linux-curproc.c revision 82c3fef5682d501d02ccb8b32dcc24ecad7986e6 
1/*
2 * GPL HEADER START
3 *
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 only,
8 * as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License
17 * version 2 along with this program; If not, see
18 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
19 *
20 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
21 * CA 95054 USA or visit www.sun.com if you need additional information or
22 * have any questions.
23 *
24 * GPL HEADER END
25 */
26/*
27 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
28 * Use is subject to license terms.
29 *
30 * Copyright (c) 2011, 2012, Intel Corporation.
31 */
32/*
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
35 *
36 * libcfs/libcfs/linux/linux-curproc.c
37 *
38 * Lustre curproc API implementation for Linux kernel
39 *
40 * Author: Nikita Danilov <nikita@clusterfs.com>
41 */
42
43#include <linux/sched.h>
44#include <linux/fs_struct.h>
45
46#include <linux/compat.h>
47#include <linux/thread_info.h>
48
49#define DEBUG_SUBSYSTEM S_LNET
50
51#include <linux/libcfs/libcfs.h>
52
53/*
54 * Implementation of cfs_curproc API (see portals/include/libcfs/curproc.h)
55 * for Linux kernel.
56 */
57
58/* Currently all the CFS_CAP_* defines match CAP_* ones. */
59#define cfs_cap_pack(cap) (cap)
60#define cfs_cap_unpack(cap) (cap)
61
62void cfs_cap_raise(cfs_cap_t cap)
63{
64	struct cred *cred;
65	if ((cred = prepare_creds())) {
66		cap_raise(cred->cap_effective, cfs_cap_unpack(cap));
67		commit_creds(cred);
68	}
69}
70
71void cfs_cap_lower(cfs_cap_t cap)
72{
73	struct cred *cred;
74	if ((cred = prepare_creds())) {
75		cap_lower(cred->cap_effective, cfs_cap_unpack(cap));
76		commit_creds(cred);
77	}
78}
79
80int cfs_cap_raised(cfs_cap_t cap)
81{
82	return cap_raised(current_cap(), cfs_cap_unpack(cap));
83}
84
85void cfs_kernel_cap_pack(kernel_cap_t kcap, cfs_cap_t *cap)
86{
87#if defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x19980330
88	*cap = cfs_cap_pack(kcap);
89#elif defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x20071026
90	*cap = cfs_cap_pack(kcap[0]);
91#elif defined(_KERNEL_CAPABILITY_VERSION) && _KERNEL_CAPABILITY_VERSION == 0x20080522
92	/* XXX lost high byte */
93	*cap = cfs_cap_pack(kcap.cap[0]);
94#else
95	#error "need correct _KERNEL_CAPABILITY_VERSION "
96#endif
97}
98
99void cfs_kernel_cap_unpack(kernel_cap_t *kcap, cfs_cap_t cap)
100{
101#if defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x19980330
102	*kcap = cfs_cap_unpack(cap);
103#elif defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x20071026
104	(*kcap)[0] = cfs_cap_unpack(cap);
105#elif defined(_KERNEL_CAPABILITY_VERSION) && _KERNEL_CAPABILITY_VERSION == 0x20080522
106	kcap->cap[0] = cfs_cap_unpack(cap);
107#else
108	#error "need correct _KERNEL_CAPABILITY_VERSION "
109#endif
110}
111
112cfs_cap_t cfs_curproc_cap_pack(void)
113{
114	cfs_cap_t cap;
115	cfs_kernel_cap_pack(current_cap(), &cap);
116	return cap;
117}
118
119void cfs_curproc_cap_unpack(cfs_cap_t cap)
120{
121	struct cred *cred;
122	if ((cred = prepare_creds())) {
123		cfs_kernel_cap_unpack(&cred->cap_effective, cap);
124		commit_creds(cred);
125	}
126}
127
128int cfs_capable(cfs_cap_t cap)
129{
130	return capable(cfs_cap_unpack(cap));
131}
132
133static int cfs_access_process_vm(struct task_struct *tsk, unsigned long addr,
134				 void *buf, int len, int write)
135{
136	/* Just copied from kernel for the kernels which doesn't
137	 * have access_process_vm() exported */
138	struct mm_struct *mm;
139	struct vm_area_struct *vma;
140	struct page *page;
141	void *old_buf = buf;
142
143	mm = get_task_mm(tsk);
144	if (!mm)
145		return 0;
146
147	down_read(&mm->mmap_sem);
148	/* ignore errors, just check how much was successfully transferred */
149	while (len) {
150		int bytes, rc, offset;
151		void *maddr;
152
153		rc = get_user_pages(tsk, mm, addr, 1,
154				     write, 1, &page, &vma);
155		if (rc <= 0)
156			break;
157
158		bytes = len;
159		offset = addr & (PAGE_SIZE-1);
160		if (bytes > PAGE_SIZE-offset)
161			bytes = PAGE_SIZE-offset;
162
163		maddr = kmap(page);
164		if (write) {
165			copy_to_user_page(vma, page, addr,
166					  maddr + offset, buf, bytes);
167			set_page_dirty_lock(page);
168		} else {
169			copy_from_user_page(vma, page, addr,
170					    buf, maddr + offset, bytes);
171		}
172		kunmap(page);
173		page_cache_release(page);
174		len -= bytes;
175		buf += bytes;
176		addr += bytes;
177	}
178	up_read(&mm->mmap_sem);
179	mmput(mm);
180
181	return buf - old_buf;
182}
183
184/* Read the environment variable of current process specified by @key. */
185int cfs_get_environ(const char *key, char *value, int *val_len)
186{
187	struct mm_struct *mm;
188	char *buffer, *tmp_buf = NULL;
189	int buf_len = PAGE_CACHE_SIZE;
190	int key_len = strlen(key);
191	unsigned long addr;
192	int rc;
193
194	buffer = kmalloc(buf_len, GFP_USER);
195	if (!buffer)
196		return -ENOMEM;
197
198	mm = get_task_mm(current);
199	if (!mm) {
200		kfree(buffer);
201		return -EINVAL;
202	}
203
204	/* Avoid deadlocks on mmap_sem if called from sys_mmap_pgoff(),
205	 * which is already holding mmap_sem for writes.  If some other
206	 * thread gets the write lock in the meantime, this thread will
207	 * block, but at least it won't deadlock on itself.  LU-1735 */
208	if (down_read_trylock(&mm->mmap_sem) == 0) {
209		kfree(buffer);
210		return -EDEADLK;
211	}
212	up_read(&mm->mmap_sem);
213
214	addr = mm->env_start;
215	while (addr < mm->env_end) {
216		int this_len, retval, scan_len;
217		char *env_start, *env_end;
218
219		memset(buffer, 0, buf_len);
220
221		this_len = min_t(int, mm->env_end - addr, buf_len);
222		retval = cfs_access_process_vm(current, addr, buffer,
223					       this_len, 0);
224		if (retval != this_len)
225			break;
226
227		addr += retval;
228
229		/* Parse the buffer to find out the specified key/value pair.
230		 * The "key=value" entries are separated by '\0'. */
231		env_start = buffer;
232		scan_len = this_len;
233		while (scan_len) {
234			char *entry;
235			int entry_len;
236
237			env_end = memscan(env_start, '\0', scan_len);
238			LASSERT(env_end >= env_start &&
239				env_end <= env_start + scan_len);
240
241			/* The last entry of this buffer cross the buffer
242			 * boundary, reread it in next cycle. */
243			if (unlikely(env_end - env_start == scan_len)) {
244				/* This entry is too large to fit in buffer */
245				if (unlikely(scan_len == this_len)) {
246					CERROR("Too long env variable.\n");
247					GOTO(out, rc = -EINVAL);
248				}
249				addr -= scan_len;
250				break;
251			}
252
253			entry = env_start;
254			entry_len = env_end - env_start;
255
256			/* Key length + length of '=' */
257			if (entry_len > key_len + 1 &&
258			    !memcmp(entry, key, key_len)) {
259				entry += key_len + 1;
260				entry_len -= key_len + 1;
261				/* The 'value' buffer passed in is too small.*/
262				if (entry_len >= *val_len)
263					GOTO(out, rc = -EOVERFLOW);
264
265				memcpy(value, entry, entry_len);
266				*val_len = entry_len;
267				GOTO(out, rc = 0);
268			}
269
270			scan_len -= (env_end - env_start + 1);
271			env_start = env_end + 1;
272		}
273	}
274	GOTO(out, rc = -ENOENT);
275
276out:
277	mmput(mm);
278	kfree((void *)buffer);
279	if (tmp_buf)
280		kfree((void *)tmp_buf);
281	return rc;
282}
283EXPORT_SYMBOL(cfs_get_environ);
284
285EXPORT_SYMBOL(cfs_cap_raise);
286EXPORT_SYMBOL(cfs_cap_lower);
287EXPORT_SYMBOL(cfs_cap_raised);
288EXPORT_SYMBOL(cfs_curproc_cap_pack);
289EXPORT_SYMBOL(cfs_curproc_cap_unpack);
290EXPORT_SYMBOL(cfs_capable);
291
292/*
293 * Local variables:
294 * c-indentation-style: "K&R"
295 * c-basic-offset: 8
296 * tab-width: 8
297 * fill-column: 80
298 * scroll-step: 1
299 * End:
300 */
301