0c69794138
These lines are generally out-of-date, incomplete and unnecessary. With SPDX and git repository much more accurate and fine grained information about licensing and authorship is available, hence let's drop the per-file copyright notice. Of course, removing copyright lines of others is problematic, hence this commit only removes my own lines and leaves all others untouched. It might be nicer if sooner or later those could go away too, making git the only and accurate source of authorship information.
245 lines
11 KiB
C
245 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/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_whitelist,
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char **syscall_blacklist) {
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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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} whitelist[] = {
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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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* @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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* pkey_alloc
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* pkey_free
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* pkey_mprotect
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* quotactl
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*/
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};
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int r, c = 0;
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size_t i;
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char **p;
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for (i = 0; i < ELEMENTSOF(whitelist); i++) {
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if (whitelist[i].capability != 0 && (cap_list_retain & (1ULL << whitelist[i].capability)) == 0)
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continue;
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r = seccomp_add_syscall_filter_item(ctx, whitelist[i].name, SCMP_ACT_ALLOW, syscall_blacklist);
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if (r < 0)
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/* If the system call is not known on this architecture, then that's fine, let's ignore it */
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log_debug_errno(r, "Failed to add rule for system call %s on %s, ignoring: %m", whitelist[i].name, seccomp_arch_to_string(arch));
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else
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c++;
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}
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STRV_FOREACH(p, syscall_whitelist) {
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r = seccomp_add_syscall_filter_item(ctx, *p, SCMP_ACT_ALLOW, syscall_blacklist);
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if (r < 0)
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log_debug_errno(r, "Failed to add rule for system call %s on %s, ignoring: %m", *p, seccomp_arch_to_string(arch));
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else
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c++;
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}
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return c;
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}
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int setup_seccomp(uint64_t cap_list_retain, char **syscall_whitelist, char **syscall_blacklist) {
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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 whitelist 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_whitelist, syscall_blacklist);
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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 (IN_SET(r, -EPERM, -EACCES))
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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 (IN_SET(r, -EPERM, -EACCES))
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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_whitelist, char **syscall_blacklist) {
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return 0;
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}
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#endif
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