TOMOYO: Add socket operation restriction support.

This patch adds support for permission checks for PF_INET/PF_INET6/PF_UNIX
socket's bind()/listen()/connect()/send() operations.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 771 insertions, 0 deletions

diff --git a/security/tomoyo/network.c b/security/tomoyo/network.c
new file mode 100644
index 000000000000..97527710a72a
--- /dev/null
+++ b/security/tomoyo/network.c
@@ -0,0 +1,771 @@
+/*
+ * security/tomoyo/network.c
+ *
+ * Copyright (C) 2005-2011  NTT DATA CORPORATION
+ */
+
+#include "common.h"
+#include <linux/slab.h>
+
+/* Structure for holding inet domain socket's address. */
+struct tomoyo_inet_addr_info {
+	__be16 port;           /* In network byte order. */
+	const __be32 *address; /* In network byte order. */
+	bool is_ipv6;
+};
+
+/* Structure for holding unix domain socket's address. */
+struct tomoyo_unix_addr_info {
+	u8 *addr; /* This may not be '\0' terminated string. */
+	unsigned int addr_len;
+};
+
+/* Structure for holding socket address. */
+struct tomoyo_addr_info {
+	u8 protocol;
+	u8 operation;
+	struct tomoyo_inet_addr_info inet;
+	struct tomoyo_unix_addr_info unix0;
+};
+
+/* String table for socket's protocols. */
+const char * const tomoyo_proto_keyword[TOMOYO_SOCK_MAX] = {
+	[SOCK_STREAM]    = "stream",
+	[SOCK_DGRAM]     = "dgram",
+	[SOCK_RAW]       = "raw",
+	[SOCK_SEQPACKET] = "seqpacket",
+	[0] = " ", /* Dummy for avoiding NULL pointer dereference. */
+	[4] = " ", /* Dummy for avoiding NULL pointer dereference. */
+};
+
+/**
+ * tomoyo_parse_ipaddr_union - Parse an IP address.
+ *
+ * @param: Pointer to "struct tomoyo_acl_param".
+ * @ptr:   Pointer to "struct tomoyo_ipaddr_union".
+ *
+ * Returns true on success, false otherwise.
+ */
+bool tomoyo_parse_ipaddr_union(struct tomoyo_acl_param *param,
+			       struct tomoyo_ipaddr_union *ptr)
+{
+	u8 * const min = ptr->ip[0].in6_u.u6_addr8;
+	u8 * const max = ptr->ip[1].in6_u.u6_addr8;
+	char *address = tomoyo_read_token(param);
+	const char *end;
+
+	if (!strchr(address, ':') &&
+	    in4_pton(address, -1, min, '-', &end) > 0) {
+		ptr->is_ipv6 = false;
+		if (!*end)
+			ptr->ip[1].s6_addr32[0] = ptr->ip[0].s6_addr32[0];
+		else if (*end++ != '-' ||
+			 in4_pton(end, -1, max, '\0', &end) <= 0 || *end)
+			return false;
+		return true;
+	}
+	if (in6_pton(address, -1, min, '-', &end) > 0) {
+		ptr->is_ipv6 = true;
+		if (!*end)
+			memmove(max, min, sizeof(u16) * 8);
+		else if (*end++ != '-' ||
+			 in6_pton(end, -1, max, '\0', &end) <= 0 || *end)
+			return false;
+		return true;
+	}
+	return false;
+}
+
+/**
+ * tomoyo_print_ipv4 - Print an IPv4 address.
+ *
+ * @buffer:     Buffer to write to.
+ * @buffer_len: Size of @buffer.
+ * @min_ip:     Pointer to __be32.
+ * @max_ip:     Pointer to __be32.
+ *
+ * Returns nothing.
+ */
+static void tomoyo_print_ipv4(char *buffer, const unsigned int buffer_len,
+			      const __be32 *min_ip, const __be32 *max_ip)
+{
+	snprintf(buffer, buffer_len, "%pI4%c%pI4", min_ip,
+		 *min_ip == *max_ip ? '\0' : '-', max_ip);
+}
+
+/**
+ * tomoyo_print_ipv6 - Print an IPv6 address.
+ *
+ * @buffer:     Buffer to write to.
+ * @buffer_len: Size of @buffer.
+ * @min_ip:     Pointer to "struct in6_addr".
+ * @max_ip:     Pointer to "struct in6_addr".
+ *
+ * Returns nothing.
+ */
+static void tomoyo_print_ipv6(char *buffer, const unsigned int buffer_len,
+			      const struct in6_addr *min_ip,
+			      const struct in6_addr *max_ip)
+{
+	snprintf(buffer, buffer_len, "%pI6c%c%pI6c", min_ip,
+		 !memcmp(min_ip, max_ip, 16) ? '\0' : '-', max_ip);
+}
+
+/**
+ * tomoyo_print_ip - Print an IP address.
+ *
+ * @buf:  Buffer to write to.
+ * @size: Size of @buf.
+ * @ptr:  Pointer to "struct ipaddr_union".
+ *
+ * Returns nothing.
+ */
+void tomoyo_print_ip(char *buf, const unsigned int size,
+		     const struct tomoyo_ipaddr_union *ptr)
+{
+	if (ptr->is_ipv6)
+		tomoyo_print_ipv6(buf, size, &ptr->ip[0], &ptr->ip[1]);
+	else
+		tomoyo_print_ipv4(buf, size, &ptr->ip[0].s6_addr32[0],
+				  &ptr->ip[1].s6_addr32[0]);
+}
+
+/*
+ * Mapping table from "enum tomoyo_network_acl_index" to
+ * "enum tomoyo_mac_index" for inet domain socket.
+ */
+static const u8 tomoyo_inet2mac
+[TOMOYO_SOCK_MAX][TOMOYO_MAX_NETWORK_OPERATION] = {
+	[SOCK_STREAM] = {
+		[TOMOYO_NETWORK_BIND]    = TOMOYO_MAC_NETWORK_INET_STREAM_BIND,
+		[TOMOYO_NETWORK_LISTEN]  =
+		TOMOYO_MAC_NETWORK_INET_STREAM_LISTEN,
+		[TOMOYO_NETWORK_CONNECT] =
+		TOMOYO_MAC_NETWORK_INET_STREAM_CONNECT,
+	},
+	[SOCK_DGRAM] = {
+		[TOMOYO_NETWORK_BIND]    = TOMOYO_MAC_NETWORK_INET_DGRAM_BIND,
+		[TOMOYO_NETWORK_SEND]    = TOMOYO_MAC_NETWORK_INET_DGRAM_SEND,
+	},
+	[SOCK_RAW]    = {
+		[TOMOYO_NETWORK_BIND]    = TOMOYO_MAC_NETWORK_INET_RAW_BIND,
+		[TOMOYO_NETWORK_SEND]    = TOMOYO_MAC_NETWORK_INET_RAW_SEND,
+	},
+};
+
+/*
+ * Mapping table from "enum tomoyo_network_acl_index" to
+ * "enum tomoyo_mac_index" for unix domain socket.
+ */
+static const u8 tomoyo_unix2mac
+[TOMOYO_SOCK_MAX][TOMOYO_MAX_NETWORK_OPERATION] = {
+	[SOCK_STREAM] = {
+		[TOMOYO_NETWORK_BIND]    = TOMOYO_MAC_NETWORK_UNIX_STREAM_BIND,
+		[TOMOYO_NETWORK_LISTEN]  =
+		TOMOYO_MAC_NETWORK_UNIX_STREAM_LISTEN,
+		[TOMOYO_NETWORK_CONNECT] =
+		TOMOYO_MAC_NETWORK_UNIX_STREAM_CONNECT,
+	},
+	[SOCK_DGRAM] = {
+		[TOMOYO_NETWORK_BIND]    = TOMOYO_MAC_NETWORK_UNIX_DGRAM_BIND,
+		[TOMOYO_NETWORK_SEND]    = TOMOYO_MAC_NETWORK_UNIX_DGRAM_SEND,
+	},
+	[SOCK_SEQPACKET] = {
+		[TOMOYO_NETWORK_BIND]    =
+		TOMOYO_MAC_NETWORK_UNIX_SEQPACKET_BIND,
+		[TOMOYO_NETWORK_LISTEN]  =
+		TOMOYO_MAC_NETWORK_UNIX_SEQPACKET_LISTEN,
+		[TOMOYO_NETWORK_CONNECT] =
+		TOMOYO_MAC_NETWORK_UNIX_SEQPACKET_CONNECT,
+	},
+};
+
+/**
+ * tomoyo_same_inet_acl - Check for duplicated "struct tomoyo_inet_acl" entry.
+ *
+ * @a: Pointer to "struct tomoyo_acl_info".
+ * @b: Pointer to "struct tomoyo_acl_info".
+ *
+ * Returns true if @a == @b except permission bits, false otherwise.
+ */
+static bool tomoyo_same_inet_acl(const struct tomoyo_acl_info *a,
+				 const struct tomoyo_acl_info *b)
+{
+	const struct tomoyo_inet_acl *p1 = container_of(a, typeof(*p1), head);
+	const struct tomoyo_inet_acl *p2 = container_of(b, typeof(*p2), head);
+
+	return p1->protocol == p2->protocol &&
+		tomoyo_same_ipaddr_union(&p1->address, &p2->address) &&
+		tomoyo_same_number_union(&p1->port, &p2->port);
+}
+
+/**
+ * tomoyo_same_unix_acl - Check for duplicated "struct tomoyo_unix_acl" entry.
+ *
+ * @a: Pointer to "struct tomoyo_acl_info".
+ * @b: Pointer to "struct tomoyo_acl_info".
+ *
+ * Returns true if @a == @b except permission bits, false otherwise.
+ */
+static bool tomoyo_same_unix_acl(const struct tomoyo_acl_info *a,
+				 const struct tomoyo_acl_info *b)
+{
+	const struct tomoyo_unix_acl *p1 = container_of(a, typeof(*p1), head);
+	const struct tomoyo_unix_acl *p2 = container_of(b, typeof(*p2), head);
+
+	return p1->protocol == p2->protocol &&
+		tomoyo_same_name_union(&p1->name, &p2->name);
+}
+
+/**
+ * tomoyo_merge_inet_acl - Merge duplicated "struct tomoyo_inet_acl" entry.
+ *
+ * @a:         Pointer to "struct tomoyo_acl_info".
+ * @b:         Pointer to "struct tomoyo_acl_info".
+ * @is_delete: True for @a &= ~@b, false for @a |= @b.
+ *
+ * Returns true if @a is empty, false otherwise.
+ */
+static bool tomoyo_merge_inet_acl(struct tomoyo_acl_info *a,
+				  struct tomoyo_acl_info *b,
+				  const bool is_delete)
+{
+	u8 * const a_perm =
+		&container_of(a, struct tomoyo_inet_acl, head)->perm;
+	u8 perm = *a_perm;
+	const u8 b_perm = container_of(b, struct tomoyo_inet_acl, head)->perm;
+
+	if (is_delete)
+		perm &= ~b_perm;
+	else
+		perm |= b_perm;
+	*a_perm = perm;
+	return !perm;
+}
+
+/**
+ * tomoyo_merge_unix_acl - Merge duplicated "struct tomoyo_unix_acl" entry.
+ *
+ * @a:         Pointer to "struct tomoyo_acl_info".
+ * @b:         Pointer to "struct tomoyo_acl_info".
+ * @is_delete: True for @a &= ~@b, false for @a |= @b.
+ *
+ * Returns true if @a is empty, false otherwise.
+ */
+static bool tomoyo_merge_unix_acl(struct tomoyo_acl_info *a,
+				  struct tomoyo_acl_info *b,
+				  const bool is_delete)
+{
+	u8 * const a_perm =
+		&container_of(a, struct tomoyo_unix_acl, head)->perm;
+	u8 perm = *a_perm;
+	const u8 b_perm = container_of(b, struct tomoyo_unix_acl, head)->perm;
+
+	if (is_delete)
+		perm &= ~b_perm;
+	else
+		perm |= b_perm;
+	*a_perm = perm;
+	return !perm;
+}
+
+/**
+ * tomoyo_write_inet_network - Write "struct tomoyo_inet_acl" list.
+ *
+ * @param: Pointer to "struct tomoyo_acl_param".
+ *
+ * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+int tomoyo_write_inet_network(struct tomoyo_acl_param *param)
+{
+	struct tomoyo_inet_acl e = { .head.type = TOMOYO_TYPE_INET_ACL };
+	int error = -EINVAL;
+	u8 type;
+	const char *protocol = tomoyo_read_token(param);
+	const char *operation = tomoyo_read_token(param);
+
+	for (e.protocol = 0; e.protocol < TOMOYO_SOCK_MAX; e.protocol++)
+		if (!strcmp(protocol, tomoyo_proto_keyword[e.protocol]))
+			break;
+	for (type = 0; type < TOMOYO_MAX_NETWORK_OPERATION; type++)
+		if (tomoyo_permstr(operation, tomoyo_socket_keyword[type]))
+			e.perm |= 1 << type;
+	if (e.protocol == TOMOYO_SOCK_MAX || !e.perm)
+		return -EINVAL;
+	if (param->data[0] == '@') {
+		param->data++;
+		e.address.group =
+			tomoyo_get_group(param, TOMOYO_ADDRESS_GROUP);
+		if (!e.address.group)
+			return -ENOMEM;
+	} else {
+		if (!tomoyo_parse_ipaddr_union(param, &e.address))
+			goto out;
+	}
+	if (!tomoyo_parse_number_union(param, &e.port) ||
+	    e.port.values[1] > 65535)
+		goto out;
+	error = tomoyo_update_domain(&e.head, sizeof(e), param,
+				     tomoyo_same_inet_acl,
+				     tomoyo_merge_inet_acl);
+out:
+	tomoyo_put_group(e.address.group);
+	tomoyo_put_number_union(&e.port);
+	return error;
+}
+
+/**
+ * tomoyo_write_unix_network - Write "struct tomoyo_unix_acl" list.
+ *
+ * @param: Pointer to "struct tomoyo_acl_param".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_write_unix_network(struct tomoyo_acl_param *param)
+{
+	struct tomoyo_unix_acl e = { .head.type = TOMOYO_TYPE_UNIX_ACL };
+	int error;
+	u8 type;
+	const char *protocol = tomoyo_read_token(param);
+	const char *operation = tomoyo_read_token(param);
+
+	for (e.protocol = 0; e.protocol < TOMOYO_SOCK_MAX; e.protocol++)
+		if (!strcmp(protocol, tomoyo_proto_keyword[e.protocol]))
+			break;
+	for (type = 0; type < TOMOYO_MAX_NETWORK_OPERATION; type++)
+		if (tomoyo_permstr(operation, tomoyo_socket_keyword[type]))
+			e.perm |= 1 << type;
+	if (e.protocol == TOMOYO_SOCK_MAX || !e.perm)
+		return -EINVAL;
+	if (!tomoyo_parse_name_union(param, &e.name))
+		return -EINVAL;
+	error = tomoyo_update_domain(&e.head, sizeof(e), param,
+				     tomoyo_same_unix_acl,
+				     tomoyo_merge_unix_acl);
+	tomoyo_put_name_union(&e.name);
+	return error;
+}
+
+/**
+ * tomoyo_audit_net_log - Audit network log.
+ *
+ * @r:         Pointer to "struct tomoyo_request_info".
+ * @family:    Name of socket family ("inet" or "unix").
+ * @protocol:  Name of protocol in @family.
+ * @operation: Name of socket operation.
+ * @address:   Name of address.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_audit_net_log(struct tomoyo_request_info *r,
+				const char *family, const u8 protocol,
+				const u8 operation, const char *address)
+{
+	return tomoyo_supervisor(r, "network %s %s %s %s\n", family,
+				 tomoyo_proto_keyword[protocol],
+				 tomoyo_socket_keyword[operation], address);
+}
+
+/**
+ * tomoyo_audit_inet_log - Audit INET network log.
+ *
+ * @r: Pointer to "struct tomoyo_request_info".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_audit_inet_log(struct tomoyo_request_info *r)
+{
+	char buf[128];
+	int len;
+	const __be32 *address = r->param.inet_network.address;
+
+	if (r->param.inet_network.is_ipv6)
+		tomoyo_print_ipv6(buf, sizeof(buf), (const struct in6_addr *)
+				  address, (const struct in6_addr *) address);
+	else
+		tomoyo_print_ipv4(buf, sizeof(buf), address, address);
+	len = strlen(buf);
+	snprintf(buf + len, sizeof(buf) - len, " %u",
+		 r->param.inet_network.port);
+	return tomoyo_audit_net_log(r, "inet", r->param.inet_network.protocol,
+				    r->param.inet_network.operation, buf);
+}
+
+/**
+ * tomoyo_audit_unix_log - Audit UNIX network log.
+ *
+ * @r: Pointer to "struct tomoyo_request_info".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_audit_unix_log(struct tomoyo_request_info *r)
+{
+	return tomoyo_audit_net_log(r, "unix", r->param.unix_network.protocol,
+				    r->param.unix_network.operation,
+				    r->param.unix_network.address->name);
+}
+
+/**
+ * tomoyo_check_inet_acl - Check permission for inet domain socket operation.
+ *
+ * @r:   Pointer to "struct tomoyo_request_info".
+ * @ptr: Pointer to "struct tomoyo_acl_info".
+ *
+ * Returns true if granted, false otherwise.
+ */
+static bool tomoyo_check_inet_acl(struct tomoyo_request_info *r,
+				  const struct tomoyo_acl_info *ptr)
+{
+	const struct tomoyo_inet_acl *acl =
+		container_of(ptr, typeof(*acl), head);
+	const u8 size = r->param.inet_network.is_ipv6 ? 16 : 4;
+
+	if (!(acl->perm & (1 << r->param.inet_network.operation)) ||
+	    !tomoyo_compare_number_union(r->param.inet_network.port,
+					 &acl->port))
+		return false;
+	if (acl->address.group)
+		return tomoyo_address_matches_group
+			(r->param.inet_network.is_ipv6,
+			 r->param.inet_network.address, acl->address.group);
+	return acl->address.is_ipv6 == r->param.inet_network.is_ipv6 &&
+		memcmp(&acl->address.ip[0],
+		       r->param.inet_network.address, size) <= 0 &&
+		memcmp(r->param.inet_network.address,
+		       &acl->address.ip[1], size) <= 0;
+}
+
+/**
+ * tomoyo_check_unix_acl - Check permission for unix domain socket operation.
+ *
+ * @r:   Pointer to "struct tomoyo_request_info".
+ * @ptr: Pointer to "struct tomoyo_acl_info".
+ *
+ * Returns true if granted, false otherwise.
+ */
+static bool tomoyo_check_unix_acl(struct tomoyo_request_info *r,
+				  const struct tomoyo_acl_info *ptr)
+{
+	const struct tomoyo_unix_acl *acl =
+		container_of(ptr, typeof(*acl), head);
+
+	return (acl->perm & (1 << r->param.unix_network.operation)) &&
+		tomoyo_compare_name_union(r->param.unix_network.address,
+					  &acl->name);
+}
+
+/**
+ * tomoyo_inet_entry - Check permission for INET network operation.
+ *
+ * @address: Pointer to "struct tomoyo_addr_info".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_inet_entry(const struct tomoyo_addr_info *address)
+{
+	const int idx = tomoyo_read_lock();
+	struct tomoyo_request_info r;
+	int error = 0;
+	const u8 type = tomoyo_inet2mac[address->protocol][address->operation];
+
+	if (type && tomoyo_init_request_info(&r, NULL, type)
+	    != TOMOYO_CONFIG_DISABLED) {
+		r.param_type = TOMOYO_TYPE_INET_ACL;
+		r.param.inet_network.protocol = address->protocol;
+		r.param.inet_network.operation = address->operation;
+		r.param.inet_network.is_ipv6 = address->inet.is_ipv6;
+		r.param.inet_network.address = address->inet.address;
+		r.param.inet_network.port = ntohs(address->inet.port);
+		do {
+			tomoyo_check_acl(&r, tomoyo_check_inet_acl);
+			error = tomoyo_audit_inet_log(&r);
+		} while (error == TOMOYO_RETRY_REQUEST);
+	}
+	tomoyo_read_unlock(idx);
+	return error;
+}
+
+/**
+ * tomoyo_check_inet_address - Check permission for inet domain socket's operation.
+ *
+ * @addr:     Pointer to "struct sockaddr".
+ * @addr_len: Size of @addr.
+ * @port:     Port number.
+ * @address:  Pointer to "struct tomoyo_addr_info".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_check_inet_address(const struct sockaddr *addr,
+				     const unsigned int addr_len,
+				     const u16 port,
+				     struct tomoyo_addr_info *address)
+{
+	struct tomoyo_inet_addr_info *i = &address->inet;
+
+	switch (addr->sa_family) {
+	case AF_INET6:
+		if (addr_len < SIN6_LEN_RFC2133)
+			goto skip;
+		i->is_ipv6 = true;
+		i->address = (__be32 *)
+			((struct sockaddr_in6 *) addr)->sin6_addr.s6_addr;
+		i->port = ((struct sockaddr_in6 *) addr)->sin6_port;
+		break;
+	case AF_INET:
+		if (addr_len < sizeof(struct sockaddr_in))
+			goto skip;
+		i->is_ipv6 = false;
+		i->address = (__be32 *)
+			&((struct sockaddr_in *) addr)->sin_addr;
+		i->port = ((struct sockaddr_in *) addr)->sin_port;
+		break;
+	default:
+		goto skip;
+	}
+	if (address->protocol == SOCK_RAW)
+		i->port = htons(port);
+	return tomoyo_inet_entry(address);
+skip:
+	return 0;
+}
+
+/**
+ * tomoyo_unix_entry - Check permission for UNIX network operation.
+ *
+ * @address: Pointer to "struct tomoyo_addr_info".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_unix_entry(const struct tomoyo_addr_info *address)
+{
+	const int idx = tomoyo_read_lock();
+	struct tomoyo_request_info r;
+	int error = 0;
+	const u8 type = tomoyo_unix2mac[address->protocol][address->operation];
+
+	if (type && tomoyo_init_request_info(&r, NULL, type)
+	    != TOMOYO_CONFIG_DISABLED) {
+		char *buf = address->unix0.addr;
+		int len = address->unix0.addr_len - sizeof(sa_family_t);
+
+		if (len <= 0) {
+			buf = "anonymous";
+			len = 9;
+		} else if (buf[0]) {
+			len = strnlen(buf, len);
+		}
+		buf = tomoyo_encode2(buf, len);
+		if (buf) {
+			struct tomoyo_path_info addr;
+
+			addr.name = buf;
+			tomoyo_fill_path_info(&addr);
+			r.param_type = TOMOYO_TYPE_UNIX_ACL;
+			r.param.unix_network.protocol = address->protocol;
+			r.param.unix_network.operation = address->operation;
+			r.param.unix_network.address = &addr;
+			do {
+				tomoyo_check_acl(&r, tomoyo_check_unix_acl);
+				error = tomoyo_audit_unix_log(&r);
+			} while (error == TOMOYO_RETRY_REQUEST);
+			kfree(buf);
+		} else
+			error = -ENOMEM;
+	}
+	tomoyo_read_unlock(idx);
+	return error;
+}
+
+/**
+ * tomoyo_check_unix_address - Check permission for unix domain socket's operation.
+ *
+ * @addr:     Pointer to "struct sockaddr".
+ * @addr_len: Size of @addr.
+ * @address:  Pointer to "struct tomoyo_addr_info".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_check_unix_address(struct sockaddr *addr,
+				     const unsigned int addr_len,
+				     struct tomoyo_addr_info *address)
+{
+	struct tomoyo_unix_addr_info *u = &address->unix0;
+
+	if (addr->sa_family != AF_UNIX)
+		return 0;
+	u->addr = ((struct sockaddr_un *) addr)->sun_path;
+	u->addr_len = addr_len;
+	return tomoyo_unix_entry(address);
+}
+
+/**
+ * tomoyo_kernel_service - Check whether I'm kernel service or not.
+ *
+ * Returns true if I'm kernel service, false otherwise.
+ */
+static bool tomoyo_kernel_service(void)
+{
+	/* Nothing to do if I am a kernel service. */
+	return segment_eq(get_fs(), KERNEL_DS);
+}
+
+/**
+ * tomoyo_sock_family - Get socket's family.
+ *
+ * @sk: Pointer to "struct sock".
+ *
+ * Returns one of PF_INET, PF_INET6, PF_UNIX or 0.
+ */
+static u8 tomoyo_sock_family(struct sock *sk)
+{
+	u8 family;
+
+	if (tomoyo_kernel_service())
+		return 0;
+	family = sk->sk_family;
+	switch (family) {
+	case PF_INET:
+	case PF_INET6:
+	case PF_UNIX:
+		return family;
+	default:
+		return 0;
+	}
+}
+
+/**
+ * tomoyo_socket_listen_permission - Check permission for listening a socket.
+ *
+ * @sock: Pointer to "struct socket".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_socket_listen_permission(struct socket *sock)
+{
+	struct tomoyo_addr_info address;
+	const u8 family = tomoyo_sock_family(sock->sk);
+	const unsigned int type = sock->type;
+	struct sockaddr_storage addr;
+	int addr_len;
+
+	if (!family || (type != SOCK_STREAM && type != SOCK_SEQPACKET))
+		return 0;
+	{
+		const int error = sock->ops->getname(sock, (struct sockaddr *)
+						     &addr, &addr_len, 0);
+
+		if (error)
+			return error;
+	}
+	address.protocol = type;
+	address.operation = TOMOYO_NETWORK_LISTEN;
+	if (family == PF_UNIX)
+		return tomoyo_check_unix_address((struct sockaddr *) &addr,
+						 addr_len, &address);
+	return tomoyo_check_inet_address((struct sockaddr *) &addr, addr_len,
+					 0, &address);
+}
+
+/**
+ * tomoyo_socket_connect_permission - Check permission for setting the remote address of a socket.
+ *
+ * @sock:     Pointer to "struct socket".
+ * @addr:     Pointer to "struct sockaddr".
+ * @addr_len: Size of @addr.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_socket_connect_permission(struct socket *sock,
+				     struct sockaddr *addr, int addr_len)
+{
+	struct tomoyo_addr_info address;
+	const u8 family = tomoyo_sock_family(sock->sk);
+	const unsigned int type = sock->type;
+
+	if (!family)
+		return 0;
+	address.protocol = type;
+	switch (type) {
+	case SOCK_DGRAM:
+	case SOCK_RAW:
+		address.operation = TOMOYO_NETWORK_SEND;
+		break;
+	case SOCK_STREAM:
+	case SOCK_SEQPACKET:
+		address.operation = TOMOYO_NETWORK_CONNECT;
+		break;
+	default:
+		return 0;
+	}
+	if (family == PF_UNIX)
+		return tomoyo_check_unix_address(addr, addr_len, &address);
+	return tomoyo_check_inet_address(addr, addr_len, sock->sk->sk_protocol,
+					 &address);
+}
+
+/**
+ * tomoyo_socket_bind_permission - Check permission for setting the local address of a socket.
+ *
+ * @sock:     Pointer to "struct socket".
+ * @addr:     Pointer to "struct sockaddr".
+ * @addr_len: Size of @addr.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_socket_bind_permission(struct socket *sock, struct sockaddr *addr,
+				  int addr_len)
+{
+	struct tomoyo_addr_info address;
+	const u8 family = tomoyo_sock_family(sock->sk);
+	const unsigned int type = sock->type;
+
+	if (!family)
+		return 0;
+	switch (type) {
+	case SOCK_STREAM:
+	case SOCK_DGRAM:
+	case SOCK_RAW:
+	case SOCK_SEQPACKET:
+		address.protocol = type;
+		address.operation = TOMOYO_NETWORK_BIND;
+		break;
+	default:
+		return 0;
+	}
+	if (family == PF_UNIX)
+		return tomoyo_check_unix_address(addr, addr_len, &address);
+	return tomoyo_check_inet_address(addr, addr_len, sock->sk->sk_protocol,
+					 &address);
+}
+
+/**
+ * tomoyo_socket_sendmsg_permission - Check permission for sending a datagram.
+ *
+ * @sock: Pointer to "struct socket".
+ * @msg:  Pointer to "struct msghdr".
+ * @size: Unused.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_socket_sendmsg_permission(struct socket *sock, struct msghdr *msg,
+				     int size)
+{
+	struct tomoyo_addr_info address;
+	const u8 family = tomoyo_sock_family(sock->sk);
+	const unsigned int type = sock->type;
+
+	if (!msg->msg_name || !family ||
+	    (type != SOCK_DGRAM && type != SOCK_RAW))
+		return 0;
+	address.protocol = type;
+	address.operation = TOMOYO_NETWORK_SEND;
+	if (family == PF_UNIX)
+		return tomoyo_check_unix_address((struct sockaddr *)
+						 msg->msg_name,
+						 msg->msg_namelen, &address);
+	return tomoyo_check_inet_address((struct sockaddr *) msg->msg_name,
+					 msg->msg_namelen,
+					 sock->sk->sk_protocol, &address);
+}