Root/security/lsm_audit.c

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
118    ip6 = ipv6_hdr(skb);
119    if (ip6 == NULL)
120        return -EINVAL;
121    ipv6_addr_copy(&ad->u.net.v6info.saddr, &ip6->saddr);
122    ipv6_addr_copy(&ad->u.net.v6info.daddr, &ip6->daddr);
123    ret = 0;
124    /* IPv6 can have several extension header before the Transport header
125     * skip them */
126    offset = skb_network_offset(skb);
127    offset += sizeof(*ip6);
128    nexthdr = ip6->nexthdr;
129    offset = ipv6_skip_exthdr(skb, offset, &nexthdr);
130    if (offset < 0)
131        return 0;
132    if (proto)
133        *proto = nexthdr;
134    switch (nexthdr) {
135    case IPPROTO_TCP: {
136        struct tcphdr _tcph, *th;
137
138        th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
139        if (th == NULL)
140            break;
141
142        ad->u.net.sport = th->source;
143        ad->u.net.dport = th->dest;
144        break;
145    }
146    case IPPROTO_UDP: {
147        struct udphdr _udph, *uh;
148
149        uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
150        if (uh == NULL)
151            break;
152
153        ad->u.net.sport = uh->source;
154        ad->u.net.dport = uh->dest;
155        break;
156    }
157    case IPPROTO_DCCP: {
158        struct dccp_hdr _dccph, *dh;
159
160        dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
161        if (dh == NULL)
162            break;
163
164        ad->u.net.sport = dh->dccph_sport;
165        ad->u.net.dport = dh->dccph_dport;
166        break;
167    }
168    case IPPROTO_SCTP: {
169        struct sctphdr _sctph, *sh;
170
171        sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph);
172        if (sh == NULL)
173            break;
174        ad->u.net.sport = sh->source;
175        ad->u.net.dport = sh->dest;
176        break;
177    }
178    default:
179        ret = -EINVAL;
180    }
181    return ret;
182}
183#endif
184
185
186static inline void print_ipv6_addr(struct audit_buffer *ab,
187                   struct in6_addr *addr, __be16 port,
188                   char *name1, char *name2)
189{
190    if (!ipv6_addr_any(addr))
191        audit_log_format(ab, " %s=%pI6c", name1, addr);
192    if (port)
193        audit_log_format(ab, " %s=%d", name2, ntohs(port));
194}
195
196static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
197                   __be16 port, char *name1, char *name2)
198{
199    if (addr)
200        audit_log_format(ab, " %s=%pI4", name1, &addr);
201    if (port)
202        audit_log_format(ab, " %s=%d", name2, ntohs(port));
203}
204
205/**
206 * dump_common_audit_data - helper to dump common audit data
207 * @a : common audit data
208 *
209 */
210static void dump_common_audit_data(struct audit_buffer *ab,
211                   struct common_audit_data *a)
212{
213    struct inode *inode = NULL;
214    struct task_struct *tsk = current;
215
216    if (a->tsk)
217        tsk = a->tsk;
218    if (tsk && tsk->pid) {
219        audit_log_format(ab, " pid=%d comm=", tsk->pid);
220        audit_log_untrustedstring(ab, tsk->comm);
221    }
222
223    switch (a->type) {
224    case LSM_AUDIT_DATA_NONE:
225        return;
226    case LSM_AUDIT_DATA_IPC:
227        audit_log_format(ab, " key=%d ", a->u.ipc_id);
228        break;
229    case LSM_AUDIT_DATA_CAP:
230        audit_log_format(ab, " capability=%d ", a->u.cap);
231        break;
232    case LSM_AUDIT_DATA_FS:
233        if (a->u.fs.path.dentry) {
234            struct dentry *dentry = a->u.fs.path.dentry;
235            if (a->u.fs.path.mnt) {
236                audit_log_d_path(ab, "path=", &a->u.fs.path);
237            } else {
238                audit_log_format(ab, " name=");
239                audit_log_untrustedstring(ab,
240                         dentry->d_name.name);
241            }
242            inode = dentry->d_inode;
243        } else if (a->u.fs.inode) {
244            struct dentry *dentry;
245            inode = a->u.fs.inode;
246            dentry = d_find_alias(inode);
247            if (dentry) {
248                audit_log_format(ab, " name=");
249                audit_log_untrustedstring(ab,
250                         dentry->d_name.name);
251                dput(dentry);
252            }
253        }
254        if (inode)
255            audit_log_format(ab, " dev=%s ino=%lu",
256                    inode->i_sb->s_id,
257                    inode->i_ino);
258        break;
259    case LSM_AUDIT_DATA_TASK:
260        tsk = a->u.tsk;
261        if (tsk && tsk->pid) {
262            audit_log_format(ab, " pid=%d comm=", tsk->pid);
263            audit_log_untrustedstring(ab, tsk->comm);
264        }
265        break;
266    case LSM_AUDIT_DATA_NET:
267        if (a->u.net.sk) {
268            struct sock *sk = a->u.net.sk;
269            struct unix_sock *u;
270            int len = 0;
271            char *p = NULL;
272
273            switch (sk->sk_family) {
274            case AF_INET: {
275                struct inet_sock *inet = inet_sk(sk);
276
277                print_ipv4_addr(ab, inet->inet_rcv_saddr,
278                        inet->inet_sport,
279                        "laddr", "lport");
280                print_ipv4_addr(ab, inet->inet_daddr,
281                        inet->inet_dport,
282                        "faddr", "fport");
283                break;
284            }
285            case AF_INET6: {
286                struct inet_sock *inet = inet_sk(sk);
287                struct ipv6_pinfo *inet6 = inet6_sk(sk);
288
289                print_ipv6_addr(ab, &inet6->rcv_saddr,
290                        inet->inet_sport,
291                        "laddr", "lport");
292                print_ipv6_addr(ab, &inet6->daddr,
293                        inet->inet_dport,
294                        "faddr", "fport");
295                break;
296            }
297            case AF_UNIX:
298                u = unix_sk(sk);
299                if (u->dentry) {
300                    struct path path = {
301                        .dentry = u->dentry,
302                        .mnt = u->mnt
303                    };
304                    audit_log_d_path(ab, "path=", &path);
305                    break;
306                }
307                if (!u->addr)
308                    break;
309                len = u->addr->len-sizeof(short);
310                p = &u->addr->name->sun_path[0];
311                audit_log_format(ab, " path=");
312                if (*p)
313                    audit_log_untrustedstring(ab, p);
314                else
315                    audit_log_n_hex(ab, p, len);
316                break;
317            }
318        }
319
320        switch (a->u.net.family) {
321        case AF_INET:
322            print_ipv4_addr(ab, a->u.net.v4info.saddr,
323                    a->u.net.sport,
324                    "saddr", "src");
325            print_ipv4_addr(ab, a->u.net.v4info.daddr,
326                    a->u.net.dport,
327                    "daddr", "dest");
328            break;
329        case AF_INET6:
330            print_ipv6_addr(ab, &a->u.net.v6info.saddr,
331                    a->u.net.sport,
332                    "saddr", "src");
333            print_ipv6_addr(ab, &a->u.net.v6info.daddr,
334                    a->u.net.dport,
335                    "daddr", "dest");
336            break;
337        }
338        if (a->u.net.netif > 0) {
339            struct net_device *dev;
340
341            /* NOTE: we always use init's namespace */
342            dev = dev_get_by_index(&init_net, a->u.net.netif);
343            if (dev) {
344                audit_log_format(ab, " netif=%s", dev->name);
345                dev_put(dev);
346            }
347        }
348        break;
349#ifdef CONFIG_KEYS
350    case LSM_AUDIT_DATA_KEY:
351        audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
352        if (a->u.key_struct.key_desc) {
353            audit_log_format(ab, " key_desc=");
354            audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
355        }
356        break;
357#endif
358    case LSM_AUDIT_DATA_KMOD:
359        audit_log_format(ab, " kmod=");
360        audit_log_untrustedstring(ab, a->u.kmod_name);
361        break;
362    } /* switch (a->type) */
363}
364
365/**
366 * common_lsm_audit - generic LSM auditing function
367 * @a: auxiliary audit data
368 *
369 * setup the audit buffer for common security information
370 * uses callback to print LSM specific information
371 */
372void common_lsm_audit(struct common_audit_data *a)
373{
374    struct audit_buffer *ab;
375
376    if (a == NULL)
377        return;
378    /* we use GFP_ATOMIC so we won't sleep */
379    ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC);
380
381    if (ab == NULL)
382        return;
383
384    if (a->lsm_pre_audit)
385        a->lsm_pre_audit(ab, a);
386
387    dump_common_audit_data(ab, a);
388
389    if (a->lsm_post_audit)
390        a->lsm_post_audit(ab, a);
391
392    audit_log_end(ab);
393}
394

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