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[52.70.167.183]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-878bae60df0sm118104746d6.3.2025.10.06.06.28.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Oct 2025 06:28:06 -0700 (PDT) From: Stephen Smalley To: selinux@vger.kernel.org Cc: paul@paul-moore.com, Stephen Smalley Subject: [RFC PATCH v2 1/2] nspawn: add --selinux-namespace option to unshare SELinux namespace Date: Mon, 6 Oct 2025 09:25:08 -0400 Message-ID: <20251006132508.3430-2-stephen.smalley.work@gmail.com> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: selinux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit RFC only, this demonstrates how to use the selinux_unshare(3) API added to libselinux by https://lore.kernel.org/selinux/20251003191922.5326-2-stephen.smalley.work@gmail.com/ and integrates it into systemd-nspawn to support launching containers with their own SELinux namespace. Signed-off-by: Stephen Smalley --- v2 drops the setting of the SELINUXNS environment variable since systemd can instead use the new is_selinux_unshared(3) API introduced by the above libselinux patch. src/nspawn/nspawn.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c index ab8746c442..4c5f3eb812 100644 --- a/src/nspawn/nspawn.c +++ b/src/nspawn/nspawn.c @@ -148,6 +148,7 @@ static char *arg_machine = NULL; /* The name used by the host to refer to th static char *arg_hostname = NULL; /* The name the payload sees by default */ static const char *arg_selinux_context = NULL; static const char *arg_selinux_apifs_context = NULL; +static bool arg_selinux_namespace = false; static char *arg_slice = NULL; static bool arg_private_network; /* initialized depending on arg_privileged in run() */ static bool arg_read_only = false; @@ -437,6 +438,7 @@ static int help(void) { " -L --selinux-apifs-context=SECLABEL\n" " Set the SELinux security context to be used by\n" " API/tmpfs file systems in the container\n" + " --selinux-namespace Unshare SELinux namespace\n" "\n%3$sResources:%4$s\n" " --rlimit=NAME=LIMIT Set a resource limit for the payload\n" " --oom-score-adjust=VALUE\n" @@ -654,6 +656,7 @@ static int parse_argv(int argc, char *argv[]) { ARG_OVERLAY, ARG_OVERLAY_RO, ARG_INACCESSIBLE, + ARG_SELINUX_NAMESPACE, ARG_SHARE_SYSTEM, ARG_REGISTER, ARG_KEEP_UNIT, @@ -731,6 +734,7 @@ static int parse_argv(int argc, char *argv[]) { { "setenv", required_argument, NULL, 'E' }, { "selinux-context", required_argument, NULL, 'Z' }, { "selinux-apifs-context", required_argument, NULL, 'L' }, + { "selinux-namespace", no_argument, NULL, ARG_SELINUX_NAMESPACE }, { "quiet", no_argument, NULL, 'q' }, { "share-system", no_argument, NULL, ARG_SHARE_SYSTEM }, /* not documented */ { "register", required_argument, NULL, ARG_REGISTER }, @@ -1005,6 +1009,10 @@ static int parse_argv(int argc, char *argv[]) { arg_selinux_apifs_context = optarg; break; + case ARG_SELINUX_NAMESPACE: + arg_selinux_namespace = true; + break; + case ARG_READ_ONLY: arg_read_only = true; arg_settings_mask |= SETTING_READ_ONLY; @@ -3502,6 +3510,12 @@ static int inner_child( if (r < 0) return log_error_errno(r, "Failed to apply resource limit RLIMIT_%s: %m", rlimit_to_string(which_failed)); +#if HAVE_SELINUX + if (arg_selinux_namespace) + if (selinux_unshare() < 0) + return log_error_errno(errno, "selinux_unshare() failed: %m"); +#endif + #if HAVE_SECCOMP if (arg_seccomp) { -- 2.51.0