bfdbb8f260
This commit updates all authorship and copyright information to include a standard header that references the AUTHORS and CREDITS file. This standard header was written by the Debian legal team at the request of Franck Joncourt.
392 lines
10 KiB
C
392 lines
10 KiB
C
/*
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*****************************************************************************
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*
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* File: extcmd.c
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*
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* Purpose: Routines for executing and processing external commands.
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*
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* Fwknop is developed primarily by the people listed in the file 'AUTHORS'.
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* Copyright (C) 2009–2014 fwknop developers and contributors. For a full
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* list of contributors, see the file 'CREDITS'.
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*
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* License (GNU General Public License):
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
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* USA
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*
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*****************************************************************************
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*/
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#include "fwknopd_common.h"
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#include "extcmd.h"
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#include "log_msg.h"
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#include "utils.h"
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/*
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <sys/select.h>
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*/
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#include <errno.h>
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#include <signal.h>
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#if HAVE_SYS_WAIT_H
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#include <sys/wait.h>
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#endif
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/*
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static sig_atomic_t got_sigalrm;
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*/
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/* Takes a file descriptor and makes it non-blocking.
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static int
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set_nonblock(int fd)
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{
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int val;
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if((val = fcntl(fd, F_GETFL, 0)) < 0)
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{
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perror("fcntl F_GETFL error:");
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return(-1);
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}
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val |= O_NONBLOCK;
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if(fcntl(fd, F_SETFL, val) < 0)
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{
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perror("fcntl F_SETFL error setting O_NONBLOCK");
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return(-1);
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}
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return(0);
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}
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static void
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alarm_handler(int sig)
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{
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got_sigalrm = 1;
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}
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*/
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/* Run en external command returning exit status, and optionally filling
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* provided buffer with STDOUT output up to the size provided.
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*
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* Note: XXX: We are not using the timeout parameter at present. We still need
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* to implement a reliable timeout mechanism.
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*/
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static int
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_run_extcmd(uid_t user_uid, const char *cmd, char *so_buf, const size_t so_buf_sz, const int timeout)
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{
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FILE *ipt;
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int retval = 0;
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char so_read_buf[IO_READ_BUF_LEN] = {0};
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pid_t pid;
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int res;
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if(so_buf == NULL)
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{
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/* Since we do not have to capture output, we will fork here (which we
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* would have to do anyway if we are running as another user as well).
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*/
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pid = fork();
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if(pid == -1)
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{
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log_msg(LOG_ERR, "run_extcmd: fork failed: %s", strerror(errno));
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return(EXTCMD_FORK_ERROR);
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}
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else if (pid == 0)
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{
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/* We are the child */
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/* If user is not null, then we setuid to that user before running the
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* command.
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*/
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if(user_uid > 0)
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{
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if(setuid(user_uid) < 0)
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{
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exit(EXTCMD_SETUID_ERROR);
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}
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}
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res = system(cmd);
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exit(WEXITSTATUS(res));
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}
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/* Retval is forced to 0 as we don't care about the exit status of
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* the child (for now)>
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*/
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retval = 0;
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}
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else
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{
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/* Looking for output use popen and fill the buffer to its limit.
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*/
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ipt = popen(cmd, "r");
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if(ipt == NULL)
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{
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log_msg(LOG_ERR, "Got popen error %i: %s", errno, strerror(errno));
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retval = -1;
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}
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else
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{
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memset(so_buf, 0x0, so_buf_sz);
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while((fgets(so_read_buf, IO_READ_BUF_LEN, ipt)) != NULL)
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{
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strlcat(so_buf, so_read_buf, so_buf_sz);
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if(strlen(so_buf) >= so_buf_sz-1)
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break;
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}
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pclose(ipt);
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}
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}
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return(retval);
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}
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#if 0 /* --DSS the original method that did not work on some systems */
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/* Create the pipes we will use for getting stdout and stderr
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* from the child process.
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*/
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if(pipe(so) != 0)
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return(EXTCMD_PIPE_ERROR);
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if(pipe(se) != 0)
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return(EXTCMD_PIPE_ERROR);
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/* Fork off a child process to run the command and provide its outputs.
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*/
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pid = fork();
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if(pid == -1)
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{
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return(EXTCMD_FORK_ERROR);
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}
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else if (pid == 0)
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{
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/* We are the child, so we dup stdout and stderr to our respective
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* write-end of the pipes, close stdin and the read-end of the pipes
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* (since we don't need them here). Then use system() to run the
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* command and exit with the exit status of that command so we can
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* grab it from the waitpid call in the parent.
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*/
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close(fileno(stdin));
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dup2(so[1], fileno(stdout));
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dup2(se[1], fileno(stderr));
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close(so[0]);
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close(se[0]);
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/* If user is not null, then we setuid to that user before running the
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* command.
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*/
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if(user_uid > 0)
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{
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if(setuid(user_uid) < 0)
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{
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exit(EXTCMD_SETUID_ERROR);
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}
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}
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/* --DSS XXX: Would it be more efficient to use one of the exec()
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* calls (i.e. 'return(execvp(ext_cmd, &argv[1]));')?
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* For now, we use system() and exit with the external
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* command exit status.
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*/
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exit(WEXITSTATUS(system(cmd)));
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}
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/* Parent from here */
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/* Give the exit status an initial value of -1.
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*/
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*status = -1;
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/* Close the write-end of the pipes (we are only reading).
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*/
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close(so[1]);
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close(se[1]);
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/* Set our pipes to non-blocking
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*/
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set_nonblock(so[0]);
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set_nonblock(se[0]);
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tv.tv_sec = EXTCMD_DEF_TIMEOUT;
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tv.tv_usec = 0;
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/* Initialize and setup our file descriptor sets for select.
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*/
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FD_ZERO(&rfds);
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FD_ZERO(&efds);
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FD_SET(so[0], &rfds);
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FD_SET(se[0], &rfds);
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FD_SET(so[0], &efds);
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FD_SET(se[0], &efds);
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/* Start with fully clear buffers.
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*/
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memset(so_buf, 0x0, so_buf_sz);
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memset(se_buf, 0x0, se_buf_sz);
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/* Read both stdout and stderr piped from the child until we get eof,
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* fill the buffers, or error out.
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*/
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while(so_buf_remaining > 0 || se_buf_remaining > 0)
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{
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selval = select(8, &rfds, NULL, &efds, &tv);
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if(selval == -1)
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{
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/* Select error - so kill the child and bail.
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*/
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kill(pid, SIGTERM);
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retval |= EXTCMD_SELECT_ERROR;
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break;
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}
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if(selval == 0)
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{
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/* Timeout - so kill the child and bail
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*/
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kill(pid, SIGTERM);
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retval |= EXTCMD_EXECUTION_TIMEOUT;
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break;
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}
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/* The stdout pipe...
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*/
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bytes_read = read(so[0], so_read_buf, IO_READ_BUF_LEN);
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if(so_buf_remaining > 0)
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{
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if(bytes_read > 0)
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{
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/* We have data, so process it...
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*/
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if(bytes_read > so_buf_remaining)
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{
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bytes_read = so_buf_remaining;
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retval |= EXTCMD_SUCCESS_PARTIAL_STDOUT;
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}
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memcpy(so_buf, so_read_buf, bytes_read);
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so_buf += bytes_read;
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so_buf_remaining -= bytes_read;
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}
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else if(bytes_read < 0)
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{
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/* Anything other than EAGAIN or EWOULDBLOCK is conisdered
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* error enough to bail. We are done here so we force the
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* buf_remaining value to 0.
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*/
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if(errno != EAGAIN && errno != EWOULDBLOCK)
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{
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retval |= EXTCMD_STDOUT_READ_ERROR;
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so_buf_remaining = 0;
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}
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}
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else
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{
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/* Bytes read was 0 which indicate end of file. So we are
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* done.
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*/
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so_buf_remaining = 0;
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}
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}
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else
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break;
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/* The stderr pipe...
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*/
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bytes_read = read(se[0], se_read_buf, IO_READ_BUF_LEN);
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if(se_buf_remaining > 0)
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{
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if(bytes_read > 0)
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{
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/* We have data, so process it...
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*/
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if(bytes_read > se_buf_remaining)
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{
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bytes_read = se_buf_remaining;
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retval |= EXTCMD_SUCCESS_PARTIAL_STDERR;
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}
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memcpy(se_buf, se_read_buf, bytes_read);
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se_buf += bytes_read;
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se_buf_remaining -= bytes_read;
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}
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else if(bytes_read < 0)
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{
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/* Anything other than EAGAIN or EWOULDBLOCK is conisdered
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* error enough to bail. We are done here so we force the
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* buf_remaining value to 0.
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*/
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if(errno != EAGAIN && errno != EWOULDBLOCK)
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{
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retval |= EXTCMD_STDERR_READ_ERROR;
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se_buf_remaining = 0;
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}
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}
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else
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{
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/* Bytes read was 0 which indicate end of file. So we are
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* done.
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*/
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se_buf_remaining = 0;
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}
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}
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else
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break;
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}
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close(so[0]);
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close(se[0]);
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/* Wait for the external command to finish and capture its exit status.
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*/
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waitpid(pid, status, 0);
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if(*status != 0)
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retval != EXTCMD_EXECUTION_ERROR;
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/* Return the our status of this operation command.
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*/
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return(retval);
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}
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#endif
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/* Run an external command. This is wrapper around _run_extcmd()
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*/
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int
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run_extcmd(const char *cmd, char *so_buf, const size_t so_buf_sz, const int timeout)
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{
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return _run_extcmd(0, cmd, so_buf, so_buf_sz, timeout);
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}
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/* Run an external command as the specified user. This is wrapper around _run_extcmd()
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*/
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int
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run_extcmd_as(uid_t user_uid, const char *cmd, char *so_buf, const size_t so_buf_sz, const int timeout)
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{
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return _run_extcmd(user_uid, cmd, so_buf, so_buf_sz, timeout);
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}
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