6b000af4f2
https://tools.ietf.org/html/draft-knodel-terminology-02 https://lwn.net/Articles/823224/ This gets rid of most but not occasions of these loaded terms: 1. scsi_id and friends are something that is supposed to be removed from our tree (see #7594) 2. The test suite defines an API used by the ubuntu CI. We can remove this too later, but this needs to be done in sync with the ubuntu CI. 3. In some cases the terms are part of APIs we call or where we expose concepts the kernel names the way it names them. (In particular all remaining uses of the word "slave" in our codebase are like this, it's used by the POSIX PTY layer, by the network subsystem, the mount API and the block device subsystem). Getting rid of the term in these contexts would mean doing some major fixes of the kernel ABI first. Regarding the replacements: when whitelist/blacklist is used as noun we replace with with allow list/deny list, and when used as verb with allow-list/deny-list.
239 lines
11 KiB
C
239 lines
11 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <errno.h>
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#include <linux/netlink.h>
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#include <sys/capability.h>
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#include <sys/socket.h>
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#include <sys/types.h>
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#if HAVE_SECCOMP
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#include <seccomp.h>
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#endif
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#include "alloc-util.h"
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#include "log.h"
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#include "nspawn-seccomp.h"
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#if HAVE_SECCOMP
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#include "seccomp-util.h"
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#endif
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#include "string-util.h"
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#include "strv.h"
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#if HAVE_SECCOMP
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static int seccomp_add_default_syscall_filter(
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scmp_filter_ctx ctx,
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uint32_t arch,
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uint64_t cap_list_retain,
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char **syscall_allow_list,
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char **syscall_deny_list) {
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static const struct {
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uint64_t capability;
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const char* name;
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} allow_list[] = {
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/* Let's use set names where we can */
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{ 0, "@aio" },
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{ 0, "@basic-io" },
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{ 0, "@chown" },
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{ 0, "@default" },
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{ 0, "@file-system" },
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{ 0, "@io-event" },
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{ 0, "@ipc" },
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{ 0, "@mount" },
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{ 0, "@network-io" },
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{ 0, "@process" },
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{ 0, "@resources" },
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{ 0, "@setuid" },
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{ 0, "@signal" },
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{ 0, "@sync" },
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{ 0, "@timer" },
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/* The following four are sets we optionally enable, in case the caps have been configured for it */
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{ CAP_SYS_TIME, "@clock" },
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{ CAP_SYS_MODULE, "@module" },
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{ CAP_SYS_RAWIO, "@raw-io" },
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{ CAP_IPC_LOCK, "@memlock" },
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/* Plus a good set of additional syscalls which are not part of any of the groups above */
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{ 0, "brk" },
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{ 0, "capget" },
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{ 0, "capset" },
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{ 0, "copy_file_range" },
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{ 0, "fadvise64" },
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{ 0, "fadvise64_64" },
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{ 0, "flock" },
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{ 0, "get_mempolicy" },
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{ 0, "getcpu" },
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{ 0, "getpriority" },
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{ 0, "getrandom" },
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{ 0, "ioctl" },
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{ 0, "ioprio_get" },
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{ 0, "kcmp" },
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{ 0, "madvise" },
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{ 0, "mincore" },
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{ 0, "mprotect" },
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{ 0, "mremap" },
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{ 0, "name_to_handle_at" },
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{ 0, "oldolduname" },
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{ 0, "olduname" },
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{ 0, "personality" },
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{ 0, "readahead" },
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{ 0, "readdir" },
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{ 0, "remap_file_pages" },
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{ 0, "sched_get_priority_max" },
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{ 0, "sched_get_priority_min" },
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{ 0, "sched_getaffinity" },
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{ 0, "sched_getattr" },
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{ 0, "sched_getparam" },
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{ 0, "sched_getscheduler" },
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{ 0, "sched_rr_get_interval" },
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{ 0, "sched_yield" },
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{ 0, "seccomp" },
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{ 0, "sendfile" },
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{ 0, "sendfile64" },
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{ 0, "setdomainname" },
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{ 0, "setfsgid" },
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{ 0, "setfsgid32" },
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{ 0, "setfsuid" },
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{ 0, "setfsuid32" },
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{ 0, "sethostname" },
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{ 0, "setpgid" },
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{ 0, "setsid" },
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{ 0, "splice" },
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{ 0, "sysinfo" },
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{ 0, "tee" },
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{ 0, "umask" },
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{ 0, "uname" },
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{ 0, "userfaultfd" },
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{ 0, "vmsplice" },
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/* The following individual syscalls are added depending on specified caps */
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{ CAP_SYS_PACCT, "acct" },
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{ CAP_SYS_PTRACE, "process_vm_readv" },
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{ CAP_SYS_PTRACE, "process_vm_writev" },
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{ CAP_SYS_PTRACE, "ptrace" },
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{ CAP_SYS_BOOT, "reboot" },
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{ CAP_SYSLOG, "syslog" },
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{ CAP_SYS_TTY_CONFIG, "vhangup" },
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/*
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* The following syscalls and groups are knowingly excluded:
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*
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* @cpu-emulation
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* @keyring (NB: keyring is not namespaced!)
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* @obsolete
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* @pkey
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* @swap
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*
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* bpf (NB: bpffs is not namespaced!)
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* fanotify_init
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* fanotify_mark
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* kexec_file_load
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* kexec_load
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* lookup_dcookie
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* nfsservctl
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* open_by_handle_at
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* perf_event_open
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* quotactl
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*/
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};
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char **p;
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int r;
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for (size_t i = 0; i < ELEMENTSOF(allow_list); i++) {
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if (allow_list[i].capability != 0 && (cap_list_retain & (1ULL << allow_list[i].capability)) == 0)
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continue;
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r = seccomp_add_syscall_filter_item(ctx, allow_list[i].name, SCMP_ACT_ALLOW, syscall_deny_list, false);
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if (r < 0)
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return log_error_errno(r, "Failed to add syscall filter item %s: %m", allow_list[i].name);
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}
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STRV_FOREACH(p, syscall_allow_list) {
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r = seccomp_add_syscall_filter_item(ctx, *p, SCMP_ACT_ALLOW, syscall_deny_list, true);
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if (r < 0)
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log_warning_errno(r, "Failed to add rule for system call %s on %s, ignoring: %m",
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*p, seccomp_arch_to_string(arch));
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}
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return 0;
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}
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int setup_seccomp(uint64_t cap_list_retain, char **syscall_allow_list, char **syscall_deny_list) {
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uint32_t arch;
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int r;
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if (!is_seccomp_available()) {
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log_debug("SECCOMP features not detected in the kernel, disabling SECCOMP filterering");
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return 0;
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}
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SECCOMP_FOREACH_LOCAL_ARCH(arch) {
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_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
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log_debug("Applying allow list on architecture: %s", seccomp_arch_to_string(arch));
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r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ERRNO(EPERM));
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if (r < 0)
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return log_error_errno(r, "Failed to allocate seccomp object: %m");
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r = seccomp_add_default_syscall_filter(seccomp, arch, cap_list_retain, syscall_allow_list, syscall_deny_list);
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if (r < 0)
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return r;
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r = seccomp_load(seccomp);
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if (ERRNO_IS_SECCOMP_FATAL(r))
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return log_error_errno(r, "Failed to install seccomp filter: %m");
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if (r < 0)
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log_debug_errno(r, "Failed to install filter set for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
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}
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SECCOMP_FOREACH_LOCAL_ARCH(arch) {
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_cleanup_(seccomp_releasep) scmp_filter_ctx seccomp = NULL;
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log_debug("Applying NETLINK_AUDIT mask on architecture: %s", seccomp_arch_to_string(arch));
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r = seccomp_init_for_arch(&seccomp, arch, SCMP_ACT_ALLOW);
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if (r < 0)
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return log_error_errno(r, "Failed to allocate seccomp object: %m");
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/*
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Audit is broken in containers, much of the userspace audit hookup will fail if running inside a
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container. We don't care and just turn off creation of audit sockets.
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This will make socket(AF_NETLINK, *, NETLINK_AUDIT) fail with EAFNOSUPPORT which audit userspace uses
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as indication that audit is disabled in the kernel.
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*/
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r = seccomp_rule_add_exact(
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seccomp,
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SCMP_ACT_ERRNO(EAFNOSUPPORT),
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SCMP_SYS(socket),
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2,
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SCMP_A0(SCMP_CMP_EQ, AF_NETLINK),
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SCMP_A2(SCMP_CMP_EQ, NETLINK_AUDIT));
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if (r < 0) {
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log_debug_errno(r, "Failed to add audit seccomp rule, ignoring: %m");
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continue;
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}
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r = seccomp_load(seccomp);
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if (ERRNO_IS_SECCOMP_FATAL(r))
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return log_error_errno(r, "Failed to install seccomp audit filter: %m");
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if (r < 0)
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log_debug_errno(r, "Failed to install filter set for architecture %s, skipping: %m", seccomp_arch_to_string(arch));
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}
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return 0;
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}
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#else
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int setup_seccomp(uint64_t cap_list_retain, char **syscall_allow_list, char **syscall_deny_list) {
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return 0;
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}
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#endif
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