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
17 static size_t
generic_acl_list(struct dentry * dentry,char * list,size_t list_size,const char * name,size_t name_len,int type)18 generic_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
46 static int
generic_acl_get(struct dentry * dentry,const char * name,void * buffer,size_t size,int type)47 generic_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(&init_user_ns, acl, buffer, size);
60 posix_acl_release(acl);
61
62 return error;
63 }
64
65 static int
generic_acl_set(struct dentry * dentry,const char * name,const void * value,size_t size,int flags,int type)66 generic_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(&init_user_ns, value, size);
81 if (IS_ERR(acl))
82 return PTR_ERR(acl);
83 }
84 if (acl) {
85 error = posix_acl_valid(acl);
86 if (error)
87 goto failed;
88 switch (type) {
89 case ACL_TYPE_ACCESS:
90 error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
91 if (error)
92 goto failed;
93 inode->i_ctime = CURRENT_TIME;
94 break;
95 case ACL_TYPE_DEFAULT:
96 if (!S_ISDIR(inode->i_mode)) {
97 error = -EINVAL;
98 goto failed;
99 }
100 break;
101 }
102 }
103 set_cached_acl(inode, type, acl);
104 error = 0;
105 failed:
106 posix_acl_release(acl);
107 return error;
108 }
109
110 /**
111 * generic_acl_init - Take care of acl inheritance at @inode create time
112 *
113 * Files created inside a directory with a default ACL inherit the
114 * directory's default ACL.
115 */
116 int
generic_acl_init(struct inode * inode,struct inode * dir)117 generic_acl_init(struct inode *inode, struct inode *dir)
118 {
119 struct posix_acl *acl = NULL;
120 int error;
121
122 if (!S_ISLNK(inode->i_mode))
123 acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);
124 if (acl) {
125 if (S_ISDIR(inode->i_mode))
126 set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
127 error = posix_acl_create(&acl, GFP_KERNEL, &inode->i_mode);
128 if (error < 0)
129 return error;
130 if (error > 0)
131 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
132 } else {
133 inode->i_mode &= ~current_umask();
134 }
135 error = 0;
136
137 posix_acl_release(acl);
138 return error;
139 }
140
141 /**
142 * generic_acl_chmod - change the access acl of @inode upon chmod()
143 *
144 * A chmod also changes the permissions of the owner, group/mask, and
145 * other ACL entries.
146 */
147 int
generic_acl_chmod(struct inode * inode)148 generic_acl_chmod(struct inode *inode)
149 {
150 struct posix_acl *acl;
151 int error = 0;
152
153 if (S_ISLNK(inode->i_mode))
154 return -EOPNOTSUPP;
155 acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
156 if (acl) {
157 error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
158 if (error)
159 return error;
160 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
161 posix_acl_release(acl);
162 }
163 return error;
164 }
165
166 const struct xattr_handler generic_acl_access_handler = {
167 .prefix = POSIX_ACL_XATTR_ACCESS,
168 .flags = ACL_TYPE_ACCESS,
169 .list = generic_acl_list,
170 .get = generic_acl_get,
171 .set = generic_acl_set,
172 };
173
174 const struct xattr_handler generic_acl_default_handler = {
175 .prefix = POSIX_ACL_XATTR_DEFAULT,
176 .flags = ACL_TYPE_DEFAULT,
177 .list = generic_acl_list,
178 .get = generic_acl_get,
179 .set = generic_acl_set,
180 };
181