smack: implement logging V3

This patch creates auditing functions usable by LSM to audit security
events. It provides standard dumping of FS, NET, task etc ... events
(code borrowed from SELinux)
and provides 2 callbacks to define LSM specific auditing, which should be
flexible enough to convert SELinux too.

Signed-off-by: Etienne Basset <etienne.basset@numericable.fr>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
cked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

2 files changed, 497 insertions, 0 deletions

diff --git a/include/linux/lsm_audit.h b/include/linux/lsm_audit.h
new file mode 100644
index 000000000000..e461b2c3d711
--- /dev/null
+++ b/include/linux/lsm_audit.h
@@ -0,0 +1,111 @@
+/*
+ * Common LSM logging functions
+ * Heavily borrowed from selinux/avc.h
+ *
+ * Author : Etienne BASSET  <etienne.basset@ensta.org>
+ *
+ * All credits to : Stephen Smalley, <sds@epoch.ncsc.mil>
+ * All BUGS to : Etienne BASSET  <etienne.basset@ensta.org>
+ */
+#ifndef _LSM_COMMON_LOGGING_
+#define _LSM_COMMON_LOGGING_
+
+#include <linux/stddef.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/kdev_t.h>
+#include <linux/spinlock.h>
+#include <linux/init.h>
+#include <linux/audit.h>
+#include <linux/in6.h>
+#include <linux/path.h>
+#include <linux/key.h>
+#include <linux/skbuff.h>
+#include <asm/system.h>
+
+
+/* Auxiliary data to use in generating the audit record. */
+struct common_audit_data {
+	char    type;
+#define LSM_AUDIT_DATA_FS      1
+#define LSM_AUDIT_DATA_NET     2
+#define LSM_AUDIT_DATA_CAP     3
+#define LSM_AUDIT_DATA_IPC     4
+#define LSM_AUDIT_DATA_TASK    5
+#define LSM_AUDIT_DATA_KEY     6
+	struct task_struct *tsk;
+	union 	{
+		struct {
+			struct path path;
+			struct inode *inode;
+		} fs;
+		struct {
+			int netif;
+			struct sock *sk;
+			u16 family;
+			__be16 dport;
+			__be16 sport;
+			union {
+				struct {
+					__be32 daddr;
+					__be32 saddr;
+				} v4;
+				struct {
+					struct in6_addr daddr;
+					struct in6_addr saddr;
+				} v6;
+			} fam;
+		} net;
+		int cap;
+		int ipc_id;
+		struct task_struct *tsk;
+#ifdef CONFIG_KEYS
+		struct {
+			key_serial_t key;
+			char *key_desc;
+		} key_struct;
+#endif
+	} u;
+	const char *function;
+	/* this union contains LSM specific data */
+	union {
+		/* SMACK data */
+		struct smack_audit_data {
+			char *subject;
+			char *object;
+			char *request;
+			int result;
+		} smack_audit_data;
+		/* SELinux data */
+		struct {
+			u32 ssid;
+			u32 tsid;
+			u16 tclass;
+			u32 requested;
+			u32 audited;
+			struct av_decision *avd;
+			int result;
+		} selinux_audit_data;
+	} lsm_priv;
+	/* these callback will be implemented by a specific LSM */
+	void (*lsm_pre_audit)(struct audit_buffer *, void *);
+	void (*lsm_post_audit)(struct audit_buffer *, void *);
+};
+
+#define v4info fam.v4
+#define v6info fam.v6
+
+int ipv4_skb_to_auditdata(struct sk_buff *skb,
+		struct common_audit_data *ad, u8 *proto);
+
+int ipv6_skb_to_auditdata(struct sk_buff *skb,
+		struct common_audit_data *ad, u8 *proto);
+
+/* Initialize an LSM audit data structure. */
+#define COMMON_AUDIT_DATA_INIT(_d, _t) \
+	{ memset((_d), 0, sizeof(struct common_audit_data)); \
+	 (_d)->type = LSM_AUDIT_DATA_##_t; (_d)->function = __func__; }
+
+void common_lsm_audit(struct common_audit_data *a);
+
+#endif
diff --git a/security/lsm_audit.c b/security/lsm_audit.c
new file mode 100644
index 000000000000..94b868494b31
--- /dev/null
+++ b/security/lsm_audit.c
@@ -0,0 +1,386 @@
+/*
+ * common LSM auditing functions
+ *
+ * Based on code written for SELinux by :
+ *			Stephen Smalley, <sds@epoch.ncsc.mil>
+ * 			James Morris <jmorris@redhat.com>
+ * Author : Etienne Basset, <etienne.basset@ensta.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2,
+ * as published by the Free Software Foundation.
+ */
+
+#include <linux/types.h>
+#include <linux/stddef.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <net/sock.h>
+#include <linux/un.h>
+#include <net/af_unix.h>
+#include <linux/audit.h>
+#include <linux/ipv6.h>
+#include <linux/ip.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <linux/dccp.h>
+#include <linux/sctp.h>
+#include <linux/lsm_audit.h>
+
+/**
+ * ipv4_skb_to_auditdata : fill auditdata from skb
+ * @skb : the skb
+ * @ad : the audit data to fill
+ * @proto : the layer 4 protocol
+ *
+ * return  0 on success
+ */
+int ipv4_skb_to_auditdata(struct sk_buff *skb,
+		struct common_audit_data *ad, u8 *proto)
+{
+	int ret = 0;
+	struct iphdr *ih;
+
+	ih = ip_hdr(skb);
+	if (ih == NULL)
+		return -EINVAL;
+
+	ad->u.net.v4info.saddr = ih->saddr;
+	ad->u.net.v4info.daddr = ih->daddr;
+
+	if (proto)
+		*proto = ih->protocol;
+	/* non initial fragment */
+	if (ntohs(ih->frag_off) & IP_OFFSET)
+		return 0;
+
+	switch (ih->protocol) {
+	case IPPROTO_TCP: {
+		struct tcphdr *th = tcp_hdr(skb);
+		if (th == NULL)
+			break;
+
+		ad->u.net.sport = th->source;
+		ad->u.net.dport = th->dest;
+		break;
+	}
+	case IPPROTO_UDP: {
+		struct udphdr *uh = udp_hdr(skb);
+		if (uh == NULL)
+			break;
+
+		ad->u.net.sport = uh->source;
+		ad->u.net.dport = uh->dest;
+		break;
+	}
+	case IPPROTO_DCCP: {
+		struct dccp_hdr *dh = dccp_hdr(skb);
+		if (dh == NULL)
+			break;
+
+		ad->u.net.sport = dh->dccph_sport;
+		ad->u.net.dport = dh->dccph_dport;
+		break;
+	}
+	case IPPROTO_SCTP: {
+		struct sctphdr *sh = sctp_hdr(skb);
+		if (sh == NULL)
+			break;
+		ad->u.net.sport = sh->source;
+		ad->u.net.dport = sh->dest;
+		break;
+	}
+	default:
+		ret = -EINVAL;
+	}
+	return ret;
+}
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+/**
+ * ipv6_skb_to_auditdata : fill auditdata from skb
+ * @skb : the skb
+ * @ad : the audit data to fill
+ * @proto : the layer 4 protocol
+ *
+ * return  0 on success
+ */
+int ipv6_skb_to_auditdata(struct sk_buff *skb,
+		struct common_audit_data *ad, u8 *proto)
+{
+	int offset, ret = 0;
+	struct ipv6hdr *ip6;
+	u8 nexthdr;
+
+	ip6 = ipv6_hdr(skb);
+	if (ip6 == NULL)
+		return -EINVAL;
+	ipv6_addr_copy(&ad->u.net.v6info.saddr, &ip6->saddr);
+	ipv6_addr_copy(&ad->u.net.v6info.daddr, &ip6->daddr);
+	ret = 0;
+	/* IPv6 can have several extension header before the Transport header
+	 * skip them */
+	offset = skb_network_offset(skb);
+	offset += sizeof(*ip6);
+	nexthdr = ip6->nexthdr;
+	offset = ipv6_skip_exthdr(skb, offset, &nexthdr);
+	if (offset < 0)
+		return 0;
+	if (proto)
+		*proto = nexthdr;
+	switch (nexthdr) {
+	case IPPROTO_TCP: {
+		struct tcphdr _tcph, *th;
+
+		th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
+		if (th == NULL)
+			break;
+
+		ad->u.net.sport = th->source;
+		ad->u.net.dport = th->dest;
+		break;
+	}
+	case IPPROTO_UDP: {
+		struct udphdr _udph, *uh;
+
+		uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
+		if (uh == NULL)
+			break;
+
+		ad->u.net.sport = uh->source;
+		ad->u.net.dport = uh->dest;
+		break;
+	}
+	case IPPROTO_DCCP: {
+		struct dccp_hdr _dccph, *dh;
+
+		dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
+		if (dh == NULL)
+			break;
+
+		ad->u.net.sport = dh->dccph_sport;
+		ad->u.net.dport = dh->dccph_dport;
+		break;
+	}
+	case IPPROTO_SCTP: {
+		struct sctphdr _sctph, *sh;
+
+		sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph);
+		if (sh == NULL)
+			break;
+		ad->u.net.sport = sh->source;
+		ad->u.net.dport = sh->dest;
+		break;
+	}
+	default:
+		ret = -EINVAL;
+	}
+	return ret;
+}
+#endif
+
+
+static inline void print_ipv6_addr(struct audit_buffer *ab,
+				   struct in6_addr *addr, __be16 port,
+				   char *name1, char *name2)
+{
+	if (!ipv6_addr_any(addr))
+		audit_log_format(ab, " %s=%pI6", name1, addr);
+	if (port)
+		audit_log_format(ab, " %s=%d", name2, ntohs(port));
+}
+
+static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
+				   __be16 port, char *name1, char *name2)
+{
+	if (addr)
+		audit_log_format(ab, " %s=%pI4", name1, &addr);
+	if (port)
+		audit_log_format(ab, " %s=%d", name2, ntohs(port));
+}
+
+/**
+ * dump_common_audit_data - helper to dump common audit data
+ * @a : common audit data
+ *
+ */
+static void dump_common_audit_data(struct audit_buffer *ab,
+				   struct common_audit_data *a)
+{
+	struct inode *inode = NULL;
+	struct task_struct *tsk = current;
+
+	if (a->tsk)
+		tsk = a->tsk;
+	if (tsk && tsk->pid) {
+		audit_log_format(ab, " pid=%d comm=", tsk->pid);
+		audit_log_untrustedstring(ab, tsk->comm);
+	}
+
+	switch (a->type) {
+	case LSM_AUDIT_DATA_IPC:
+		audit_log_format(ab, " key=%d ", a->u.ipc_id);
+		break;
+	case LSM_AUDIT_DATA_CAP:
+		audit_log_format(ab, " capability=%d ", a->u.cap);
+		break;
+	case LSM_AUDIT_DATA_FS:
+		if (a->u.fs.path.dentry) {
+			struct dentry *dentry = a->u.fs.path.dentry;
+			if (a->u.fs.path.mnt) {
+				audit_log_d_path(ab, "path=", &a->u.fs.path);
+			} else {
+				audit_log_format(ab, " name=");
+				audit_log_untrustedstring(ab,
+						 dentry->d_name.name);
+			}
+			inode = dentry->d_inode;
+		} else if (a->u.fs.inode) {
+			struct dentry *dentry;
+			inode = a->u.fs.inode;
+			dentry = d_find_alias(inode);
+			if (dentry) {
+				audit_log_format(ab, " name=");
+				audit_log_untrustedstring(ab,
+						 dentry->d_name.name);
+				dput(dentry);
+			}
+		}
+		if (inode)
+			audit_log_format(ab, " dev=%s ino=%lu",
+					inode->i_sb->s_id,
+					inode->i_ino);
+		break;
+	case LSM_AUDIT_DATA_TASK:
+		tsk = a->u.tsk;
+		if (tsk && tsk->pid) {
+			audit_log_format(ab, " pid=%d comm=", tsk->pid);
+			audit_log_untrustedstring(ab, tsk->comm);
+		}
+		break;
+	case LSM_AUDIT_DATA_NET:
+		if (a->u.net.sk) {
+			struct sock *sk = a->u.net.sk;
+			struct unix_sock *u;
+			int len = 0;
+			char *p = NULL;
+
+			switch (sk->sk_family) {
+			case AF_INET: {
+				struct inet_sock *inet = inet_sk(sk);
+
+				print_ipv4_addr(ab, inet->rcv_saddr,
+						inet->sport,
+						"laddr", "lport");
+				print_ipv4_addr(ab, inet->daddr,
+						inet->dport,
+						"faddr", "fport");
+				break;
+			}
+			case AF_INET6: {
+				struct inet_sock *inet = inet_sk(sk);
+				struct ipv6_pinfo *inet6 = inet6_sk(sk);
+
+				print_ipv6_addr(ab, &inet6->rcv_saddr,
+						inet->sport,
+						"laddr", "lport");
+				print_ipv6_addr(ab, &inet6->daddr,
+						inet->dport,
+						"faddr", "fport");
+				break;
+			}
+			case AF_UNIX:
+				u = unix_sk(sk);
+				if (u->dentry) {
+					struct path path = {
+						.dentry = u->dentry,
+						.mnt = u->mnt
+					};
+					audit_log_d_path(ab, "path=", &path);
+					break;
+				}
+				if (!u->addr)
+					break;
+				len = u->addr->len-sizeof(short);
+				p = &u->addr->name->sun_path[0];
+				audit_log_format(ab, " path=");
+				if (*p)
+					audit_log_untrustedstring(ab, p);
+				else
+					audit_log_n_hex(ab, p, len);
+				break;
+			}
+		}
+
+		switch (a->u.net.family) {
+		case AF_INET:
+			print_ipv4_addr(ab, a->u.net.v4info.saddr,
+					a->u.net.sport,
+					"saddr", "src");
+			print_ipv4_addr(ab, a->u.net.v4info.daddr,
+					a->u.net.dport,
+					"daddr", "dest");
+			break;
+		case AF_INET6:
+			print_ipv6_addr(ab, &a->u.net.v6info.saddr,
+					a->u.net.sport,
+					"saddr", "src");
+			print_ipv6_addr(ab, &a->u.net.v6info.daddr,
+					a->u.net.dport,
+					"daddr", "dest");
+			break;
+		}
+		if (a->u.net.netif > 0) {
+			struct net_device *dev;
+
+			/* NOTE: we always use init's namespace */
+			dev = dev_get_by_index(&init_net, a->u.net.netif);
+			if (dev) {
+				audit_log_format(ab, " netif=%s", dev->name);
+				dev_put(dev);
+			}
+		}
+		break;
+#ifdef CONFIG_KEYS
+	case LSM_AUDIT_DATA_KEY:
+		audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
+		if (a->u.key_struct.key_desc) {
+			audit_log_format(ab, " key_desc=");
+			audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
+		}
+		break;
+#endif
+	} /* switch (a->type) */
+}
+
+/**
+ * common_lsm_audit - generic LSM auditing function
+ * @a:  auxiliary audit data
+ *
+ * setup the audit buffer for common security information
+ * uses callback to print LSM specific information
+ */
+void common_lsm_audit(struct common_audit_data *a)
+{
+	struct audit_buffer *ab;
+
+	if (a == NULL)
+		return;
+	/* we use GFP_ATOMIC so we won't sleep */
+	ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC);
+
+	if (ab == NULL)
+		return;
+
+	if (a->lsm_pre_audit)
+		a->lsm_pre_audit(ab, a);
+
+	dump_common_audit_data(ab, a);
+
+	if (a->lsm_post_audit)
+		a->lsm_post_audit(ab, a);
+
+	audit_log_end(ab);
+}