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 (!inode_owner_or_capable(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            inode->i_ctime = CURRENT_TIME;
98            if (error == 0) {
99                posix_acl_release(acl);
100                acl = NULL;
101            }
102            break;
103        case ACL_TYPE_DEFAULT:
104            if (!S_ISDIR(inode->i_mode)) {
105                error = -EINVAL;
106                goto failed;
107            }
108            break;
109        }
110    }
111    set_cached_acl(inode, type, acl);
112    error = 0;
113failed:
114    posix_acl_release(acl);
115    return error;
116}
117
118/**
119 * generic_acl_init - Take care of acl inheritance at @inode create time
120 *
121 * Files created inside a directory with a default ACL inherit the
122 * directory's default ACL.
123 */
124int
125generic_acl_init(struct inode *inode, struct inode *dir)
126{
127    struct posix_acl *acl = NULL;
128    mode_t mode = inode->i_mode;
129    int error;
130
131    inode->i_mode = mode & ~current_umask();
132    if (!S_ISLNK(inode->i_mode))
133        acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);
134    if (acl) {
135        struct posix_acl *clone;
136
137        if (S_ISDIR(inode->i_mode)) {
138            clone = posix_acl_clone(acl, GFP_KERNEL);
139            error = -ENOMEM;
140            if (!clone)
141                goto cleanup;
142            set_cached_acl(inode, ACL_TYPE_DEFAULT, clone);
143            posix_acl_release(clone);
144        }
145        clone = posix_acl_clone(acl, GFP_KERNEL);
146        error = -ENOMEM;
147        if (!clone)
148            goto cleanup;
149        error = posix_acl_create_masq(clone, &mode);
150        if (error >= 0) {
151            inode->i_mode = mode;
152            if (error > 0)
153                set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
154        }
155        posix_acl_release(clone);
156    }
157    error = 0;
158
159cleanup:
160    posix_acl_release(acl);
161    return error;
162}
163
164/**
165 * generic_acl_chmod - change the access acl of @inode upon chmod()
166 *
167 * A chmod also changes the permissions of the owner, group/mask, and
168 * other ACL entries.
169 */
170int
171generic_acl_chmod(struct inode *inode)
172{
173    struct posix_acl *acl, *clone;
174    int error = 0;
175
176    if (S_ISLNK(inode->i_mode))
177        return -EOPNOTSUPP;
178    acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
179    if (acl) {
180        clone = posix_acl_clone(acl, GFP_KERNEL);
181        posix_acl_release(acl);
182        if (!clone)
183            return -ENOMEM;
184        error = posix_acl_chmod_masq(clone, inode->i_mode);
185        if (!error)
186            set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
187        posix_acl_release(clone);
188    }
189    return error;
190}
191
192int
193generic_check_acl(struct inode *inode, int mask, unsigned int flags)
194{
195    if (flags & IPERM_FLAG_RCU) {
196        if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
197            return -ECHILD;
198    } else {
199        struct posix_acl *acl;
200
201        acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
202        if (acl) {
203            int error = posix_acl_permission(inode, acl, mask);
204            posix_acl_release(acl);
205            return error;
206        }
207    }
208    return -EAGAIN;
209}
210
211const struct xattr_handler generic_acl_access_handler = {
212    .prefix = POSIX_ACL_XATTR_ACCESS,
213    .flags = ACL_TYPE_ACCESS,
214    .list = generic_acl_list,
215    .get = generic_acl_get,
216    .set = generic_acl_set,
217};
218
219const struct xattr_handler generic_acl_default_handler = {
220    .prefix = POSIX_ACL_XATTR_DEFAULT,
221    .flags = ACL_TYPE_DEFAULT,
222    .list = generic_acl_list,
223    .get = generic_acl_get,
224    .set = generic_acl_set,
225};
226

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