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/*
* Copyright (C) 2014-2016 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.
*/
#define _XOPEN_SOURCE 500
#include "firejail.h"
#include <ftw.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <syslog.h>
#include <errno.h>
#include <dirent.h>
#include <grp.h>
#include <sys/ioctl.h>
#include <termios.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) {
EUID_ROOT();
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");
}
int mkpath_as_root(const char* path) {
assert(path && *path);
// work on a copy of the path
char *file_path = strdup(path);
if (!file_path)
errExit("strdup");
char* p;
int done = 0;
for (p=strchr(file_path+1, '/'); p; p=strchr(p+1, '/')) {
*p='\0';
if (mkdir(file_path, 0755)==-1) {
if (errno != EEXIST) {
*p='/';
free(file_path);
return -1;
}
}
else {
if (set_perms(file_path, 0, 0, 0755))
errExit("set_perms");
done = 1;
}
*p='/';
}
if (done)
fs_logger2("mkpath", path);
free(file_path);
return 0;
}
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; if destname already exists, return error
int copy_file(const char *srcname, const char *destname, uid_t uid, gid_t gid, mode_t mode) {
assert(srcname);
assert(destname);
// open source
int src = open(srcname, O_RDONLY);
if (src < 0) {
fprintf(stderr, "Warning: cannot open source file %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 destination file %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;
}
}
fflush(0);
if (fchown(dst, uid, gid) == -1)
errExit("fchown");
if (fchmod(dst, mode) == -1)
errExit("fchmod");
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) {
EUID_ASSERT();
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 > rv && *(ptr2 - 1) == ' ')
--ptr2;
*ptr2 = '\0';
// if (arg_debug)
// printf("Processing line #%s#\n", rv);
return rv;
}
char *split_comma(char *str) {
EUID_ASSERT();
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) {
EUID_ASSERT();
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) {
EUID_ASSERT();
*child = 0; // use it to flag a found child
DIR *dir;
EUID_ROOT(); // grsecurity fix
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);
EUID_USER();
return (*child)? 0:1; // 0 = found, 1 = not found
}
void extract_command_name(int index, char **argv) {
EUID_ASSERT();
assert(argv);
assert(argv[index]);
// configure command index
cfg.original_program_index = index;
char *str = strdup(argv[index]);
if (!str)
errExit("strdup");
// if we have a symbolic link, use the real path to extract the name
// if (is_link(argv[index])) {
// char*newname = realpath(argv[index], NULL);
// if (newname) {
// free(str);
// str = newname;
// }
// }
// configure command name
cfg.command_name = 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");
// limit the command to the first '.'
char *ptr2 = tmp;
while (*ptr2 != '.' && *ptr2 != '\0')
ptr2++;
*ptr2 = '\0';
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);
}
if (strcmp(childstr, "arg_noroot=0") == 0)
arg_noroot = 0;
fclose(stream);
}
void notify_other(int fd) {
FILE* stream;
int newfd = dup(fd);
if (newfd == -1)
errExit("dup");
stream = fdopen(newfd, "w");
fprintf(stream, "arg_noroot=%d\n", arg_noroot);
fflush(stream);
fclose(stream);
}
// This function takes a pathname supplied by the user and expands '~' and
// '${HOME}' at the start, to refer to a path relative to the user's home
// directory (supplied).
// The return value is allocated using malloc and must be freed by the caller.
// The function returns NULL if there are any errors.
char *expand_home(const char *path, const char* homedir) {
assert(path);
assert(homedir);
// Replace home macro
char *new_name = NULL;
if (strncmp(path, "${HOME}", 7) == 0) {
if (asprintf(&new_name, "%s%s", homedir, path + 7) == -1)
errExit("asprintf");
return new_name;
}
else if (*path == '~') {
if (asprintf(&new_name, "%s%s", homedir, path + 1) == -1)
errExit("asprintf");
return new_name;
}
char *rv = strdup(path);
if (!rv)
errExit("strdup");
return rv;
}
// Equivalent to the GNU version of basename, which is incompatible with
// the POSIX basename. A few lines of code saves any portability pain.
// https://www.gnu.org/software/libc/manual/html_node/Finding-Tokens-in-a-String.html#index-basename
const char *gnu_basename(const char *path) {
const char *last_slash = strrchr(path, '/');
if (!last_slash)
return path;
return last_slash+1;
}
uid_t pid_get_uid(pid_t pid) {
EUID_ASSERT();
uid_t rv = 0;
// open status file
char *file;
if (asprintf(&file, "/proc/%u/status", pid) == -1) {
perror("asprintf");
exit(1);
}
EUID_ROOT(); // grsecurity fix
FILE *fp = fopen(file, "r");
if (!fp) {
free(file);
fprintf(stderr, "Error: cannot open /proc file\n");
exit(1);
}
// extract uid
static const int PIDS_BUFLEN = 1024;
char buf[PIDS_BUFLEN];
while (fgets(buf, PIDS_BUFLEN - 1, fp)) {
if (strncmp(buf, "Uid:", 4) == 0) {
char *ptr = buf + 5;
while (*ptr != '\0' && (*ptr == ' ' || *ptr == '\t')) {
ptr++;
}
if (*ptr == '\0')
break;
rv = atoi(ptr);
break; // break regardless!
}
}
fclose(fp);
free(file);
EUID_USER(); // grsecurity fix
if (rv == 0) {
fprintf(stderr, "Error: cannot read /proc file\n");
exit(1);
}
return rv;
}
void invalid_filename(const char *fname) {
// EUID_ASSERT();
assert(fname);
const char *ptr = fname;
if (arg_debug_check_filename)
printf("Checking filename %s\n", fname);
if (strncmp(ptr, "${HOME}", 7) == 0)
ptr = fname + 7;
else if (strncmp(ptr, "${PATH}", 7) == 0)
ptr = fname + 7;
else if (strcmp(fname, "${DOWNLOADS}") == 0)
return;
int len = strlen(ptr);
// file globbing ('*') is allowed
if (strcspn(ptr, "\\&!?\"'<>%^(){}[];,") != (size_t)len) {
fprintf(stderr, "Error: \"%s\" is an invalid filename\n", ptr);
exit(1);
}
}
uid_t get_group_id(const char *group) {
// find tty group id
gid_t gid = 0;
struct group *g = getgrnam(group);
if (g)
gid = g->gr_gid;
return gid;
}
static int remove_callback(const char *fpath, const struct stat *sb, int typeflag, struct FTW *ftwbuf) {
(void) sb;
(void) typeflag;
(void) ftwbuf;
int rv = remove(fpath);
if (rv)
perror(fpath);
return rv;
}
int remove_directory(const char *path) {
// FTW_PHYS - do not follow symbolic links
return nftw(path, remove_callback, 64, FTW_DEPTH | FTW_PHYS);
}
void flush_stdin(void) {
if (isatty(STDIN_FILENO)) {
int cnt = 0;
int rv = ioctl(STDIN_FILENO, FIONREAD, &cnt);
if (rv == 0 && cnt) {
if (!arg_quiet)
printf("Warning: removing %d bytes from stdin\n", cnt);
rv = ioctl(STDIN_FILENO, TCFLSH, TCIFLUSH);
(void) rv;
}
}
}
void create_empty_dir_as_root(const char *dir, mode_t mode) {
assert(dir);
mode &= 07777;
struct stat s;
if (stat(dir, &s)) {
if (arg_debug)
printf("Creating empty %s directory\n", dir);
/* coverity[toctou] */
if (mkdir(dir, mode) == -1)
errExit("mkdir");
if (set_perms(dir, 0, 0, mode))
errExit("set_perms");
ASSERT_PERMS(dir, 0, 0, mode);
}
}
void create_empty_file_as_root(const char *fname, mode_t mode) {
assert(fname);
mode &= 07777;
struct stat s;
if (stat(fname, &s)) {
if (arg_debug)
printf("Creating empty %s file\n", fname);
/* coverity[toctou] */
FILE *fp = fopen(fname, "w");
if (!fp)
errExit("fopen");
SET_PERMS_STREAM(fp, 0, 0, S_IRUSR);
fclose(fp);
if (chmod(fname, mode) == -1)
errExit("chmod");
}
}
// return 1 if error
int set_perms(const char *fname, uid_t uid, gid_t gid, mode_t mode) {
assert(fname);
if (chmod(fname, mode) == -1)
return 1;
if (chown(fname, uid, gid) == -1)
return 1;
return 0;
}
void mkdir_attr(const char *fname, mode_t mode, uid_t uid, gid_t gid) {
assert(fname);
mode &= 07777;
#if 0
printf("fname %s, uid %d, gid %d, mode %x - ", fname, uid, gid, (unsigned) mode);
if (S_ISLNK(mode))
printf("l");
else if (S_ISDIR(mode))
printf("d");
else if (S_ISCHR(mode))
printf("c");
else if (S_ISBLK(mode))
printf("b");
else if (S_ISSOCK(mode))
printf("s");
else
printf("-");
printf( (mode & S_IRUSR) ? "r" : "-");
printf( (mode & S_IWUSR) ? "w" : "-");
printf( (mode & S_IXUSR) ? "x" : "-");
printf( (mode & S_IRGRP) ? "r" : "-");
printf( (mode & S_IWGRP) ? "w" : "-");
printf( (mode & S_IXGRP) ? "x" : "-");
printf( (mode & S_IROTH) ? "r" : "-");
printf( (mode & S_IWOTH) ? "w" : "-");
printf( (mode & S_IXOTH) ? "x" : "-");
printf("\n");
#endif
if (mkdir(fname, mode) == -1 ||
chmod(fname, mode) == -1 ||
chown(fname, uid, gid)) {
fprintf(stderr, "Error: failed to create %s directory\n", fname);
errExit("mkdir/chmod");
}
ASSERT_PERMS(fname, uid, gid, mode);
}
char *read_text_file_or_exit(const char *fname) {
assert(fname);
// open file
int fd = open(fname, O_RDONLY);
if (fd == -1) {
fprintf(stderr, "Error: cannot read %s\n", fname);
exit(1);
}
int size = lseek(fd, 0, SEEK_END);
if (size == -1)
goto errexit;
if (lseek(fd, 0 , SEEK_SET) == -1)
goto errexit;
// allocate memory
char *data = malloc(size + 1); // + '\0'
if (data == NULL)
goto errexit;
memset(data, 0, size + 1);
// read file
int rd = 0;
while (rd < size) {
int rv = read(fd, (unsigned char *) data + rd, size - rd);
if (rv == -1) {
goto errexit;
}
rd += rv;
}
// close file
close(fd);
return data;
errexit:
close(fd);
fprintf(stderr, "Error: cannot read %s\n", fname);
exit(1);
}
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