filemon.c revision 280258 
1/*-
2 * Copyright (c) 2011, David E. O'Brien.
3 * Copyright (c) 2009-2011, Juniper Networks, Inc.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY JUNIPER NETWORKS AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL JUNIPER NETWORKS OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <sys/cdefs.h>
29__FBSDID("$FreeBSD: stable/10/sys/dev/filemon/filemon.c 280258 2015-03-19 13:37:36Z rwatson $");
30
31#include "opt_compat.h"
32
33#include <sys/param.h>
34#include <sys/file.h>
35#include <sys/systm.h>
36#include <sys/buf.h>
37#include <sys/condvar.h>
38#include <sys/conf.h>
39#include <sys/fcntl.h>
40#include <sys/ioccom.h>
41#include <sys/kernel.h>
42#include <sys/malloc.h>
43#include <sys/module.h>
44#include <sys/mutex.h>
45#include <sys/poll.h>
46#include <sys/proc.h>
47#include <sys/queue.h>
48#include <sys/syscall.h>
49#include <sys/sysent.h>
50#include <sys/sysproto.h>
51#include <sys/uio.h>
52
53#if __FreeBSD_version >= 900041
54#include <sys/capsicum.h>
55#endif
56
57#include "filemon.h"
58
59#if defined(COMPAT_IA32) || defined(COMPAT_FREEBSD32) || defined(COMPAT_ARCH32)
60#include <compat/freebsd32/freebsd32_syscall.h>
61#include <compat/freebsd32/freebsd32_proto.h>
62
63extern struct sysentvec ia32_freebsd_sysvec;
64#endif
65
66extern struct sysentvec elf32_freebsd_sysvec;
67extern struct sysentvec elf64_freebsd_sysvec;
68
69static d_close_t	filemon_close;
70static d_ioctl_t	filemon_ioctl;
71static d_open_t		filemon_open;
72static int		filemon_unload(void);
73static void		filemon_load(void *);
74
75static struct cdevsw filemon_cdevsw = {
76	.d_version	= D_VERSION,
77	.d_close	= filemon_close,
78	.d_ioctl	= filemon_ioctl,
79	.d_open		= filemon_open,
80	.d_name		= "filemon",
81};
82
83MALLOC_DECLARE(M_FILEMON);
84MALLOC_DEFINE(M_FILEMON, "filemon", "File access monitor");
85
86struct filemon {
87	TAILQ_ENTRY(filemon) link;	/* Link into the in-use list. */
88	struct mtx	mtx;		/* Lock mutex for this filemon. */
89	struct cv	cv;		/* Lock condition variable for this
90					   filemon. */
91	struct file	*fp;		/* Output file pointer. */
92	struct thread	*locker;	/* Ptr to the thread locking this
93					   filemon. */
94	pid_t		pid;		/* The process ID being monitored. */
95	char		fname1[MAXPATHLEN]; /* Temporary filename buffer. */
96	char		fname2[MAXPATHLEN]; /* Temporary filename buffer. */
97	char		msgbufr[1024];	/* Output message buffer. */
98};
99
100static TAILQ_HEAD(, filemon) filemons_inuse = TAILQ_HEAD_INITIALIZER(filemons_inuse);
101static TAILQ_HEAD(, filemon) filemons_free = TAILQ_HEAD_INITIALIZER(filemons_free);
102static int n_readers = 0;
103static struct mtx access_mtx;
104static struct cv access_cv;
105static struct thread *access_owner = NULL;
106static struct thread *access_requester = NULL;
107
108static struct cdev *filemon_dev;
109
110#include "filemon_lock.c"
111#include "filemon_wrapper.c"
112
113static void
114filemon_dtr(void *data)
115{
116	struct filemon *filemon = data;
117
118	if (filemon != NULL) {
119		struct file *fp = filemon->fp;
120
121		/* Get exclusive write access. */
122		filemon_lock_write();
123
124		/* Remove from the in-use list. */
125		TAILQ_REMOVE(&filemons_inuse, filemon, link);
126
127		filemon->fp = NULL;
128		filemon->pid = -1;
129
130		/* Add to the free list. */
131		TAILQ_INSERT_TAIL(&filemons_free, filemon, link);
132
133		/* Give up write access. */
134		filemon_unlock_write();
135
136		if (fp != NULL)
137			fdrop(fp, curthread);
138	}
139}
140
141static int
142filemon_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag __unused,
143    struct thread *td)
144{
145	int error = 0;
146	struct filemon *filemon;
147	struct proc *p;
148#if __FreeBSD_version >= 900041
149	cap_rights_t rights;
150#endif
151
152	devfs_get_cdevpriv((void **) &filemon);
153
154	switch (cmd) {
155	/* Set the output file descriptor. */
156	case FILEMON_SET_FD:
157		error = fget_write(td, *(int *)data,
158#if __FreeBSD_version >= 900041
159		    cap_rights_init(&rights, CAP_PWRITE),
160#endif
161		    &filemon->fp);
162		if (error == 0)
163			/* Write the file header. */
164			filemon_comment(filemon);
165		break;
166
167	/* Set the monitored process ID. */
168	case FILEMON_SET_PID:
169		error = pget(*((pid_t *)data), PGET_CANDEBUG | PGET_NOTWEXIT,
170		    &p);
171		if (error == 0) {
172			filemon->pid = p->p_pid;
173			PROC_UNLOCK(p);
174		}
175		break;
176
177	default:
178		error = EINVAL;
179		break;
180	}
181
182	return (error);
183}
184
185static int
186filemon_open(struct cdev *dev, int oflags __unused, int devtype __unused,
187    struct thread *td __unused)
188{
189	struct filemon *filemon;
190
191	/* Get exclusive write access. */
192	filemon_lock_write();
193
194	if ((filemon = TAILQ_FIRST(&filemons_free)) != NULL)
195		TAILQ_REMOVE(&filemons_free, filemon, link);
196
197	/* Give up write access. */
198	filemon_unlock_write();
199
200	if (filemon == NULL) {
201		filemon = malloc(sizeof(struct filemon), M_FILEMON,
202		    M_WAITOK | M_ZERO);
203
204		filemon->fp = NULL;
205
206		mtx_init(&filemon->mtx, "filemon", "filemon", MTX_DEF);
207		cv_init(&filemon->cv, "filemon");
208	}
209
210	filemon->pid = curproc->p_pid;
211
212	devfs_set_cdevpriv(filemon, filemon_dtr);
213
214	/* Get exclusive write access. */
215	filemon_lock_write();
216
217	/* Add to the in-use list. */
218	TAILQ_INSERT_TAIL(&filemons_inuse, filemon, link);
219
220	/* Give up write access. */
221	filemon_unlock_write();
222
223	return (0);
224}
225
226static int
227filemon_close(struct cdev *dev __unused, int flag __unused, int fmt __unused,
228    struct thread *td __unused)
229{
230
231	return (0);
232}
233
234static void
235filemon_load(void *dummy __unused)
236{
237	mtx_init(&access_mtx, "filemon", "filemon", MTX_DEF);
238	cv_init(&access_cv, "filemon");
239
240	/* Install the syscall wrappers. */
241	filemon_wrapper_install();
242
243	filemon_dev = make_dev(&filemon_cdevsw, 0, UID_ROOT, GID_WHEEL, 0666,
244	    "filemon");
245}
246
247static int
248filemon_unload(void)
249{
250 	struct filemon *filemon;
251	int error = 0;
252
253	/* Get exclusive write access. */
254	filemon_lock_write();
255
256	if (TAILQ_FIRST(&filemons_inuse) != NULL)
257		error = EBUSY;
258	else {
259		destroy_dev(filemon_dev);
260
261		/* Deinstall the syscall wrappers. */
262		filemon_wrapper_deinstall();
263	}
264
265	/* Give up write access. */
266	filemon_unlock_write();
267
268	if (error == 0) {
269		/* free() filemon structs free list. */
270		filemon_lock_write();
271		while ((filemon = TAILQ_FIRST(&filemons_free)) != NULL) {
272			TAILQ_REMOVE(&filemons_free, filemon, link);
273			mtx_destroy(&filemon->mtx);
274			cv_destroy(&filemon->cv);
275			free(filemon, M_FILEMON);
276		}
277		filemon_unlock_write();
278
279		mtx_destroy(&access_mtx);
280		cv_destroy(&access_cv);
281	}
282
283	return (error);
284}
285
286static int
287filemon_modevent(module_t mod __unused, int type, void *data)
288{
289	int error = 0;
290
291	switch (type) {
292	case MOD_LOAD:
293		filemon_load(data);
294		break;
295
296	case MOD_UNLOAD:
297		error = filemon_unload();
298		break;
299
300	case MOD_SHUTDOWN:
301		break;
302
303	default:
304		error = EOPNOTSUPP;
305		break;
306
307	}
308
309	return (error);
310}
311
312DEV_MODULE(filemon, filemon_modevent, NULL);
313MODULE_VERSION(filemon, 1);
314