1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright (c) 1990, 2010, Oracle and/or its affiliates. All rights reserved.
23 */
24
25 #include <sys/types.h>
26 #include <sys/errno.h>
27 #include <sys/param.h>
28 #include <sys/t_lock.h>
29 #include <sys/systm.h>
30 #include <sys/sysmacros.h>
31 #include <sys/debug.h>
32 #include <sys/time.h>
33 #include <sys/cmn_err.h>
34 #include <sys/vnode.h>
35 #include <sys/stat.h>
36 #include <sys/vfs.h>
37 #include <sys/cred.h>
38 #include <sys/kmem.h>
39 #include <sys/atomic.h>
40 #include <sys/policy.h>
41 #include <sys/fs/tmp.h>
42 #include <sys/fs/tmpnode.h>
43
44 #define MODESHIFT 3
45
46 int
47 tmp_taccess(void *vtp, int mode, struct cred *cred)
48 {
49 struct tmpnode *tp = vtp;
50 int shift = 0;
51 /*
52 * Check access based on owner, group and
53 * public permissions in tmpnode.
54 */
55 if (crgetuid(cred) != tp->tn_uid) {
56 shift += MODESHIFT;
57 if (groupmember(tp->tn_gid, cred) == 0)
58 shift += MODESHIFT;
59 }
60
61 return (secpolicy_vnode_access2(cred, TNTOV(tp), tp->tn_uid,
62 tp->tn_mode << shift, mode));
63 }
64
65 /*
66 * Decide whether it is okay to remove within a sticky directory.
67 * Two conditions need to be met: write access to the directory
68 * is needed. In sticky directories, write access is not sufficient;
69 * you can remove entries from a directory only if you own the directory,
70 * if you are privileged, if you own the entry or if they entry is
71 * a plain file and you have write access to that file.
72 * Function returns 0 if remove access is granted.
73 */
74
75 int
76 tmp_sticky_remove_access(struct tmpnode *dir, struct tmpnode *entry,
77 struct cred *cr)
78 {
79 uid_t uid = crgetuid(cr);
80
81 if ((dir->tn_mode & S_ISVTX) &&
82 uid != dir->tn_uid &&
83 uid != entry->tn_uid &&
84 (entry->tn_type != VREG ||
85 tmp_taccess(entry, VWRITE, cr) != 0))
86 return (secpolicy_vnode_remove(cr));
87
88 return (0);
89 }
90
91 /*
92 * Allocate zeroed memory if tmpfs_maxkmem has not been exceeded
93 * or the 'musthave' flag is set. 'musthave' allocations should
94 * always be subordinate to normal allocations so that tmpfs_maxkmem
95 * can't be exceeded by more than a few KB. Example: when creating
96 * a new directory, the tmpnode is a normal allocation; if that
97 * succeeds, the dirents for "." and ".." are 'musthave' allocations.
98 */
99 void *
100 tmp_memalloc(size_t size, int musthave)
101 {
102 static time_t last_warning;
103 time_t now;
104
105 if (atomic_add_long_nv(&tmp_kmemspace, size) < tmpfs_maxkmem ||
106 musthave)
107 return (kmem_zalloc(size, KM_SLEEP));
108
109 atomic_add_long(&tmp_kmemspace, -size);
110 now = gethrestime_sec();
111 if (last_warning != now) {
112 last_warning = now;
113 cmn_err(CE_WARN, "tmp_memalloc: tmpfs over memory limit");
114 }
115 return (NULL);
116 }
117
118 void
119 tmp_memfree(void *cp, size_t size)
120 {
121 kmem_free(cp, size);
122 atomic_add_long(&tmp_kmemspace, -size);
123 }
124
125 /*
126 * Convert a string containing a number (number of bytes) to a pgcnt_t,
127 * containing the corresponding number of pages. On 32-bit kernels, the
128 * maximum value encoded in 'str' is PAGESIZE * ULONG_MAX, while the value
129 * returned in 'maxpg' is at most ULONG_MAX.
130 *
131 * If the number is followed by a "k" or "K", the value is converted from
132 * kilobytes to bytes. If it is followed by an "m" or "M" it is converted
133 * from megabytes to bytes. If it is not followed by a character it is
134 * assumed to be in bytes. Multiple letter options are allowed, so for instance
135 * '2mk' is interpreted as 2gb.
136 *
137 * Parse and overflow errors are detected and a non-zero number returned on
138 * error.
139 */
140
141 int
142 tmp_convnum(char *str, pgcnt_t *maxpg)
143 {
144 uint64_t num = 0, oldnum;
145 #ifdef _LP64
146 uint64_t max_bytes = ULONG_MAX;
147 #else
148 uint64_t max_bytes = PAGESIZE * (uint64_t)ULONG_MAX;
149 #endif
150 char *c;
151
152 if (str == NULL)
153 return (EINVAL);
154 c = str;
155
156 /*
157 * Convert str to number
158 */
159 while ((*c >= '0') && (*c <= '9')) {
160 oldnum = num;
161 num = num * 10 + (*c++ - '0');
162 if (oldnum > num) /* overflow */
163 return (EINVAL);
164 }
165
166 /*
167 * Terminate on null
168 */
169 while (*c != '\0') {
170 switch (*c++) {
171
172 /*
173 * convert from kilobytes
174 */
175 case 'k':
176 case 'K':
177 if (num > max_bytes / 1024) /* will overflow */
178 return (EINVAL);
179 num *= 1024;
180 break;
181
182 /*
183 * convert from megabytes
184 */
185 case 'm':
186 case 'M':
187 if (num > max_bytes / (1024 * 1024)) /* will overflow */
188 return (EINVAL);
189 num *= 1024 * 1024;
190 break;
191
192 default:
193 return (EINVAL);
194 }
195 }
196
197 /*
198 * Since btopr() rounds up to page granularity, this round-up can
199 * cause an overflow only if 'num' is between (max_bytes - PAGESIZE)
200 * and (max_bytes). In this case the resulting number is zero, which
201 * is what we check for below.
202 */
203 if ((*maxpg = (pgcnt_t)btopr(num)) == 0 && num != 0)
204 return (EINVAL);
205 return (0);
206 }