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[52.70.167.183]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-793546dd333sm28205366d6.56.2025.09.19.05.22.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Sep 2025 05:22:47 -0700 (PDT) From: Stephen Smalley To: selinux@vger.kernel.org Cc: Stephen Smalley Subject: [RFC PATCH 1/2] nspawn: add --selinux-namespace option to unshare SELinux namespace Date: Fri, 19 Sep 2025 08:21:00 -0400 Message-ID: <20250919122100.181107-2-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/20250918135118.9896-2-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 --- src/nspawn/nspawn.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c index 2dcab7d379..9c4bcb7688 100644 --- a/src/nspawn/nspawn.c +++ b/src/nspawn/nspawn.c @@ -138,6 +138,7 @@ 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; @@ -422,6 +423,7 @@ 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" @@ -639,6 +641,7 @@ 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, @@ -714,6 +717,7 @@ 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 }, @@ -986,6 +990,10 @@ 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; @@ -3257,6 +3265,7 @@ static int inner_child( NULL, /* NOTIFY_SOCKET */ NULL, /* CREDENTIALS_DIRECTORY */ NULL, /* LANG */ + NULL, /* SELINUXNS */ NULL }; const char *exec_target; @@ -3468,6 +3477,9 @@ static int inner_child( if (arg_selinux_context) if (setexeccon(arg_selinux_context) < 0) return log_error_errno(errno, "setexeccon(\"%s\") failed: %m", arg_selinux_context); + if (arg_selinux_namespace) + if (selinux_unshare() < 0) + return log_error_errno(errno, "selinux_unshare() failed: %m"); #endif /* Make sure we keep the caps across the uid/gid dropping, so that we can retain some selected caps @@ -3545,6 +3557,15 @@ static int inner_child( n_env++; } +#if HAVE_SELINUX + if (arg_selinux_namespace) { + envp[n_env] = strdup("SELINUXNS=1"); + if (!envp[n_env]) + return log_oom(); + n_env++; + } +#endif + env_use = strv_env_merge(envp, os_release_pairs, arg_setenv); if (!env_use) return log_oom(); -- 2.51.0