1 files changed, 799 insertions, 0 deletions
diff --git a/security/apparmor/af_unix.c b/security/apparmor/af_unix.c
new file mode 100644
index 000000000000..9129766d1e9c
--- /dev/null
+++ b/security/apparmor/af_unix.c
@@ -0,0 +1,799 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor af_unix fine grained mediation
+ *
+ * Copyright 2023 Canonical Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ */
+
+#include <linux/fs.h>
+#include <net/tcp_states.h>
+
+#include "include/audit.h"
+#include "include/af_unix.h"
+#include "include/apparmor.h"
+#include "include/file.h"
+#include "include/label.h"
+#include "include/path.h"
+#include "include/policy.h"
+#include "include/cred.h"
+
+
+static inline struct sock *aa_unix_sk(struct unix_sock *u)
+{
+	return &u->sk;
+}
+
+static int unix_fs_perm(const char *op, u32 mask, const struct cred *subj_cred,
+			struct aa_label *label, struct path *path)
+{
+	AA_BUG(!label);
+	AA_BUG(!path);
+
+	if (unconfined(label) || !label_mediates(label, AA_CLASS_FILE))
+		return 0;
+
+	mask &= NET_FS_PERMS;
+	/* if !u->path.dentry socket is being shutdown - implicit delegation
+	 * until obj delegation is supported
+	 */
+	if (path->dentry) {
+		/* the sunpath may not be valid for this ns so use the path */
+		struct inode *inode = path->dentry->d_inode;
+		vfsuid_t vfsuid = i_uid_into_vfsuid(mnt_idmap(path->mnt), inode);
+		struct path_cond cond = {
+			.uid = vfsuid_into_kuid(vfsuid),
+			.mode = inode->i_mode,
+		};
+
+		return aa_path_perm(op, subj_cred, label, path,
+				    PATH_SOCK_COND, mask, &cond);
+	} /* else implicitly delegated */
+
+	return 0;
+}
+
+/* match_addr special constants */
+#define ABSTRACT_ADDR "\x00"		/* abstract socket addr */
+#define ANONYMOUS_ADDR "\x01"		/* anonymous endpoint, no addr */
+#define DISCONNECTED_ADDR "\x02"	/* addr is another namespace */
+#define SHUTDOWN_ADDR "\x03"		/* path addr is shutdown and cleared */
+#define FS_ADDR "/"			/* path addr in fs */
+
+static aa_state_t match_addr(struct aa_dfa *dfa, aa_state_t state,
+			     struct sockaddr_un *addr, int addrlen)
+{
+	if (addr)
+		/* include leading \0 */
+		state = aa_dfa_match_len(dfa, state, addr->sun_path,
+					 unix_addr_len(addrlen));
+	else
+		state = aa_dfa_match_len(dfa, state, ANONYMOUS_ADDR, 1);
+	/* todo: could change to out of band for cleaner separation */
+	state = aa_dfa_null_transition(dfa, state);
+
+	return state;
+}
+
+static aa_state_t match_to_local(struct aa_policydb *policy,
+				 aa_state_t state, u32 request,
+				 int type, int protocol,
+				 struct sockaddr_un *addr, int addrlen,
+				 struct aa_perms **p,
+				 const char **info)
+{
+	state = aa_match_to_prot(policy, state, request, PF_UNIX, type,
+				 protocol, NULL, info);
+	if (state) {
+		state = match_addr(policy->dfa, state, addr, addrlen);
+		if (state) {
+			/* todo: local label matching */
+			state = aa_dfa_null_transition(policy->dfa, state);
+			if (!state)
+				*info = "failed local label match";
+		} else {
+			*info = "failed local address match";
+		}
+	}
+
+	return state;
+}
+
+struct sockaddr_un *aa_sunaddr(const struct unix_sock *u, int *addrlen)
+{
+	struct unix_address *addr;
+
+	/* memory barrier is sufficient see note in net/unix/af_unix.c */
+	addr = smp_load_acquire(&u->addr);
+	if (addr) {
+		*addrlen = addr->len;
+		return addr->name;
+	}
+	*addrlen = 0;
+	return NULL;
+}
+
+static aa_state_t match_to_sk(struct aa_policydb *policy,
+			      aa_state_t state, u32 request,
+			      struct unix_sock *u, struct aa_perms **p,
+			      const char **info)
+{
+	int addrlen;
+	struct sockaddr_un *addr = aa_sunaddr(u, &addrlen);
+
+	return match_to_local(policy, state, request, u->sk.sk_type,
+			      u->sk.sk_protocol, addr, addrlen, p, info);
+}
+
+#define CMD_ADDR	1
+#define CMD_LISTEN	2
+#define CMD_OPT		4
+
+static aa_state_t match_to_cmd(struct aa_policydb *policy, aa_state_t state,
+			       u32 request, struct unix_sock *u,
+			       char cmd, struct aa_perms **p,
+			       const char **info)
+{
+	AA_BUG(!p);
+
+	state = match_to_sk(policy, state, request, u, p, info);
+	if (state && !*p) {
+		state = aa_dfa_match_len(policy->dfa, state, &cmd, 1);
+		if (!state)
+			*info = "failed cmd selection match";
+	}
+
+	return state;
+}
+
+static aa_state_t match_to_peer(struct aa_policydb *policy, aa_state_t state,
+				u32 request, struct unix_sock *u,
+				struct sockaddr_un *peer_addr, int peer_addrlen,
+				struct aa_perms **p, const char **info)
+{
+	AA_BUG(!p);
+
+	state = match_to_cmd(policy, state, request, u, CMD_ADDR, p, info);
+	if (state && !*p) {
+		state = match_addr(policy->dfa, state, peer_addr, peer_addrlen);
+		if (!state)
+			*info = "failed peer address match";
+	}
+
+	return state;
+}
+
+static aa_state_t match_label(struct aa_profile *profile,
+			      struct aa_ruleset *rule, aa_state_t state,
+			      u32 request, struct aa_profile *peer,
+			      struct aa_perms *p,
+			      struct apparmor_audit_data *ad)
+{
+	AA_BUG(!profile);
+	AA_BUG(!peer);
+
+	ad->peer = &peer->label;
+
+	if (state && !p) {
+		state = aa_dfa_match(rule->policy->dfa, state,
+				     peer->base.hname);
+		if (!state)
+			ad->info = "failed peer label match";
+
+	}
+
+	return aa_do_perms(profile, rule->policy, state, request, p, ad);
+}
+
+
+/* unix sock creation comes before we know if the socket will be an fs
+ * socket
+ * v6 - semantics are handled by mapping in profile load
+ * v7 - semantics require sock create for tasks creating an fs socket.
+ * v8 - same as v7
+ */
+static int profile_create_perm(struct aa_profile *profile, int family,
+			       int type, int protocol,
+			       struct apparmor_audit_data *ad)
+{
+	struct aa_ruleset *rules = profile->label.rules[0];
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(profile_unconfined(profile));
+
+	state = RULE_MEDIATES_v9NET(rules);
+	if (state) {
+		state = aa_match_to_prot(rules->policy, state, AA_MAY_CREATE,
+					 PF_UNIX, type, protocol, NULL,
+					 &ad->info);
+
+		return aa_do_perms(profile, rules->policy, state, AA_MAY_CREATE,
+				   NULL, ad);
+	}
+
+	return aa_profile_af_perm(profile, ad, AA_MAY_CREATE, family, type,
+				  protocol);
+}
+
+static int profile_sk_perm(struct aa_profile *profile,
+			   struct apparmor_audit_data *ad,
+			   u32 request, struct sock *sk, struct path *path)
+{
+	struct aa_ruleset *rules = profile->label.rules[0];
+	struct aa_perms *p = NULL;
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(!sk);
+	AA_BUG(profile_unconfined(profile));
+
+	state = RULE_MEDIATES_v9NET(rules);
+	if (state) {
+		if (is_unix_fs(sk))
+			return unix_fs_perm(ad->op, request, ad->subj_cred,
+					    &profile->label,
+					    &unix_sk(sk)->path);
+
+		state = match_to_sk(rules->policy, state, request, unix_sk(sk),
+				    &p, &ad->info);
+
+		return aa_do_perms(profile, rules->policy, state, request, p,
+				   ad);
+	}
+
+	return aa_profile_af_sk_perm(profile, ad, request, sk);
+}
+
+static int profile_bind_perm(struct aa_profile *profile, struct sock *sk,
+			     struct apparmor_audit_data *ad)
+{
+	struct aa_ruleset *rules = profile->label.rules[0];
+	struct aa_perms *p = NULL;
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(!sk);
+	AA_BUG(!ad);
+	AA_BUG(profile_unconfined(profile));
+
+	state = RULE_MEDIATES_v9NET(rules);
+	if (state) {
+		if (is_unix_addr_fs(ad->net.addr, ad->net.addrlen))
+			/* under v7-9 fs hook handles bind */
+			return 0;
+		/* bind for abstract socket */
+		state = match_to_local(rules->policy, state, AA_MAY_BIND,
+				       sk->sk_type, sk->sk_protocol,
+				       unix_addr(ad->net.addr),
+				       ad->net.addrlen,
+				       &p, &ad->info);
+
+		return aa_do_perms(profile, rules->policy, state, AA_MAY_BIND,
+				   p, ad);
+	}
+
+	return aa_profile_af_sk_perm(profile, ad, AA_MAY_BIND, sk);
+}
+
+static int profile_listen_perm(struct aa_profile *profile, struct sock *sk,
+			       int backlog, struct apparmor_audit_data *ad)
+{
+	struct aa_ruleset *rules = profile->label.rules[0];
+	struct aa_perms *p = NULL;
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(!sk);
+	AA_BUG(!ad);
+	AA_BUG(profile_unconfined(profile));
+
+	state = RULE_MEDIATES_v9NET(rules);
+	if (state) {
+		__be16 b = cpu_to_be16(backlog);
+
+		if (is_unix_fs(sk))
+			return unix_fs_perm(ad->op, AA_MAY_LISTEN,
+					    ad->subj_cred, &profile->label,
+					    &unix_sk(sk)->path);
+
+		state = match_to_cmd(rules->policy, state, AA_MAY_LISTEN,
+				     unix_sk(sk), CMD_LISTEN, &p, &ad->info);
+		if (state && !p) {
+			state = aa_dfa_match_len(rules->policy->dfa, state,
+						 (char *) &b, 2);
+			if (!state)
+				ad->info = "failed listen backlog match";
+		}
+		return aa_do_perms(profile, rules->policy, state, AA_MAY_LISTEN,
+				   p, ad);
+	}
+
+	return aa_profile_af_sk_perm(profile, ad, AA_MAY_LISTEN, sk);
+}
+
+static int profile_accept_perm(struct aa_profile *profile,
+			       struct sock *sk,
+			       struct apparmor_audit_data *ad)
+{
+	struct aa_ruleset *rules = profile->label.rules[0];
+	struct aa_perms *p = NULL;
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(!sk);
+	AA_BUG(!ad);
+	AA_BUG(profile_unconfined(profile));
+
+	state = RULE_MEDIATES_v9NET(rules);
+	if (state) {
+		if (is_unix_fs(sk))
+			return unix_fs_perm(ad->op, AA_MAY_ACCEPT,
+					    ad->subj_cred, &profile->label,
+					    &unix_sk(sk)->path);
+
+		state = match_to_sk(rules->policy, state, AA_MAY_ACCEPT,
+				    unix_sk(sk), &p, &ad->info);
+
+		return aa_do_perms(profile, rules->policy, state, AA_MAY_ACCEPT,
+				   p, ad);
+	}
+
+	return aa_profile_af_sk_perm(profile, ad, AA_MAY_ACCEPT, sk);
+}
+
+static int profile_opt_perm(struct aa_profile *profile, u32 request,
+			    struct sock *sk, int optname,
+			    struct apparmor_audit_data *ad)
+{
+	struct aa_ruleset *rules = profile->label.rules[0];
+	struct aa_perms *p = NULL;
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(!sk);
+	AA_BUG(!ad);
+	AA_BUG(profile_unconfined(profile));
+
+	state = RULE_MEDIATES_v9NET(rules);
+	if (state) {
+		__be16 b = cpu_to_be16(optname);
+		if (is_unix_fs(sk))
+			return unix_fs_perm(ad->op, request,
+					    ad->subj_cred, &profile->label,
+					    &unix_sk(sk)->path);
+
+		state = match_to_cmd(rules->policy, state, request, unix_sk(sk),
+				     CMD_OPT, &p, &ad->info);
+		if (state && !p) {
+			state = aa_dfa_match_len(rules->policy->dfa, state,
+						 (char *) &b, 2);
+			if (!state)
+				ad->info = "failed sockopt match";
+		}
+		return aa_do_perms(profile, rules->policy, state, request, p,
+				   ad);
+	}
+
+	return aa_profile_af_sk_perm(profile, ad, request, sk);
+}
+
+/* null peer_label is allowed, in which case the peer_sk label is used */
+static int profile_peer_perm(struct aa_profile *profile, u32 request,
+			     struct sock *sk, struct path *path,
+			     struct sockaddr_un *peer_addr,
+			     int peer_addrlen, struct path *peer_path,
+			     struct aa_label *peer_label,
+			     struct apparmor_audit_data *ad)
+{
+	struct aa_ruleset *rules = profile->label.rules[0];
+	struct aa_perms *p = NULL;
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(profile_unconfined(profile));
+	AA_BUG(!sk);
+	AA_BUG(!peer_label);
+	AA_BUG(!ad);
+
+	state = RULE_MEDIATES_v9NET(rules);
+	if (state) {
+		struct aa_profile *peerp;
+
+		if (peer_path)
+			return unix_fs_perm(ad->op, request, ad->subj_cred,
+					    &profile->label, peer_path);
+		else if (path)
+			return unix_fs_perm(ad->op, request, ad->subj_cred,
+					    &profile->label, path);
+		state = match_to_peer(rules->policy, state, request,
+				      unix_sk(sk),
+				      peer_addr, peer_addrlen, &p, &ad->info);
+
+		return fn_for_each_in_ns(peer_label, peerp,
+				match_label(profile, rules, state, request,
+					    peerp, p, ad));
+	}
+
+	return aa_profile_af_sk_perm(profile, ad, request, sk);
+}
+
+/* -------------------------------- */
+
+int aa_unix_create_perm(struct aa_label *label, int family, int type,
+			int protocol)
+{
+	if (!unconfined(label)) {
+		struct aa_profile *profile;
+		DEFINE_AUDIT_NET(ad, OP_CREATE, current_cred(), NULL, family,
+				 type, protocol);
+
+		return fn_for_each_confined(label, profile,
+				profile_create_perm(profile, family, type,
+						    protocol, &ad));
+	}
+
+	return 0;
+}
+
+static int aa_unix_label_sk_perm(const struct cred *subj_cred,
+				 struct aa_label *label,
+				 const char *op, u32 request, struct sock *sk,
+				 struct path *path)
+{
+	if (!unconfined(label)) {
+		struct aa_profile *profile;
+		DEFINE_AUDIT_SK(ad, op, subj_cred, sk);
+
+		return fn_for_each_confined(label, profile,
+				profile_sk_perm(profile, &ad, request, sk,
+						path));
+	}
+	return 0;
+}
+
+/* revalidation, get/set attr, shutdown */
+int aa_unix_sock_perm(const char *op, u32 request, struct socket *sock)
+{
+	struct aa_label *label;
+	int error;
+
+	label = begin_current_label_crit_section();
+	error = aa_unix_label_sk_perm(current_cred(), label, op,
+				      request, sock->sk,
+				      is_unix_fs(sock->sk) ? &unix_sk(sock->sk)->path : NULL);
+	end_current_label_crit_section(label);
+
+	return error;
+}
+
+static int valid_addr(struct sockaddr *addr, int addr_len)
+{
+	struct sockaddr_un *sunaddr = unix_addr(addr);
+
+	/* addr_len == offsetof(struct sockaddr_un, sun_path) is autobind */
+	if (addr_len < offsetof(struct sockaddr_un, sun_path) ||
+	    addr_len > sizeof(*sunaddr))
+		return -EINVAL;
+	return 0;
+}
+
+int aa_unix_bind_perm(struct socket *sock, struct sockaddr *addr,
+		      int addrlen)
+{
+	struct aa_profile *profile;
+	struct aa_label *label;
+	int error = 0;
+
+	error = valid_addr(addr, addrlen);
+	if (error)
+		return error;
+
+	label = begin_current_label_crit_section();
+	/* fs bind is handled by mknod */
+	if (!unconfined(label)) {
+		DEFINE_AUDIT_SK(ad, OP_BIND, current_cred(), sock->sk);
+
+		ad.net.addr = unix_addr(addr);
+		ad.net.addrlen = addrlen;
+
+		error = fn_for_each_confined(label, profile,
+				profile_bind_perm(profile, sock->sk, &ad));
+	}
+	end_current_label_crit_section(label);
+
+	return error;
+}
+
+/*
+ * unix connections are covered by the
+ * - unix_stream_connect (stream) and unix_may_send hooks (dgram)
+ * - fs connect is handled by open
+ * This is just here to document this is not needed for af_unix
+ *
+int aa_unix_connect_perm(struct socket *sock, struct sockaddr *address,
+			 int addrlen)
+{
+	return 0;
+}
+*/
+
+int aa_unix_listen_perm(struct socket *sock, int backlog)
+{
+	struct aa_profile *profile;
+	struct aa_label *label;
+	int error = 0;
+
+	label = begin_current_label_crit_section();
+	if (!unconfined(label)) {
+		DEFINE_AUDIT_SK(ad, OP_LISTEN, current_cred(), sock->sk);
+
+		error = fn_for_each_confined(label, profile,
+				profile_listen_perm(profile, sock->sk,
+						    backlog, &ad));
+	}
+	end_current_label_crit_section(label);
+
+	return error;
+}
+
+
+/* ability of sock to connect, not peer address binding */
+int aa_unix_accept_perm(struct socket *sock, struct socket *newsock)
+{
+	struct aa_profile *profile;
+	struct aa_label *label;
+	int error = 0;
+
+	label = begin_current_label_crit_section();
+	if (!unconfined(label)) {
+		DEFINE_AUDIT_SK(ad, OP_ACCEPT, current_cred(), sock->sk);
+
+		error = fn_for_each_confined(label, profile,
+				profile_accept_perm(profile, sock->sk, &ad));
+	}
+	end_current_label_crit_section(label);
+
+	return error;
+}
+
+
+/*
+ * dgram handled by unix_may_sendmsg, right to send on stream done at connect
+ * could do per msg unix_stream here, but connect + socket transfer is
+ * sufficient. This is just here to document this is not needed for af_unix
+ *
+ * sendmsg, recvmsg
+int aa_unix_msg_perm(const char *op, u32 request, struct socket *sock,
+		     struct msghdr *msg, int size)
+{
+	return 0;
+}
+*/
+
+int aa_unix_opt_perm(const char *op, u32 request, struct socket *sock,
+		     int level, int optname)
+{
+	struct aa_profile *profile;
+	struct aa_label *label;
+	int error = 0;
+
+	label = begin_current_label_crit_section();
+	if (!unconfined(label)) {
+		DEFINE_AUDIT_SK(ad, op, current_cred(), sock->sk);
+
+		error = fn_for_each_confined(label, profile,
+				profile_opt_perm(profile, request, sock->sk,
+						 optname, &ad));
+	}
+	end_current_label_crit_section(label);
+
+	return error;
+}
+
+static int unix_peer_perm(const struct cred *subj_cred,
+			  struct aa_label *label, const char *op, u32 request,
+			  struct sock *sk, struct path *path,
+			  struct sockaddr_un *peer_addr, int peer_addrlen,
+			  struct path *peer_path, struct aa_label *peer_label)
+{
+	struct aa_profile *profile;
+	DEFINE_AUDIT_SK(ad, op, subj_cred, sk);
+
+	ad.net.peer.addr = peer_addr;
+	ad.net.peer.addrlen = peer_addrlen;
+
+	return fn_for_each_confined(label, profile,
+			profile_peer_perm(profile, request, sk, path,
+					  peer_addr, peer_addrlen, peer_path,
+					  peer_label, &ad));
+}
+
+/**
+ *
+ * Requires: lock held on both @sk and @peer_sk
+ *           called by unix_stream_connect, unix_may_send
+ */
+int aa_unix_peer_perm(const struct cred *subj_cred,
+		      struct aa_label *label, const char *op, u32 request,
+		      struct sock *sk, struct sock *peer_sk,
+		      struct aa_label *peer_label)
+{
+	struct unix_sock *peeru = unix_sk(peer_sk);
+	struct unix_sock *u = unix_sk(sk);
+	int plen;
+	struct sockaddr_un *paddr = aa_sunaddr(unix_sk(peer_sk), &plen);
+
+	AA_BUG(!label);
+	AA_BUG(!sk);
+	AA_BUG(!peer_sk);
+	AA_BUG(!peer_label);
+
+	return unix_peer_perm(subj_cred, label, op, request, sk,
+			      is_unix_fs(sk) ? &u->path : NULL,
+			      paddr, plen,
+			      is_unix_fs(peer_sk) ? &peeru->path : NULL,
+			      peer_label);
+}
+
+/* sk_plabel for comparison only */
+static void update_sk_ctx(struct sock *sk, struct aa_label *label,
+			  struct aa_label *plabel)
+{
+	struct aa_label *l, *old;
+	struct aa_sk_ctx *ctx = aa_sock(sk);
+	bool update_sk;
+
+	rcu_read_lock();
+	update_sk = (plabel &&
+		     (plabel != rcu_access_pointer(ctx->peer_lastupdate) ||
+		      !aa_label_is_subset(plabel, rcu_dereference(ctx->peer)))) ||
+	  !__aa_subj_label_is_cached(label, rcu_dereference(ctx->label));
+	rcu_read_unlock();
+	if (!update_sk)
+		return;
+
+	spin_lock(&unix_sk(sk)->lock);
+	old = rcu_dereference_protected(ctx->label,
+					lockdep_is_held(&unix_sk(sk)->lock));
+	l = aa_label_merge(old, label, GFP_ATOMIC);
+	if (l) {
+		if (l != old) {
+			rcu_assign_pointer(ctx->label, l);
+			aa_put_label(old);
+		} else
+			aa_put_label(l);
+	}
+	if (plabel && rcu_access_pointer(ctx->peer_lastupdate) != plabel) {
+		old = rcu_dereference_protected(ctx->peer, lockdep_is_held(&unix_sk(sk)->lock));
+
+		if (old == plabel) {
+			rcu_assign_pointer(ctx->peer_lastupdate, plabel);
+		} else if (aa_label_is_subset(plabel, old)) {
+			rcu_assign_pointer(ctx->peer_lastupdate, plabel);
+			rcu_assign_pointer(ctx->peer, aa_get_label(plabel));
+			aa_put_label(old);
+		} /* else race or a subset - don't update */
+	}
+	spin_unlock(&unix_sk(sk)->lock);
+}
+
+static void update_peer_ctx(struct sock *sk, struct aa_sk_ctx *ctx,
+			    struct aa_label *label)
+{
+	struct aa_label *l, *old;
+
+	spin_lock(&unix_sk(sk)->lock);
+	old = rcu_dereference_protected(ctx->peer,
+					lockdep_is_held(&unix_sk(sk)->lock));
+	l = aa_label_merge(old, label, GFP_ATOMIC);
+	if (l) {
+		if (l != old) {
+			rcu_assign_pointer(ctx->peer, l);
+			aa_put_label(old);
+		} else
+			aa_put_label(l);
+	}
+	spin_unlock(&unix_sk(sk)->lock);
+}
+
+/* This fn is only checked if something has changed in the security
+ * boundaries. Otherwise cached info off file is sufficient
+ */
+int aa_unix_file_perm(const struct cred *subj_cred, struct aa_label *label,
+		      const char *op, u32 request, struct file *file)
+{
+	struct socket *sock = (struct socket *) file->private_data;
+	struct sockaddr_un *addr, *peer_addr;
+	int addrlen, peer_addrlen;
+	struct aa_label *plabel = NULL;
+	struct sock *peer_sk = NULL;
+	u32 sk_req = request & ~NET_PEER_MASK;
+	struct path path;
+	bool is_sk_fs;
+	int error = 0;
+
+	AA_BUG(!label);
+	AA_BUG(!sock);
+	AA_BUG(!sock->sk);
+	AA_BUG(sock->sk->sk_family != PF_UNIX);
+
+	/* investigate only using lock via unix_peer_get()
+	 * addr only needs the memory barrier, but need to investigate
+	 * path
+	 */
+	unix_state_lock(sock->sk);
+	peer_sk = unix_peer(sock->sk);
+	if (peer_sk)
+		sock_hold(peer_sk);
+
+	is_sk_fs = is_unix_fs(sock->sk);
+	addr = aa_sunaddr(unix_sk(sock->sk), &addrlen);
+	path = unix_sk(sock->sk)->path;
+	unix_state_unlock(sock->sk);
+
+	if (is_sk_fs && peer_sk)
+		sk_req = request;
+	if (sk_req) {
+			error = aa_unix_label_sk_perm(subj_cred, label, op,
+						      sk_req, sock->sk,
+						      is_sk_fs ? &path : NULL);
+	}
+	if (!peer_sk)
+		goto out;
+
+	peer_addr = aa_sunaddr(unix_sk(peer_sk), &peer_addrlen);
+
+	struct path peer_path;
+
+	peer_path = unix_sk(peer_sk)->path;
+	if (!is_sk_fs && is_unix_fs(peer_sk)) {
+		last_error(error,
+			   unix_fs_perm(op, request, subj_cred, label,
+					is_unix_fs(peer_sk) ? &peer_path : NULL));
+	} else if (!is_sk_fs) {
+		struct aa_label *plabel;
+		struct aa_sk_ctx *pctx = aa_sock(peer_sk);
+
+		rcu_read_lock();
+		plabel = aa_get_label_rcu(&pctx->label);
+		rcu_read_unlock();
+		/* no fs check of aa_unix_peer_perm because conditions above
+		 * ensure they will never be done
+		 */
+		last_error(error,
+			xcheck(unix_peer_perm(subj_cred, label, op,
+					      MAY_READ | MAY_WRITE, sock->sk,
+					      is_sk_fs ? &path : NULL,
+					      peer_addr, peer_addrlen,
+					      is_unix_fs(peer_sk) ?
+							&peer_path : NULL,
+					      plabel),
+			       unix_peer_perm(file->f_cred, plabel, op,
+					      MAY_READ | MAY_WRITE, peer_sk,
+					      is_unix_fs(peer_sk) ?
+							&peer_path : NULL,
+					      addr, addrlen,
+					      is_sk_fs ? &path : NULL,
+					      label)));
+		if (!error && !__aa_subj_label_is_cached(plabel, label))
+			update_peer_ctx(peer_sk, pctx, label);
+	}
+	sock_put(peer_sk);
+
+out:
+
+	/* update peer cache to latest successful perm check */
+	if (error == 0)
+		update_sk_ctx(sock->sk, label, plabel);
+	aa_put_label(plabel);
+
+	return error;
+}
+