1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * common LSM auditing functions
4 *
5 * Based on code written for SELinux by :
6 *			Stephen Smalley, <sds@tycho.nsa.gov>
7 * 			James Morris <jmorris@redhat.com>
8 * Author : Etienne Basset, <etienne.basset@ensta.org>
9 */
10
11#include <linux/types.h>
12#include <linux/stddef.h>
13#include <linux/kernel.h>
14#include <linux/gfp.h>
15#include <linux/fs.h>
16#include <linux/init.h>
17#include <net/sock.h>
18#include <linux/un.h>
19#include <net/af_unix.h>
20#include <linux/audit.h>
21#include <linux/ipv6.h>
22#include <linux/ip.h>
23#include <net/ip.h>
24#include <net/ipv6.h>
25#include <linux/tcp.h>
26#include <linux/udp.h>
27#include <linux/dccp.h>
28#include <linux/sctp.h>
29#include <linux/lsm_audit.h>
30#include <linux/security.h>
31
32/**
33 * ipv4_skb_to_auditdata : fill auditdata from skb
34 * @skb : the skb
35 * @ad : the audit data to fill
36 * @proto : the layer 4 protocol
37 *
38 * return  0 on success
39 */
40int ipv4_skb_to_auditdata(struct sk_buff *skb,
41		struct common_audit_data *ad, u8 *proto)
42{
43	int ret = 0;
44	struct iphdr *ih;
45
46	ih = ip_hdr(skb);
47	ad->u.net->v4info.saddr = ih->saddr;
48	ad->u.net->v4info.daddr = ih->daddr;
49
50	if (proto)
51		*proto = ih->protocol;
52	/* non initial fragment */
53	if (ntohs(ih->frag_off) & IP_OFFSET)
54		return 0;
55
56	switch (ih->protocol) {
57	case IPPROTO_TCP: {
58		struct tcphdr *th = tcp_hdr(skb);
59
60		ad->u.net->sport = th->source;
61		ad->u.net->dport = th->dest;
62		break;
63	}
64	case IPPROTO_UDP: {
65		struct udphdr *uh = udp_hdr(skb);
66
67		ad->u.net->sport = uh->source;
68		ad->u.net->dport = uh->dest;
69		break;
70	}
71	case IPPROTO_DCCP: {
72		struct dccp_hdr *dh = dccp_hdr(skb);
73
74		ad->u.net->sport = dh->dccph_sport;
75		ad->u.net->dport = dh->dccph_dport;
76		break;
77	}
78	case IPPROTO_SCTP: {
79		struct sctphdr *sh = sctp_hdr(skb);
80
81		ad->u.net->sport = sh->source;
82		ad->u.net->dport = sh->dest;
83		break;
84	}
85	default:
86		ret = -EINVAL;
87	}
88	return ret;
89}
90#if IS_ENABLED(CONFIG_IPV6)
91/**
92 * ipv6_skb_to_auditdata : fill auditdata from skb
93 * @skb : the skb
94 * @ad : the audit data to fill
95 * @proto : the layer 4 protocol
96 *
97 * return  0 on success
98 */
99int ipv6_skb_to_auditdata(struct sk_buff *skb,
100		struct common_audit_data *ad, u8 *proto)
101{
102	int offset, ret = 0;
103	struct ipv6hdr *ip6;
104	u8 nexthdr;
105	__be16 frag_off;
106
107	ip6 = ipv6_hdr(skb);
108	ad->u.net->v6info.saddr = ip6->saddr;
109	ad->u.net->v6info.daddr = ip6->daddr;
110	/* IPv6 can have several extension header before the Transport header
111	 * skip them */
112	offset = skb_network_offset(skb);
113	offset += sizeof(*ip6);
114	nexthdr = ip6->nexthdr;
115	offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
116	if (offset < 0)
117		return 0;
118	if (proto)
119		*proto = nexthdr;
120	switch (nexthdr) {
121	case IPPROTO_TCP: {
122		struct tcphdr _tcph, *th;
123
124		th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
125		if (th == NULL)
126			break;
127
128		ad->u.net->sport = th->source;
129		ad->u.net->dport = th->dest;
130		break;
131	}
132	case IPPROTO_UDP: {
133		struct udphdr _udph, *uh;
134
135		uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
136		if (uh == NULL)
137			break;
138
139		ad->u.net->sport = uh->source;
140		ad->u.net->dport = uh->dest;
141		break;
142	}
143	case IPPROTO_DCCP: {
144		struct dccp_hdr _dccph, *dh;
145
146		dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
147		if (dh == NULL)
148			break;
149
150		ad->u.net->sport = dh->dccph_sport;
151		ad->u.net->dport = dh->dccph_dport;
152		break;
153	}
154	case IPPROTO_SCTP: {
155		struct sctphdr _sctph, *sh;
156
157		sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph);
158		if (sh == NULL)
159			break;
160		ad->u.net->sport = sh->source;
161		ad->u.net->dport = sh->dest;
162		break;
163	}
164	default:
165		ret = -EINVAL;
166	}
167	return ret;
168}
169#endif
170
171
172static inline void print_ipv6_addr(struct audit_buffer *ab,
173				   const struct in6_addr *addr, __be16 port,
174				   char *name1, char *name2)
175{
176	if (!ipv6_addr_any(addr))
177		audit_log_format(ab, " %s=%pI6c", name1, addr);
178	if (port)
179		audit_log_format(ab, " %s=%d", name2, ntohs(port));
180}
181
182static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
183				   __be16 port, char *name1, char *name2)
184{
185	if (addr)
186		audit_log_format(ab, " %s=%pI4", name1, &addr);
187	if (port)
188		audit_log_format(ab, " %s=%d", name2, ntohs(port));
189}
190
191/**
192 * dump_common_audit_data - helper to dump common audit data
193 * @ab : the audit buffer
194 * @a : common audit data
195 *
196 */
197static void dump_common_audit_data(struct audit_buffer *ab,
198				   struct common_audit_data *a)
199{
200	char comm[sizeof(current->comm)];
201
202	/*
203	 * To keep stack sizes in check force programmers to notice if they
204	 * start making this union too large!  See struct lsm_network_audit
205	 * as an example of how to deal with large data.
206	 */
207	BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);
208
209	audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
210	audit_log_untrustedstring(ab, memcpy(comm, current->comm, sizeof(comm)));
211
212	switch (a->type) {
213	case LSM_AUDIT_DATA_NONE:
214		return;
215	case LSM_AUDIT_DATA_IPC:
216		audit_log_format(ab, " ipc_key=%d ", a->u.ipc_id);
217		break;
218	case LSM_AUDIT_DATA_CAP:
219		audit_log_format(ab, " capability=%d ", a->u.cap);
220		break;
221	case LSM_AUDIT_DATA_PATH: {
222		struct inode *inode;
223
224		audit_log_d_path(ab, " path=", &a->u.path);
225
226		inode = d_backing_inode(a->u.path.dentry);
227		if (inode) {
228			audit_log_format(ab, " dev=");
229			audit_log_untrustedstring(ab, inode->i_sb->s_id);
230			audit_log_format(ab, " ino=%lu", inode->i_ino);
231		}
232		break;
233	}
234	case LSM_AUDIT_DATA_FILE: {
235		struct inode *inode;
236
237		audit_log_d_path(ab, " path=", &a->u.file->f_path);
238
239		inode = file_inode(a->u.file);
240		if (inode) {
241			audit_log_format(ab, " dev=");
242			audit_log_untrustedstring(ab, inode->i_sb->s_id);
243			audit_log_format(ab, " ino=%lu", inode->i_ino);
244		}
245		break;
246	}
247	case LSM_AUDIT_DATA_IOCTL_OP: {
248		struct inode *inode;
249
250		audit_log_d_path(ab, " path=", &a->u.op->path);
251
252		inode = a->u.op->path.dentry->d_inode;
253		if (inode) {
254			audit_log_format(ab, " dev=");
255			audit_log_untrustedstring(ab, inode->i_sb->s_id);
256			audit_log_format(ab, " ino=%lu", inode->i_ino);
257		}
258
259		audit_log_format(ab, " ioctlcmd=0x%hx", a->u.op->cmd);
260		break;
261	}
262	case LSM_AUDIT_DATA_DENTRY: {
263		struct inode *inode;
264
265		audit_log_format(ab, " name=");
266		spin_lock(&a->u.dentry->d_lock);
267		audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
268		spin_unlock(&a->u.dentry->d_lock);
269
270		inode = d_backing_inode(a->u.dentry);
271		if (inode) {
272			audit_log_format(ab, " dev=");
273			audit_log_untrustedstring(ab, inode->i_sb->s_id);
274			audit_log_format(ab, " ino=%lu", inode->i_ino);
275		}
276		break;
277	}
278	case LSM_AUDIT_DATA_INODE: {
279		struct dentry *dentry;
280		struct inode *inode;
281
282		rcu_read_lock();
283		inode = a->u.inode;
284		dentry = d_find_alias_rcu(inode);
285		if (dentry) {
286			audit_log_format(ab, " name=");
287			spin_lock(&dentry->d_lock);
288			audit_log_untrustedstring(ab, dentry->d_name.name);
289			spin_unlock(&dentry->d_lock);
290		}
291		audit_log_format(ab, " dev=");
292		audit_log_untrustedstring(ab, inode->i_sb->s_id);
293		audit_log_format(ab, " ino=%lu", inode->i_ino);
294		rcu_read_unlock();
295		break;
296	}
297	case LSM_AUDIT_DATA_TASK: {
298		struct task_struct *tsk = a->u.tsk;
299		if (tsk) {
300			pid_t pid = task_tgid_nr(tsk);
301			if (pid) {
302				char comm[sizeof(tsk->comm)];
303				audit_log_format(ab, " opid=%d ocomm=", pid);
304				audit_log_untrustedstring(ab,
305				    memcpy(comm, tsk->comm, sizeof(comm)));
306			}
307		}
308		break;
309	}
310	case LSM_AUDIT_DATA_NET:
311		if (a->u.net->sk) {
312			const struct sock *sk = a->u.net->sk;
313			const struct unix_sock *u;
314			struct unix_address *addr;
315			int len = 0;
316			char *p = NULL;
317
318			switch (sk->sk_family) {
319			case AF_INET: {
320				const struct inet_sock *inet = inet_sk(sk);
321
322				print_ipv4_addr(ab, inet->inet_rcv_saddr,
323						inet->inet_sport,
324						"laddr", "lport");
325				print_ipv4_addr(ab, inet->inet_daddr,
326						inet->inet_dport,
327						"faddr", "fport");
328				break;
329			}
330#if IS_ENABLED(CONFIG_IPV6)
331			case AF_INET6: {
332				const struct inet_sock *inet = inet_sk(sk);
333
334				print_ipv6_addr(ab, &sk->sk_v6_rcv_saddr,
335						inet->inet_sport,
336						"laddr", "lport");
337				print_ipv6_addr(ab, &sk->sk_v6_daddr,
338						inet->inet_dport,
339						"faddr", "fport");
340				break;
341			}
342#endif
343			case AF_UNIX:
344				u = unix_sk(sk);
345				addr = smp_load_acquire(&u->addr);
346				if (!addr)
347					break;
348				if (u->path.dentry) {
349					audit_log_d_path(ab, " path=", &u->path);
350					break;
351				}
352				len = addr->len-sizeof(short);
353				p = &addr->name->sun_path[0];
354				audit_log_format(ab, " path=");
355				if (*p)
356					audit_log_untrustedstring(ab, p);
357				else
358					audit_log_n_hex(ab, p, len);
359				break;
360			}
361		}
362
363		switch (a->u.net->family) {
364		case AF_INET:
365			print_ipv4_addr(ab, a->u.net->v4info.saddr,
366					a->u.net->sport,
367					"saddr", "src");
368			print_ipv4_addr(ab, a->u.net->v4info.daddr,
369					a->u.net->dport,
370					"daddr", "dest");
371			break;
372		case AF_INET6:
373			print_ipv6_addr(ab, &a->u.net->v6info.saddr,
374					a->u.net->sport,
375					"saddr", "src");
376			print_ipv6_addr(ab, &a->u.net->v6info.daddr,
377					a->u.net->dport,
378					"daddr", "dest");
379			break;
380		}
381		if (a->u.net->netif > 0) {
382			struct net_device *dev;
383
384			/* NOTE: we always use init's namespace */
385			dev = dev_get_by_index(&init_net, a->u.net->netif);
386			if (dev) {
387				audit_log_format(ab, " netif=%s", dev->name);
388				dev_put(dev);
389			}
390		}
391		break;
392#ifdef CONFIG_KEYS
393	case LSM_AUDIT_DATA_KEY:
394		audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
395		if (a->u.key_struct.key_desc) {
396			audit_log_format(ab, " key_desc=");
397			audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
398		}
399		break;
400#endif
401	case LSM_AUDIT_DATA_KMOD:
402		audit_log_format(ab, " kmod=");
403		audit_log_untrustedstring(ab, a->u.kmod_name);
404		break;
405	case LSM_AUDIT_DATA_IBPKEY: {
406		struct in6_addr sbn_pfx;
407
408		memset(&sbn_pfx.s6_addr, 0,
409		       sizeof(sbn_pfx.s6_addr));
410		memcpy(&sbn_pfx.s6_addr, &a->u.ibpkey->subnet_prefix,
411		       sizeof(a->u.ibpkey->subnet_prefix));
412		audit_log_format(ab, " pkey=0x%x subnet_prefix=%pI6c",
413				 a->u.ibpkey->pkey, &sbn_pfx);
414		break;
415	}
416	case LSM_AUDIT_DATA_IBENDPORT:
417		audit_log_format(ab, " device=%s port_num=%u",
418				 a->u.ibendport->dev_name,
419				 a->u.ibendport->port);
420		break;
421	case LSM_AUDIT_DATA_LOCKDOWN:
422		audit_log_format(ab, " lockdown_reason=\"%s\"",
423				 lockdown_reasons[a->u.reason]);
424		break;
425	case LSM_AUDIT_DATA_ANONINODE:
426		audit_log_format(ab, " anonclass=%s", a->u.anonclass);
427		break;
428	} /* switch (a->type) */
429}
430
431/**
432 * common_lsm_audit - generic LSM auditing function
433 * @a:  auxiliary audit data
434 * @pre_audit: lsm-specific pre-audit callback
435 * @post_audit: lsm-specific post-audit callback
436 *
437 * setup the audit buffer for common security information
438 * uses callback to print LSM specific information
439 */
440void common_lsm_audit(struct common_audit_data *a,
441	void (*pre_audit)(struct audit_buffer *, void *),
442	void (*post_audit)(struct audit_buffer *, void *))
443{
444	struct audit_buffer *ab;
445
446	if (a == NULL)
447		return;
448	/* we use GFP_ATOMIC so we won't sleep */
449	ab = audit_log_start(audit_context(), GFP_ATOMIC | __GFP_NOWARN,
450			     AUDIT_AVC);
451
452	if (ab == NULL)
453		return;
454
455	if (pre_audit)
456		pre_audit(ab, a);
457
458	dump_common_audit_data(ab, a);
459
460	if (post_audit)
461		post_audit(ab, a);
462
463	audit_log_end(ab);
464}
465