Introduce is_owner_or_cap() to wrap CAP_FOWNER use with fsuid check
[linux-2.6.git] / fs / reiserfs / ioctl.c
1 /*
2  * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
3  */
4
5 #include <linux/capability.h>
6 #include <linux/fs.h>
7 #include <linux/reiserfs_fs.h>
8 #include <linux/time.h>
9 #include <asm/uaccess.h>
10 #include <linux/pagemap.h>
11 #include <linux/smp_lock.h>
12 #include <linux/compat.h>
13
14 static int reiserfs_unpack(struct inode *inode, struct file *filp);
15
16 /*
17 ** reiserfs_ioctl - handler for ioctl for inode
18 ** supported commands:
19 **  1) REISERFS_IOC_UNPACK - try to unpack tail from direct item into indirect
20 **                           and prevent packing file (argument arg has to be non-zero)
21 **  2) REISERFS_IOC_[GS]ETFLAGS, REISERFS_IOC_[GS]ETVERSION
22 **  3) That's all for a while ...
23 */
24 int reiserfs_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
25                    unsigned long arg)
26 {
27         unsigned int flags;
28
29         switch (cmd) {
30         case REISERFS_IOC_UNPACK:
31                 if (S_ISREG(inode->i_mode)) {
32                         if (arg)
33                                 return reiserfs_unpack(inode, filp);
34                         else
35                                 return 0;
36                 } else
37                         return -ENOTTY;
38                 /* following two cases are taken from fs/ext2/ioctl.c by Remy
39                    Card (card@masi.ibp.fr) */
40         case REISERFS_IOC_GETFLAGS:
41                 if (!reiserfs_attrs(inode->i_sb))
42                         return -ENOTTY;
43
44                 flags = REISERFS_I(inode)->i_attrs;
45                 i_attrs_to_sd_attrs(inode, (__u16 *) & flags);
46                 return put_user(flags, (int __user *)arg);
47         case REISERFS_IOC_SETFLAGS:{
48                         if (!reiserfs_attrs(inode->i_sb))
49                                 return -ENOTTY;
50
51                         if (IS_RDONLY(inode))
52                                 return -EROFS;
53
54                         if (!is_owner_or_cap(inode))
55                                 return -EPERM;
56
57                         if (get_user(flags, (int __user *)arg))
58                                 return -EFAULT;
59
60                         if (((flags ^ REISERFS_I(inode)->
61                               i_attrs) & (REISERFS_IMMUTABLE_FL |
62                                           REISERFS_APPEND_FL))
63                             && !capable(CAP_LINUX_IMMUTABLE))
64                                 return -EPERM;
65
66                         if ((flags & REISERFS_NOTAIL_FL) &&
67                             S_ISREG(inode->i_mode)) {
68                                 int result;
69
70                                 result = reiserfs_unpack(inode, filp);
71                                 if (result)
72                                         return result;
73                         }
74                         sd_attrs_to_i_attrs(flags, inode);
75                         REISERFS_I(inode)->i_attrs = flags;
76                         inode->i_ctime = CURRENT_TIME_SEC;
77                         mark_inode_dirty(inode);
78                         return 0;
79                 }
80         case REISERFS_IOC_GETVERSION:
81                 return put_user(inode->i_generation, (int __user *)arg);
82         case REISERFS_IOC_SETVERSION:
83                 if (!is_owner_or_cap(inode))
84                         return -EPERM;
85                 if (IS_RDONLY(inode))
86                         return -EROFS;
87                 if (get_user(inode->i_generation, (int __user *)arg))
88                         return -EFAULT;
89                 inode->i_ctime = CURRENT_TIME_SEC;
90                 mark_inode_dirty(inode);
91                 return 0;
92         default:
93                 return -ENOTTY;
94         }
95 }
96
97 #ifdef CONFIG_COMPAT
98 long reiserfs_compat_ioctl(struct file *file, unsigned int cmd,
99                                 unsigned long arg)
100 {
101         struct inode *inode = file->f_path.dentry->d_inode;
102         int ret;
103
104         /* These are just misnamed, they actually get/put from/to user an int */
105         switch (cmd) {
106         case REISERFS_IOC32_UNPACK:
107                 cmd = REISERFS_IOC_UNPACK;
108                 break;
109         case REISERFS_IOC32_GETFLAGS:
110                 cmd = REISERFS_IOC_GETFLAGS;
111                 break;
112         case REISERFS_IOC32_SETFLAGS:
113                 cmd = REISERFS_IOC_SETFLAGS;
114                 break;
115         case REISERFS_IOC32_GETVERSION:
116                 cmd = REISERFS_IOC_GETVERSION;
117                 break;
118         case REISERFS_IOC32_SETVERSION:
119                 cmd = REISERFS_IOC_SETVERSION;
120                 break;
121         default:
122                 return -ENOIOCTLCMD;
123         }
124         lock_kernel();
125         ret = reiserfs_ioctl(inode, file, cmd, (unsigned long) compat_ptr(arg));
126         unlock_kernel();
127         return ret;
128 }
129 #endif
130
131 /*
132 ** reiserfs_unpack
133 ** Function try to convert tail from direct item into indirect.
134 ** It set up nopack attribute in the REISERFS_I(inode)->nopack
135 */
136 static int reiserfs_unpack(struct inode *inode, struct file *filp)
137 {
138         int retval = 0;
139         int index;
140         struct page *page;
141         struct address_space *mapping;
142         unsigned long write_from;
143         unsigned long blocksize = inode->i_sb->s_blocksize;
144
145         if (inode->i_size == 0) {
146                 REISERFS_I(inode)->i_flags |= i_nopack_mask;
147                 return 0;
148         }
149         /* ioctl already done */
150         if (REISERFS_I(inode)->i_flags & i_nopack_mask) {
151                 return 0;
152         }
153
154         /* we need to make sure nobody is changing the file size beneath
155          ** us
156          */
157         mutex_lock(&inode->i_mutex);
158         reiserfs_write_lock(inode->i_sb);
159
160         write_from = inode->i_size & (blocksize - 1);
161         /* if we are on a block boundary, we are already unpacked.  */
162         if (write_from == 0) {
163                 REISERFS_I(inode)->i_flags |= i_nopack_mask;
164                 goto out;
165         }
166
167         /* we unpack by finding the page with the tail, and calling
168          ** reiserfs_prepare_write on that page.  This will force a 
169          ** reiserfs_get_block to unpack the tail for us.
170          */
171         index = inode->i_size >> PAGE_CACHE_SHIFT;
172         mapping = inode->i_mapping;
173         page = grab_cache_page(mapping, index);
174         retval = -ENOMEM;
175         if (!page) {
176                 goto out;
177         }
178         retval =
179             mapping->a_ops->prepare_write(NULL, page, write_from, write_from);
180         if (retval)
181                 goto out_unlock;
182
183         /* conversion can change page contents, must flush */
184         flush_dcache_page(page);
185         retval =
186             mapping->a_ops->commit_write(NULL, page, write_from, write_from);
187         REISERFS_I(inode)->i_flags |= i_nopack_mask;
188
189       out_unlock:
190         unlock_page(page);
191         page_cache_release(page);
192
193       out:
194         mutex_unlock(&inode->i_mutex);
195         reiserfs_write_unlock(inode->i_sb);
196         return retval;
197 }