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fwknop/server/extcmd.c

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/*
*****************************************************************************
*
* File: extcmd.c
*
* Purpose: Routines for executing and processing external commands.
*
* Fwknop is developed primarily by the people listed in the file 'AUTHORS'.
* Copyright (C) 2009-2014 fwknop developers and contributors. For a full
* list of contributors, see the file 'CREDITS'.
*
* License (GNU General Public License):
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*
*****************************************************************************
*/
#include "fwknopd_common.h"
#include "extcmd.h"
#include "log_msg.h"
#include "utils.h"
#include <errno.h>
#include <signal.h>
#if HAVE_SYS_WAIT_H
#include <sys/wait.h>
#endif
/*
static sig_atomic_t got_sigalrm;
*/
/* Takes a file descriptor and makes it non-blocking.
static int
set_nonblock(int fd)
{
int val;
if((val = fcntl(fd, F_GETFL, 0)) < 0)
{
perror("fcntl F_GETFL error:");
return(-1);
}
val |= O_NONBLOCK;
if(fcntl(fd, F_SETFL, val) < 0)
{
perror("fcntl F_SETFL error setting O_NONBLOCK");
return(-1);
}
return(0);
}
static void
alarm_handler(int sig)
{
got_sigalrm = 1;
}
*/
/* Run an external command returning exit status, and optionally filling
* provided buffer with STDOUT output up to the size provided.
*
* Note: XXX: We are not using the timeout parameter at present. We still need
* to implement a reliable timeout mechanism.
*/
static int
_run_extcmd(uid_t uid, gid_t gid, const char *cmd, char *so_buf,
const size_t so_buf_sz, const int want_stderr, const int timeout,
const char *substr_search, int *pid_status,
const fko_srv_options_t * const opts)
{
char so_read_buf[IO_READ_BUF_LEN] = {0};
pid_t pid=0;
FILE *output;
int retval = EXTCMD_SUCCESS_ALL_OUTPUT;
int line_ctr = 0, found_str = 0;
char *argv_new[MAX_CMDLINE_ARGS]; /* for validation and/or execvpe() */
int argc_new=0;
#if HAVE_EXECVPE
int pipe_fd[2];
#endif
#if AFL_FUZZING
return 0;
#endif
*pid_status = 0;
/* Even without execvpe() we examine the command for basic validity
* in term of number of args
*/
memset(argv_new, 0x0, sizeof(argv_new));
if(strtoargv(cmd, argv_new, &argc_new, opts) != 1)
{
log_msg(LOG_ERR,
"run_extcmd(): Error converting cmd str to argv via strtoargv()");
return EXTCMD_ARGV_ERROR;
}
#if !HAVE_EXECVPE
/* if we are not using execvpe() then free up argv_new unconditionally
* since was used only for validation
*/
free_argv(argv_new, &argc_new);
#endif
#if HAVE_EXECVPE
if(opts->verbose > 1)
log_msg(LOG_INFO, "run_extcmd() (with execvpe()): running CMD: %s", cmd);
if(so_buf != NULL || substr_search != NULL)
{
if(pipe(pipe_fd) < 0)
{
log_msg(LOG_ERR, "run_extcmd(): pipe() failed: %s", strerror(errno));
free_argv(argv_new, &argc_new);
return EXTCMD_PIPE_ERROR;
}
}
pid = fork();
if (pid == 0)
{
if(chdir("/") != 0)
exit(EXTCMD_CHDIR_ERROR);
if(so_buf != NULL || substr_search != NULL)
{
close(pipe_fd[0]);
dup2(pipe_fd[1], STDOUT_FILENO);
if(want_stderr)
dup2(pipe_fd[1], STDERR_FILENO);
else
close(STDERR_FILENO);
}
/* Take care of gid/uid settings before running the command.
*/
if(gid > 0)
if(setgid(gid) < 0)
exit(EXTCMD_SETGID_ERROR);
if(uid > 0)
if(setuid(uid) < 0)
exit(EXTCMD_SETUID_ERROR);
/* don't use env
*/
execvpe(argv_new[0], argv_new, (char * const *)NULL);
}
else if(pid == -1)
{
log_msg(LOG_ERR, "run_extcmd(): fork() failed: %s", strerror(errno));
free_argv(argv_new, &argc_new);
return EXTCMD_FORK_ERROR;
}
/* Only the parent process makes it here
*/
if(so_buf != NULL || substr_search != NULL)
{
close(pipe_fd[1]);
if ((output = fdopen(pipe_fd[0], "r")) != NULL)
{
if(so_buf != NULL)
memset(so_buf, 0x0, so_buf_sz);
while((fgets(so_read_buf, IO_READ_BUF_LEN, output)) != NULL)
{
line_ctr++;
if(so_buf != NULL)
{
strlcat(so_buf, so_read_buf, so_buf_sz);
if(strlen(so_buf) >= so_buf_sz-1)
break;
}
else /* we are looking for a substring */
{
/* Get past comments and empty lines (note: we only look at the
* first character).
*/
if(IS_EMPTY_LINE(so_read_buf[0]))
continue;
if(strstr(so_read_buf, substr_search) != NULL)
{
found_str = 1;
break;
}
}
}
fclose(output);
}
else
{
log_msg(LOG_ERR,
"run_extcmd(): could not fdopen() pipe output file descriptor.");
free_argv(argv_new, &argc_new);
return EXTCMD_OPEN_ERROR;
}
}
free_argv(argv_new, &argc_new);
waitpid(pid, pid_status, 0);
#else
if(opts->verbose > 1)
log_msg(LOG_INFO, "run_extcmd() (without execvpe()): running CMD: %s", cmd);
if(so_buf == NULL && substr_search == NULL)
{
/* Since we do not have to capture output, we will fork here (which we
* * would have to do anyway if we are running as another user as well).
* */
pid = fork();
if(pid == -1)
{
log_msg(LOG_ERR, "run_extcmd: fork failed: %s", strerror(errno));
return(EXTCMD_FORK_ERROR);
}
else if (pid == 0)
{
/* We are the child */
if(chdir("/") != 0)
exit(EXTCMD_CHDIR_ERROR);
/* Take care of gid/uid settings before running the command.
*/
if(gid > 0)
if(setgid(gid) < 0)
exit(EXTCMD_SETGID_ERROR);
if(uid > 0)
if(setuid(uid) < 0)
exit(EXTCMD_SETUID_ERROR);
*pid_status = system(cmd);
exit(*pid_status);
}
/* Retval is forced to 0 as we don't care about the exit status of
* the child (for now)
*/
retval = EXTCMD_SUCCESS_ALL_OUTPUT;
}
else
{
/* Looking for output use popen and fill the buffer to its limit.
*/
output = popen(cmd, "r");
if(output == NULL)
{
log_msg(LOG_ERR, "Got popen error %i: %s", errno, strerror(errno));
retval = EXTCMD_OPEN_ERROR;
}
else
{
if(so_buf != NULL)
memset(so_buf, 0x0, so_buf_sz);
while((fgets(so_read_buf, IO_READ_BUF_LEN, output)) != NULL)
{
line_ctr++;
if(so_buf != NULL)
{
strlcat(so_buf, so_read_buf, so_buf_sz);
if(strlen(so_buf) >= so_buf_sz-1)
break;
}
else /* we are looking for a substring */
{
/* Get past comments and empty lines (note: we only look at the
* first character).
*/
if(IS_EMPTY_LINE(so_read_buf[0]))
continue;
if(strstr(so_read_buf, substr_search) != NULL)
{
found_str = 1;
break;
}
}
}
pclose(output);
}
}
#endif
if(substr_search != NULL)
{
/* The semantics of the return value changes in search mode to the line
* number where the substring match was found, or zero if it wasn't found
*/
if(found_str)
retval = line_ctr;
else
retval = 0;
}
else
{
if(WIFEXITED(*pid_status))
{
/* Even if the child exited with an error condition, if we make it here
* then the child exited normally as far as the OS is concerned (i.e. didn't
* crash or get hit with a signal)
*/
retval = EXTCMD_SUCCESS_ALL_OUTPUT;
}
else
retval = EXTCMD_EXECUTION_ERROR;
}
if(opts->verbose > 1)
log_msg(LOG_INFO,
"run_extcmd(): returning %d, pid_status: %d",
retval, WIFEXITED(*pid_status) ? WEXITSTATUS(*pid_status) : *pid_status);
return(retval);
}
#if 0 /* --DSS the original method that did not work on some systems */
/* Create the pipes we will use for getting stdout and stderr
* from the child process.
*/
if(pipe(so) != 0)
return(EXTCMD_PIPE_ERROR);
if(pipe(se) != 0)
return(EXTCMD_PIPE_ERROR);
/* Fork off a child process to run the command and provide its outputs.
*/
pid = fork();
if(pid == -1)
{
return(EXTCMD_FORK_ERROR);
}
else if (pid == 0)
{
/* We are the child, so we dup stdout and stderr to our respective
* write-end of the pipes, close stdin and the read-end of the pipes
* (since we don't need them here). Then use system() to run the
* command and exit with the exit status of that command so we can
* grab it from the waitpid call in the parent.
*/
close(fileno(stdin));
dup2(so[1], fileno(stdout));
dup2(se[1], fileno(stderr));
close(so[0]);
close(se[0]);
/* If user is not null, then we setuid to that user before running the
* command.
*/
if(uid > 0)
{
if(setuid(uid) < 0)
{
exit(EXTCMD_SETUID_ERROR);
}
}
/* --DSS XXX: Would it be more efficient to use one of the exec()
* calls (i.e. 'return(execvp(ext_cmd, &argv[1]));')?
* For now, we use system() and exit with the external
* command exit status.
*/
exit(WEXITSTATUS(system(cmd)));
}
/* Parent from here */
/* Give the exit status an initial value of -1.
*/
*status = -1;
/* Close the write-end of the pipes (we are only reading).
*/
close(so[1]);
close(se[1]);
/* Set our pipes to non-blocking
*/
set_nonblock(so[0]);
set_nonblock(se[0]);
tv.tv_sec = EXTCMD_DEF_TIMEOUT;
tv.tv_usec = 0;
/* Initialize and setup our file descriptor sets for select.
*/
FD_ZERO(&rfds);
FD_ZERO(&efds);
FD_SET(so[0], &rfds);
FD_SET(se[0], &rfds);
FD_SET(so[0], &efds);
FD_SET(se[0], &efds);
/* Start with fully clear buffers.
*/
memset(so_buf, 0x0, so_buf_sz);
memset(se_buf, 0x0, se_buf_sz);
/* Read both stdout and stderr piped from the child until we get eof,
* fill the buffers, or error out.
*/
while(so_buf_remaining > 0 || se_buf_remaining > 0)
{
selval = select(8, &rfds, NULL, &efds, &tv);
if(selval == -1)
{
/* Select error - so kill the child and bail.
*/
kill(pid, SIGTERM);
retval |= EXTCMD_SELECT_ERROR;
break;
}
if(selval == 0)
{
/* Timeout - so kill the child and bail
*/
kill(pid, SIGTERM);
retval |= EXTCMD_EXECUTION_TIMEOUT;
break;
}
/* The stdout pipe...
*/
bytes_read = read(so[0], so_read_buf, IO_READ_BUF_LEN);
if(so_buf_remaining > 0)
{
if(bytes_read > 0)
{
/* We have data, so process it...
*/
if(bytes_read > so_buf_remaining)
{
bytes_read = so_buf_remaining;
retval |= EXTCMD_SUCCESS_PARTIAL_STDOUT;
}
memcpy(so_buf, so_read_buf, bytes_read);
so_buf += bytes_read;
so_buf_remaining -= bytes_read;
}
else if(bytes_read < 0)
{
/* Anything other than EAGAIN or EWOULDBLOCK is conisdered
* error enough to bail. We are done here so we force the
* buf_remaining value to 0.
*/
if(errno != EAGAIN && errno != EWOULDBLOCK)
{
retval |= EXTCMD_STDOUT_READ_ERROR;
so_buf_remaining = 0;
}
}
else
{
/* Bytes read was 0 which indicate end of file. So we are
* done.
*/
so_buf_remaining = 0;
}
}
else
break;
/* The stderr pipe...
*/
bytes_read = read(se[0], se_read_buf, IO_READ_BUF_LEN);
if(se_buf_remaining > 0)
{
if(bytes_read > 0)
{
/* We have data, so process it...
*/
if(bytes_read > se_buf_remaining)
{
bytes_read = se_buf_remaining;
retval |= EXTCMD_SUCCESS_PARTIAL_STDERR;
}
memcpy(se_buf, se_read_buf, bytes_read);
se_buf += bytes_read;
se_buf_remaining -= bytes_read;
}
else if(bytes_read < 0)
{
/* Anything other than EAGAIN or EWOULDBLOCK is conisdered
* error enough to bail. We are done here so we force the
* buf_remaining value to 0.
*/
if(errno != EAGAIN && errno != EWOULDBLOCK)
{
retval |= EXTCMD_STDERR_READ_ERROR;
se_buf_remaining = 0;
}
}
else
{
/* Bytes read was 0 which indicate end of file. So we are
* done.
*/
se_buf_remaining = 0;
}
}
else
break;
}
close(so[0]);
close(se[0]);
/* Wait for the external command to finish and capture its exit status.
*/
waitpid(pid, status, 0);
if(*status != 0)
retval != EXTCMD_EXECUTION_ERROR;
/* Return the our status of this operation command.
*/
return(retval);
}
#endif
int _run_extcmd_write(const char *cmd, const char *cmd_write, int *pid_status,
const fko_srv_options_t * const opts)
{
int retval = EXTCMD_SUCCESS_ALL_OUTPUT;
char *argv_new[MAX_CMDLINE_ARGS]; /* for validation and/or execvpe() */
int argc_new=0;
#if HAVE_EXECVPE
int pipe_fd[2];
pid_t pid=0;
#else
FILE *fd = NULL;
#endif
#if AFL_FUZZING
return 0;
#endif
*pid_status = 0;
/* Even without execvpe() we examine the command for basic validity
* in term of number of args
*/
memset(argv_new, 0x0, sizeof(argv_new));
if(strtoargv(cmd, argv_new, &argc_new, opts) != 1)
{
log_msg(LOG_ERR,
"run_extcmd_write(): Error converting cmd str to argv via strtoargv()");
return EXTCMD_ARGV_ERROR;
}
#if !HAVE_EXECVPE
/* if we are not using execvpe() then free up argv_new unconditionally
* since was used only for validation
*/
free_argv(argv_new, &argc_new);
#endif
#if HAVE_EXECVPE
if(opts->verbose > 1)
log_msg(LOG_INFO, "run_extcmd_write() (with execvpe()): running CMD: %s | %s",
cmd_write, cmd);
if(pipe(pipe_fd) < 0)
{
log_msg(LOG_ERR, "run_extcmd_write(): pipe() failed: %s", strerror(errno));
free_argv(argv_new, &argc_new);
return EXTCMD_PIPE_ERROR;
}
pid = fork();
if (pid == 0)
{
if(chdir("/") != 0)
exit(EXTCMD_CHDIR_ERROR);
close(pipe_fd[1]);
dup2(pipe_fd[0], STDIN_FILENO);
/* don't use env
*/
execvpe(argv_new[0], argv_new, (char * const *)NULL);
}
else if(pid == -1)
{
log_msg(LOG_ERR, "run_extcmd_write(): fork() failed: %s", strerror(errno));
free_argv(argv_new, &argc_new);
return EXTCMD_FORK_ERROR;
}
close(pipe_fd[0]);
if(write(pipe_fd[1], cmd_write, strlen(cmd_write)) < 0)
retval = EXTCMD_WRITE_ERROR;
close(pipe_fd[1]);
free_argv(argv_new, &argc_new);
waitpid(pid, pid_status, 0);
#else
if(opts->verbose > 1)
log_msg(LOG_INFO, "run_extcmd_write() (without execvpe()): running CMD: %s | %s",
cmd_write, cmd);
if ((fd = popen(cmd, "w")) == NULL)
{
log_msg(LOG_ERR, "Got popen error %i: %s", errno, strerror(errno));
retval = EXTCMD_OPEN_ERROR;
}
else
{
if (fwrite(cmd_write, strlen(cmd_write), 1, fd) != 1)
{
log_msg(LOG_ERR, "Could not write to cmd stdin");
retval = -1;
}
pclose(fd);
}
#endif
return retval;
}
/* _run_extcmd() wrapper, run an external command.
*/
int
run_extcmd(const char *cmd, char *so_buf, const size_t so_buf_sz,
const int want_stderr, const int timeout, int *pid_status,
const fko_srv_options_t * const opts)
{
return _run_extcmd(0, 0, cmd, so_buf, so_buf_sz, want_stderr,
timeout, NULL, pid_status, opts);
}
/* _run_extcmd() wrapper, run an external command as the specified user.
*/
int
run_extcmd_as(uid_t uid, gid_t gid, const char *cmd,char *so_buf,
const size_t so_buf_sz, const int want_stderr, const int timeout,
int *pid_status, const fko_srv_options_t * const opts)
{
return _run_extcmd(uid, gid, cmd, so_buf, so_buf_sz,
want_stderr, timeout, NULL, pid_status, opts);
}
/* _run_extcmd() wrapper, search command output for a substring.
*/
int
search_extcmd(const char *cmd, const int want_stderr, const int timeout,
const char *substr_search, int *pid_status,
const fko_srv_options_t * const opts)
{
return _run_extcmd(0, 0, cmd, NULL, 0, want_stderr, timeout,
substr_search, pid_status, opts);
}
/* _run_extcmd_write() wrapper, run a command which is expecting input via stdin
*/
int run_extcmd_write(const char *cmd, const char *cmd_write, int *pid_status,
const fko_srv_options_t * const opts)
{
return _run_extcmd_write(cmd, cmd_write, pid_status, opts);
}
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