selinux: Transition to pasta_t in containers

Currently, pasta runs in the container_runtime_exec_t context when
running in a container. This is not ideal since it means that pasta runs
with more privileges than strictly necessary. This commit updates the
SELinux policy to have pasta transition to the pasta_t context when
started from the container_runtime_t context, adds the appropriate
labels to $XDG_RUNTIME_DIR/netns and
$XDG_RUNTIME_DIR/containers/networks/rootless-netns, and grants the
necessary permissions to the pasta_t context.

Link: https://bugs.passt.top/show_bug.cgi?id=81
Link: https://github.com/containers/podman/discussions/26100#discussioncomment-13088518
Signed-off-by: Max Chernoff <git@maxchernoff.ca>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

2 files changed, 49 insertions, 5 deletions

diff --git a/contrib/selinux/pasta.fc b/contrib/selinux/pasta.fc
index 41ee46d..e4aefc4 100644
--- a/contrib/selinux/pasta.fc
+++ b/contrib/selinux/pasta.fc
@@ -8,7 +8,9 @@
 # Copyright (c) 2022 Red Hat GmbH
 # Author: Stefano Brivio <sbrivio@redhat.com>
 
-/usr/bin/pasta			system_u:object_r:pasta_exec_t:s0
-/usr/bin/pasta.avx2		system_u:object_r:pasta_exec_t:s0
-/tmp/pasta\.pcap		system_u:object_r:pasta_log_t:s0
-/var/run/pasta\.pid		system_u:object_r:pasta_pid_t:s0
+/usr/bin/pasta						system_u:object_r:pasta_exec_t:s0
+/usr/bin/pasta.avx2					system_u:object_r:pasta_exec_t:s0
+/tmp/pasta\.pcap					system_u:object_r:pasta_log_t:s0
+/var/run/pasta\.pid					system_u:object_r:pasta_pid_t:s0
+/run/user/%{USERID}/netns				system_u:object_r:ifconfig_var_run_t:s0
+/run/user/%{USERID}/containers/networks/rootless-netns	system_u:object_r:ifconfig_var_run_t:s0
diff --git a/contrib/selinux/pasta.te b/contrib/selinux/pasta.te
index 89c8043..9440d05 100644
--- a/contrib/selinux/pasta.te
+++ b/contrib/selinux/pasta.te
@@ -89,6 +89,15 @@ require {
 	class capability { sys_tty_config setuid setgid };
 	class cap_userns { setpcap sys_admin sys_ptrace net_bind_service net_admin };
 	class user_namespace create;
+
+	# Container requires
+	attribute_role usernetctl_roles;
+	role container_user_r;
+	role staff_r;
+	role user_r;
+	type container_runtime_t;
+	type container_t;
+	type systemd_user_runtimedir_t;
 }
 
 type pasta_t;
@@ -113,6 +122,9 @@ init_daemon_domain(pasta_t, pasta_exec_t)
 
 allow pasta_t self:capability { setpcap net_bind_service sys_tty_config dac_read_search net_admin sys_resource setuid setgid };
 allow pasta_t self:cap_userns { setpcap sys_admin sys_ptrace net_admin net_bind_service };
+# pasta only calls setuid and setgid with the current UID and GID, so this
+# denial is harmless. See https://bugzilla.redhat.com/show_bug.cgi?id=2330512#c10
+dontaudit pasta_t self:cap_userns { setgid setuid };
 allow pasta_t self:user_namespace create;
 
 auth_read_passwd(pasta_t)
@@ -130,7 +142,7 @@ allow pasta_t user_home_t:file { open read getattr setattr execute execute_no_tr
 allow pasta_t user_home_dir_t:dir { search getattr open add_name read write };
 allow pasta_t user_home_dir_t:file { create open read write };
 allow pasta_t tmp_t:dir { add_name mounton remove_name write };
-allow pasta_t tmpfs_t:filesystem mount;
+allow pasta_t tmpfs_t:filesystem { getattr mount };
 allow pasta_t fs_t:filesystem unmount;
 allow pasta_t root_t:dir mounton;
 manage_files_pattern(pasta_t, pasta_pid_t, pasta_pid_t)
@@ -156,6 +168,11 @@ allow pasta_t tmp_t:sock_file { create unlink write };
 allow pasta_t self:tcp_socket create_stream_socket_perms;
 corenet_tcp_sendrecv_generic_node(pasta_t)
 corenet_tcp_bind_generic_node(pasta_t)
+allow pasta_t container_runtime_t:dir { open read search };
+allow pasta_t container_runtime_t:fifo_file { getattr write };
+allow pasta_t container_runtime_t:file read;
+allow pasta_t container_runtime_t:lnk_file read;
+allow pasta_t container_t:lnk_file read;
 allow pasta_t pasta_port_t:tcp_socket { name_bind name_connect };
 allow pasta_t pasta_port_t:udp_socket { name_bind };
 allow pasta_t http_port_t:tcp_socket { name_bind name_connect };
@@ -213,3 +230,28 @@ allow pasta_t netutils_t:process { noatsecure rlimitinh siginh };
 allow pasta_t ping_t:process { noatsecure rlimitinh siginh };
 allow pasta_t user_tty_device_t:chr_file { append read write };
 allow pasta_t user_devpts_t:chr_file { append read write };
+
+# Allow network administration commands for non-privileged users
+roleattribute container_user_r usernetctl_roles;
+roleattribute staff_r usernetctl_roles;
+roleattribute user_r usernetctl_roles;
+role usernetctl_roles types pasta_t;
+
+# Make pasta in a container run under the pasta_t context
+type_transition container_runtime_t pasta_exec_t : process pasta_t;
+allow container_runtime_t pasta_t:process transition;
+
+# Label the user network namespace files
+type_transition container_runtime_t user_tmp_t : dir ifconfig_var_run_t "netns";
+type_transition container_runtime_t user_tmp_t : dir ifconfig_var_run_t "rootless-netns";
+allow pasta_t ifconfig_var_run_t:dir { add_name open rmdir write };
+allow pasta_t ifconfig_var_run_t:file { create open write };
+allow systemd_user_runtimedir_t ifconfig_var_run_t:dir rmdir;
+
+# Allow pasta to bind to any port
+bool pasta_bind_all_ports true;
+if (pasta_bind_all_ports) {
+	allow pasta_t port_type:icmp_socket { accept getopt name_bind };
+	allow pasta_t port_type:tcp_socket { accept getopt name_bind name_connect };
+	allow pasta_t port_type:udp_socket { accept getopt name_bind };
+}