = EMSGSIZE;
goto done;
}
if((*key = malloc(sb.st_size)) == NULL) goto done;
if(read(fd, *key, sb.st_size) != sb.st_size) goto done;
*keylen = sb.st_size;
r = 0;
done:
if(fd >= 0) {
close(fd);
}
return r;
}
/* execute the child process (must be called in child context
* after fork).
*/
static void
execKeyScript(char *cmd, int pipefd[])
{
char *newargv[] = { NULL };
char *newenviron[] = { NULL };
dup2(pipefd[0], STDIN_FILENO);
dup2(pipefd[1], STDOUT_FILENO);
/* finally exec child */
fprintf(stderr, "pre execve: %s\n", cmd);
execve(cmd, newargv, newenviron);
/* switch to?
execlp((char*)program, (char*) program, (char*)arg, NULL);
*/
/* we should never reach this point, but if we do, we terminate */
return;
}
static int
openPipe(char *cmd, int *fd)
{
int pipefd[2];
pid_t cpid;
int r;
if(pipe(pipefd) == -1) {
r = 1; goto done;
}
cpid = fork();
if(cpid == -1) {
r = 1; goto done;
}
if(cpid == 0) {
/* we are the child */
execKeyScript(cmd, pipefd);
exit(1);
}
close(pipefd[1]);
*fd = pipefd[0];
r = 0;
done: return r;
}
/* Read a character from the program's output. */
// TODO: highly unoptimized version, should be used in buffered
// mode
static int
readProgChar(int fd, char *c)
{
int r;
if(read(fd, c, 1) != 1) {
r = 1; goto done;
}
r = 0;
done: return r;
}
/* Read a line from the script. Line is terminated by LF, which
* is NOT put into the buffer.
* buf must be 64KiB
*/
static int
readProgLine(int fd, char *buf)
{
char c;
int r;
unsigned i;
for(i = 0 ; i < 64*1024 ; ++i) {
if((r = readProgChar(fd, &c)) != 0) goto done;
if(c == '\n')
break;
buf[i] = c;
};
if(i >= 64*1024) {
r = 1; goto done;
}
buf[i] = '\0';
r = 0;
done: return r;
}
static int
readProgKey(int fd, char *buf, unsigned keylen)
{
char c;
int r;
unsigned i;
for(i = 0 ; i < keylen ; ++i) {
if((r = readProgChar(fd, &c)) != 0) goto done;
buf[i] = c;
};
r = 0;
done: return r;
}
int
gcryGetKeyFromProg(char *cmd, char **key, unsigned *keylen)
{
int r;
int fd;
char rcvBuf[64*1024];
if((r = openPipe(cmd, &fd)) != 0) goto done;
if((r = readProgLine(fd, rcvBuf)) != 0) goto done;
if(strcmp(rcvBuf, "RSYSLOG-KEY-PROVIDER:0")) {
r = 2; goto done;
}
if((r = readProgLine(fd, rcvBuf)) != 0) goto done;
*keylen = atoi(rcvBuf);
if((*key = malloc(*keylen)) == NULL) {
r = -1; goto done;
}
if((r = readProgKey(fd, *key, *keylen)) != 0) goto done;
done: return r;
}
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