make generic_acl slightly more generic
[linux-2.6.git] / fs / generic_acl.c
1 /*
2  * (C) 2005 Andreas Gruenbacher <agruen@suse.de>
3  *
4  * This file is released under the GPL.
5  *
6  * Generic ACL support for in-memory filesystems.
7  */
8
9 #include <linux/sched.h>
10 #include <linux/fs.h>
11 #include <linux/generic_acl.h>
12 #include <linux/posix_acl.h>
13 #include <linux/posix_acl_xattr.h>
14
15
16 static size_t
17 generic_acl_list(struct dentry *dentry, char *list, size_t list_size,
18                 const char *name, size_t name_len, int type)
19 {
20         struct posix_acl *acl;
21         const char *xname;
22         size_t size;
23
24         acl = get_cached_acl(dentry->d_inode, type);
25         if (!acl)
26                 return 0;
27         posix_acl_release(acl);
28
29         switch (type) {
30         case ACL_TYPE_ACCESS:
31                 xname = POSIX_ACL_XATTR_ACCESS;
32                 break;
33         case ACL_TYPE_DEFAULT:
34                 xname = POSIX_ACL_XATTR_DEFAULT;
35                 break;
36         default:
37                 return 0;
38         }
39         size = strlen(xname) + 1;
40         if (list && size <= list_size)
41                 memcpy(list, xname, size);
42         return size;
43 }
44
45 static int
46 generic_acl_get(struct dentry *dentry, const char *name, void *buffer,
47                      size_t size, int type)
48 {
49         struct posix_acl *acl;
50         int error;
51
52         if (strcmp(name, "") != 0)
53                 return -EINVAL;
54
55         acl = get_cached_acl(dentry->d_inode, type);
56         if (!acl)
57                 return -ENODATA;
58         error = posix_acl_to_xattr(acl, buffer, size);
59         posix_acl_release(acl);
60
61         return error;
62 }
63
64 static int
65 generic_acl_set(struct dentry *dentry, const char *name, const void *value,
66                      size_t size, int flags, int type)
67 {
68         struct inode *inode = dentry->d_inode;
69         struct posix_acl *acl = NULL;
70         int error;
71
72         if (strcmp(name, "") != 0)
73                 return -EINVAL;
74         if (S_ISLNK(inode->i_mode))
75                 return -EOPNOTSUPP;
76         if (!is_owner_or_cap(inode))
77                 return -EPERM;
78         if (value) {
79                 acl = posix_acl_from_xattr(value, size);
80                 if (IS_ERR(acl))
81                         return PTR_ERR(acl);
82         }
83         if (acl) {
84                 mode_t mode;
85
86                 error = posix_acl_valid(acl);
87                 if (error)
88                         goto failed;
89                 switch (type) {
90                 case ACL_TYPE_ACCESS:
91                         mode = inode->i_mode;
92                         error = posix_acl_equiv_mode(acl, &mode);
93                         if (error < 0)
94                                 goto failed;
95                         inode->i_mode = mode;
96                         if (error == 0) {
97                                 posix_acl_release(acl);
98                                 acl = NULL;
99                         }
100                         break;
101                 case ACL_TYPE_DEFAULT:
102                         if (!S_ISDIR(inode->i_mode)) {
103                                 error = -EINVAL;
104                                 goto failed;
105                         }
106                         break;
107                 }
108         }
109         set_cached_acl(inode, type, acl);
110         error = 0;
111 failed:
112         posix_acl_release(acl);
113         return error;
114 }
115
116 /**
117  * generic_acl_init  -  Take care of acl inheritance at @inode create time
118  *
119  * Files created inside a directory with a default ACL inherit the
120  * directory's default ACL.
121  */
122 int
123 generic_acl_init(struct inode *inode, struct inode *dir)
124 {
125         struct posix_acl *acl = NULL;
126         mode_t mode = inode->i_mode;
127         int error;
128
129         inode->i_mode = mode & ~current_umask();
130         if (!S_ISLNK(inode->i_mode))
131                 acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);
132         if (acl) {
133                 struct posix_acl *clone;
134
135                 if (S_ISDIR(inode->i_mode)) {
136                         clone = posix_acl_clone(acl, GFP_KERNEL);
137                         error = -ENOMEM;
138                         if (!clone)
139                                 goto cleanup;
140                         set_cached_acl(inode, ACL_TYPE_DEFAULT, clone);
141                         posix_acl_release(clone);
142                 }
143                 clone = posix_acl_clone(acl, GFP_KERNEL);
144                 error = -ENOMEM;
145                 if (!clone)
146                         goto cleanup;
147                 error = posix_acl_create_masq(clone, &mode);
148                 if (error >= 0) {
149                         inode->i_mode = mode;
150                         if (error > 0)
151                                 set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
152                 }
153                 posix_acl_release(clone);
154         }
155         error = 0;
156
157 cleanup:
158         posix_acl_release(acl);
159         return error;
160 }
161
162 /**
163  * generic_acl_chmod  -  change the access acl of @inode upon chmod()
164  *
165  * A chmod also changes the permissions of the owner, group/mask, and
166  * other ACL entries.
167  */
168 int
169 generic_acl_chmod(struct inode *inode)
170 {
171         struct posix_acl *acl, *clone;
172         int error = 0;
173
174         if (S_ISLNK(inode->i_mode))
175                 return -EOPNOTSUPP;
176         acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
177         if (acl) {
178                 clone = posix_acl_clone(acl, GFP_KERNEL);
179                 posix_acl_release(acl);
180                 if (!clone)
181                         return -ENOMEM;
182                 error = posix_acl_chmod_masq(clone, inode->i_mode);
183                 if (!error)
184                         set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
185                 posix_acl_release(clone);
186         }
187         return error;
188 }
189
190 int
191 generic_check_acl(struct inode *inode, int mask)
192 {
193         struct posix_acl *acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
194
195         if (acl) {
196                 int error = posix_acl_permission(inode, acl, mask);
197                 posix_acl_release(acl);
198                 return error;
199         }
200         return -EAGAIN;
201 }
202
203 struct xattr_handler generic_acl_access_handler = {
204         .prefix = POSIX_ACL_XATTR_ACCESS,
205         .flags  = ACL_TYPE_ACCESS,
206         .list   = generic_acl_list,
207         .get    = generic_acl_get,
208         .set    = generic_acl_set,
209 };
210
211 struct xattr_handler generic_acl_default_handler = {
212         .prefix = POSIX_ACL_XATTR_DEFAULT,
213         .flags  = ACL_TYPE_DEFAULT,
214         .list   = generic_acl_list,
215         .get    = generic_acl_get,
216         .set    = generic_acl_set,
217 };