Merge tag 'selinux-pr-20241112' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

torvalds · torvalds · commit 8ffc7dbce2d5 · 2024-11-18T17:30:52.000-08:00
Pull selinux updates from Paul Moore:

 - Add support for netlink xperms

   Some time ago we added the concept of "xperms" to the SELinux policy
   so that we could write policy for individual ioctls, this builds upon
   this by using extending xperms to netlink so that we can write
   SELinux policy for individual netlnk message types and not rely on
   the fairly coarse read/write mapping tables we currently have.

   There are limitations involving generic netlink due to the
   multiplexing that is done, but it's no worse that what we currently
   have. As usual, more information can be found in the commit message.

 - Deprecate /sys/fs/selinux/user

   We removed the only known userspace use of this back in 2020 and now
   that several years have elapsed we're starting down the path of
   deprecating it in the kernel.

 - Cleanup the build under scripts/selinux

   A couple of patches to move the genheaders tool under
   security/selinux and correct our usage of kernel headers in the tools
   located under scripts/selinux. While these changes originated out of
   an effort to build Linux on different systems, they are arguably the
   right thing to do regardless.

 - Minor code cleanups and style fixes

   Not much to say here, two minor cleanup patches that came out of the
   netlink xperms work

* tag 'selinux-pr-20241112' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: Deprecate /sys/fs/selinux/user
  selinux: apply clang format to security/selinux/nlmsgtab.c
  selinux: streamline selinux_nlmsg_lookup()
  selinux: Add netlink xperm support
  selinux: move genheaders to security/selinux/
  selinux: do not include &lt;linux/*.h&gt; headers from host programs
diff --git a/Documentation/ABI/obsolete/sysfs-selinux-user b/Documentation/ABI/obsolete/sysfs-selinux-user
@@ -0,0 +1,12 @@
+What:		/sys/fs/selinux/user
+Date:		April 2005 (predates git)
+KernelVersion:	2.6.12-rc2 (predates git)
+Contact:	selinux@vger.kernel.org
+Description:
+
+	The selinuxfs "user" node allows userspace to request a list
+	of security contexts that can be reached for a given SELinux
+	user from a given starting context. This was used by libselinux
+	when various login-style programs requested contexts for
+	users, but libselinux stopped using it in 2020.
+	Kernel support will be removed no sooner than Dec 2025.
diff --git a/scripts/remove-stale-files b/scripts/remove-stale-files
@@ -20,6 +20,9 @@ set -e
 # yard. Stale files stay in this file for a while (for some release cycles?),
 # then will be really dead and removed from the code base entirely.
 
+# moved to security/selinux/genheaders
+rm -f scripts/selinux/genheaders/genheaders
+
 rm -f *.spec
 
 rm -f lib/test_fortify.log
diff --git a/scripts/selinux/Makefile b/scripts/selinux/Makefile
@@ -1,2 +1,2 @@
 # SPDX-License-Identifier: GPL-2.0-only
-subdir-y := mdp genheaders
+subdir-y := mdp
diff --git a/scripts/selinux/genheaders/.gitignore b/scripts/selinux/genheaders/.gitignore
diff --git a/scripts/selinux/genheaders/Makefile b/scripts/selinux/genheaders/Makefile
diff --git a/scripts/selinux/mdp/Makefile b/scripts/selinux/mdp/Makefile
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 hostprogs-always-y += mdp
 HOST_EXTRACFLAGS += \
-	-I$(srctree)/include/uapi -I$(srctree)/include \
+	-I$(srctree)/include \
 	-I$(srctree)/security/selinux/include -I$(objtree)/include
 
 clean-files	:= policy.* file_contexts
diff --git a/scripts/selinux/mdp/mdp.c b/scripts/selinux/mdp/mdp.c
@@ -11,10 +11,6 @@
  * Authors: Serge E. Hallyn <serue@us.ibm.com>
  */
 
-
-/* NOTE: we really do want to use the kernel headers here */
-#define __EXPORTED_HEADERS__
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
diff --git a/security/selinux/.gitignore b/security/selinux/.gitignore
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 av_permissions.h
 flask.h
+/genheaders
diff --git a/security/selinux/Makefile b/security/selinux/Makefile
@@ -36,7 +36,10 @@ quiet_cmd_genhdrs = GEN     $(addprefix $(obj)/,$(genhdrs))
 # see the note above, replace the $targets and 'flask.h' rule with the lines
 # below:
 #  targets += $(genhdrs)
-#  $(addprefix $(obj)/,$(genhdrs)) &: scripts/selinux/...
+#  $(addprefix $(obj)/,$(genhdrs)) &: $(obj)/genheaders FORCE
 targets += flask.h
-$(obj)/flask.h: scripts/selinux/genheaders/genheaders FORCE
+$(obj)/flask.h: $(obj)/genheaders FORCE
 	$(call if_changed,genhdrs)
+
+hostprogs := genheaders
+HOST_EXTRACFLAGS += -I$(srctree)/security/selinux/include
diff --git a/security/selinux/genheaders.c b/security/selinux/genheaders.c
@@ -1,8 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
 
-/* NOTE: we really do want to use the kernel headers here */
-#define __EXPORTED_HEADERS__
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
@@ -4590,14 +4590,10 @@ static int socket_sockcreate_sid(const struct task_security_struct *tsec,
 				       secclass, NULL, socksid);
 }
 
-static int sock_has_perm(struct sock *sk, u32 perms)
+static bool sock_skip_has_perm(u32 sid)
 {
-	struct sk_security_struct *sksec = selinux_sock(sk);
-	struct common_audit_data ad;
-	struct lsm_network_audit net;
-
-	if (sksec->sid == SECINITSID_KERNEL)
-		return 0;
+	if (sid == SECINITSID_KERNEL)
+		return true;
 
 	/*
 	 * Before POLICYDB_CAP_USERSPACE_INITIAL_CONTEXT, sockets that
@@ -4611,7 +4607,19 @@ static int sock_has_perm(struct sock *sk, u32 perms)
 	 * setting.
 	 */
 	if (!selinux_policycap_userspace_initial_context() &&
-	    sksec->sid == SECINITSID_INIT)
+	    sid == SECINITSID_INIT)
+		return true;
+	return false;
+}
+
+
+static int sock_has_perm(struct sock *sk, u32 perms)
+{
+	struct sk_security_struct *sksec = sk->sk_security;
+	struct common_audit_data ad;
+	struct lsm_network_audit net;
+
+	if (sock_skip_has_perm(sksec->sid))
 		return 0;
 
 	ad_net_init_from_sk(&ad, &net, sk);
@@ -5920,6 +5928,26 @@ static unsigned int selinux_ip_postroute(void *priv,
 }
 #endif	/* CONFIG_NETFILTER */
 
+static int nlmsg_sock_has_extended_perms(struct sock *sk, u32 perms, u16 nlmsg_type)
+{
+	struct sk_security_struct *sksec = sk->sk_security;
+	struct common_audit_data ad;
+	struct lsm_network_audit net;
+	u8 driver;
+	u8 xperm;
+
+	if (sock_skip_has_perm(sksec->sid))
+		return 0;
+
+	ad_net_init_from_sk(&ad, &net, sk);
+
+	driver = nlmsg_type >> 8;
+	xperm = nlmsg_type & 0xff;
+
+	return avc_has_extended_perms(current_sid(), sksec->sid, sksec->sclass,
+			perms, driver, xperm, &ad);
+}
+
 static int selinux_netlink_send(struct sock *sk, struct sk_buff *skb)
 {
 	int rc = 0;
@@ -5945,7 +5973,12 @@ static int selinux_netlink_send(struct sock *sk, struct sk_buff *skb)
 
 		rc = selinux_nlmsg_lookup(sclass, nlh->nlmsg_type, &perm);
 		if (rc == 0) {
-			rc = sock_has_perm(sk, perm);
+			if (selinux_policycap_netlink_xperm()) {
+				rc = nlmsg_sock_has_extended_perms(
+					sk, perm, nlh->nlmsg_type);
+			} else {
+				rc = sock_has_perm(sk, perm);
+			}
 			if (rc)
 				return rc;
 		} else if (rc == -EINVAL) {
diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
@@ -1,8 +1,5 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 
-#include <linux/capability.h>
-#include <linux/socket.h>
-
 #define COMMON_FILE_SOCK_PERMS                                            \
 	"ioctl", "read", "write", "create", "getattr", "setattr", "lock", \
 		"relabelfrom", "relabelto", "append", "map"
@@ -36,9 +33,13 @@
 	"mac_override", "mac_admin", "syslog", "wake_alarm", "block_suspend", \
 		"audit_read", "perfmon", "bpf", "checkpoint_restore"
 
+#ifdef __KERNEL__ /* avoid this check when building host programs */
+#include <linux/capability.h>
+
 #if CAP_LAST_CAP > CAP_CHECKPOINT_RESTORE
 #error New capability defined, please update COMMON_CAP2_PERMS.
 #endif
+#endif
 
 /*
  * Note: The name for any socket class should be suffixed by "socket",
@@ -96,17 +97,17 @@ const struct security_class_mapping secclass_map[] = {
 	{ "shm", { COMMON_IPC_PERMS, "lock", NULL } },
 	{ "ipc", { COMMON_IPC_PERMS, NULL } },
 	{ "netlink_route_socket",
-	  { COMMON_SOCK_PERMS, "nlmsg_read", "nlmsg_write", NULL } },
+	  { COMMON_SOCK_PERMS, "nlmsg_read", "nlmsg_write", "nlmsg", NULL } },
 	{ "netlink_tcpdiag_socket",
-	  { COMMON_SOCK_PERMS, "nlmsg_read", "nlmsg_write", NULL } },
+	  { COMMON_SOCK_PERMS, "nlmsg_read", "nlmsg_write", "nlmsg", NULL } },
 	{ "netlink_nflog_socket", { COMMON_SOCK_PERMS, NULL } },
 	{ "netlink_xfrm_socket",
-	  { COMMON_SOCK_PERMS, "nlmsg_read", "nlmsg_write", NULL } },
+	  { COMMON_SOCK_PERMS, "nlmsg_read", "nlmsg_write", "nlmsg", NULL } },
 	{ "netlink_selinux_socket", { COMMON_SOCK_PERMS, NULL } },
 	{ "netlink_iscsi_socket", { COMMON_SOCK_PERMS, NULL } },
 	{ "netlink_audit_socket",
 	  { COMMON_SOCK_PERMS, "nlmsg_read", "nlmsg_write", "nlmsg_relay",
-	    "nlmsg_readpriv", "nlmsg_tty_audit", NULL } },
+	    "nlmsg_readpriv", "nlmsg_tty_audit", "nlmsg", NULL } },
 	{ "netlink_fib_lookup_socket", { COMMON_SOCK_PERMS, NULL } },
 	{ "netlink_connector_socket", { COMMON_SOCK_PERMS, NULL } },
 	{ "netlink_netfilter_socket", { COMMON_SOCK_PERMS, NULL } },
@@ -181,6 +182,10 @@ const struct security_class_mapping secclass_map[] = {
 	{ NULL }
 };
 
+#ifdef __KERNEL__ /* avoid this check when building host programs */
+#include <linux/socket.h>
+
 #if PF_MAX > 46
 #error New address family defined, please update secclass_map.
 #endif
+#endif
diff --git a/security/selinux/include/initial_sid_to_string.h b/security/selinux/include/initial_sid_to_string.h
@@ -1,6 +1,10 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 
+#ifdef __KERNEL__
 #include <linux/stddef.h>
+#else
+#include <stddef.h>
+#endif
 
 static const char *const initial_sid_to_string[] = {
 	NULL, /* zero placeholder, not used */
diff --git a/security/selinux/include/policycap.h b/security/selinux/include/policycap.h
@@ -14,6 +14,7 @@ enum {
 	POLICYDB_CAP_GENFS_SECLABEL_SYMLINKS,
 	POLICYDB_CAP_IOCTL_SKIP_CLOEXEC,
 	POLICYDB_CAP_USERSPACE_INITIAL_CONTEXT,
+	POLICYDB_CAP_NETLINK_XPERM,
 	__POLICYDB_CAP_MAX
 };
 #define POLICYDB_CAP_MAX (__POLICYDB_CAP_MAX - 1)
diff --git a/security/selinux/include/policycap_names.h b/security/selinux/include/policycap_names.h
@@ -17,6 +17,7 @@ const char *const selinux_policycap_names[__POLICYDB_CAP_MAX] = {
 	"genfs_seclabel_symlinks",
 	"ioctl_skip_cloexec",
 	"userspace_initial_context",
+	"netlink_xperm",
 };
 /* clang-format on */
 
diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
@@ -195,6 +195,12 @@ static inline bool selinux_policycap_userspace_initial_context(void)
 		selinux_state.policycap[POLICYDB_CAP_USERSPACE_INITIAL_CONTEXT]);
 }
 
+static inline bool selinux_policycap_netlink_xperm(void)
+{
+	return READ_ONCE(
+		selinux_state.policycap[POLICYDB_CAP_NETLINK_XPERM]);
+}
+
 struct selinux_policy_convert_data;
 
 struct selinux_load_state {
diff --git a/security/selinux/nlmsgtab.c b/security/selinux/nlmsgtab.c
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
diff --git a/security/selinux/ss/avtab.h b/security/selinux/ss/avtab.h
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c

Original file line number	Diff line number	Diff line change
`@@ -1,2 +1,2 @@`
`1`	`1`	`# SPDX-License-Identifier: GPL-2.0-only`
`2`		`-subdir-y := mdp genheaders`
	`2`	`+subdir-y := mdp`