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systemd/SOURCES/0568-seccomp-allow-turning-...

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From e706f5df66b7189a7df526aeeb45c86b8c4b057a Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Mon, 2 Nov 2020 14:51:10 +0100
Subject: [PATCH] seccomp: allow turning off of seccomp filtering via env var
Fixes: #17504
(While we are it, also move $SYSTEMD_SECCOMP_LOG= env var description
into the right document section)
Also suggested in: https://github.com/systemd/systemd/issues/17245#issuecomment-704773603
(cherry picked from commit ce8f6d478e3f6c6a313fb19615aa5029bb18f86d)
Resolves: #1916835
---
doc/ENVIRONMENT.md | 3 +++
src/nspawn/nspawn-seccomp.c | 2 +-
src/shared/seccomp-util.c | 19 +++++++++++++++----
3 files changed, 19 insertions(+), 5 deletions(-)
diff --git a/doc/ENVIRONMENT.md b/doc/ENVIRONMENT.md
index 0e763b6302..36b649afe1 100644
--- a/doc/ENVIRONMENT.md
+++ b/doc/ENVIRONMENT.md
@@ -117,3 +117,6 @@ systemd-sulogin-shell:
* `$SYSTEMD_SULOGIN_FORCE=1` — This skips asking for the root password if the
root password is not available (such as when the root account is locked).
See `sulogin(8)` for more details.
+
+* `$SYSTEMD_SECCOMP=0` if set, seccomp filters will not be enforced, even if
+ support for it is compiled in and available in the kernel.
diff --git a/src/nspawn/nspawn-seccomp.c b/src/nspawn/nspawn-seccomp.c
index b56c5b04a8..fba22644da 100644
--- a/src/nspawn/nspawn-seccomp.c
+++ b/src/nspawn/nspawn-seccomp.c
@@ -172,7 +172,7 @@ int setup_seccomp(uint64_t cap_list_retain, char **syscall_whitelist, char **sys
int r;
if (!is_seccomp_available()) {
- log_debug("SECCOMP features not detected in the kernel, disabling SECCOMP filterering");
+ log_debug("SECCOMP features not detected in the kernel or disabled at runtime, disabling SECCOMP filtering");
return 0;
}
diff --git a/src/shared/seccomp-util.c b/src/shared/seccomp-util.c
index d91fb4e269..e903512d45 100644
--- a/src/shared/seccomp-util.c
+++ b/src/shared/seccomp-util.c
@@ -12,6 +12,7 @@
#include "af-list.h"
#include "alloc-util.h"
+#include "env-util.h"
#include "macro.h"
#include "nsflags.h"
#include "process-util.h"
@@ -244,10 +245,20 @@ static bool is_seccomp_filter_available(void) {
bool is_seccomp_available(void) {
static int cached_enabled = -1;
- if (cached_enabled < 0)
- cached_enabled =
- is_basic_seccomp_available() &&
- is_seccomp_filter_available();
+ if (cached_enabled < 0) {
+ int b;
+
+ b = getenv_bool("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;
}