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1 | /* |
2 | * linux/fs/attr.c |
3 | * |
4 | * Copyright (C) 1991, 1992 Linus Torvalds |
5 | * changes by Thomas Schoebel-Theuer |
6 | */ |
7 | |
8 | #include <linux/module.h> |
9 | #include <linux/time.h> |
10 | #include <linux/mm.h> |
11 | #include <linux/string.h> |
12 | #include <linux/capability.h> |
13 | #include <linux/fsnotify.h> |
14 | #include <linux/fcntl.h> |
15 | #include <linux/security.h> |
16 | |
17 | /* Taken over from the old code... */ |
18 | |
19 | /* POSIX UID/GID verification for setting inode attributes. */ |
20 | int inode_change_ok(const struct inode *inode, struct iattr *attr) |
21 | { |
22 | int retval = -EPERM; |
23 | unsigned int ia_valid = attr->ia_valid; |
24 | |
25 | /* If force is set do it anyway. */ |
26 | if (ia_valid & ATTR_FORCE) |
27 | goto fine; |
28 | |
29 | /* Make sure a caller can chown. */ |
30 | if ((ia_valid & ATTR_UID) && |
31 | (current_fsuid() != inode->i_uid || |
32 | attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN)) |
33 | goto error; |
34 | |
35 | /* Make sure caller can chgrp. */ |
36 | if ((ia_valid & ATTR_GID) && |
37 | (current_fsuid() != inode->i_uid || |
38 | (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) && |
39 | !capable(CAP_CHOWN)) |
40 | goto error; |
41 | |
42 | /* Make sure a caller can chmod. */ |
43 | if (ia_valid & ATTR_MODE) { |
44 | if (!is_owner_or_cap(inode)) |
45 | goto error; |
46 | /* Also check the setgid bit! */ |
47 | if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid : |
48 | inode->i_gid) && !capable(CAP_FSETID)) |
49 | attr->ia_mode &= ~S_ISGID; |
50 | } |
51 | |
52 | /* Check for setting the inode time. */ |
53 | if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) { |
54 | if (!is_owner_or_cap(inode)) |
55 | goto error; |
56 | } |
57 | fine: |
58 | retval = 0; |
59 | error: |
60 | return retval; |
61 | } |
62 | EXPORT_SYMBOL(inode_change_ok); |
63 | |
64 | /** |
65 | * inode_newsize_ok - may this inode be truncated to a given size |
66 | * @inode: the inode to be truncated |
67 | * @offset: the new size to assign to the inode |
68 | * @Returns: 0 on success, -ve errno on failure |
69 | * |
70 | * inode_newsize_ok will check filesystem limits and ulimits to check that the |
71 | * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ |
72 | * when necessary. Caller must not proceed with inode size change if failure is |
73 | * returned. @inode must be a file (not directory), with appropriate |
74 | * permissions to allow truncate (inode_newsize_ok does NOT check these |
75 | * conditions). |
76 | * |
77 | * inode_newsize_ok must be called with i_mutex held. |
78 | */ |
79 | int inode_newsize_ok(const struct inode *inode, loff_t offset) |
80 | { |
81 | if (inode->i_size < offset) { |
82 | unsigned long limit; |
83 | |
84 | limit = rlimit(RLIMIT_FSIZE); |
85 | if (limit != RLIM_INFINITY && offset > limit) |
86 | goto out_sig; |
87 | if (offset > inode->i_sb->s_maxbytes) |
88 | goto out_big; |
89 | } else { |
90 | /* |
91 | * truncation of in-use swapfiles is disallowed - it would |
92 | * cause subsequent swapout to scribble on the now-freed |
93 | * blocks. |
94 | */ |
95 | if (IS_SWAPFILE(inode)) |
96 | return -ETXTBSY; |
97 | } |
98 | |
99 | return 0; |
100 | out_sig: |
101 | send_sig(SIGXFSZ, current, 0); |
102 | out_big: |
103 | return -EFBIG; |
104 | } |
105 | EXPORT_SYMBOL(inode_newsize_ok); |
106 | |
107 | int inode_setattr(struct inode * inode, struct iattr * attr) |
108 | { |
109 | unsigned int ia_valid = attr->ia_valid; |
110 | |
111 | if (ia_valid & ATTR_SIZE && |
112 | attr->ia_size != i_size_read(inode)) { |
113 | int error = vmtruncate(inode, attr->ia_size); |
114 | if (error) |
115 | return error; |
116 | } |
117 | |
118 | if (ia_valid & ATTR_UID) |
119 | inode->i_uid = attr->ia_uid; |
120 | if (ia_valid & ATTR_GID) |
121 | inode->i_gid = attr->ia_gid; |
122 | if (ia_valid & ATTR_ATIME) |
123 | inode->i_atime = timespec_trunc(attr->ia_atime, |
124 | inode->i_sb->s_time_gran); |
125 | if (ia_valid & ATTR_MTIME) |
126 | inode->i_mtime = timespec_trunc(attr->ia_mtime, |
127 | inode->i_sb->s_time_gran); |
128 | if (ia_valid & ATTR_CTIME) |
129 | inode->i_ctime = timespec_trunc(attr->ia_ctime, |
130 | inode->i_sb->s_time_gran); |
131 | if (ia_valid & ATTR_MODE) { |
132 | umode_t mode = attr->ia_mode; |
133 | |
134 | if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) |
135 | mode &= ~S_ISGID; |
136 | inode->i_mode = mode; |
137 | } |
138 | mark_inode_dirty(inode); |
139 | |
140 | return 0; |
141 | } |
142 | EXPORT_SYMBOL(inode_setattr); |
143 | |
144 | int notify_change(struct dentry * dentry, struct iattr * attr) |
145 | { |
146 | struct inode *inode = dentry->d_inode; |
147 | mode_t mode = inode->i_mode; |
148 | int error; |
149 | struct timespec now; |
150 | unsigned int ia_valid = attr->ia_valid; |
151 | |
152 | if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) { |
153 | if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) |
154 | return -EPERM; |
155 | } |
156 | |
157 | now = current_fs_time(inode->i_sb); |
158 | |
159 | attr->ia_ctime = now; |
160 | if (!(ia_valid & ATTR_ATIME_SET)) |
161 | attr->ia_atime = now; |
162 | if (!(ia_valid & ATTR_MTIME_SET)) |
163 | attr->ia_mtime = now; |
164 | if (ia_valid & ATTR_KILL_PRIV) { |
165 | attr->ia_valid &= ~ATTR_KILL_PRIV; |
166 | ia_valid &= ~ATTR_KILL_PRIV; |
167 | error = security_inode_need_killpriv(dentry); |
168 | if (error > 0) |
169 | error = security_inode_killpriv(dentry); |
170 | if (error) |
171 | return error; |
172 | } |
173 | |
174 | /* |
175 | * We now pass ATTR_KILL_S*ID to the lower level setattr function so |
176 | * that the function has the ability to reinterpret a mode change |
177 | * that's due to these bits. This adds an implicit restriction that |
178 | * no function will ever call notify_change with both ATTR_MODE and |
179 | * ATTR_KILL_S*ID set. |
180 | */ |
181 | if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) && |
182 | (ia_valid & ATTR_MODE)) |
183 | BUG(); |
184 | |
185 | if (ia_valid & ATTR_KILL_SUID) { |
186 | if (mode & S_ISUID) { |
187 | ia_valid = attr->ia_valid |= ATTR_MODE; |
188 | attr->ia_mode = (inode->i_mode & ~S_ISUID); |
189 | } |
190 | } |
191 | if (ia_valid & ATTR_KILL_SGID) { |
192 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { |
193 | if (!(ia_valid & ATTR_MODE)) { |
194 | ia_valid = attr->ia_valid |= ATTR_MODE; |
195 | attr->ia_mode = inode->i_mode; |
196 | } |
197 | attr->ia_mode &= ~S_ISGID; |
198 | } |
199 | } |
200 | if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID))) |
201 | return 0; |
202 | |
203 | error = security_inode_setattr(dentry, attr); |
204 | if (error) |
205 | return error; |
206 | |
207 | if (ia_valid & ATTR_SIZE) |
208 | down_write(&dentry->d_inode->i_alloc_sem); |
209 | |
210 | if (inode->i_op && inode->i_op->setattr) { |
211 | error = inode->i_op->setattr(dentry, attr); |
212 | } else { |
213 | error = inode_change_ok(inode, attr); |
214 | if (!error) |
215 | error = inode_setattr(inode, attr); |
216 | } |
217 | |
218 | if (ia_valid & ATTR_SIZE) |
219 | up_write(&dentry->d_inode->i_alloc_sem); |
220 | |
221 | if (!error) |
222 | fsnotify_change(dentry, ia_valid); |
223 | |
224 | return error; |
225 | } |
226 | |
227 | EXPORT_SYMBOL(notify_change); |
228 |
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