| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #include <errno.h> |
| #include <linux/netlink.h> |
| #include <sys/capability.h> |
| #include <sys/socket.h> |
| #include <sys/types.h> |
| |
| #if HAVE_SECCOMP |
| #include <seccomp.h> |
| #endif |
| |
| #include "alloc-util.h" |
| #include "log.h" |
| #include "nspawn-seccomp.h" |
| #if HAVE_SECCOMP |
| #include "seccomp-util.h" |
| #endif |
| #include "string-util.h" |
| #include "strv.h" |
| |
| #if HAVE_SECCOMP |
| |
| static int add_syscall_filters( |
| scmp_filter_ctx ctx, |
| uint32_t arch, |
| uint64_t cap_list_retain, |
| char **syscall_allow_list, |
| char **syscall_deny_list) { |
| |
| static const struct { |
| uint64_t capability; |
| const char* name; |
| } allow_list[] = { |
| /* Let's use set names where we can */ |
| { 0, "@aio" }, |
| { 0, "@basic-io" }, |
| { 0, "@chown" }, |
| { 0, "@default" }, |
| { 0, "@file-system" }, |
| { 0, "@io-event" }, |
| { 0, "@ipc" }, |
| { 0, "@mount" }, |
| { 0, "@network-io" }, |
| { 0, "@process" }, |
| { 0, "@resources" }, |
| { 0, "@setuid" }, |
| { 0, "@signal" }, |
| { 0, "@sync" }, |
| { 0, "@timer" }, |
| |
| /* The following four are sets we optionally enable, n case the caps have been configured for it */ |
| { CAP_SYS_TIME, "@clock" }, |
| { CAP_SYS_MODULE, "@module" }, |
| { CAP_SYS_RAWIO, "@raw-io" }, |
| { CAP_IPC_LOCK, "@memlock" }, |
| |
| /* Plus a good set of additional syscalls which are not part of any of the groups above */ |
| { 0, "brk" }, |
| { 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, "mincore" }, |
| { 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, "seccomp" }, |
| { 0, "sendfile" }, |
| { 0, "sendfile64" }, |
| { 0, "setdomainname" }, |
| { 0, "setfsgid" }, |
| { 0, "setfsgid32" }, |
| { 0, "setfsuid" }, |
| { 0, "setfsuid32" }, |
| { 0, "sethostname" }, |
| { 0, "setpgid" }, |
| { 0, "setsid" }, |
| { 0, "splice" }, |
| { 0, "sysinfo" }, |
| { 0, "tee" }, |
| { 0, "umask" }, |
| { 0, "uname" }, |
| { 0, "userfaultfd" }, |
| { 0, "vmsplice" }, |
| |
| /* The following individual syscalls are added depending on specified caps */ |
| { CAP_SYS_PACCT, "acct" }, |
| { CAP_SYS_PTRACE, "process_vm_readv" }, |
| { CAP_SYS_PTRACE, "process_vm_writev" }, |
| { CAP_SYS_PTRACE, "ptrace" }, |
| { CAP_SYS_BOOT, "reboot" }, |
| { CAP_SYSLOG, "syslog" }, |
| { CAP_SYS_TTY_CONFIG, "vhangup" }, |
| |
| /* |
| * The following syscalls and groups are knowingly excluded: |
| * |
| * @cpu-emulation |
| * @keyring (NB: keyring is not namespaced!) |
| * @obsolete |
| * @pkey |
| * @swap |
| * |
| * bpf |
| * fanotify_init |
| * fanotify_mark |
| * kexec_file_load |
| * kexec_load |
| * lookup_dcookie |
| * nfsservctl |
| * open_by_handle_at |
| * perf_event_open |
| * quotactl |
| */ |
| }; |
| |
| _cleanup_strv_free_ char **added = NULL; |
| int r; |
| |
| for (size_t i = 0; i < ELEMENTSOF(allow_list); i++) { |
| if (allow_list[i].capability != 0 && (cap_list_retain & (1ULL << allow_list[i].capability)) == 0) |
| continue; |
| |
| r = seccomp_add_syscall_filter_item(ctx, |
| allow_list[i].name, |
| SCMP_ACT_ALLOW, |
| syscall_deny_list, |
| false, |
| &added); |
| if (r < 0) |
| return log_error_errno(r, "Failed to add syscall filter item %s: %m", allow_list[i].name); |
| } |
| |
| STRV_FOREACH(p, syscall_allow_list) { |
| r = seccomp_add_syscall_filter_item(ctx, *p, SCMP_ACT_ALLOW, syscall_deny_list, true, &added); |
| if (r < 0) |
| log_warning_errno(r, "Failed to add rule for system call %s on %s, ignoring: %m", |
| *p, seccomp_arch_to_string(arch)); |
| } |
| |
| /* The default action is ENOSYS. Respond with EPERM to all other "known" but not allow-listed |
| * syscalls. */ |
| r = seccomp_add_syscall_filter_item(ctx, "@known", SCMP_ACT_ERRNO(EPERM), added, true, NULL); |
| if (r < 0) |
| log_warning_errno(r, "Failed to add rule for @known set on %s, ignoring: %m", |
| seccomp_arch_to_string(arch)); |
| |
| #if (SCMP_VER_MAJOR == 2 && SCMP_VER_MINOR >= 5) || SCMP_VER_MAJOR > 2 |
| /* We have a large filter here, so let's turn on the binary tree mode if possible. */ |
| r = seccomp_attr_set(ctx, SCMP_FLTATR_CTL_OPTIMIZE, 2); |
| if (r < 0) |
| return r; |
| #endif |
| |
| return 0; |
| } |
| |
| int setup_seccomp(uint64_t cap_list_retain, char **syscall_allow_list, char **syscall_deny_list) { |
| uint32_t arch; |
| int r; |
| |
| if (!is_seccomp_available()) { |
| log_debug("SECCOMP features not detected in the kernel or disabled at runtime, disabling SECCOMP filtering"); |
| return 0; |
| } |
| |
| SECCOMP_FOREACH_LOCAL_ARCH(arch) { |
| _cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL; |
| |
| log_debug("Applying allow list on architecture: %s", seccomp_arch_to_string(arch)); |
| |
| /* We install ENOSYS as the default action, but it will only apply to syscalls which are not |
| * in the @known set, see above. */ |
| r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ERRNO(ENOSYS)); |
| if (r < 0) |
| return log_error_errno(r, "Failed to allocate seccomp object: %m"); |
| |
| r = add_syscall_filters(seccomp, arch, cap_list_retain, syscall_allow_list, syscall_deny_list); |
| if (r < 0) |
| return r; |
| |
| r = seccomp_load(seccomp); |
| if (ERRNO_IS_SECCOMP_FATAL(r)) |
| return log_error_errno(r, "Failed to install seccomp filter: %m"); |
| if (r < 0) |
| log_debug_errno(r, "Failed to install filter set for architecture %s, skipping: %m", seccomp_arch_to_string(arch)); |
| } |
| |
| SECCOMP_FOREACH_LOCAL_ARCH(arch) { |
| _cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL; |
| |
| log_debug("Applying NETLINK_AUDIT mask on architecture: %s", seccomp_arch_to_string(arch)); |
| |
| r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ALLOW); |
| if (r < 0) |
| return log_error_errno(r, "Failed to allocate seccomp object: %m"); |
| |
| /* |
| Audit is broken in containers, much of the userspace audit hookup will fail if running inside a |
| container. We don't care and just turn off creation of audit sockets. |
| |
| This will make socket(AF_NETLINK, *, NETLINK_AUDIT) fail with EAFNOSUPPORT which audit userspace uses |
| as indication that audit is disabled in the kernel. |
| */ |
| |
| r = seccomp_rule_add_exact( |
| seccomp, |
| SCMP_ACT_ERRNO(EAFNOSUPPORT), |
| SCMP_SYS(socket), |
| 2, |
| SCMP_A0(SCMP_CMP_EQ, AF_NETLINK), |
| SCMP_A2(SCMP_CMP_EQ, NETLINK_AUDIT)); |
| if (r < 0) { |
| log_debug_errno(r, "Failed to add audit seccomp rule, ignoring: %m"); |
| continue; |
| } |
| |
| r = seccomp_load(seccomp); |
| if (ERRNO_IS_SECCOMP_FATAL(r)) |
| return log_error_errno(r, "Failed to install seccomp audit filter: %m"); |
| if (r < 0) |
| log_debug_errno(r, "Failed to install filter set for architecture %s, skipping: %m", seccomp_arch_to_string(arch)); |
| } |
| |
| return 0; |
| } |
| |
| #else |
| |
| int setup_seccomp(uint64_t cap_list_retain, char **syscall_allow_list, char **syscall_deny_list) { |
| return 0; |
| } |
| |
| #endif |
