1 files changed, 702 insertions, 0 deletions

diff --git a/security/apparmor/af_unix.c b/security/apparmor/af_unix.c
new file mode 100644
index 000000000000..ce7dc9d98fb1
--- /dev/null
+++ b/security/apparmor/af_unix.c
@@ -0,0 +1,702 @@
+// 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 <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 unix_sock *u)
+{
+	AA_BUG(!label);
+	AA_BUG(!u);
+	AA_BUG(!is_unix_fs(aa_unix_sk(u)));
+
+	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 (u->path.dentry) {
+		/* the sunpath may not be valid for this ns so use the path */
+		struct path_cond cond = { u->path.dentry->d_inode->i_uid,
+					  u->path.dentry->d_inode->i_mode
+		};
+
+		return aa_path_perm(op, subj_cred, label, &u->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;
+}
+
+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)
+{
+	struct sockaddr_un *addr = NULL;
+	int addrlen = 0;
+
+	if (u->addr) {
+		addr = u->addr->name;
+		addrlen = u->addr->len;
+	}
+
+	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 = list_first_entry(&profile->rules,
+						    typeof(*rules), list);
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(profile_unconfined(profile));
+
+	state = RULE_MEDIATES_NET(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 aa_ruleset *rules = list_first_entry(&profile->rules,
+						    typeof(*rules),
+						    list);
+	struct aa_perms *p = NULL;
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(!sk);
+	AA_BUG(is_unix_fs(sk));
+	AA_BUG(profile_unconfined(profile));
+
+	state = RULE_MEDIATES_NET(rules);
+	if (state) {
+		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 = list_first_entry(&profile->rules,
+						    typeof(*rules), list);
+	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_NET(rules);
+	if (state) {
+		/* 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 = list_first_entry(&profile->rules,
+						    typeof(*rules), list);
+	struct aa_perms *p = NULL;
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(!sk);
+	AA_BUG(is_unix_fs(sk));
+	AA_BUG(!ad);
+	AA_BUG(profile_unconfined(profile));
+
+	state = RULE_MEDIATES_NET(rules);
+	if (state) {
+		__be16 b = cpu_to_be16(backlog);
+
+		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 = list_first_entry(&profile->rules,
+						    typeof(*rules), list);
+	struct aa_perms *p = NULL;
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(!sk);
+	AA_BUG(is_unix_fs(sk));
+	AA_BUG(!ad);
+	AA_BUG(profile_unconfined(profile));
+
+	state = RULE_MEDIATES_NET(rules);
+	if (state) {
+		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 = list_first_entry(&profile->rules,
+						    typeof(*rules), list);
+	struct aa_perms *p = NULL;
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(!sk);
+	AA_BUG(is_unix_fs(sk));
+	AA_BUG(!ad);
+	AA_BUG(profile_unconfined(profile));
+
+	state = RULE_MEDIATES_NET(rules);
+	if (state) {
+		__be16 b = cpu_to_be16(optname);
+
+		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 sock *peer_sk,
+			     struct aa_label *peer_label,
+			     struct apparmor_audit_data *ad)
+{
+	struct aa_ruleset *rules = list_first_entry(&profile->rules,
+						    typeof(*rules), list);
+	struct aa_perms *p = NULL;
+	aa_state_t state;
+
+	AA_BUG(!profile);
+	AA_BUG(profile_unconfined(profile));
+	AA_BUG(!sk);
+	AA_BUG(!peer_sk);
+	AA_BUG(!ad);
+	AA_BUG(is_unix_fs(peer_sk)); /* currently always calls unix_fs_perm */
+
+	state = RULE_MEDIATES_NET(rules);
+	if (state) {
+		struct aa_sk_ctx *peer_ctx = aa_sock(peer_sk);
+		struct aa_profile *peerp;
+		struct sockaddr_un *addr = NULL;
+		int len = 0;
+
+		if (unix_sk(peer_sk)->addr) {
+			addr = unix_sk(peer_sk)->addr->name;
+			len = unix_sk(peer_sk)->addr->len;
+		}
+		state = match_to_peer(rules->policy, state, request,
+				      unix_sk(sk),
+				      addr, len, &p, &ad->info);
+		if (!peer_label)
+			peer_label = peer_ctx->label;
+
+		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;
+}
+
+int aa_unix_label_sk_perm(const struct cred *subj_cred,
+			  struct aa_label *label, const char *op, u32 request,
+			  struct sock *sk)
+{
+	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));
+	}
+	return 0;
+}
+
+static int unix_label_sock_perm(const struct cred *subj_cred,
+				struct aa_label *label, const char *op,
+				u32 request, struct socket *sock)
+{
+	if (unconfined(label))
+		return 0;
+	if (is_unix_fs(sock->sk))
+		return unix_fs_perm(op, request, subj_cred, label,
+				    unix_sk(sock->sk));
+
+	return aa_unix_label_sk_perm(subj_cred, label, op, request, sock->sk);
+}
+
+/* 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 = unix_label_sock_perm(current_cred(), label, op, request, sock);
+	end_current_label_crit_section(label);
+
+	return error;
+}
+
+static int valid_addr(struct sockaddr *addr, int addr_len)
+{
+	struct sockaddr_un *sunaddr = (struct sockaddr_un *)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) || is_unix_addr_fs(addr, addrlen))) {
+		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) || is_unix_fs(sock->sk))) {
+		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) || is_unix_fs(sock->sk))) {
+		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) || is_unix_fs(sock->sk))) {
+		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;
+}
+
+/**
+ *
+ * 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);
+
+	AA_BUG(!label);
+	AA_BUG(!sk);
+	AA_BUG(!peer_sk);
+
+	if (is_unix_fs(aa_unix_sk(peeru))) {
+		return unix_fs_perm(op, request, subj_cred, label, peeru);
+	} else if (is_unix_fs(aa_unix_sk(u))) {
+		return unix_fs_perm(op, request, subj_cred, label, u);
+	} else if (!unconfined(label)) {
+		struct aa_profile *profile;
+		DEFINE_AUDIT_SK(ad, op, subj_cred, sk);
+
+		ad.net.peer_sk = peer_sk;
+
+		return fn_for_each_confined(label, profile,
+				profile_peer_perm(profile, request, sk,
+						  peer_sk, peer_label, &ad));
+	}
+
+	return 0;
+}
+
+static void unix_state_double_lock(struct sock *sk1, struct sock *sk2)
+{
+	if (unlikely(sk1 == sk2) || !sk2) {
+		unix_state_lock(sk1);
+		return;
+	}
+	if (sk1 < sk2) {
+		unix_state_lock(sk1);
+		unix_state_lock(sk2);
+	} else {
+		unix_state_lock(sk2);
+		unix_state_lock(sk1);
+	}
+}
+
+static void unix_state_double_unlock(struct sock *sk1, struct sock *sk2)
+{
+	if (unlikely(sk1 == sk2) || !sk2) {
+		unix_state_unlock(sk1);
+		return;
+	}
+	unix_state_unlock(sk1);
+	unix_state_unlock(sk2);
+}
+
+/* TODO: examine replacing double lock with cached addr */
+
+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 sock *peer_sk = NULL;
+	u32 sk_req = request & ~NET_PEER_MASK;
+	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);
+
+	/* TODO: update sock label with new task label */
+	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);
+	if (is_sk_fs && peer_sk)
+		sk_req = request;
+	if (sk_req)
+		error = unix_label_sock_perm(subj_cred, label, op, sk_req,
+					     sock);
+	unix_state_unlock(sock->sk);
+	if (!peer_sk)
+		return error;
+
+	unix_state_double_lock(sock->sk, peer_sk);
+	if (!is_sk_fs && is_unix_fs(peer_sk)) {
+		last_error(error,
+			   unix_fs_perm(op, request, subj_cred, label,
+					unix_sk(peer_sk)));
+	} else if (!is_sk_fs) {
+		struct aa_sk_ctx *pctx = aa_sock(peer_sk);
+
+		last_error(error,
+			xcheck(aa_unix_peer_perm(subj_cred, label, op,
+						 MAY_READ | MAY_WRITE,
+						 sock->sk, peer_sk, NULL),
+			       aa_unix_peer_perm(file->f_cred, pctx->label, op,
+						 MAY_READ | MAY_WRITE,
+						 peer_sk, sock->sk, label)));
+	}
+	unix_state_double_unlock(sock->sk, peer_sk);
+
+	sock_put(peer_sk);
+
+	return error;
+}