1 /*
2 * FUSE: Filesystem in Userspace
3 * Copyright (C) 2016 Canonical Ltd. <seth.forshee@canonical.com>
4 *
5 * This program can be distributed under the terms of the GNU GPL.
6 * See the file COPYING.
7 */
8
9 #include "fuse_i.h"
10
11 #include <linux/posix_acl.h>
12 #include <linux/posix_acl_xattr.h>
13
fuse_get_acl(struct inode * inode,int type,bool rcu)14 struct posix_acl *fuse_get_acl(struct inode *inode, int type, bool rcu)
15 {
16 struct fuse_conn *fc = get_fuse_conn(inode);
17 int size;
18 const char *name;
19 void *value = NULL;
20 struct posix_acl *acl;
21
22 if (rcu)
23 return ERR_PTR(-ECHILD);
24
25 if (fuse_is_bad(inode))
26 return ERR_PTR(-EIO);
27
28 if (!fc->posix_acl || fc->no_getxattr)
29 return NULL;
30
31 if (type == ACL_TYPE_ACCESS)
32 name = XATTR_NAME_POSIX_ACL_ACCESS;
33 else if (type == ACL_TYPE_DEFAULT)
34 name = XATTR_NAME_POSIX_ACL_DEFAULT;
35 else
36 return ERR_PTR(-EOPNOTSUPP);
37
38 value = kmalloc(PAGE_SIZE, GFP_KERNEL);
39 if (!value)
40 return ERR_PTR(-ENOMEM);
41 size = fuse_getxattr(inode, name, value, PAGE_SIZE);
42 if (size > 0)
43 acl = posix_acl_from_xattr(fc->user_ns, value, size);
44 else if ((size == 0) || (size == -ENODATA) ||
45 (size == -EOPNOTSUPP && fc->no_getxattr))
46 acl = NULL;
47 else if (size == -ERANGE)
48 acl = ERR_PTR(-E2BIG);
49 else
50 acl = ERR_PTR(size);
51
52 kfree(value);
53 return acl;
54 }
55
fuse_set_acl(struct user_namespace * mnt_userns,struct inode * inode,struct posix_acl * acl,int type)56 int fuse_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
57 struct posix_acl *acl, int type)
58 {
59 struct fuse_conn *fc = get_fuse_conn(inode);
60 const char *name;
61 int ret;
62
63 if (fuse_is_bad(inode))
64 return -EIO;
65
66 if (!fc->posix_acl || fc->no_setxattr)
67 return -EOPNOTSUPP;
68
69 if (type == ACL_TYPE_ACCESS)
70 name = XATTR_NAME_POSIX_ACL_ACCESS;
71 else if (type == ACL_TYPE_DEFAULT)
72 name = XATTR_NAME_POSIX_ACL_DEFAULT;
73 else
74 return -EINVAL;
75
76 if (acl) {
77 unsigned int extra_flags = 0;
78 /*
79 * Fuse userspace is responsible for updating access
80 * permissions in the inode, if needed. fuse_setxattr
81 * invalidates the inode attributes, which will force
82 * them to be refreshed the next time they are used,
83 * and it also updates i_ctime.
84 */
85 size_t size = posix_acl_xattr_size(acl->a_count);
86 void *value;
87
88 if (size > PAGE_SIZE)
89 return -E2BIG;
90
91 value = kmalloc(size, GFP_KERNEL);
92 if (!value)
93 return -ENOMEM;
94
95 ret = posix_acl_to_xattr(fc->user_ns, acl, value, size);
96 if (ret < 0) {
97 kfree(value);
98 return ret;
99 }
100
101 if (!in_group_p(i_gid_into_mnt(&init_user_ns, inode)) &&
102 !capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_FSETID))
103 extra_flags |= FUSE_SETXATTR_ACL_KILL_SGID;
104
105 ret = fuse_setxattr(inode, name, value, size, 0, extra_flags);
106 kfree(value);
107 } else {
108 ret = fuse_removexattr(inode, name);
109 }
110 forget_all_cached_acls(inode);
111 fuse_invalidate_attr(inode);
112
113 return ret;
114 }
115