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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.
*/
#ifdef HAVE_SECCOMP
#include "firejail.h"
#include "seccomp.h"
#define SECSIZE 128 // initial filter size
static struct sock_filter *sfilter = NULL;
static int sfilter_alloc_size = 0;
static int sfilter_index = 0;
// debug filter
void filter_debug(void) {
// start filter
struct sock_filter filter[] = {
VALIDATE_ARCHITECTURE,
EXAMINE_SYSCALL
};
// print sizes
printf("SECCOMP Filter:\n");
if (sfilter == NULL) {
printf("SECCOMP filter not allocated\n");
return;
}
if (sfilter_index < 4)
return;
// test the start of the filter
if (memcmp(sfilter, filter, sizeof(filter)) == 0) {
printf(" VALIDATE_ARCHITECTURE\n");
printf(" EXAMINE_SYSCAL\n");
}
// loop trough blacklists
int i = 4;
while (i < sfilter_index) {
// minimal parsing!
unsigned char *ptr = (unsigned char *) &sfilter[i];
int *nr = (int *) (ptr + 4);
if (*ptr == 0x15 && *(ptr +14) == 0xff && *(ptr + 15) == 0x7f ) {
printf(" WHITELIST %d %s\n", *nr, syscall_find_nr(*nr));
i += 2;
}
else if (*ptr == 0x15 && *(ptr +14) == 0 && *(ptr + 15) == 0) {
printf(" BLACKLIST %d %s\n", *nr, syscall_find_nr(*nr));
i += 2;
}
else if (*ptr == 0x15 && *(ptr +14) == 0x5 && *(ptr + 15) == 0) {
int err = *(ptr + 13) << 8 | *(ptr + 12);
printf(" ERRNO %d %s %d %s\n", *nr, syscall_find_nr(*nr), err, errno_find_nr(err));
i += 2;
}
else if (*ptr == 0x06 && *(ptr +6) == 0 && *(ptr + 7) == 0 ) {
printf(" KILL_PROCESS\n");
i++;
}
else if (*ptr == 0x06 && *(ptr +6) == 0xff && *(ptr + 7) == 0x7f ) {
printf(" RETURN_ALLOW\n");
i++;
}
else {
printf(" UNKNOWN ENTRY!!!\n");
i++;
}
}
}
// initialize filter
static void filter_init(void) {
if (sfilter) {
assert(0);
return;
}
// if (arg_debug)
// printf("Initialize seccomp filter\n");
// allocate a filter of SECSIZE
sfilter = malloc(sizeof(struct sock_filter) * SECSIZE);
if (!sfilter)
errExit("malloc");
memset(sfilter, 0, sizeof(struct sock_filter) * SECSIZE);
sfilter_alloc_size = SECSIZE;
// copy the start entries
struct sock_filter filter[] = {
VALIDATE_ARCHITECTURE,
EXAMINE_SYSCALL
};
sfilter_index = sizeof(filter) / sizeof(struct sock_filter);
memcpy(sfilter, filter, sizeof(filter));
}
static void filter_realloc(void) {
assert(sfilter);
assert(sfilter_alloc_size);
assert(sfilter_index);
if (arg_debug)
printf("Allocating more seccomp filter entries\n");
// allocate the new memory
struct sock_filter *old = sfilter;
sfilter = malloc(sizeof(struct sock_filter) * (sfilter_alloc_size + SECSIZE));
if (!sfilter)
errExit("malloc");
memset(sfilter, 0, sizeof(struct sock_filter) * (sfilter_alloc_size + SECSIZE));
// copy old filter
memcpy(sfilter, old, sizeof(struct sock_filter) * sfilter_alloc_size);
sfilter_alloc_size += SECSIZE;
}
static void filter_add_whitelist(int syscall, int arg) {
(void) arg;
assert(sfilter);
assert(sfilter_alloc_size);
assert(sfilter_index);
// if (arg_debug)
// printf("Whitelisting syscall %d %s\n", syscall, syscall_find_nr(syscall));
if ((sfilter_index + 2) > sfilter_alloc_size)
filter_realloc();
struct sock_filter filter[] = {
WHITELIST(syscall)
};
#if 0
{
int i;
unsigned char *ptr = (unsigned char *) &filter[0];
for (i = 0; i < sizeof(filter); i++, ptr++)
printf("%x, ", (*ptr) & 0xff);
printf("\n");
}
#endif
memcpy(&sfilter[sfilter_index], filter, sizeof(filter));
sfilter_index += sizeof(filter) / sizeof(struct sock_filter);
}
static void filter_add_blacklist(int syscall, int arg) {
(void) arg;
assert(sfilter);
assert(sfilter_alloc_size);
assert(sfilter_index);
// if (arg_debug)
// printf("Blacklisting syscall %d %s\n", syscall, syscall_find_nr(syscall));
if ((sfilter_index + 2) > sfilter_alloc_size)
filter_realloc();
struct sock_filter filter[] = {
BLACKLIST(syscall)
};
#if 0
{
int i;
unsigned char *ptr = (unsigned char *) &filter[0];
for (i = 0; i < sizeof(filter); i++, ptr++)
printf("%x, ", (*ptr) & 0xff);
printf("\n");
}
#endif
memcpy(&sfilter[sfilter_index], filter, sizeof(filter));
sfilter_index += sizeof(filter) / sizeof(struct sock_filter);
}
static void filter_add_errno(int syscall, int arg) {
assert(sfilter);
assert(sfilter_alloc_size);
assert(sfilter_index);
// if (arg_debug)
// printf("Errno syscall %d %d %s\n", syscall, arg, syscall_find_nr(syscall));
if ((sfilter_index + 2) > sfilter_alloc_size)
filter_realloc();
struct sock_filter filter[] = {
BLACKLIST_ERRNO(syscall, arg)
};
#if 0
{
int i;
unsigned char *ptr = (unsigned char *) &filter[0];
for (i = 0; i < sizeof(filter); i++, ptr++)
printf("%x, ", (*ptr) & 0xff);
printf("\n");
}
#endif
memcpy(&sfilter[sfilter_index], filter, sizeof(filter));
sfilter_index += sizeof(filter) / sizeof(struct sock_filter);
}
static void filter_end_blacklist(void) {
assert(sfilter);
assert(sfilter_alloc_size);
assert(sfilter_index);
// if (arg_debug)
// printf("Ending syscall filter\n");
if ((sfilter_index + 2) > sfilter_alloc_size)
filter_realloc();
struct sock_filter filter[] = {
RETURN_ALLOW
};
#if 0
{
int i;
unsigned char *ptr = (unsigned char *) &filter[0];
for (i = 0; i < sizeof(filter); i++, ptr++)
printf("%x, ", (*ptr) & 0xff);
printf("\n");
}
#endif
memcpy(&sfilter[sfilter_index], filter, sizeof(filter));
sfilter_index += sizeof(filter) / sizeof(struct sock_filter);
}
static void filter_end_whitelist(void) {
assert(sfilter);
assert(sfilter_alloc_size);
assert(sfilter_index);
if (arg_debug)
printf("Ending syscall filter\n");
if ((sfilter_index + 2) > sfilter_alloc_size)
filter_realloc();
struct sock_filter filter[] = {
KILL_PROCESS
};
#if 0
{
int i;
unsigned char *ptr = (unsigned char *) &filter[0];
for (i = 0; i < sizeof(filter); i++, ptr++)
printf("%x, ", (*ptr) & 0xff);
printf("\n");
}
#endif
memcpy(&sfilter[sfilter_index], filter, sizeof(filter));
sfilter_index += sizeof(filter) / sizeof(struct sock_filter);
}
// save seccomp filter in /tmp/firejail/mnt/seccomp
static void write_seccomp_file(void) {
fs_build_mnt_dir();
assert(sfilter);
int fd = open(RUN_SECCOMP_CFG, O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR);
if (fd == -1)
errExit("open");
if (arg_debug)
printf("Save seccomp filter, size %u bytes\n", (unsigned) (sfilter_index * sizeof(struct sock_filter)));
errno = 0;
ssize_t sz = write(fd, sfilter, sfilter_index * sizeof(struct sock_filter));
if (sz != (ssize_t)(sfilter_index * sizeof(struct sock_filter))) {
fprintf(stderr, "Error: cannot save seccomp filter\n");
exit(1);
}
close(fd);
if (chown(RUN_SECCOMP_CFG, 0, 0) < 0)
errExit("chown");
}
// read seccomp filter from /tmp/firejail/mnt/seccomp
static void read_seccomp_file(const char *fname) {
assert(sfilter == NULL && sfilter_index == 0);
// check file
struct stat s;
if (stat(fname, &s) == -1) {
fprintf(stderr, "Error: seccomp file not found\n");
exit(1);
}
ssize_t sz = s.st_size;
if (sz == 0 || (sz % sizeof(struct sock_filter)) != 0) {
fprintf(stderr, "Error: invalid seccomp file\n");
exit(1);
}
sfilter = malloc(sz);
if (!sfilter)
errExit("malloc");
// read file
/* coverity[toctou] */
int fd = open(fname,O_RDONLY);
if (fd == -1)
errExit("open");
errno = 0;
ssize_t size = read(fd, sfilter, sz);
if (size != sz) {
fprintf(stderr, "Error: invalid seccomp file\n");
exit(1);
}
sfilter_index = sz / sizeof(struct sock_filter);
if (arg_debug)
printf("Read seccomp filter, size %u bytes\n", (unsigned) (sfilter_index * sizeof(struct sock_filter)));
close(fd);
if (arg_debug)
filter_debug();
}
// i386 filter installed on amd64 architectures
void seccomp_filter_32(void) {
// hardcoded syscall values
struct sock_filter filter[] = {
VALIDATE_ARCHITECTURE_32,
EXAMINE_SYSCALL,
BLACKLIST(21), // mount
BLACKLIST(52), // umount2
BLACKLIST(26), // ptrace
BLACKLIST(283), // kexec_load
BLACKLIST(342), // open_by_handle_at
BLACKLIST(128), // init_module
BLACKLIST(350), // finit_module
BLACKLIST(129), // delete_module
BLACKLIST(110), // iopl
BLACKLIST(101), // ioperm
BLACKLIST(87), // swapon
BLACKLIST(115), // swapoff
BLACKLIST(103), // syslog
BLACKLIST(347), // process_vm_readv
BLACKLIST(348), // process_vm_writev
BLACKLIST(135), // sysfs
BLACKLIST(149), // _sysctl
BLACKLIST(124), // adjtimex
BLACKLIST(343), // clock_adjtime
BLACKLIST(253), // lookup_dcookie
BLACKLIST(336), // perf_event_open
BLACKLIST(338), // fanotify_init
BLACKLIST(349), // kcmp
BLACKLIST(286), // add_key
BLACKLIST(287), // request_key
BLACKLIST(288), // keyctl
BLACKLIST(86), // uselib
BLACKLIST(51), // acct
BLACKLIST(123), // modify_ldt
BLACKLIST(217), // pivot_root
BLACKLIST(245), // io_setup
BLACKLIST(246), // io_destroy
BLACKLIST(247), // io_getevents
BLACKLIST(248), // io_submit
BLACKLIST(249), // io_cancel
BLACKLIST(257), // remap_file_pages
BLACKLIST(274), // mbind
BLACKLIST(275), // get_mempolicy
BLACKLIST(276), // set_mempolicy
BLACKLIST(294), // migrate_pages
BLACKLIST(317), // move_pages
BLACKLIST(316), // vmsplice
BLACKLIST(61), // chroot
BLACKLIST(88), // reboot
BLACKLIST(169), // nfsservctl
BLACKLIST(130), // get_kernel_syms
RETURN_ALLOW
};
struct sock_fprog prog = {
.len = (unsigned short)(sizeof(filter) / sizeof(filter[0])),
.filter = filter,
};
if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) || prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
;
}
else if (arg_debug) {
printf("Dual i386/amd64 seccomp filter configured\n");
}
}
// amd64 filter installed on i386 architectures
void seccomp_filter_64(void) {
// hardcoded syscall values
struct sock_filter filter[] = {
VALIDATE_ARCHITECTURE_64,
EXAMINE_SYSCALL,
BLACKLIST(165), // mount
BLACKLIST(166), // umount2
BLACKLIST(101), // ptrace
BLACKLIST(246), // kexec_load
BLACKLIST(304), // open_by_handle_at
BLACKLIST(175), // init_module
BLACKLIST(313), // finit_module
BLACKLIST(176), // delete_module
BLACKLIST(172), // iopl
BLACKLIST(173), // ioperm
BLACKLIST(167), // swapon
BLACKLIST(168), // swapoff
BLACKLIST(103), // syslog
BLACKLIST(310), // process_vm_readv
BLACKLIST(311), // process_vm_writev
BLACKLIST(139), // sysfs
BLACKLIST(156), // _sysctl
BLACKLIST(159), // adjtimex
BLACKLIST(305), // clock_adjtime
BLACKLIST(212), // lookup_dcookie
BLACKLIST(298), // perf_event_open
BLACKLIST(300), // fanotify_init
BLACKLIST(312), // kcmp
BLACKLIST(248), // add_key
BLACKLIST(249), // request_key
BLACKLIST(250), // keyctl
BLACKLIST(134), // uselib
BLACKLIST(163), // acct
BLACKLIST(154), // modify_ldt
BLACKLIST(155), // pivot_root
BLACKLIST(206), // io_setup
BLACKLIST(207), // io_destroy
BLACKLIST(208), // io_getevents
BLACKLIST(209), // io_submit
BLACKLIST(210), // io_cancel
BLACKLIST(216), // remap_file_pages
BLACKLIST(237), // mbind
BLACKLIST(239), // get_mempolicy
BLACKLIST(238), // set_mempolicy
BLACKLIST(256), // migrate_pages
BLACKLIST(279), // move_pages
BLACKLIST(278), // vmsplice
BLACKLIST(161), // chroot
BLACKLIST(184), // tuxcall
BLACKLIST(169), // reboot
BLACKLIST(180), // nfsservctl
BLACKLIST(177), // get_kernel_syms
RETURN_ALLOW
};
struct sock_fprog prog = {
.len = (unsigned short)(sizeof(filter) / sizeof(filter[0])),
.filter = filter,
};
if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) || prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
;
}
else if (arg_debug) {
printf("Dual i386/amd64 seccomp filter configured\n");
}
}
// drop filter for seccomp option
int seccomp_filter_drop(int enforce_seccomp) {
filter_init();
// default seccomp
if (cfg.seccomp_list_drop == NULL) {
#if defined(__x86_64__)
seccomp_filter_32();
#endif
#if defined(__i386__)
seccomp_filter_64();
#endif
#ifdef SYS_mount
filter_add_blacklist(SYS_mount, 0);
#endif
#ifdef SYS_umount2
filter_add_blacklist(SYS_umount2, 0);
#endif
#ifdef SYS_ptrace
filter_add_blacklist(SYS_ptrace, 0);
#endif
#ifdef SYS_kexec_load
filter_add_blacklist(SYS_kexec_load, 0);
#endif
#ifdef SYS_kexec_file_load
filter_add_blacklist(SYS_kexec_file_load, 0);
#endif
#ifdef SYS_open_by_handle_at
filter_add_blacklist(SYS_open_by_handle_at, 0);
#endif
#ifdef SYS_init_module
filter_add_blacklist(SYS_init_module, 0);
#endif
#ifdef SYS_finit_module // introduced in 2013
filter_add_blacklist(SYS_finit_module, 0);
#endif
#ifdef SYS_delete_module
filter_add_blacklist(SYS_delete_module, 0);
#endif
#ifdef SYS_iopl
filter_add_blacklist(SYS_iopl, 0);
#endif
#ifdef SYS_ioperm
filter_add_blacklist(SYS_ioperm, 0);
#endif
#ifdef SYS_ni_syscall // new io permissions call on arm devices
filter_add_blacklist(SYS_ni_syscall, 0);
#endif
#ifdef SYS_swapon
filter_add_blacklist(SYS_swapon, 0);
#endif
#ifdef SYS_swapoff
filter_add_blacklist(SYS_swapoff, 0);
#endif
#ifdef SYS_syslog
filter_add_blacklist(SYS_syslog, 0);
#endif
#ifdef SYS_process_vm_readv
filter_add_blacklist(SYS_process_vm_readv, 0);
#endif
#ifdef SYS_process_vm_writev
filter_add_blacklist(SYS_process_vm_writev, 0);
#endif
// mknod removed in 0.9.29 - it brakes Zotero extension
//#ifdef SYS_mknod
// filter_add_blacklist(SYS_mknod, 0);
//#endif
// new syscalls in 0.9,23
#ifdef SYS_sysfs
filter_add_blacklist(SYS_sysfs, 0);
#endif
#ifdef SYS__sysctl
filter_add_blacklist(SYS__sysctl, 0);
#endif
#ifdef SYS_adjtimex
filter_add_blacklist(SYS_adjtimex, 0);
#endif
#ifdef SYS_clock_adjtime
filter_add_blacklist(SYS_clock_adjtime, 0);
#endif
#ifdef SYS_lookup_dcookie
filter_add_blacklist(SYS_lookup_dcookie, 0);
#endif
#ifdef SYS_perf_event_open
filter_add_blacklist(SYS_perf_event_open, 0);
#endif
#ifdef SYS_fanotify_init
filter_add_blacklist(SYS_fanotify_init, 0);
#endif
#ifdef SYS_kcmp
filter_add_blacklist(SYS_kcmp, 0);
#endif
// 0.9.32
#ifdef SYS_add_key
filter_add_blacklist(SYS_add_key, 0);
#endif
#ifdef SYS_request_key
filter_add_blacklist(SYS_request_key, 0);
#endif
#ifdef SYS_keyctl
filter_add_blacklist(SYS_keyctl, 0);
#endif
#ifdef SYS_uselib
filter_add_blacklist(SYS_uselib, 0);
#endif
#ifdef SYS_acct
filter_add_blacklist(SYS_acct, 0);
#endif
#ifdef SYS_modify_ldt
filter_add_blacklist(SYS_modify_ldt, 0);
#endif
//#ifdef SYS_unshare
// filter_add_blacklist(SYS_unshare, 0);
//#endif
#ifdef SYS_pivot_root
filter_add_blacklist(SYS_pivot_root, 0);
#endif
//#ifdef SYS_quotactl
// filter_add_blacklist(SYS_quotactl, 0);
//#endif
#ifdef SYS_io_setup
filter_add_blacklist(SYS_io_setup, 0);
#endif
#ifdef SYS_io_destroy
filter_add_blacklist(SYS_io_destroy, 0);
#endif
#ifdef SYS_io_getevents
filter_add_blacklist(SYS_io_getevents, 0);
#endif
#ifdef SYS_io_submit
filter_add_blacklist(SYS_io_submit, 0);
#endif
#ifdef SYS_io_cancel
filter_add_blacklist(SYS_io_cancel, 0);
#endif
#ifdef SYS_remap_file_pages
filter_add_blacklist(SYS_remap_file_pages, 0);
#endif
#ifdef SYS_mbind
filter_add_blacklist(SYS_mbind, 0);
#endif
#ifdef SYS_get_mempolicy
filter_add_blacklist(SYS_get_mempolicy, 0);
#endif
#ifdef SYS_set_mempolicy
filter_add_blacklist(SYS_set_mempolicy, 0);
#endif
#ifdef SYS_migrate_pages
filter_add_blacklist(SYS_migrate_pages, 0);
#endif
#ifdef SYS_move_pages
filter_add_blacklist(SYS_move_pages, 0);
#endif
#ifdef SYS_vmsplice
filter_add_blacklist(SYS_vmsplice, 0);
#endif
#ifdef SYS_chroot
filter_add_blacklist(SYS_chroot, 0);
#endif
//#ifdef SYS_set_robust_list
// filter_add_blacklist(SYS_set_robust_list, 0);
//#endif
//#ifdef SYS_get_robust_list
// filter_add_blacklist(SYS_get_robust_list, 0);
//#endif
// CHECK_SECCOMP(seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EPERM), SCMP_SYS(clone), 1,
// SCMP_A0(SCMP_CMP_MASKED_EQ, CLONE_NEWUSER, CLONE_NEWUSER)));
// 0.9.39
#ifdef SYS_tuxcall
filter_add_blacklist(SYS_tuxcall, 0);
#endif
#ifdef SYS_reboot
filter_add_blacklist(SYS_reboot, 0);
#endif
#ifdef SYS_nfsservctl
filter_add_blacklist(SYS_nfsservctl, 0);
#endif
#ifdef SYS_get_kernel_syms
filter_add_blacklist(SYS_get_kernel_syms, 0);
#endif
}
// default seccomp filter with additional drop list
if (cfg.seccomp_list && cfg.seccomp_list_drop == NULL) {
if (syscall_check_list(cfg.seccomp_list, filter_add_blacklist, 0)) {
fprintf(stderr, "Error: cannot load seccomp filter\n");
exit(1);
}
}
// drop list
else if (cfg.seccomp_list == NULL && cfg.seccomp_list_drop) {
if (syscall_check_list(cfg.seccomp_list_drop, filter_add_blacklist, 0)) {
fprintf(stderr, "Error: cannot load seccomp filter\n");
exit(1);
}
}
filter_end_blacklist();
if (arg_debug)
filter_debug();
// save seccomp filter in /tmp/firejail/mnt/seccomp
// in order to use it in --join operations
write_seccomp_file();
struct sock_fprog prog = {
.len = sfilter_index,
.filter = sfilter,
};
if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) || prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
if (enforce_seccomp) {
fprintf(stderr, "Error: a seccomp-enabled Linux kernel is required, exiting...\n");
exit(1);
}
else
fprintf(stderr, "Warning: seccomp disabled, it requires a Linux kernel version 3.5 or newer.\n");
return 1;
}
return 0;
}
// keep filter for seccomp option
int seccomp_filter_keep(void) {
filter_init();
// these 4 syscalls are used by firejail after the seccomp filter is initialized
filter_add_whitelist(SYS_setuid, 0);
filter_add_whitelist(SYS_setgid, 0);
filter_add_whitelist(SYS_setgroups, 0);
filter_add_whitelist(SYS_dup, 0);
// apply keep list
if (cfg.seccomp_list_keep) {
if (syscall_check_list(cfg.seccomp_list_keep, filter_add_whitelist, 0)) {
fprintf(stderr, "Error: cannot load seccomp filter\n");
exit(1);
}
}
filter_end_whitelist();
if (arg_debug)
filter_debug();
// save seccomp filter in /tmp/firejail/mnt/seccomp
// in order to use it in --join operations
write_seccomp_file();
struct sock_fprog prog = {
.len = sfilter_index,
.filter = sfilter,
};
if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) || prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
fprintf(stderr, "Warning: seccomp disabled, it requires a Linux kernel version 3.5 or newer.\n");
return 1;
}
else if (arg_debug) {
printf("seccomp enabled\n");
}
return 0;
}
// errno filter for seccomp option
int seccomp_filter_errno(void) {
int i;
int higest_errno = errno_highest_nr();
filter_init();
// apply errno list
for (i = 0; i < higest_errno; i++) {
if (cfg.seccomp_list_errno[i]) {
if (syscall_check_list(cfg.seccomp_list_errno[i], filter_add_errno, i)) {
fprintf(stderr, "Error: cannot load seccomp filter\n");
exit(1);
}
}
}
filter_end_blacklist();
if (arg_debug)
filter_debug();
// save seccomp filter in /tmp/firejail/mnt/seccomp
// in order to use it in --join operations
write_seccomp_file();
struct sock_fprog prog = {
.len = sfilter_index,
.filter = sfilter,
};
if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) || prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
fprintf(stderr, "Warning: seccomp disabled, it requires a Linux kernel version 3.5 or newer.\n");
return 1;
}
else if (arg_debug) {
printf("seccomp enabled\n");
}
return 0;
}
void seccomp_set(void) {
// read seccomp filter from /tmp/firejail/mnt/seccomp
read_seccomp_file(RUN_SECCOMP_CFG);
// apply filter
struct sock_fprog prog = {
.len = sfilter_index,
.filter = sfilter,
};
if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) || prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
fprintf(stderr, "Warning: seccomp disabled, it requires a Linux kernel version 3.5 or newer.\n");
return;
}
else if (arg_debug) {
printf("seccomp enabled\n");
}
}
void seccomp_print_filter_name(const char *name) {
EUID_ASSERT();
if (!name || strlen(name) == 0) {
fprintf(stderr, "Error: invalid sandbox name\n");
exit(1);
}
pid_t pid;
if (name2pid(name, &pid)) {
fprintf(stderr, "Error: cannot find sandbox %s\n", name);
exit(1);
}
seccomp_print_filter(pid);
}
void seccomp_print_filter(pid_t pid) {
EUID_ASSERT();
// if the pid is that of a firejail process, use the pid of the first child process
char *comm = pid_proc_comm(pid);
if (comm) {
// remove \n
char *ptr = strchr(comm, '\n');
if (ptr)
*ptr = '\0';
if (strcmp(comm, "firejail") == 0) {
pid_t child;
if (find_child(pid, &child) == 0) {
pid = child;
}
}
free(comm);
}
// check privileges for non-root users
uid_t uid = getuid();
if (uid != 0) {
uid_t sandbox_uid = pid_get_uid(pid);
if (uid != sandbox_uid) {
fprintf(stderr, "Error: permission denied.\n");
exit(1);
}
}
// find the seccomp filter
EUID_ROOT();
char *fname;
if (asprintf(&fname, "/proc/%d/root%s", pid, RUN_SECCOMP_CFG) == -1)
errExit("asprintf");
struct stat s;
if (stat(fname, &s) == -1) {
printf("Cannot access seccomp filter.\n");
exit(1);
}
// read and print the filter
read_seccomp_file(fname);
drop_privs(1);
filter_debug();
free(fname);
exit(0);
}
#endif // HAVE_SECCOMP
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