Commit | Line | Data |
---|---|---|
60bcc88a SF |
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 | ||
facd6105 | 14 | static struct posix_acl *__fuse_get_acl(struct fuse_conn *fc, |
facd6105 | 15 | struct inode *inode, int type, bool rcu) |
60bcc88a | 16 | { |
60bcc88a SF |
17 | int size; |
18 | const char *name; | |
19 | void *value = NULL; | |
20 | struct posix_acl *acl; | |
21 | ||
0cad6246 MS |
22 | if (rcu) |
23 | return ERR_PTR(-ECHILD); | |
24 | ||
5d069dbe MS |
25 | if (fuse_is_bad(inode)) |
26 | return ERR_PTR(-EIO); | |
27 | ||
facd6105 | 28 | if (fc->no_getxattr) |
60bcc88a SF |
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) | |
8cb08329 | 43 | acl = posix_acl_from_xattr(fc->user_ns, value, size); |
60bcc88a SF |
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 | ||
facd6105 CB |
56 | static inline bool fuse_no_acl(const struct fuse_conn *fc, |
57 | const struct inode *inode) | |
58 | { | |
59 | /* | |
60 | * Refuse interacting with POSIX ACLs for daemons that | |
61 | * don't support FUSE_POSIX_ACL and are not mounted on | |
62 | * the host to retain backwards compatibility. | |
63 | */ | |
64 | return !fc->posix_acl && (i_user_ns(inode) != &init_user_ns); | |
65 | } | |
66 | ||
05e6295f | 67 | struct posix_acl *fuse_get_acl(struct mnt_idmap *idmap, |
facd6105 CB |
68 | struct dentry *dentry, int type) |
69 | { | |
70 | struct inode *inode = d_inode(dentry); | |
71 | struct fuse_conn *fc = get_fuse_conn(inode); | |
72 | ||
73 | if (fuse_no_acl(fc, inode)) | |
74 | return ERR_PTR(-EOPNOTSUPP); | |
75 | ||
4d833bef | 76 | return __fuse_get_acl(fc, inode, type, false); |
facd6105 CB |
77 | } |
78 | ||
79 | struct posix_acl *fuse_get_inode_acl(struct inode *inode, int type, bool rcu) | |
80 | { | |
81 | struct fuse_conn *fc = get_fuse_conn(inode); | |
82 | ||
83 | /* | |
84 | * FUSE daemons before FUSE_POSIX_ACL was introduced could get and set | |
85 | * POSIX ACLs without them being used for permission checking by the | |
86 | * vfs. Retain that behavior for backwards compatibility as there are | |
87 | * filesystems that do all permission checking for acls in the daemon | |
88 | * and not in the kernel. | |
89 | */ | |
90 | if (!fc->posix_acl) | |
91 | return NULL; | |
4d833bef | 92 | return __fuse_get_acl(fc, inode, type, rcu); |
facd6105 CB |
93 | } |
94 | ||
13e83a49 | 95 | int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, |
549c7297 | 96 | struct posix_acl *acl, int type) |
60bcc88a | 97 | { |
138060ba | 98 | struct inode *inode = d_inode(dentry); |
60bcc88a SF |
99 | struct fuse_conn *fc = get_fuse_conn(inode); |
100 | const char *name; | |
101 | int ret; | |
102 | ||
5d069dbe MS |
103 | if (fuse_is_bad(inode)) |
104 | return -EIO; | |
105 | ||
facd6105 | 106 | if (fc->no_setxattr || fuse_no_acl(fc, inode)) |
60bcc88a SF |
107 | return -EOPNOTSUPP; |
108 | ||
109 | if (type == ACL_TYPE_ACCESS) | |
110 | name = XATTR_NAME_POSIX_ACL_ACCESS; | |
111 | else if (type == ACL_TYPE_DEFAULT) | |
112 | name = XATTR_NAME_POSIX_ACL_DEFAULT; | |
113 | else | |
114 | return -EINVAL; | |
115 | ||
116 | if (acl) { | |
550a7d3b | 117 | unsigned int extra_flags = 0; |
60bcc88a SF |
118 | /* |
119 | * Fuse userspace is responsible for updating access | |
120 | * permissions in the inode, if needed. fuse_setxattr | |
121 | * invalidates the inode attributes, which will force | |
122 | * them to be refreshed the next time they are used, | |
123 | * and it also updates i_ctime. | |
124 | */ | |
125 | size_t size = posix_acl_xattr_size(acl->a_count); | |
126 | void *value; | |
127 | ||
128 | if (size > PAGE_SIZE) | |
129 | return -E2BIG; | |
130 | ||
131 | value = kmalloc(size, GFP_KERNEL); | |
132 | if (!value) | |
133 | return -ENOMEM; | |
134 | ||
8cb08329 | 135 | ret = posix_acl_to_xattr(fc->user_ns, acl, value, size); |
60bcc88a SF |
136 | if (ret < 0) { |
137 | kfree(value); | |
138 | return ret; | |
139 | } | |
140 | ||
facd6105 CB |
141 | /* |
142 | * Fuse daemons without FUSE_POSIX_ACL never changed the passed | |
143 | * through POSIX ACLs. Such daemons don't expect setgid bits to | |
144 | * be stripped. | |
145 | */ | |
146 | if (fc->posix_acl && | |
d395d0a5 AM |
147 | !in_group_or_capable(idmap, inode, |
148 | i_gid_into_vfsgid(idmap, inode))) | |
550a7d3b VG |
149 | extra_flags |= FUSE_SETXATTR_ACL_KILL_SGID; |
150 | ||
151 | ret = fuse_setxattr(inode, name, value, size, 0, extra_flags); | |
60bcc88a SF |
152 | kfree(value); |
153 | } else { | |
154 | ret = fuse_removexattr(inode, name); | |
155 | } | |
facd6105 CB |
156 | |
157 | if (fc->posix_acl) { | |
158 | /* | |
159 | * Fuse daemons without FUSE_POSIX_ACL never cached POSIX ACLs | |
160 | * and didn't invalidate attributes. Retain that behavior. | |
161 | */ | |
162 | forget_all_cached_acls(inode); | |
163 | fuse_invalidate_attr(inode); | |
164 | } | |
60bcc88a SF |
165 | |
166 | return ret; | |
167 | } |