125 lines
3.9 KiB
C
125 lines
3.9 KiB
C
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/***************************************************************************
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open_syslog_on_stderr.c - description
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-------------------
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begin : Feb 10 2003
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copyright : (C) 2003,2004,2005 by Noberasco Michele
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e-mail : noberasco.gnu@disi.unige.it
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***************************************************************************/
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/***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (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 *
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* Free Software Foundation, Inc., *
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* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
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* *
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***************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <pthread.h>
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#include <syslog.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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/* this is the thread that will actually read
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* from our redirected stderr, forwarding to syslog
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*/
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void syslog_writer(char *filename)
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{
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FILE *fp = fopen(filename, "r");
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char buf[1024];
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if (!fp)
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{ /* we write this to stdout as stderr is probably compromised at this point */
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printf("wmpower: syslog_writer thread: fatal error: unable to hook to main thread's stderr!\n");
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abort();
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}
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/* inititalize syslog writer */
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openlog("wmpower", 0, LOG_USER);
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/* we remove it so that noone will tamper */
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unlink(filename);
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while (1)
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{
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fflush(NULL);
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while (fgets(buf, 1023, fp))
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syslog(LOG_INFO, "%s", buf);
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sleep(1);
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}
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}
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/*
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* Redirect writes to sterr on syslog...
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* we achieve this by starting a new thread, creating a file
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* that the father will write to, and the child read from,
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* rewriting it to syslog. Also, we unlink() the file as soon
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* as both father and child have it open, so that no other
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* process will be able to tamper with it.
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*/
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void open_syslog_on_stderr(void)
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{
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pthread_t thread;
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char *filename;
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int fd;
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filename = (char*) malloc(19*sizeof(char));
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if (!filename)
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{
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fprintf(stderr, "wmpower: fatal error: failed allocating memory!\n");
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abort();
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}
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strcpy(filename, "/tmp/wmpowerXXXXXX");
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fd = mkstemp(filename);
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if (fd == -1)
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{
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fprintf(stderr, "wmpower: fatal error: could not create temporary file!\n");
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abort();
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}
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/* set file mode to 600 */
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if (chmod(filename, S_IRUSR|S_IWUSR))
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{
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fprintf(stderr, "wmpower: fatal error: cannot chmod() file!\n");
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abort();
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}
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if (!freopen(filename, "w", stderr))
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{
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fprintf(stderr, "wmpower: fatal error: unable to redirect stderr!\n");
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abort();
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}
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/* close the file descriptor as we have no need for it */
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close(fd);
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/* spawn our syslog_writer baby */
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if (pthread_create(&thread, NULL, (void*)(&syslog_writer), filename))
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{
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fprintf(stderr, "wmpower: fatal error: failed to create syslog-writer thread!\n");
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abort();
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}
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}
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