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/*
* Copyright (C) 2014, 2015 Firejail Authors
*
* 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.
*/
#include "firejail.h"
#include <sys/stat.h>
#include <fcntl.h>
#include <syslog.h>
#include <errno.h>
#include <dirent.h>
#include <grp.h>
#define MAX_GROUPS 1024
// drop privileges
// - for root group or if nogroups is set, supplementary groups are not configured
void drop_privs(int nogroups) {
gid_t gid = getgid();
// configure supplementary groups
if (gid == 0 || nogroups) {
if (setgroups(0, NULL) < 0)
errExit("setgroups");
if (arg_debug)
printf("Username %s, no supplementary groups\n", cfg.username);
}
else {
assert(cfg.username);
gid_t groups[MAX_GROUPS];
int ngroups = MAX_GROUPS;
int rv = getgrouplist(cfg.username, gid, groups, &ngroups);
if (arg_debug && rv) {
printf("Username %s, groups ", cfg.username);
int i;
for (i = 0; i < ngroups; i++)
printf("%u, ", groups[i]);
printf("\n");
}
if (rv == -1) {
fprintf(stderr, "Warning: cannot extract supplementary group list, dropping them\n");
if (setgroups(0, NULL) < 0)
errExit("setgroups");
}
else {
rv = setgroups(ngroups, groups);
if (rv) {
fprintf(stderr, "Warning: cannot set supplementary group list, dropping them\n");
if (setgroups(0, NULL) < 0)
errExit("setgroups");
}
}
}
// set uid/gid
if (setgid(getgid()) < 0)
errExit("setgid/getgid");
if (setuid(getuid()) < 0)
errExit("setuid/getuid");
}
void logsignal(int s) {
if (!arg_debug)
return;
openlog("firejail", LOG_NDELAY | LOG_PID, LOG_USER);
syslog(LOG_INFO, "Signal %d caught", s);
closelog();
}
void logmsg(const char *msg) {
if (!arg_debug)
return;
openlog("firejail", LOG_NDELAY | LOG_PID, LOG_USER);
syslog(LOG_INFO, "%s\n", msg);
closelog();
}
void logargs(int argc, char **argv) {
if (!arg_debug)
return;
int i;
int len = 0;
// calculate message length
for (i = 0; i < argc; i++)
len += strlen(argv[i]) + 1; // + ' '
// build message
char msg[len + 1];
char *ptr = msg;
for (i = 0; i < argc; i++) {
sprintf(ptr, "%s ", argv[i]);
ptr += strlen(ptr);
}
// log message
logmsg(msg);
}
void logerr(const char *msg) {
if (!arg_debug)
return;
openlog("firejail", LOG_NDELAY | LOG_PID, LOG_USER);
syslog(LOG_ERR, "%s\n", msg);
closelog();
}
// return -1 if error, 0 if no error
int copy_file(const char *srcname, const char *destname) {
assert(srcname);
assert(destname);
// open source
int src = open(srcname, O_RDONLY);
if (src < 0) {
fprintf(stderr, "Warning: cannot open %s, file not copied\n", srcname);
return -1;
}
// open destination
int dst = open(destname, O_CREAT|O_WRONLY|O_TRUNC, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
if (dst < 0) {
fprintf(stderr, "Warning: cannot open %s, file not copied\n", destname);
close(src);
return -1;
}
// copy
ssize_t len;
static const int BUFLEN = 1024;
unsigned char buf[BUFLEN];
while ((len = read(src, buf, BUFLEN)) > 0) {
int done = 0;
while (done != len) {
int rv = write(dst, buf + done, len - done);
if (rv == -1) {
close(src);
close(dst);
return -1;
}
done += rv;
}
}
close(src);
close(dst);
return 0;
}
// return 1 if the file is a directory
int is_dir(const char *fname) {
assert(fname);
if (*fname == '\0')
return 0;
// if fname doesn't end in '/', add one
int rv;
struct stat s;
if (fname[strlen(fname) - 1] == '/')
rv = stat(fname, &s);
else {
char *tmp;
if (asprintf(&tmp, "%s/", fname) == -1) {
fprintf(stderr, "Error: cannot allocate memory, %s:%d\n", __FILE__, __LINE__);
errExit("asprintf");
}
rv = stat(tmp, &s);
free(tmp);
}
if (rv == -1)
return 0;
if (S_ISDIR(s.st_mode))
return 1;
return 0;
}
// return 1 if the file is a link
int is_link(const char *fname) {
assert(fname);
if (*fname == '\0')
return 0;
struct stat s;
if (lstat(fname, &s) == 0) {
if (S_ISLNK(s.st_mode))
return 1;
}
return 0;
}
// remove multiple spaces and return allocated memory
char *line_remove_spaces(const char *buf) {
assert(buf);
if (strlen(buf) == 0)
return NULL;
// allocate memory for the new string
char *rv = malloc(strlen(buf) + 1);
if (rv == NULL)
errExit("malloc");
// remove space at start of line
const char *ptr1 = buf;
while (*ptr1 == ' ' || *ptr1 == '\t')
ptr1++;
// copy data and remove additional spaces
char *ptr2 = rv;
int state = 0;
while (*ptr1 != '\0') {
if (*ptr1 == '\n' || *ptr1 == '\r')
break;
if (state == 0) {
if (*ptr1 != ' ' && *ptr1 != '\t')
*ptr2++ = *ptr1++;
else {
*ptr2++ = ' ';
ptr1++;
state = 1;
}
}
else { // state == 1
while (*ptr1 == ' ' || *ptr1 == '\t')
ptr1++;
state = 0;
}
}
// strip last blank character if any
if (*(ptr2 - 1) == ' ')
--ptr2;
*ptr2 = '\0';
// if (arg_debug)
// printf("Processing line #%s#\n", rv);
return rv;
}
char *split_comma(char *str) {
if (str == NULL || *str == '\0')
return NULL;
char *ptr = strchr(str, ',');
if (!ptr)
return NULL;
*ptr = '\0';
ptr++;
if (*ptr == '\0')
return NULL;
return ptr;
}
int not_unsigned(const char *str) {
int rv = 0;
const char *ptr = str;
while (*ptr != ' ' && *ptr != '\t' && *ptr != '\0') {
if (!isdigit(*ptr)) {
rv = 1;
break;
}
ptr++;
}
return rv;
}
#define BUFLEN 4096
// find the first child for this parent; return 1 if error
int find_child(pid_t parent, pid_t *child) {
*child = 0; // use it to flag a found child
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 (*child == 0 && (entry = readdir(dir))) {
pid_t pid = strtol(entry->d_name, &end, 10);
if (end == entry->d_name || *end)
continue;
if (pid == parent)
continue;
// open stat file
char *file;
if (asprintf(&file, "/proc/%u/status", pid) == -1) {
perror("asprintf");
exit(1);
}
FILE *fp = fopen(file, "r");
if (!fp) {
free(file);
continue;
}
// look for firejail executable name
char buf[BUFLEN];
while (fgets(buf, BUFLEN - 1, fp)) {
if (strncmp(buf, "PPid:", 5) == 0) {
char *ptr = buf + 5;
while (*ptr != '\0' && (*ptr == ' ' || *ptr == '\t')) {
ptr++;
}
if (*ptr == '\0') {
fprintf(stderr, "Error: cannot read /proc file\n");
exit(1);
}
if (parent == atoi(ptr))
*child = pid;
break; // stop reading the file
}
}
fclose(fp);
free(file);
}
closedir(dir);
return (*child)? 0:1; // 0 = found, 1 = not found
}
void extract_command_name(const char *str) {
assert(str);
cfg.command_name = strdup(str);
if (!cfg.command_name)
errExit("strdup");
// restrict the command name to the first word
char *ptr = cfg.command_name;
while (*ptr != ' ' && *ptr != '\t' && *ptr != '\0')
ptr++;
*ptr = '\0';
// remove the path: /usr/bin/firefox becomes firefox
ptr = strrchr(cfg.command_name, '/');
if (ptr) {
ptr++;
if (*ptr == '\0') {
fprintf(stderr, "Error: invalid command name\n");
exit(1);
}
char *tmp = strdup(ptr);
if (!tmp)
errExit("strdup");
free(cfg.command_name);
cfg.command_name = tmp;
}
}
void update_map(char *mapping, char *map_file) {
int fd;
size_t j;
size_t map_len; /* Length of 'mapping' */
/* Replace commas in mapping string with newlines */
map_len = strlen(mapping);
for (j = 0; j < map_len; j++)
if (mapping[j] == ',')
mapping[j] = '\n';
fd = open(map_file, O_RDWR);
if (fd == -1) {
fprintf(stderr, "Error: cannot open %s: %s\n", map_file, strerror(errno));
exit(EXIT_FAILURE);
}
if (write(fd, mapping, map_len) != (ssize_t)map_len) {
fprintf(stderr, "Error: cannot write to %s: %s\n", map_file, strerror(errno));
exit(EXIT_FAILURE);
}
close(fd);
}
void wait_for_other(int fd) {
//****************************
// wait for the parent to be initialized
//****************************
char childstr[BUFLEN + 1];
int newfd = dup(fd);
if (newfd == -1)
errExit("dup");
FILE* stream;
stream = fdopen(newfd, "r");
*childstr = '\0';
if (fgets(childstr, BUFLEN, stream)) {
// remove \n)
char *ptr = childstr;
while(*ptr !='\0' && *ptr != '\n')
ptr++;
if (*ptr == '\0')
errExit("fgets");
*ptr = '\0';
}
else {
fprintf(stderr, "Error: cannot establish communication with the parent, exiting...\n");
exit(1);
}
fclose(stream);
}
void notify_other(int fd) {
FILE* stream;
int newfd = dup(fd);
if (newfd == -1)
errExit("dup");
stream = fdopen(newfd, "w");
fprintf(stream, "%u\n", getpid());
fflush(stream);
fclose(stream);
}
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