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Systemd/src/shared/seccomp-util.c

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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <errno.h>
#include <fcntl.h>
#include <linux/seccomp.h>
#include <seccomp.h>
#include <stddef.h>
#include <sys/mman.h>
#include <sys/prctl.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include "af-list.h"
#include "alloc-util.h"
#include "env-util.h"
#include "errno-list.h"
#include "macro.h"
#include "nsflags.h"
#include "nulstr-util.h"
#include "process-util.h"
#include "seccomp-util.h"
#include "set.h"
#include "string-util.h"
#include "strv.h"
/* This array will be modified at runtime as seccomp_restrict_archs is called. */
uint32_t seccomp_local_archs[] = {
/* Note: always list the native arch we are compiled as last, so that users can deny-list seccomp(), but our own calls to it still succeed */
#if defined(__x86_64__) && defined(__ILP32__)
SCMP_ARCH_X86,
SCMP_ARCH_X86_64,
SCMP_ARCH_X32, /* native */
#elif defined(__x86_64__) && !defined(__ILP32__)
SCMP_ARCH_X86,
SCMP_ARCH_X32,
SCMP_ARCH_X86_64, /* native */
#elif defined(__i386__)
SCMP_ARCH_X86,
#elif defined(__aarch64__)
SCMP_ARCH_ARM,
SCMP_ARCH_AARCH64, /* native */
#elif defined(__arm__)
SCMP_ARCH_ARM,
#elif defined(__mips__) && __BYTE_ORDER == __BIG_ENDIAN && _MIPS_SIM == _MIPS_SIM_ABI32
SCMP_ARCH_MIPSEL,
SCMP_ARCH_MIPS, /* native */
#elif defined(__mips__) && __BYTE_ORDER == __LITTLE_ENDIAN && _MIPS_SIM == _MIPS_SIM_ABI32
SCMP_ARCH_MIPS,
SCMP_ARCH_MIPSEL, /* native */
#elif defined(__mips__) && __BYTE_ORDER == __BIG_ENDIAN && _MIPS_SIM == _MIPS_SIM_ABI64
SCMP_ARCH_MIPSEL,
SCMP_ARCH_MIPS,
SCMP_ARCH_MIPSEL64N32,
SCMP_ARCH_MIPS64N32,
SCMP_ARCH_MIPSEL64,
SCMP_ARCH_MIPS64, /* native */
#elif defined(__mips__) && __BYTE_ORDER == __LITTLE_ENDIAN && _MIPS_SIM == _MIPS_SIM_ABI64
SCMP_ARCH_MIPS,
SCMP_ARCH_MIPSEL,
SCMP_ARCH_MIPS64N32,
SCMP_ARCH_MIPSEL64N32,
SCMP_ARCH_MIPS64,
SCMP_ARCH_MIPSEL64, /* native */
#elif defined(__mips__) && __BYTE_ORDER == __BIG_ENDIAN && _MIPS_SIM == _MIPS_SIM_NABI32
SCMP_ARCH_MIPSEL,
SCMP_ARCH_MIPS,
SCMP_ARCH_MIPSEL64,
SCMP_ARCH_MIPS64,
SCMP_ARCH_MIPSEL64N32,
SCMP_ARCH_MIPS64N32, /* native */
#elif defined(__mips__) && __BYTE_ORDER == __LITTLE_ENDIAN && _MIPS_SIM == _MIPS_SIM_NABI32
SCMP_ARCH_MIPS,
SCMP_ARCH_MIPSEL,
SCMP_ARCH_MIPS64,
SCMP_ARCH_MIPSEL64,
SCMP_ARCH_MIPS64N32,
SCMP_ARCH_MIPSEL64N32, /* native */
#elif defined(__powerpc64__) && __BYTE_ORDER == __BIG_ENDIAN
SCMP_ARCH_PPC,
SCMP_ARCH_PPC64LE,
SCMP_ARCH_PPC64, /* native */
#elif defined(__powerpc64__) && __BYTE_ORDER == __LITTLE_ENDIAN
SCMP_ARCH_PPC,
SCMP_ARCH_PPC64,
SCMP_ARCH_PPC64LE, /* native */
#elif defined(__powerpc__)
SCMP_ARCH_PPC,
#elif defined(__riscv) && __riscv_xlen == 64 && defined(SCMP_ARCH_RISCV64)
SCMP_ARCH_RISCV64,
#elif defined(__s390x__)
SCMP_ARCH_S390,
SCMP_ARCH_S390X, /* native */
#elif defined(__s390__)
SCMP_ARCH_S390,
#endif
SECCOMP_LOCAL_ARCH_END
};
const char* seccomp_arch_to_string(uint32_t c) {
/* Maintain order used in <seccomp.h>.
*
* Names used here should be the same as those used for ConditionArchitecture=,
* except for "subarchitectures" like x32. */
switch(c) {
case SCMP_ARCH_NATIVE:
return "native";
case SCMP_ARCH_X86:
return "x86";
case SCMP_ARCH_X86_64:
return "x86-64";
case SCMP_ARCH_X32:
return "x32";
case SCMP_ARCH_ARM:
return "arm";
case SCMP_ARCH_AARCH64:
return "arm64";
case SCMP_ARCH_MIPS:
return "mips";
case SCMP_ARCH_MIPS64:
return "mips64";
case SCMP_ARCH_MIPS64N32:
return "mips64-n32";
case SCMP_ARCH_MIPSEL:
return "mips-le";
case SCMP_ARCH_MIPSEL64:
return "mips64-le";
case SCMP_ARCH_MIPSEL64N32:
return "mips64-le-n32";
case SCMP_ARCH_PPC:
return "ppc";
case SCMP_ARCH_PPC64:
return "ppc64";
case SCMP_ARCH_PPC64LE:
return "ppc64-le";
#ifdef SCMP_ARCH_RISCV64
case SCMP_ARCH_RISCV64:
return "riscv64";
#endif
case SCMP_ARCH_S390:
return "s390";
case SCMP_ARCH_S390X:
return "s390x";
default:
return NULL;
}
}
int seccomp_arch_from_string(const char *n, uint32_t *ret) {
if (!n)
return -EINVAL;
assert(ret);
if (streq(n, "native"))
*ret = SCMP_ARCH_NATIVE;
else if (streq(n, "x86"))
*ret = SCMP_ARCH_X86;
else if (streq(n, "x86-64"))
*ret = SCMP_ARCH_X86_64;
else if (streq(n, "x32"))
*ret = SCMP_ARCH_X32;
else if (streq(n, "arm"))
*ret = SCMP_ARCH_ARM;
else if (streq(n, "arm64"))
*ret = SCMP_ARCH_AARCH64;
else if (streq(n, "mips"))
*ret = SCMP_ARCH_MIPS;
else if (streq(n, "mips64"))
*ret = SCMP_ARCH_MIPS64;
else if (streq(n, "mips64-n32"))
*ret = SCMP_ARCH_MIPS64N32;
else if (streq(n, "mips-le"))
*ret = SCMP_ARCH_MIPSEL;
else if (streq(n, "mips64-le"))
*ret = SCMP_ARCH_MIPSEL64;
else if (streq(n, "mips64-le-n32"))
*ret = SCMP_ARCH_MIPSEL64N32;
else if (streq(n, "ppc"))
*ret = SCMP_ARCH_PPC;
else if (streq(n, "ppc64"))
*ret = SCMP_ARCH_PPC64;
else if (streq(n, "ppc64-le"))
*ret = SCMP_ARCH_PPC64LE;
#ifdef SCMP_ARCH_RISCV64
else if (streq(n, "riscv64"))
*ret = SCMP_ARCH_RISCV64;
#endif
else if (streq(n, "s390"))
*ret = SCMP_ARCH_S390;
else if (streq(n, "s390x"))
*ret = SCMP_ARCH_S390X;
else
return -EINVAL;
return 0;
}
int seccomp_init_for_arch(scmp_filter_ctx *ret, uint32_t arch, uint32_t default_action) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
int r;
/* Much like seccomp_init(), but initializes the filter for one specific architecture only, without affecting
* any others. Also, turns off the NNP fiddling. */
seccomp = seccomp_init(default_action);
if (!seccomp)
return -ENOMEM;
if (arch != SCMP_ARCH_NATIVE &&
arch != seccomp_arch_native()) {
r = seccomp_arch_remove(seccomp, seccomp_arch_native());
if (r < 0)
return r;
r = seccomp_arch_add(seccomp, arch);
if (r < 0)
return r;
assert(seccomp_arch_exist(seccomp, arch) >= 0);
assert(seccomp_arch_exist(seccomp, SCMP_ARCH_NATIVE) == -EEXIST);
assert(seccomp_arch_exist(seccomp, seccomp_arch_native()) == -EEXIST);
} else {
assert(seccomp_arch_exist(seccomp, SCMP_ARCH_NATIVE) >= 0);
assert(seccomp_arch_exist(seccomp, seccomp_arch_native()) >= 0);
}
r = seccomp_attr_set(seccomp, SCMP_FLTATR_ACT_BADARCH, SCMP_ACT_ALLOW);
if (r < 0)
return r;
r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0);
if (r < 0)
return r;
#if SCMP_VER_MAJOR >= 3 || (SCMP_VER_MAJOR == 2 && SCMP_VER_MINOR >= 4)
if (getenv_bool("SYSTEMD_LOG_SECCOMP") > 0) {
r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_LOG, 1);
if (r < 0)
log_debug_errno(r, "Failed to enable seccomp event logging: %m");
}
#endif
*ret = TAKE_PTR(seccomp);
return 0;
}
static bool is_basic_seccomp_available(void) {
return prctl(PR_GET_SECCOMP, 0, 0, 0, 0) >= 0;
}
static bool is_seccomp_filter_available(void) {
return prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, NULL, 0, 0) < 0 &&
errno == EFAULT;
}
bool is_seccomp_available(void) {
static int cached_enabled = -1;
if (cached_enabled < 0) {
int b;
b = getenv_bool_secure("SYSTEMD_SECCOMP");
if (b != 0) {
if (b < 0 && b != -ENXIO) /* ENXIO: env var unset */
log_debug_errno(b, "Failed to parse $SYSTEMD_SECCOMP value, ignoring.");
cached_enabled =
is_basic_seccomp_available() &&
is_seccomp_filter_available();
} else
cached_enabled = false;
}
return cached_enabled;
}
const SyscallFilterSet syscall_filter_sets[_SYSCALL_FILTER_SET_MAX] = {
[SYSCALL_FILTER_SET_DEFAULT] = {
.name = "@default",
.help = "System calls that are always permitted",
.value =
"brk\0"
"cacheflush\0"
"clock_getres\0"
"clock_getres_time64\0"
"clock_gettime\0"
"clock_gettime64\0"
"clock_nanosleep\0"
"clock_nanosleep_time64\0"
"execve\0"
"exit\0"
"exit_group\0"
"futex\0"
"futex_time64\0"
"get_robust_list\0"
"get_thread_area\0"
"getegid\0"
"getegid32\0"
"geteuid\0"
"geteuid32\0"
"getgid\0"
"getgid32\0"
"getgroups\0"
"getgroups32\0"
"getpgid\0"
"getpgrp\0"
"getpid\0"
"getppid\0"
"getresgid\0"
"getresgid32\0"
"getresuid\0"
"getresuid32\0"
"getrlimit\0" /* make sure processes can query stack size and such */
"getsid\0"
"gettid\0"
"gettimeofday\0"
"getuid\0"
"getuid32\0"
"membarrier\0"
"mmap\0"
"mmap2\0"
"munmap\0"
"nanosleep\0"
"pause\0"
"prlimit64\0"
"restart_syscall\0"
"rseq\0"
"rt_sigreturn\0"
"sched_yield\0"
"set_robust_list\0"
"set_thread_area\0"
"set_tid_address\0"
"set_tls\0"
"sigreturn\0"
"time\0"
"ugetrlimit\0"
},
[SYSCALL_FILTER_SET_AIO] = {
.name = "@aio",
.help = "Asynchronous IO",
.value =
"io_cancel\0"
"io_destroy\0"
"io_getevents\0"
"io_pgetevents\0"
"io_pgetevents_time64\0"
"io_setup\0"
"io_submit\0"
"io_uring_enter\0"
"io_uring_register\0"
"io_uring_setup\0"
},
[SYSCALL_FILTER_SET_BASIC_IO] = {
.name = "@basic-io",
.help = "Basic IO",
.value =
"_llseek\0"
"close\0"
"close_range\0"
"dup\0"
"dup2\0"
"dup3\0"
"lseek\0"
"pread64\0"
"preadv\0"
"preadv2\0"
"pwrite64\0"
"pwritev\0"
"pwritev2\0"
"read\0"
"readv\0"
"write\0"
"writev\0"
},
[SYSCALL_FILTER_SET_CHOWN] = {
.name = "@chown",
.help = "Change ownership of files and directories",
.value =
"chown\0"
"chown32\0"
"fchown\0"
"fchown32\0"
"fchownat\0"
"lchown\0"
"lchown32\0"
},
[SYSCALL_FILTER_SET_CLOCK] = {
.name = "@clock",
.help = "Change the system time",
.value =
"adjtimex\0"
"clock_adjtime\0"
"clock_adjtime64\0"
"clock_settime\0"
"clock_settime64\0"
"settimeofday\0"
},
[SYSCALL_FILTER_SET_CPU_EMULATION] = {
.name = "@cpu-emulation",
.help = "System calls for CPU emulation functionality",
.value =
"modify_ldt\0"
"subpage_prot\0"
"switch_endian\0"
"vm86\0"
"vm86old\0"
},
[SYSCALL_FILTER_SET_DEBUG] = {
.name = "@debug",
.help = "Debugging, performance monitoring and tracing functionality",
.value =
"lookup_dcookie\0"
"perf_event_open\0"
"pidfd_getfd\0"
"ptrace\0"
"rtas\0"
#if defined __s390__ || defined __s390x__
"s390_runtime_instr\0"
#endif
"sys_debug_setcontext\0"
},
[SYSCALL_FILTER_SET_FILE_SYSTEM] = {
.name = "@file-system",
.help = "File system operations",
.value =
"access\0"
"chdir\0"
"chmod\0"
"close\0"
"creat\0"
"faccessat\0"
"faccessat2\0"
"fallocate\0"
"fchdir\0"
"fchmod\0"
"fchmodat\0"
"fcntl\0"
"fcntl64\0"
"fgetxattr\0"
"flistxattr\0"
"fremovexattr\0"
"fsetxattr\0"
"fstat\0"
"fstat64\0"
"fstatat64\0"
"fstatfs\0"
"fstatfs64\0"
"ftruncate\0"
"ftruncate64\0"
"futimesat\0"
"getcwd\0"
"getdents\0"
"getdents64\0"
"getxattr\0"
"inotify_add_watch\0"
"inotify_init\0"
"inotify_init1\0"
"inotify_rm_watch\0"
"lgetxattr\0"
"link\0"
"linkat\0"
"listxattr\0"
"llistxattr\0"
"lremovexattr\0"
"lsetxattr\0"
"lstat\0"
"lstat64\0"
"mkdir\0"
"mkdirat\0"
"mknod\0"
"mknodat\0"
"newfstatat\0"
"oldfstat\0"
"oldlstat\0"
"oldstat\0"
"open\0"
"openat\0"
"openat2\0"
"readlink\0"
"readlinkat\0"
"removexattr\0"
"rename\0"
"renameat\0"
"renameat2\0"
"rmdir\0"
"setxattr\0"
"stat\0"
"stat64\0"
"statfs\0"
"statfs64\0"
"statx\0"
"symlink\0"
"symlinkat\0"
"truncate\0"
"truncate64\0"
"unlink\0"
"unlinkat\0"
"utime\0"
"utimensat\0"
"utimensat_time64\0"
"utimes\0"
},
[SYSCALL_FILTER_SET_IO_EVENT] = {
.name = "@io-event",
.help = "Event loop system calls",
.value =
"_newselect\0"
"epoll_create\0"
"epoll_create1\0"
"epoll_ctl\0"
"epoll_ctl_old\0"
"epoll_pwait\0"
"epoll_wait\0"
"epoll_wait_old\0"
"eventfd\0"
"eventfd2\0"
"poll\0"
"ppoll\0"
"ppoll_time64\0"
"pselect6\0"
"pselect6_time64\0"
"select\0"
},
[SYSCALL_FILTER_SET_IPC] = {
.name = "@ipc",
.help = "SysV IPC, POSIX Message Queues or other IPC",
.value =
"ipc\0"
"memfd_create\0"
"mq_getsetattr\0"
"mq_notify\0"
"mq_open\0"
"mq_timedreceive\0"
"mq_timedreceive_time64\0"
"mq_timedsend\0"
"mq_timedsend_time64\0"
"mq_unlink\0"
"msgctl\0"
"msgget\0"
"msgrcv\0"
"msgsnd\0"
"pipe\0"
"pipe2\0"
"process_vm_readv\0"
"process_vm_writev\0"
"semctl\0"
"semget\0"
"semop\0"
"semtimedop\0"
"semtimedop_time64\0"
"shmat\0"
"shmctl\0"
"shmdt\0"
"shmget\0"
},
[SYSCALL_FILTER_SET_KEYRING] = {
.name = "@keyring",
.help = "Kernel keyring access",
.value =
"add_key\0"
"keyctl\0"
"request_key\0"
},
[SYSCALL_FILTER_SET_MEMLOCK] = {
.name = "@memlock",
.help = "Memory locking control",
.value =
"mlock\0"
"mlock2\0"
"mlockall\0"
"munlock\0"
"munlockall\0"
},
[SYSCALL_FILTER_SET_MODULE] = {
.name = "@module",
.help = "Loading and unloading of kernel modules",
.value =
"delete_module\0"
"finit_module\0"
"init_module\0"
},
[SYSCALL_FILTER_SET_MOUNT] = {
.name = "@mount",
.help = "Mounting and unmounting of file systems",
.value =
"chroot\0"
"fsconfig\0"
"fsmount\0"
"fsopen\0"
"fspick\0"
"mount\0"
"move_mount\0"
"open_tree\0"
"pivot_root\0"
"umount\0"
"umount2\0"
},
[SYSCALL_FILTER_SET_NETWORK_IO] = {
.name = "@network-io",
.help = "Network or Unix socket IO, should not be needed if not network facing",
.value =
"accept\0"
"accept4\0"
"bind\0"
"connect\0"
"getpeername\0"
"getsockname\0"
"getsockopt\0"
"listen\0"
"recv\0"
"recvfrom\0"
"recvmmsg\0"
"recvmmsg_time64\0"
"recvmsg\0"
"send\0"
"sendmmsg\0"
"sendmsg\0"
"sendto\0"
"setsockopt\0"
"shutdown\0"
"socket\0"
"socketcall\0"
"socketpair\0"
},
[SYSCALL_FILTER_SET_OBSOLETE] = {
/* some unknown even to libseccomp */
.name = "@obsolete",
.help = "Unusual, obsolete or unimplemented system calls",
.value =
"_sysctl\0"
"afs_syscall\0"
"bdflush\0"
"break\0"
"create_module\0"
"ftime\0"
"get_kernel_syms\0"
"getpmsg\0"
"gtty\0"
"idle\0"
"lock\0"
"mpx\0"
"prof\0"
"profil\0"
"putpmsg\0"
"query_module\0"
"security\0"
"sgetmask\0"
"ssetmask\0"
"stime\0"
"stty\0"
"sysfs\0"
"tuxcall\0"
"ulimit\0"
"uselib\0"
"ustat\0"
"vserver\0"
},
[SYSCALL_FILTER_SET_PKEY] = {
.name = "@pkey",
.help = "System calls used for memory protection keys",
.value =
"pkey_alloc\0"
"pkey_free\0"
"pkey_mprotect\0"
},
[SYSCALL_FILTER_SET_PRIVILEGED] = {
.name = "@privileged",
.help = "All system calls which need super-user capabilities",
.value =
"@chown\0"
"@clock\0"
"@module\0"
"@raw-io\0"
"@reboot\0"
"@swap\0"
"_sysctl\0"
"acct\0"
"bpf\0"
"capset\0"
"chroot\0"
"fanotify_init\0"
"fanotify_mark\0"
"nfsservctl\0"
"open_by_handle_at\0"
"pivot_root\0"
"quotactl\0"
"setdomainname\0"
"setfsuid\0"
"setfsuid32\0"
"setgroups\0"
"setgroups32\0"
"sethostname\0"
"setresuid\0"
"setresuid32\0"
"setreuid\0"
"setreuid32\0"
"setuid\0" /* We list the explicit system calls here, as @setuid also includes setgid() which is not necessarily privileged */
"setuid32\0"
"vhangup\0"
},
[SYSCALL_FILTER_SET_PROCESS] = {
.name = "@process",
.help = "Process control, execution, namespacing operations",
.value =
"arch_prctl\0"
"capget\0" /* Able to query arbitrary processes */
"clone\0"
"clone3\0"
"execveat\0"
"fork\0"
"getrusage\0"
"kill\0"
"pidfd_open\0"
"pidfd_send_signal\0"
"prctl\0"
"rt_sigqueueinfo\0"
"rt_tgsigqueueinfo\0"
"setns\0"
"swapcontext\0" /* Some archs e.g. powerpc32 are using it to do userspace context switches */
"tgkill\0"
"times\0"
"tkill\0"
"unshare\0"
"vfork\0"
"wait4\0"
"waitid\0"
"waitpid\0"
},
[SYSCALL_FILTER_SET_RAW_IO] = {
.name = "@raw-io",
.help = "Raw I/O port access",
.value =
"ioperm\0"
"iopl\0"
"pciconfig_iobase\0"
"pciconfig_read\0"
"pciconfig_write\0"
#if defined __s390__ || defined __s390x__
"s390_pci_mmio_read\0"
"s390_pci_mmio_write\0"
#endif
},
[SYSCALL_FILTER_SET_REBOOT] = {
.name = "@reboot",
.help = "Reboot and reboot preparation/kexec",
.value =
"kexec_file_load\0"
"kexec_load\0"
"reboot\0"
},
[SYSCALL_FILTER_SET_RESOURCES] = {
.name = "@resources",
.help = "Alter resource settings",
.value =
"ioprio_set\0"
"mbind\0"
"migrate_pages\0"
"move_pages\0"
"nice\0"
"sched_setaffinity\0"
"sched_setattr\0"
"sched_setparam\0"
"sched_setscheduler\0"
"set_mempolicy\0"
"setpriority\0"
"setrlimit\0"
},
[SYSCALL_FILTER_SET_SETUID] = {
.name = "@setuid",
.help = "Operations for changing user/group credentials",
.value =
"setgid\0"
"setgid32\0"
"setgroups\0"
"setgroups32\0"
"setregid\0"
"setregid32\0"
"setresgid\0"
"setresgid32\0"
"setresuid\0"
"setresuid32\0"
"setreuid\0"
"setreuid32\0"
"setuid\0"
"setuid32\0"
},
[SYSCALL_FILTER_SET_SIGNAL] = {
.name = "@signal",
.help = "Process signal handling",
.value =
"rt_sigaction\0"
"rt_sigpending\0"
"rt_sigprocmask\0"
"rt_sigsuspend\0"
"rt_sigtimedwait\0"
"rt_sigtimedwait_time64\0"
"sigaction\0"
"sigaltstack\0"
"signal\0"
"signalfd\0"
"signalfd4\0"
"sigpending\0"
"sigprocmask\0"
"sigsuspend\0"
},
[SYSCALL_FILTER_SET_SWAP] = {
.name = "@swap",
.help = "Enable/disable swap devices",
.value =
"swapoff\0"
"swapon\0"
},
[SYSCALL_FILTER_SET_SYNC] = {
.name = "@sync",
.help = "Synchronize files and memory to storage",
.value =
"fdatasync\0"
"fsync\0"
"msync\0"
"sync\0"
"sync_file_range\0"
"sync_file_range2\0"
"syncfs\0"
},
[SYSCALL_FILTER_SET_SYSTEM_SERVICE] = {
.name = "@system-service",
.help = "General system service operations",
.value =
"@aio\0"
"@basic-io\0"
"@chown\0"
"@default\0"
"@file-system\0"
"@io-event\0"
"@ipc\0"
"@keyring\0"
"@memlock\0"
"@network-io\0"
"@process\0"
"@resources\0"
"@setuid\0"
"@signal\0"
"@sync\0"
"@timer\0"
"capget\0"
"capset\0"
"copy_file_range\0"
"fadvise64\0"
"fadvise64_64\0"
"flock\0"
"get_mempolicy\0"
"getcpu\0"
"getpriority\0"
"getrandom\0"
"ioctl\0"
"ioprio_get\0"
"kcmp\0"
"madvise\0"
"mprotect\0"
"mremap\0"
"name_to_handle_at\0"
"oldolduname\0"
"olduname\0"
"personality\0"
"readahead\0"
"readdir\0"
"remap_file_pages\0"
"sched_get_priority_max\0"
"sched_get_priority_min\0"
"sched_getaffinity\0"
"sched_getattr\0"
"sched_getparam\0"
"sched_getscheduler\0"
"sched_rr_get_interval\0"
"sched_rr_get_interval_time64\0"
"sched_yield\0"
"sendfile\0"
"sendfile64\0"
"setfsgid\0"
"setfsgid32\0"
"setfsuid\0"
"setfsuid32\0"
"setpgid\0"
"setsid\0"
"splice\0"
"sysinfo\0"
"tee\0"
"umask\0"
"uname\0"
"userfaultfd\0"
"vmsplice\0"
},
[SYSCALL_FILTER_SET_TIMER] = {
.name = "@timer",
.help = "Schedule operations by time",
.value =
"alarm\0"
"getitimer\0"
"setitimer\0"
"timer_create\0"
"timer_delete\0"
"timer_getoverrun\0"
"timer_gettime\0"
"timer_gettime64\0"
"timer_settime\0"
"timer_settime64\0"
"timerfd_create\0"
"timerfd_gettime\0"
"timerfd_gettime64\0"
"timerfd_settime\0"
"timerfd_settime64\0"
"times\0"
},
[SYSCALL_FILTER_SET_KNOWN] = {
.name = "@known",
.help = "All known syscalls declared in the kernel",
.value =
#include "syscall-list.h"
},
};
const SyscallFilterSet *syscall_filter_set_find(const char *name) {
if (isempty(name) || name[0] != '@')
return NULL;
for (unsigned i = 0; i < _SYSCALL_FILTER_SET_MAX; i++)
if (streq(syscall_filter_sets[i].name, name))
return syscall_filter_sets + i;
return NULL;
}
static int add_syscall_filter_set(
scmp_filter_ctx seccomp,
const SyscallFilterSet *set,
uint32_t action,
char **exclude,
bool log_missing,
char ***added);
int seccomp_add_syscall_filter_item(
scmp_filter_ctx *seccomp,
const char *name,
uint32_t action,
char **exclude,
bool log_missing,
char ***added) {
assert(seccomp);
assert(name);
if (strv_contains(exclude, name))
return 0;
/* Any syscalls that are handled are added to the *added strv. The pointer
* must be either NULL or point to a valid pre-initialized possibly-empty strv. */
if (name[0] == '@') {
const SyscallFilterSet *other;
other = syscall_filter_set_find(name);
if (!other)
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
"Filter set %s is not known!",
name);
return add_syscall_filter_set(seccomp, other, action, exclude, log_missing, added);
} else {
int id, r;
id = seccomp_syscall_resolve_name(name);
if (id == __NR_SCMP_ERROR) {
if (log_missing)
log_debug("System call %s is not known, ignoring.", name);
return 0;
}
r = seccomp_rule_add_exact(seccomp, action, id, 0);
if (r < 0) {
/* If the system call is not known on this architecture, then that's fine, let's ignore it */
bool ignore = r == -EDOM;
if (!ignore || log_missing)
log_debug_errno(r, "Failed to add rule for system call %s() / %d%s: %m",
name, id, ignore ? ", ignoring" : "");
if (!ignore)
return r;
}
if (added) {
r = strv_extend(added, name);
if (r < 0)
return r;
}
return 0;
}
}
static int add_syscall_filter_set(
scmp_filter_ctx seccomp,
const SyscallFilterSet *set,
uint32_t action,
char **exclude,
bool log_missing,
char ***added) {
const char *sys;
int r;
/* Any syscalls that are handled are added to the *added strv. It needs to be initialized. */
assert(seccomp);
assert(set);
NULSTR_FOREACH(sys, set->value) {
r = seccomp_add_syscall_filter_item(seccomp, sys, action, exclude, log_missing, added);
if (r < 0)
return r;
}
return 0;
}
int seccomp_load_syscall_filter_set(uint32_t default_action, const SyscallFilterSet *set, uint32_t action, bool log_missing) {
uint32_t arch;
int r;
assert(set);
/* The one-stop solution: allocate a seccomp object, add the specified filter to it, and apply it. Once for
* each local arch. */
SECCOMP_FOREACH_LOCAL_ARCH(arch) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
log_debug("Operating on architecture: %s", seccomp_arch_to_string(arch));
r = seccomp_init_for_arch(&seccomp, arch, default_action);
if (r < 0)
return r;
r = add_syscall_filter_set(seccomp, set, action, NULL, log_missing, NULL);
if (r < 0)
return log_debug_errno(r, "Failed to add filter set: %m");
r = seccomp_load(seccomp);
if (ERRNO_IS_SECCOMP_FATAL(r))
return r;
if (r < 0)
log_debug_errno(r, "Failed to install filter set for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
}
return 0;
}
int seccomp_load_syscall_filter_set_raw(uint32_t default_action, Hashmap* set, uint32_t action, bool log_missing) {
uint32_t arch;
int r;
/* Similar to seccomp_load_syscall_filter_set(), but takes a raw Set* of syscalls, instead of a
* SyscallFilterSet* table. */
if (hashmap_isempty(set) && default_action == SCMP_ACT_ALLOW)
return 0;
SECCOMP_FOREACH_LOCAL_ARCH(arch) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
void *syscall_id, *val;
log_debug("Operating on architecture: %s", seccomp_arch_to_string(arch));
r = seccomp_init_for_arch(&seccomp, arch, default_action);
if (r < 0)
return r;
HASHMAP_FOREACH_KEY(val, syscall_id, set) {
uint32_t a = action;
int id = PTR_TO_INT(syscall_id) - 1;
int error = PTR_TO_INT(val);
if (error == SECCOMP_ERROR_NUMBER_KILL)
a = scmp_act_kill_process();
#ifdef SCMP_ACT_LOG
else if (action == SCMP_ACT_LOG)
a = SCMP_ACT_LOG;
#endif
else if (action != SCMP_ACT_ALLOW && error >= 0)
a = SCMP_ACT_ERRNO(error);
r = seccomp_rule_add_exact(seccomp, a, id, 0);
if (r < 0) {
/* If the system call is not known on this architecture, then that's fine, let's ignore it */
_cleanup_free_ char *n = NULL;
bool ignore;
n = seccomp_syscall_resolve_num_arch(SCMP_ARCH_NATIVE, id);
ignore = r == -EDOM;
if (!ignore || log_missing)
log_debug_errno(r, "Failed to add rule for system call %s() / %d%s: %m",
strna(n), id, ignore ? ", ignoring" : "");
if (!ignore)
return r;
}
}
r = seccomp_load(seccomp);
if (ERRNO_IS_SECCOMP_FATAL(r))
return r;
if (r < 0)
log_debug_errno(r, "Failed to install filter set for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
}
return 0;
}
int seccomp_parse_syscall_filter(
const char *name,
int errno_num,
Hashmap *filter,
SeccompParseFlags flags,
const char *unit,
const char *filename,
unsigned line) {
int r;
assert(name);
assert(filter);
if (name[0] == '@') {
const SyscallFilterSet *set;
const char *i;
set = syscall_filter_set_find(name);
if (!set) {
if (!(flags & SECCOMP_PARSE_PERMISSIVE))
return -EINVAL;
log_syntax(unit, flags & SECCOMP_PARSE_LOG ? LOG_WARNING : LOG_DEBUG, filename, line, 0,
"Unknown system call group, ignoring: %s", name);
return 0;
}
NULSTR_FOREACH(i, set->value) {
/* Call ourselves again, for the group to parse. Note that we downgrade logging here (i.e. take
* away the SECCOMP_PARSE_LOG flag) since any issues in the group table are our own problem,
* not a problem in user configuration data and we shouldn't pretend otherwise by complaining
* about them. */
r = seccomp_parse_syscall_filter(i, errno_num, filter, flags &~ SECCOMP_PARSE_LOG, unit, filename, line);
if (r < 0)
return r;
}
} else {
int id;
id = seccomp_syscall_resolve_name(name);
if (id == __NR_SCMP_ERROR) {
if (!(flags & SECCOMP_PARSE_PERMISSIVE))
return -EINVAL;
log_syntax(unit, flags & SECCOMP_PARSE_LOG ? LOG_WARNING : LOG_DEBUG, filename, line, 0,
"Failed to parse system call, ignoring: %s", name);
return 0;
}
/* If we previously wanted to forbid a syscall and now
* we want to allow it, then remove it from the list. */
if (!(flags & SECCOMP_PARSE_INVERT) == !!(flags & SECCOMP_PARSE_ALLOW_LIST)) {
r = hashmap_put(filter, INT_TO_PTR(id + 1), INT_TO_PTR(errno_num));
if (r < 0)
switch (r) {
case -ENOMEM:
return flags & SECCOMP_PARSE_LOG ? log_oom() : -ENOMEM;
case -EEXIST:
assert_se(hashmap_update(filter, INT_TO_PTR(id + 1), INT_TO_PTR(errno_num)) == 0);
break;
default:
return r;
}
} else
(void) hashmap_remove(filter, INT_TO_PTR(id + 1));
}
return 0;
}
int seccomp_restrict_namespaces(unsigned long retain) {
uint32_t arch;
int r;
if (DEBUG_LOGGING) {
_cleanup_free_ char *s = NULL;
(void) namespace_flags_to_string(retain, &s);
log_debug("Restricting namespace to: %s.", strna(s));
}
/* NOOP? */
if (FLAGS_SET(retain, NAMESPACE_FLAGS_ALL))
return 0;
SECCOMP_FOREACH_LOCAL_ARCH(arch) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
log_debug("Operating on architecture: %s", seccomp_arch_to_string(arch));
r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ALLOW);
if (r < 0)
return r;
if ((retain & NAMESPACE_FLAGS_ALL) == 0)
/* If every single kind of namespace shall be prohibited, then let's block the whole setns() syscall
* altogether. */
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(setns),
0);
else
/* Otherwise, block only the invocations with the appropriate flags in the loop below, but also the
* special invocation with a zero flags argument, right here. */
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(setns),
1,
SCMP_A1(SCMP_CMP_EQ, 0));
if (r < 0) {
log_debug_errno(r, "Failed to add setns() rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
continue;
}
for (unsigned i = 0; namespace_flag_map[i].name; i++) {
unsigned long f;
f = namespace_flag_map[i].flag;
if (FLAGS_SET(retain, f)) {
log_debug("Permitting %s.", namespace_flag_map[i].name);
continue;
}
log_debug("Blocking %s.", namespace_flag_map[i].name);
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(unshare),
1,
SCMP_A0(SCMP_CMP_MASKED_EQ, f, f));
if (r < 0) {
log_debug_errno(r, "Failed to add unshare() rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
break;
}
/* On s390/s390x the first two parameters to clone are switched */
if (!IN_SET(arch, SCMP_ARCH_S390, SCMP_ARCH_S390X))
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(clone),
1,
SCMP_A0(SCMP_CMP_MASKED_EQ, f, f));
else
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(clone),
1,
SCMP_A1(SCMP_CMP_MASKED_EQ, f, f));
if (r < 0) {
log_debug_errno(r, "Failed to add clone() rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
break;
}
if ((retain & NAMESPACE_FLAGS_ALL) != 0) {
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(setns),
1,
SCMP_A1(SCMP_CMP_MASKED_EQ, f, f));
if (r < 0) {
log_debug_errno(r, "Failed to add setns() rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
break;
}
}
}
if (r < 0)
continue;
r = seccomp_load(seccomp);
if (ERRNO_IS_SECCOMP_FATAL(r))
return r;
if (r < 0)
log_debug_errno(r, "Failed to install namespace restriction rules for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
}
return 0;
}
int seccomp_protect_sysctl(void) {
uint32_t arch;
int r;
SECCOMP_FOREACH_LOCAL_ARCH(arch) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
log_debug("Operating on architecture: %s", seccomp_arch_to_string(arch));
if (IN_SET(arch,
SCMP_ARCH_AARCH64,
#ifdef SCMP_ARCH_RISCV64
SCMP_ARCH_RISCV64,
#endif
SCMP_ARCH_X32
))
/* No _sysctl syscall */
continue;
r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ALLOW);
if (r < 0)
return r;
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(_sysctl),
0);
if (r < 0) {
log_debug_errno(r, "Failed to add _sysctl() rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
continue;
}
r = seccomp_load(seccomp);
if (ERRNO_IS_SECCOMP_FATAL(r))
return r;
if (r < 0)
log_debug_errno(r, "Failed to install sysctl protection rules for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
}
return 0;
}
int seccomp_protect_syslog(void) {
uint32_t arch;
int r;
SECCOMP_FOREACH_LOCAL_ARCH(arch) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ALLOW);
if (r < 0)
return r;
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(syslog),
0);
if (r < 0) {
log_debug_errno(r, "Failed to add syslog() rule for architecture %s, skipping %m", seccomp_arch_to_string(arch));
continue;
}
r = seccomp_load(seccomp);
if (ERRNO_IS_SECCOMP_FATAL(r))
return r;
if (r < 0)
log_debug_errno(r, "Failed to install syslog protection rules for architecture %s, skipping %m", seccomp_arch_to_string(arch));
}
return 0;
}
int seccomp_restrict_address_families(Set *address_families, bool allow_list) {
uint32_t arch;
int r;
SECCOMP_FOREACH_LOCAL_ARCH(arch) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
bool supported;
log_debug("Operating on architecture: %s", seccomp_arch_to_string(arch));
switch (arch) {
case SCMP_ARCH_X86_64:
case SCMP_ARCH_X32:
case SCMP_ARCH_ARM:
case SCMP_ARCH_AARCH64:
case SCMP_ARCH_MIPSEL64N32:
case SCMP_ARCH_MIPS64N32:
case SCMP_ARCH_MIPSEL64:
case SCMP_ARCH_MIPS64:
#ifdef SCMP_ARCH_RISCV64
case SCMP_ARCH_RISCV64:
#endif
/* These we know we support (i.e. are the ones that do not use socketcall()) */
supported = true;
break;
case SCMP_ARCH_S390:
case SCMP_ARCH_S390X:
case SCMP_ARCH_X86:
case SCMP_ARCH_MIPSEL:
case SCMP_ARCH_MIPS:
case SCMP_ARCH_PPC:
case SCMP_ARCH_PPC64:
case SCMP_ARCH_PPC64LE:
default:
/* These we either know we don't support (i.e. are the ones that do use socketcall()), or we
* don't know */
supported = false;
break;
}
if (!supported)
continue;
r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ALLOW);
if (r < 0)
return r;
if (allow_list) {
int first = 0, last = 0;
void *afp;
/* If this is an allow list, we first block the address families that are out of
* range and then everything that is not in the set. First, we find the lowest and
* highest address family in the set. */
SET_FOREACH(afp, address_families) {
int af = PTR_TO_INT(afp);
if (af <= 0 || af >= af_max())
continue;
if (first == 0 || af < first)
first = af;
if (last == 0 || af > last)
last = af;
}
assert((first == 0) == (last == 0));
if (first == 0) {
/* No entries in the valid range, block everything */
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EAFNOSUPPORT),
SCMP_SYS(socket),
0);
if (r < 0) {
log_debug_errno(r, "Failed to add socket() rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
continue;
}
} else {
/* Block everything below the first entry */
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EAFNOSUPPORT),
SCMP_SYS(socket),
1,
SCMP_A0(SCMP_CMP_LT, first));
if (r < 0) {
log_debug_errno(r, "Failed to add socket() rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
continue;
}
/* Block everything above the last entry */
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EAFNOSUPPORT),
SCMP_SYS(socket),
1,
SCMP_A0(SCMP_CMP_GT, last));
if (r < 0) {
log_debug_errno(r, "Failed to add socket() rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
continue;
}
/* Block everything between the first and last entry */
for (int af = 1; af < af_max(); af++) {
if (set_contains(address_families, INT_TO_PTR(af)))
continue;
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EAFNOSUPPORT),
SCMP_SYS(socket),
1,
SCMP_A0(SCMP_CMP_EQ, af));
if (r < 0)
break;
}
if (r < 0) {
log_debug_errno(r, "Failed to add socket() rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
continue;
}
}
} else {
void *af;
/* If this is a deny list, then generate one rule for each address family that are
* then combined in OR checks. */
SET_FOREACH(af, address_families) {
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EAFNOSUPPORT),
SCMP_SYS(socket),
1,
SCMP_A0(SCMP_CMP_EQ, PTR_TO_INT(af)));
if (r < 0)
break;
}
if (r < 0) {
log_debug_errno(r, "Failed to add socket() rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
continue;
}
}
r = seccomp_load(seccomp);
if (ERRNO_IS_SECCOMP_FATAL(r))
return r;
if (r < 0)
log_debug_errno(r, "Failed to install socket family rules for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
}
return 0;
}
int seccomp_restrict_realtime(void) {
static const int permitted_policies[] = {
SCHED_OTHER,
SCHED_BATCH,
SCHED_IDLE,
};
int r, max_policy = 0;
uint32_t arch;
unsigned i;
/* Determine the highest policy constant we want to allow */
for (i = 0; i < ELEMENTSOF(permitted_policies); i++)
if (permitted_policies[i] > max_policy)
max_policy = permitted_policies[i];
SECCOMP_FOREACH_LOCAL_ARCH(arch) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
int p;
log_debug("Operating on architecture: %s", seccomp_arch_to_string(arch));
r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ALLOW);
if (r < 0)
return r;
/* Go through all policies with lower values than that, and block them -- unless they appear in the
* allow list. */
for (p = 0; p < max_policy; p++) {
bool good = false;
/* Check if this is in the allow list. */
for (i = 0; i < ELEMENTSOF(permitted_policies); i++)
if (permitted_policies[i] == p) {
good = true;
break;
}
if (good)
continue;
/* Deny this policy */
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(sched_setscheduler),
1,
SCMP_A1(SCMP_CMP_EQ, p));
if (r < 0) {
log_debug_errno(r, "Failed to add scheduler rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
continue;
}
}
/* Deny-list all other policies, i.e. the ones with higher values. Note that all comparisons
* are unsigned here, hence no need no check for < 0 values. */
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(sched_setscheduler),
1,
SCMP_A1(SCMP_CMP_GT, max_policy));
if (r < 0) {
log_debug_errno(r, "Failed to add scheduler rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
continue;
}
r = seccomp_load(seccomp);
if (ERRNO_IS_SECCOMP_FATAL(r))
return r;
if (r < 0)
log_debug_errno(r, "Failed to install realtime protection rules for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
}
return 0;
}
static int add_seccomp_syscall_filter(scmp_filter_ctx seccomp,
uint32_t arch,
int nr,
unsigned arg_cnt,
const struct scmp_arg_cmp arg) {
int r;
r = seccomp_rule_add_exact(seccomp, SCMP_ACT_ERRNO(EPERM), nr, arg_cnt, arg);
if (r < 0) {
_cleanup_free_ char *n = NULL;
n = seccomp_syscall_resolve_num_arch(arch, nr);
log_debug_errno(r, "Failed to add %s() rule for architecture %s, skipping: %m",
strna(n),
seccomp_arch_to_string(arch));
}
return r;
}
/* For known architectures, check that syscalls are indeed defined or not. */
#if defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) || (defined(__riscv) && __riscv_xlen == 64)
assert_cc(SCMP_SYS(shmget) > 0);
assert_cc(SCMP_SYS(shmat) > 0);
assert_cc(SCMP_SYS(shmdt) > 0);
#endif
int seccomp_memory_deny_write_execute(void) {
uint32_t arch;
unsigned loaded = 0;
SECCOMP_FOREACH_LOCAL_ARCH(arch) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
int filter_syscall = 0, block_syscall = 0, shmat_syscall = 0, r;
log_debug("Operating on architecture: %s", seccomp_arch_to_string(arch));
switch (arch) {
/* Note that on some architectures shmat() isn't available, and the call is multiplexed through ipc().
* We ignore that here, which means there's still a way to get writable/executable
* memory, if an IPC key is mapped like this. That's a pity, but no total loss. */
case SCMP_ARCH_X86:
case SCMP_ARCH_S390:
filter_syscall = SCMP_SYS(mmap2);
block_syscall = SCMP_SYS(mmap);
/* shmat multiplexed, see above */
break;
case SCMP_ARCH_PPC:
case SCMP_ARCH_PPC64:
case SCMP_ARCH_PPC64LE:
case SCMP_ARCH_S390X:
filter_syscall = SCMP_SYS(mmap);
/* shmat multiplexed, see above */
break;
case SCMP_ARCH_ARM:
filter_syscall = SCMP_SYS(mmap2); /* arm has only mmap2 */
shmat_syscall = SCMP_SYS(shmat);
break;
case SCMP_ARCH_X86_64:
case SCMP_ARCH_X32:
case SCMP_ARCH_AARCH64:
#ifdef SCMP_ARCH_RISCV64
case SCMP_ARCH_RISCV64:
#endif
filter_syscall = SCMP_SYS(mmap); /* amd64, x32, arm64 and riscv64 have only mmap */
shmat_syscall = SCMP_SYS(shmat);
break;
/* Please add more definitions here, if you port systemd to other architectures! */
#if !defined(__i386__) && !defined(__x86_64__) && !defined(__powerpc__) && !defined(__powerpc64__) && !defined(__arm__) && !defined(__aarch64__) && !defined(__s390__) && !defined(__s390x__) && !(defined(__riscv) && __riscv_xlen == 64)
#warning "Consider adding the right mmap() syscall definitions here!"
#endif
}
/* Can't filter mmap() on this arch, then skip it */
if (filter_syscall == 0)
continue;
r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ALLOW);
if (r < 0)
return r;
r = add_seccomp_syscall_filter(seccomp, arch, filter_syscall,
1,
SCMP_A2(SCMP_CMP_MASKED_EQ, PROT_EXEC|PROT_WRITE, PROT_EXEC|PROT_WRITE));
if (r < 0)
continue;
if (block_syscall != 0) {
r = add_seccomp_syscall_filter(seccomp, arch, block_syscall, 0, (const struct scmp_arg_cmp){} );
if (r < 0)
continue;
}
r = add_seccomp_syscall_filter(seccomp, arch, SCMP_SYS(mprotect),
1,
SCMP_A2(SCMP_CMP_MASKED_EQ, PROT_EXEC, PROT_EXEC));
if (r < 0)
continue;
#ifdef __NR_pkey_mprotect
r = add_seccomp_syscall_filter(seccomp, arch, SCMP_SYS(pkey_mprotect),
1,
SCMP_A2(SCMP_CMP_MASKED_EQ, PROT_EXEC, PROT_EXEC));
if (r < 0)
continue;
#endif
if (shmat_syscall > 0) {
r = add_seccomp_syscall_filter(seccomp, arch, shmat_syscall,
1,
SCMP_A2(SCMP_CMP_MASKED_EQ, SHM_EXEC, SHM_EXEC));
if (r < 0)
continue;
}
r = seccomp_load(seccomp);
if (ERRNO_IS_SECCOMP_FATAL(r))
return r;
if (r < 0)
log_debug_errno(r, "Failed to install MemoryDenyWriteExecute= rule for architecture %s, skipping: %m",
seccomp_arch_to_string(arch));
loaded++;
}
if (loaded == 0)
log_debug("Failed to install any seccomp rules for MemoryDenyWriteExecute=.");
return loaded;
}
int seccomp_restrict_archs(Set *archs) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
int r;
bool blocked_new = false;
/* This installs a filter with no rules, but that restricts the system call architectures to the specified
* list.
*
* There are some qualifications. However the most important use is to stop processes from bypassing
* system call restrictions, in case they used a broader (multiplexing) syscall which is only available
* in a non-native architecture. There are no holes in this use case, at least so far. */
/* Note libseccomp includes our "native" (current) architecture in the filter by default.
* We do not remove it. For example, our callers expect to be able to call execve() afterwards
* to run a program with the restrictions applied. */
seccomp = seccomp_init(SCMP_ACT_ALLOW);
if (!seccomp)
return -ENOMEM;
for (unsigned i = 0; seccomp_local_archs[i] != SECCOMP_LOCAL_ARCH_END; ++i) {
uint32_t arch = seccomp_local_archs[i];
/* That architecture might have already been blocked by a previous call to seccomp_restrict_archs. */
if (arch == SECCOMP_LOCAL_ARCH_BLOCKED)
continue;
bool block = !set_contains(archs, UINT32_TO_PTR(arch + 1));
/* The vdso for x32 assumes that x86-64 syscalls are available. Let's allow them, since x32
* x32 syscalls should basically match x86-64 for everything except the pointer type.
* The important thing is that you can block the old 32-bit x86 syscalls.
* https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=850047 */
if (block && arch == SCMP_ARCH_X86_64 && seccomp_arch_native() == SCMP_ARCH_X32)
block = !set_contains(archs, UINT32_TO_PTR(SCMP_ARCH_X32 + 1));
if (block) {
seccomp_local_archs[i] = SECCOMP_LOCAL_ARCH_BLOCKED;
blocked_new = true;
} else {
r = seccomp_arch_add(seccomp, arch);
if (r < 0 && r != -EEXIST)
return r;
}
}
/* All architectures that will be blocked by the seccomp program were
* already blocked. */
if (!blocked_new)
return 0;
r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0);
if (r < 0)
return r;
r = seccomp_load(seccomp);
if (ERRNO_IS_SECCOMP_FATAL(r))
return r;
if (r < 0)
log_debug_errno(r, "Failed to restrict system call architectures, skipping: %m");
return 0;
}
int parse_syscall_archs(char **l, Set **ret_archs) {
_cleanup_set_free_ Set *archs = NULL;
char **s;
int r;
assert(l);
assert(ret_archs);
STRV_FOREACH(s, l) {
uint32_t a;
r = seccomp_arch_from_string(*s, &a);
if (r < 0)
return -EINVAL;
r = set_ensure_put(&archs, NULL, UINT32_TO_PTR(a + 1));
if (r < 0)
return -ENOMEM;
}
*ret_archs = TAKE_PTR(archs);
return 0;
}
int seccomp_filter_set_add(Hashmap *filter, bool add, const SyscallFilterSet *set) {
const char *i;
int r;
assert(set);
NULSTR_FOREACH(i, set->value) {
if (i[0] == '@') {
const SyscallFilterSet *more;
more = syscall_filter_set_find(i);
if (!more)
return -ENXIO;
r = seccomp_filter_set_add(filter, add, more);
if (r < 0)
return r;
} else {
int id;
id = seccomp_syscall_resolve_name(i);
if (id == __NR_SCMP_ERROR) {
log_debug("Couldn't resolve system call, ignoring: %s", i);
continue;
}
if (add) {
r = hashmap_put(filter, INT_TO_PTR(id + 1), INT_TO_PTR(-1));
if (r < 0)
return r;
} else
(void) hashmap_remove(filter, INT_TO_PTR(id + 1));
}
}
return 0;
}
int seccomp_lock_personality(unsigned long personality) {
uint32_t arch;
int r;
if (personality >= PERSONALITY_INVALID)
return -EINVAL;
SECCOMP_FOREACH_LOCAL_ARCH(arch) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ALLOW);
if (r < 0)
return r;
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(personality),
1,
SCMP_A0(SCMP_CMP_NE, personality));
if (r < 0) {
log_debug_errno(r, "Failed to add scheduler rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
continue;
}
r = seccomp_load(seccomp);
if (ERRNO_IS_SECCOMP_FATAL(r))
return r;
if (r < 0)
log_debug_errno(r, "Failed to enable personality lock for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
}
return 0;
}
int seccomp_protect_hostname(void) {
uint32_t arch;
int r;
SECCOMP_FOREACH_LOCAL_ARCH(arch) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ALLOW);
if (r < 0)
return r;
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(sethostname),
0);
if (r < 0) {
log_debug_errno(r, "Failed to add sethostname() rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
continue;
}
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(setdomainname),
0);
if (r < 0) {
log_debug_errno(r, "Failed to add setdomainname() rule for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
continue;
}
r = seccomp_load(seccomp);
if (ERRNO_IS_SECCOMP_FATAL(r))
return r;
if (r < 0)
log_debug_errno(r, "Failed to apply hostname restrictions for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
}
return 0;
}
static int seccomp_restrict_sxid(scmp_filter_ctx seccomp, mode_t m) {
/* Checks the mode_t parameter of the following system calls:
*
* → chmod() + fchmod() + fchmodat()
* → open() + creat() + openat()
* → mkdir() + mkdirat()
* → mknod() + mknodat()
*
* Returns error if *everything* failed, and 0 otherwise.
*/
int r;
bool any = false;
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(chmod),
1,
SCMP_A1(SCMP_CMP_MASKED_EQ, m, m));
if (r < 0)
log_debug_errno(r, "Failed to add filter for chmod: %m");
else
any = true;
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(fchmod),
1,
SCMP_A1(SCMP_CMP_MASKED_EQ, m, m));
if (r < 0)
log_debug_errno(r, "Failed to add filter for fchmod: %m");
else
any = true;
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(fchmodat),
1,
SCMP_A2(SCMP_CMP_MASKED_EQ, m, m));
if (r < 0)
log_debug_errno(r, "Failed to add filter for fchmodat: %m");
else
any = true;
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(mkdir),
1,
SCMP_A1(SCMP_CMP_MASKED_EQ, m, m));
if (r < 0)
log_debug_errno(r, "Failed to add filter for mkdir: %m");
else
any = true;
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(mkdirat),
1,
SCMP_A2(SCMP_CMP_MASKED_EQ, m, m));
if (r < 0)
log_debug_errno(r, "Failed to add filter for mkdirat: %m");
else
any = true;
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(mknod),
1,
SCMP_A1(SCMP_CMP_MASKED_EQ, m, m));
if (r < 0)
log_debug_errno(r, "Failed to add filter for mknod: %m");
else
any = true;
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(mknodat),
1,
SCMP_A2(SCMP_CMP_MASKED_EQ, m, m));
if (r < 0)
log_debug_errno(r, "Failed to add filter for mknodat: %m");
else
any = true;
#if SCMP_SYS(open) > 0
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(open),
2,
SCMP_A1(SCMP_CMP_MASKED_EQ, O_CREAT, O_CREAT),
SCMP_A2(SCMP_CMP_MASKED_EQ, m, m));
if (r < 0)
log_debug_errno(r, "Failed to add filter for open: %m");
else
any = true;
#endif
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(openat),
2,
SCMP_A2(SCMP_CMP_MASKED_EQ, O_CREAT, O_CREAT),
SCMP_A3(SCMP_CMP_MASKED_EQ, m, m));
if (r < 0)
log_debug_errno(r, "Failed to add filter for openat: %m");
else
any = true;
#if defined(__SNR_openat2)
/* The new openat2() system call can't be filtered sensibly, since it moves the flags parameter into
* an indirect structure. Let's block it entirely for now. That should be a reasonably OK thing to do
* for now, since openat2() is very new and code generally needs fallback logic anyway to be
* compatible with kernels that are not absolutely recent. */
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(openat2),
0);
if (r < 0)
log_debug_errno(r, "Failed to add filter for openat2: %m");
else
any = true;
#endif
r = seccomp_rule_add_exact(
seccomp,
SCMP_ACT_ERRNO(EPERM),
SCMP_SYS(creat),
1,
SCMP_A1(SCMP_CMP_MASKED_EQ, m, m));
if (r < 0)
log_debug_errno(r, "Failed to add filter for creat: %m");
else
any = true;
return any ? 0 : r;
}
int seccomp_restrict_suid_sgid(void) {
uint32_t arch;
int r, k;
SECCOMP_FOREACH_LOCAL_ARCH(arch) {
_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ALLOW);
if (r < 0)
return r;
r = seccomp_restrict_sxid(seccomp, S_ISUID);
if (r < 0)
log_debug_errno(r, "Failed to add suid rule for architecture %s, ignoring: %m", seccomp_arch_to_string(arch));
k = seccomp_restrict_sxid(seccomp, S_ISGID);
if (k < 0)
log_debug_errno(r, "Failed to add sgid rule for architecture %s, ignoring: %m", seccomp_arch_to_string(arch));
if (r < 0 && k < 0)
continue;
r = seccomp_load(seccomp);
if (ERRNO_IS_SECCOMP_FATAL(r))
return r;
if (r < 0)
log_debug_errno(r, "Failed to apply suid/sgid restrictions for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
}
return 0;
}
uint32_t scmp_act_kill_process(void) {
/* Returns SCMP_ACT_KILL_PROCESS if it's supported, and SCMP_ACT_KILL_THREAD otherwise. We never
* actually want to use SCMP_ACT_KILL_THREAD as its semantics are nuts (killing arbitrary threads of
* a program is just a bad idea), but on old kernels/old libseccomp it is all we have, and at least
* for single-threaded apps does the right thing. */
#ifdef SCMP_ACT_KILL_PROCESS
if (seccomp_api_get() >= 3)
return SCMP_ACT_KILL_PROCESS;
#endif
return SCMP_ACT_KILL; /* same as SCMP_ACT_KILL_THREAD */
}
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