Root/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/gfp.h>
11#include <linux/fs.h>
12#include <linux/generic_acl.h>
13#include <linux/posix_acl.h>
14#include <linux/posix_acl_xattr.h>
15
16
17static size_t
18generic_acl_list(struct dentry *dentry, char *list, size_t list_size,
19        const char *name, size_t name_len, int type)
20{
21    struct posix_acl *acl;
22    const char *xname;
23    size_t size;
24
25    acl = get_cached_acl(dentry->d_inode, type);
26    if (!acl)
27        return 0;
28    posix_acl_release(acl);
29
30    switch (type) {
31    case ACL_TYPE_ACCESS:
32        xname = POSIX_ACL_XATTR_ACCESS;
33        break;
34    case ACL_TYPE_DEFAULT:
35        xname = POSIX_ACL_XATTR_DEFAULT;
36        break;
37    default:
38        return 0;
39    }
40    size = strlen(xname) + 1;
41    if (list && size <= list_size)
42        memcpy(list, xname, size);
43    return size;
44}
45
46static int
47generic_acl_get(struct dentry *dentry, const char *name, void *buffer,
48             size_t size, int type)
49{
50    struct posix_acl *acl;
51    int error;
52
53    if (strcmp(name, "") != 0)
54        return -EINVAL;
55
56    acl = get_cached_acl(dentry->d_inode, type);
57    if (!acl)
58        return -ENODATA;
59    error = posix_acl_to_xattr(acl, buffer, size);
60    posix_acl_release(acl);
61
62    return error;
63}
64
65static int
66generic_acl_set(struct dentry *dentry, const char *name, const void *value,
67             size_t size, int flags, int type)
68{
69    struct inode *inode = dentry->d_inode;
70    struct posix_acl *acl = NULL;
71    int error;
72
73    if (strcmp(name, "") != 0)
74        return -EINVAL;
75    if (S_ISLNK(inode->i_mode))
76        return -EOPNOTSUPP;
77    if (!is_owner_or_cap(inode))
78        return -EPERM;
79    if (value) {
80        acl = posix_acl_from_xattr(value, size);
81        if (IS_ERR(acl))
82            return PTR_ERR(acl);
83    }
84    if (acl) {
85        mode_t mode;
86
87        error = posix_acl_valid(acl);
88        if (error)
89            goto failed;
90        switch (type) {
91        case ACL_TYPE_ACCESS:
92            mode = inode->i_mode;
93            error = posix_acl_equiv_mode(acl, &mode);
94            if (error < 0)
95                goto failed;
96            inode->i_mode = mode;
97            if (error == 0) {
98                posix_acl_release(acl);
99                acl = NULL;
100            }
101            break;
102        case ACL_TYPE_DEFAULT:
103            if (!S_ISDIR(inode->i_mode)) {
104                error = -EINVAL;
105                goto failed;
106            }
107            break;
108        }
109    }
110    set_cached_acl(inode, type, acl);
111    error = 0;
112failed:
113    posix_acl_release(acl);
114    return error;
115}
116
117/**
118 * generic_acl_init - Take care of acl inheritance at @inode create time
119 *
120 * Files created inside a directory with a default ACL inherit the
121 * directory's default ACL.
122 */
123int
124generic_acl_init(struct inode *inode, struct inode *dir)
125{
126    struct posix_acl *acl = NULL;
127    mode_t mode = inode->i_mode;
128    int error;
129
130    inode->i_mode = mode & ~current_umask();
131    if (!S_ISLNK(inode->i_mode))
132        acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);
133    if (acl) {
134        struct posix_acl *clone;
135
136        if (S_ISDIR(inode->i_mode)) {
137            clone = posix_acl_clone(acl, GFP_KERNEL);
138            error = -ENOMEM;
139            if (!clone)
140                goto cleanup;
141            set_cached_acl(inode, ACL_TYPE_DEFAULT, clone);
142            posix_acl_release(clone);
143        }
144        clone = posix_acl_clone(acl, GFP_KERNEL);
145        error = -ENOMEM;
146        if (!clone)
147            goto cleanup;
148        error = posix_acl_create_masq(clone, &mode);
149        if (error >= 0) {
150            inode->i_mode = mode;
151            if (error > 0)
152                set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
153        }
154        posix_acl_release(clone);
155    }
156    error = 0;
157
158cleanup:
159    posix_acl_release(acl);
160    return error;
161}
162
163/**
164 * generic_acl_chmod - change the access acl of @inode upon chmod()
165 *
166 * A chmod also changes the permissions of the owner, group/mask, and
167 * other ACL entries.
168 */
169int
170generic_acl_chmod(struct inode *inode)
171{
172    struct posix_acl *acl, *clone;
173    int error = 0;
174
175    if (S_ISLNK(inode->i_mode))
176        return -EOPNOTSUPP;
177    acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
178    if (acl) {
179        clone = posix_acl_clone(acl, GFP_KERNEL);
180        posix_acl_release(acl);
181        if (!clone)
182            return -ENOMEM;
183        error = posix_acl_chmod_masq(clone, inode->i_mode);
184        if (!error)
185            set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
186        posix_acl_release(clone);
187    }
188    return error;
189}
190
191int
192generic_check_acl(struct inode *inode, int mask)
193{
194    struct posix_acl *acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
195
196    if (acl) {
197        int error = posix_acl_permission(inode, acl, mask);
198        posix_acl_release(acl);
199        return error;
200    }
201    return -EAGAIN;
202}
203
204struct xattr_handler generic_acl_access_handler = {
205    .prefix = POSIX_ACL_XATTR_ACCESS,
206    .flags = ACL_TYPE_ACCESS,
207    .list = generic_acl_list,
208    .get = generic_acl_get,
209    .set = generic_acl_set,
210};
211
212struct xattr_handler generic_acl_default_handler = {
213    .prefix = POSIX_ACL_XATTR_DEFAULT,
214    .flags = ACL_TYPE_DEFAULT,
215    .list = generic_acl_list,
216    .get = generic_acl_get,
217    .set = generic_acl_set,
218};
219

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