1/*
2 * common LSM auditing functions
3 *
4 * Based on code written for SELinux by :
5 *			Stephen Smalley, <sds@epoch.ncsc.mil>
6 * 			James Morris <jmorris@redhat.com>
7 * Author : Etienne Basset, <etienne.basset@ensta.org>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2,
11 * as published by the Free Software Foundation.
12 */
13
14#include <linux/types.h>
15#include <linux/stddef.h>
16#include <linux/kernel.h>
17#include <linux/gfp.h>
18#include <linux/fs.h>
19#include <linux/init.h>
20#include <net/sock.h>
21#include <linux/un.h>
22#include <net/af_unix.h>
23#include <linux/audit.h>
24#include <linux/ipv6.h>
25#include <linux/ip.h>
26#include <net/ip.h>
27#include <net/ipv6.h>
28#include <linux/tcp.h>
29#include <linux/udp.h>
30#include <linux/dccp.h>
31#include <linux/sctp.h>
32#include <linux/lsm_audit.h>
33
34/**
35 * ipv4_skb_to_auditdata : fill auditdata from skb
36 * @skb : the skb
37 * @ad : the audit data to fill
38 * @proto : the layer 4 protocol
39 *
40 * return  0 on success
41 */
42int ipv4_skb_to_auditdata(struct sk_buff *skb,
43		struct common_audit_data *ad, u8 *proto)
44{
45	int ret = 0;
46	struct iphdr *ih;
47
48	ih = ip_hdr(skb);
49	if (ih == NULL)
50		return -EINVAL;
51
52	ad->u.net->v4info.saddr = ih->saddr;
53	ad->u.net->v4info.daddr = ih->daddr;
54
55	if (proto)
56		*proto = ih->protocol;
57	/* non initial fragment */
58	if (ntohs(ih->frag_off) & IP_OFFSET)
59		return 0;
60
61	switch (ih->protocol) {
62	case IPPROTO_TCP: {
63		struct tcphdr *th = tcp_hdr(skb);
64		if (th == NULL)
65			break;
66
67		ad->u.net->sport = th->source;
68		ad->u.net->dport = th->dest;
69		break;
70	}
71	case IPPROTO_UDP: {
72		struct udphdr *uh = udp_hdr(skb);
73		if (uh == NULL)
74			break;
75
76		ad->u.net->sport = uh->source;
77		ad->u.net->dport = uh->dest;
78		break;
79	}
80	case IPPROTO_DCCP: {
81		struct dccp_hdr *dh = dccp_hdr(skb);
82		if (dh == NULL)
83			break;
84
85		ad->u.net->sport = dh->dccph_sport;
86		ad->u.net->dport = dh->dccph_dport;
87		break;
88	}
89	case IPPROTO_SCTP: {
90		struct sctphdr *sh = sctp_hdr(skb);
91		if (sh == NULL)
92			break;
93		ad->u.net->sport = sh->source;
94		ad->u.net->dport = sh->dest;
95		break;
96	}
97	default:
98		ret = -EINVAL;
99	}
100	return ret;
101}
102#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
103/**
104 * ipv6_skb_to_auditdata : fill auditdata from skb
105 * @skb : the skb
106 * @ad : the audit data to fill
107 * @proto : the layer 4 protocol
108 *
109 * return  0 on success
110 */
111int ipv6_skb_to_auditdata(struct sk_buff *skb,
112		struct common_audit_data *ad, u8 *proto)
113{
114	int offset, ret = 0;
115	struct ipv6hdr *ip6;
116	u8 nexthdr;
117	__be16 frag_off;
118
119	ip6 = ipv6_hdr(skb);
120	if (ip6 == NULL)
121		return -EINVAL;
122	ad->u.net->v6info.saddr = ip6->saddr;
123	ad->u.net->v6info.daddr = ip6->daddr;
124	ret = 0;
125	/* IPv6 can have several extension header before the Transport header
126	 * skip them */
127	offset = skb_network_offset(skb);
128	offset += sizeof(*ip6);
129	nexthdr = ip6->nexthdr;
130	offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
131	if (offset < 0)
132		return 0;
133	if (proto)
134		*proto = nexthdr;
135	switch (nexthdr) {
136	case IPPROTO_TCP: {
137		struct tcphdr _tcph, *th;
138
139		th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
140		if (th == NULL)
141			break;
142
143		ad->u.net->sport = th->source;
144		ad->u.net->dport = th->dest;
145		break;
146	}
147	case IPPROTO_UDP: {
148		struct udphdr _udph, *uh;
149
150		uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
151		if (uh == NULL)
152			break;
153
154		ad->u.net->sport = uh->source;
155		ad->u.net->dport = uh->dest;
156		break;
157	}
158	case IPPROTO_DCCP: {
159		struct dccp_hdr _dccph, *dh;
160
161		dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
162		if (dh == NULL)
163			break;
164
165		ad->u.net->sport = dh->dccph_sport;
166		ad->u.net->dport = dh->dccph_dport;
167		break;
168	}
169	case IPPROTO_SCTP: {
170		struct sctphdr _sctph, *sh;
171
172		sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph);
173		if (sh == NULL)
174			break;
175		ad->u.net->sport = sh->source;
176		ad->u.net->dport = sh->dest;
177		break;
178	}
179	default:
180		ret = -EINVAL;
181	}
182	return ret;
183}
184#endif
185
186
187static inline void print_ipv6_addr(struct audit_buffer *ab,
188				   struct in6_addr *addr, __be16 port,
189				   char *name1, char *name2)
190{
191	if (!ipv6_addr_any(addr))
192		audit_log_format(ab, " %s=%pI6c", name1, addr);
193	if (port)
194		audit_log_format(ab, " %s=%d", name2, ntohs(port));
195}
196
197static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
198				   __be16 port, char *name1, char *name2)
199{
200	if (addr)
201		audit_log_format(ab, " %s=%pI4", name1, &addr);
202	if (port)
203		audit_log_format(ab, " %s=%d", name2, ntohs(port));
204}
205
206/**
207 * dump_common_audit_data - helper to dump common audit data
208 * @a : common audit data
209 *
210 */
211static void dump_common_audit_data(struct audit_buffer *ab,
212				   struct common_audit_data *a)
213{
214	char comm[sizeof(current->comm)];
215
216	/*
217	 * To keep stack sizes in check force programers to notice if they
218	 * start making this union too large!  See struct lsm_network_audit
219	 * as an example of how to deal with large data.
220	 */
221	BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);
222
223	audit_log_format(ab, " pid=%d comm=", task_pid_nr(current));
224	audit_log_untrustedstring(ab, memcpy(comm, current->comm, sizeof(comm)));
225
226	switch (a->type) {
227	case LSM_AUDIT_DATA_NONE:
228		return;
229	case LSM_AUDIT_DATA_IPC:
230		audit_log_format(ab, " key=%d ", a->u.ipc_id);
231		break;
232	case LSM_AUDIT_DATA_CAP:
233		audit_log_format(ab, " capability=%d ", a->u.cap);
234		break;
235	case LSM_AUDIT_DATA_PATH: {
236		struct inode *inode;
237
238		audit_log_d_path(ab, " path=", &a->u.path);
239
240		inode = d_backing_inode(a->u.path.dentry);
241		if (inode) {
242			audit_log_format(ab, " dev=");
243			audit_log_untrustedstring(ab, inode->i_sb->s_id);
244			audit_log_format(ab, " ino=%lu", inode->i_ino);
245		}
246		break;
247	}
248	case LSM_AUDIT_DATA_DENTRY: {
249		struct inode *inode;
250
251		audit_log_format(ab, " name=");
252		audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
253
254		inode = d_backing_inode(a->u.dentry);
255		if (inode) {
256			audit_log_format(ab, " dev=");
257			audit_log_untrustedstring(ab, inode->i_sb->s_id);
258			audit_log_format(ab, " ino=%lu", inode->i_ino);
259		}
260		break;
261	}
262	case LSM_AUDIT_DATA_INODE: {
263		struct dentry *dentry;
264		struct inode *inode;
265
266		inode = a->u.inode;
267		dentry = d_find_alias(inode);
268		if (dentry) {
269			audit_log_format(ab, " name=");
270			audit_log_untrustedstring(ab,
271					 dentry->d_name.name);
272			dput(dentry);
273		}
274		audit_log_format(ab, " dev=");
275		audit_log_untrustedstring(ab, inode->i_sb->s_id);
276		audit_log_format(ab, " ino=%lu", inode->i_ino);
277		break;
278	}
279	case LSM_AUDIT_DATA_TASK: {
280		struct task_struct *tsk = a->u.tsk;
281		if (tsk) {
282			pid_t pid = task_pid_nr(tsk);
283			if (pid) {
284				char comm[sizeof(tsk->comm)];
285				audit_log_format(ab, " pid=%d comm=", pid);
286				audit_log_untrustedstring(ab,
287				    memcpy(comm, tsk->comm, sizeof(comm)));
288			}
289		}
290		break;
291	}
292	case LSM_AUDIT_DATA_NET:
293		if (a->u.net->sk) {
294			struct sock *sk = a->u.net->sk;
295			struct unix_sock *u;
296			int len = 0;
297			char *p = NULL;
298
299			switch (sk->sk_family) {
300			case AF_INET: {
301				struct inet_sock *inet = inet_sk(sk);
302
303				print_ipv4_addr(ab, inet->inet_rcv_saddr,
304						inet->inet_sport,
305						"laddr", "lport");
306				print_ipv4_addr(ab, inet->inet_daddr,
307						inet->inet_dport,
308						"faddr", "fport");
309				break;
310			}
311#if IS_ENABLED(CONFIG_IPV6)
312			case AF_INET6: {
313				struct inet_sock *inet = inet_sk(sk);
314
315				print_ipv6_addr(ab, &sk->sk_v6_rcv_saddr,
316						inet->inet_sport,
317						"laddr", "lport");
318				print_ipv6_addr(ab, &sk->sk_v6_daddr,
319						inet->inet_dport,
320						"faddr", "fport");
321				break;
322			}
323#endif
324			case AF_UNIX:
325				u = unix_sk(sk);
326				if (u->path.dentry) {
327					audit_log_d_path(ab, " path=", &u->path);
328					break;
329				}
330				if (!u->addr)
331					break;
332				len = u->addr->len-sizeof(short);
333				p = &u->addr->name->sun_path[0];
334				audit_log_format(ab, " path=");
335				if (*p)
336					audit_log_untrustedstring(ab, p);
337				else
338					audit_log_n_hex(ab, p, len);
339				break;
340			}
341		}
342
343		switch (a->u.net->family) {
344		case AF_INET:
345			print_ipv4_addr(ab, a->u.net->v4info.saddr,
346					a->u.net->sport,
347					"saddr", "src");
348			print_ipv4_addr(ab, a->u.net->v4info.daddr,
349					a->u.net->dport,
350					"daddr", "dest");
351			break;
352		case AF_INET6:
353			print_ipv6_addr(ab, &a->u.net->v6info.saddr,
354					a->u.net->sport,
355					"saddr", "src");
356			print_ipv6_addr(ab, &a->u.net->v6info.daddr,
357					a->u.net->dport,
358					"daddr", "dest");
359			break;
360		}
361		if (a->u.net->netif > 0) {
362			struct net_device *dev;
363
364			/* NOTE: we always use init's namespace */
365			dev = dev_get_by_index(&init_net, a->u.net->netif);
366			if (dev) {
367				audit_log_format(ab, " netif=%s", dev->name);
368				dev_put(dev);
369			}
370		}
371		break;
372#ifdef CONFIG_KEYS
373	case LSM_AUDIT_DATA_KEY:
374		audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
375		if (a->u.key_struct.key_desc) {
376			audit_log_format(ab, " key_desc=");
377			audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
378		}
379		break;
380#endif
381	case LSM_AUDIT_DATA_KMOD:
382		audit_log_format(ab, " kmod=");
383		audit_log_untrustedstring(ab, a->u.kmod_name);
384		break;
385	} /* switch (a->type) */
386}
387
388/**
389 * common_lsm_audit - generic LSM auditing function
390 * @a:  auxiliary audit data
391 * @pre_audit: lsm-specific pre-audit callback
392 * @post_audit: lsm-specific post-audit callback
393 *
394 * setup the audit buffer for common security information
395 * uses callback to print LSM specific information
396 */
397void common_lsm_audit(struct common_audit_data *a,
398	void (*pre_audit)(struct audit_buffer *, void *),
399	void (*post_audit)(struct audit_buffer *, void *))
400{
401	struct audit_buffer *ab;
402
403	if (a == NULL)
404		return;
405	/* we use GFP_ATOMIC so we won't sleep */
406	ab = audit_log_start(current->audit_context, GFP_ATOMIC | __GFP_NOWARN,
407			     AUDIT_AVC);
408
409	if (ab == NULL)
410		return;
411
412	if (pre_audit)
413		pre_audit(ab, a);
414
415	dump_common_audit_data(ab, a);
416
417	if (post_audit)
418		post_audit(ab, a);
419
420	audit_log_end(ab);
421}
422