firejail/src/lib/common.c

/*
 * Copyright (C) 2014-2016 netblue30 (netblue30@yahoo.com)
 *
 * This file is part of firejail project
 *
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <sys/syscall.h>
#include <errno.h>
#include <unistd.h>
#include <sys/prctl.h>
#include <signal.h>
#include <dirent.h>
#include <string.h>
#include "../include/common.h"
#define BUFLEN 4096

int join_namespace(pid_t pid, char *type) {
	char *path;
	if (asprintf(&path, "/proc/%u/ns/%s", pid, type) == -1)
		errExit("asprintf");
	
	int fd = open(path, O_RDONLY);
	if (fd < 0) {
		free(path);
		fprintf(stderr, "Error: cannot open /proc/%u/ns/%s.\n", pid, type);
		return -1;
	}

	if (syscall(__NR_setns, fd, 0) < 0) {
		free(path);
		fprintf(stderr, "Error: cannot join namespace %s.\n", type);
		close(fd);
		return -1;
	}

	close(fd);
	free(path);
	return 0;
}

// return 1 if error
// this function requires root access - todo: fix it!
int name2pid(const char *name, pid_t *pid) {
	pid_t parent = getpid();
	
	DIR *dir;
	if (!(dir = opendir("/proc"))) {
		// sleep 2 seconds and try again
		sleep(2);
		if (!(dir = opendir("/proc"))) {
			fprintf(stderr, "Error: cannot open /proc directory\n");
			exit(1);
		}
	}
	
	struct dirent *entry;
	char *end;
	while ((entry = readdir(dir))) {
		pid_t newpid = strtol(entry->d_name, &end, 10);
		if (end == entry->d_name || *end)
			continue;
		if (newpid == parent)
			continue;

		// check if this is a firejail executable
		char *comm = pid_proc_comm(newpid);
		if (comm) {
			// remove \n
			char *ptr = strchr(comm, '\n');
			if (ptr)
				*ptr = '\0';
			if (strcmp(comm, "firejail")) {
				free(comm);
				continue;
			}
			free(comm);
		}
		
		char *cmd = pid_proc_cmdline(newpid);
		if (cmd) {
			// mark the end of the name
			char *ptr = strstr(cmd, "--name=");
			char *start = ptr;
			if (!ptr) {
				free(cmd);
				
				// extract name for /run/mnt/firejail/fslogger file
				char *fname;
				if (asprintf(&fname, "/proc/%d/root/run/firejail/mnt/fslogger", newpid) == -1)
					errExit("asprintf");

				struct stat s;
				if (stat(fname, &s) == 0) {
					FILE *fp = fopen(fname, "r");
					if (fp) {
						char buf[BUFLEN];
						if (fgets(buf, BUFLEN, fp)) {
							if (strncmp(buf, "sandbox name: ", 14) == 0) {
								char *ptr2 = buf + 14;
								if (strncmp(name, ptr2, strlen(name)) == 0) {
									fclose(fp);
									*pid = newpid;
									closedir(dir);
									return 0;
								}
							}
						}
						fclose(fp);
					}
				}	
				
				continue;
			}
			while (*ptr != ' ' && *ptr != '\t' && *ptr != '\0')
				ptr++;
			*ptr = '\0';
			int rv = strcmp(start + 7, name);
			if (rv == 0) {
				free(cmd);
				*pid = newpid;
				closedir(dir);
				return 0;
			}
			free(cmd);
		}
	}
	closedir(dir);
	return 1;
}

char *pid_proc_comm(const pid_t pid) {
	// open /proc/pid/cmdline file
	char *fname;
	int fd;
	if (asprintf(&fname, "/proc/%d//comm", pid) == -1)
		return NULL;
	if ((fd = open(fname, O_RDONLY)) < 0) {
		free(fname);
		return NULL;
	}
	free(fname);

	// read file
	unsigned char buffer[BUFLEN];
	ssize_t len;
	if ((len = read(fd, buffer, sizeof(buffer) - 1)) <= 0) {
		close(fd);
		return NULL;
	}
	buffer[len] = '\0';
	close(fd);

	// return a malloc copy of the command line
	char *rv = strdup((char *) buffer);
	if (strlen(rv) == 0) {
		free(rv);
		return NULL;
	}
	return rv;
}

char *pid_proc_cmdline(const pid_t pid) {
	// open /proc/pid/cmdline file
	char *fname;
	int fd;
	if (asprintf(&fname, "/proc/%d/cmdline", pid) == -1)
		return NULL;
	if ((fd = open(fname, O_RDONLY)) < 0) {
		free(fname);
		return NULL;
	}
	free(fname);

	// read file
	unsigned char buffer[BUFLEN];
	ssize_t len;
	if ((len = read(fd, buffer, sizeof(buffer) - 1)) <= 0) {
		close(fd);
		return NULL;
	}
	buffer[len] = '\0';
	close(fd);

	// clean data
	int i;
	for (i = 0; i < len; i++) {
		if (buffer[i] == '\0')
			buffer[i] = ' ';
//		if (buffer[i] >= 0x80) // execv in progress!!!
//			return NULL;
	}

	// return a malloc copy of the command line
	char *rv = strdup((char *) buffer);
	if (strlen(rv) == 0) {
		free(rv);
		return NULL;
	}
	return rv;
}