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1 | /* |
2 | * linux/fs/xattr_acl.c |
3 | * |
4 | * Almost all from linux/fs/ext2/acl.c: |
5 | * Copyright (C) 2001 by Andreas Gruenbacher, <a.gruenbacher@computer.org> |
6 | */ |
7 | |
8 | #include <linux/export.h> |
9 | #include <linux/fs.h> |
10 | #include <linux/posix_acl_xattr.h> |
11 | #include <linux/gfp.h> |
12 | #include <linux/user_namespace.h> |
13 | |
14 | /* |
15 | * Fix up the uids and gids in posix acl extended attributes in place. |
16 | */ |
17 | static void posix_acl_fix_xattr_userns( |
18 | struct user_namespace *to, struct user_namespace *from, |
19 | void *value, size_t size) |
20 | { |
21 | posix_acl_xattr_header *header = (posix_acl_xattr_header *)value; |
22 | posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end; |
23 | int count; |
24 | kuid_t uid; |
25 | kgid_t gid; |
26 | |
27 | if (!value) |
28 | return; |
29 | if (size < sizeof(posix_acl_xattr_header)) |
30 | return; |
31 | if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) |
32 | return; |
33 | |
34 | count = posix_acl_xattr_count(size); |
35 | if (count < 0) |
36 | return; |
37 | if (count == 0) |
38 | return; |
39 | |
40 | for (end = entry + count; entry != end; entry++) { |
41 | switch(le16_to_cpu(entry->e_tag)) { |
42 | case ACL_USER: |
43 | uid = make_kuid(from, le32_to_cpu(entry->e_id)); |
44 | entry->e_id = cpu_to_le32(from_kuid(to, uid)); |
45 | break; |
46 | case ACL_GROUP: |
47 | gid = make_kgid(from, le32_to_cpu(entry->e_id)); |
48 | entry->e_id = cpu_to_le32(from_kgid(to, gid)); |
49 | break; |
50 | default: |
51 | break; |
52 | } |
53 | } |
54 | } |
55 | |
56 | void posix_acl_fix_xattr_from_user(void *value, size_t size) |
57 | { |
58 | struct user_namespace *user_ns = current_user_ns(); |
59 | if (user_ns == &init_user_ns) |
60 | return; |
61 | posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size); |
62 | } |
63 | |
64 | void posix_acl_fix_xattr_to_user(void *value, size_t size) |
65 | { |
66 | struct user_namespace *user_ns = current_user_ns(); |
67 | if (user_ns == &init_user_ns) |
68 | return; |
69 | posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size); |
70 | } |
71 | |
72 | /* |
73 | * Convert from extended attribute to in-memory representation. |
74 | */ |
75 | struct posix_acl * |
76 | posix_acl_from_xattr(struct user_namespace *user_ns, |
77 | const void *value, size_t size) |
78 | { |
79 | posix_acl_xattr_header *header = (posix_acl_xattr_header *)value; |
80 | posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end; |
81 | int count; |
82 | struct posix_acl *acl; |
83 | struct posix_acl_entry *acl_e; |
84 | |
85 | if (!value) |
86 | return NULL; |
87 | if (size < sizeof(posix_acl_xattr_header)) |
88 | return ERR_PTR(-EINVAL); |
89 | if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) |
90 | return ERR_PTR(-EOPNOTSUPP); |
91 | |
92 | count = posix_acl_xattr_count(size); |
93 | if (count < 0) |
94 | return ERR_PTR(-EINVAL); |
95 | if (count == 0) |
96 | return NULL; |
97 | |
98 | acl = posix_acl_alloc(count, GFP_NOFS); |
99 | if (!acl) |
100 | return ERR_PTR(-ENOMEM); |
101 | acl_e = acl->a_entries; |
102 | |
103 | for (end = entry + count; entry != end; acl_e++, entry++) { |
104 | acl_e->e_tag = le16_to_cpu(entry->e_tag); |
105 | acl_e->e_perm = le16_to_cpu(entry->e_perm); |
106 | |
107 | switch(acl_e->e_tag) { |
108 | case ACL_USER_OBJ: |
109 | case ACL_GROUP_OBJ: |
110 | case ACL_MASK: |
111 | case ACL_OTHER: |
112 | break; |
113 | |
114 | case ACL_USER: |
115 | acl_e->e_uid = |
116 | make_kuid(user_ns, |
117 | le32_to_cpu(entry->e_id)); |
118 | if (!uid_valid(acl_e->e_uid)) |
119 | goto fail; |
120 | break; |
121 | case ACL_GROUP: |
122 | acl_e->e_gid = |
123 | make_kgid(user_ns, |
124 | le32_to_cpu(entry->e_id)); |
125 | if (!gid_valid(acl_e->e_gid)) |
126 | goto fail; |
127 | break; |
128 | |
129 | default: |
130 | goto fail; |
131 | } |
132 | } |
133 | return acl; |
134 | |
135 | fail: |
136 | posix_acl_release(acl); |
137 | return ERR_PTR(-EINVAL); |
138 | } |
139 | EXPORT_SYMBOL (posix_acl_from_xattr); |
140 | |
141 | /* |
142 | * Convert from in-memory to extended attribute representation. |
143 | */ |
144 | int |
145 | posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl, |
146 | void *buffer, size_t size) |
147 | { |
148 | posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer; |
149 | posix_acl_xattr_entry *ext_entry = ext_acl->a_entries; |
150 | int real_size, n; |
151 | |
152 | real_size = posix_acl_xattr_size(acl->a_count); |
153 | if (!buffer) |
154 | return real_size; |
155 | if (real_size > size) |
156 | return -ERANGE; |
157 | |
158 | ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION); |
159 | |
160 | for (n=0; n < acl->a_count; n++, ext_entry++) { |
161 | const struct posix_acl_entry *acl_e = &acl->a_entries[n]; |
162 | ext_entry->e_tag = cpu_to_le16(acl_e->e_tag); |
163 | ext_entry->e_perm = cpu_to_le16(acl_e->e_perm); |
164 | switch(acl_e->e_tag) { |
165 | case ACL_USER: |
166 | ext_entry->e_id = |
167 | cpu_to_le32(from_kuid(user_ns, acl_e->e_uid)); |
168 | break; |
169 | case ACL_GROUP: |
170 | ext_entry->e_id = |
171 | cpu_to_le32(from_kgid(user_ns, acl_e->e_gid)); |
172 | break; |
173 | default: |
174 | ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID); |
175 | break; |
176 | } |
177 | } |
178 | return real_size; |
179 | } |
180 | EXPORT_SYMBOL (posix_acl_to_xattr); |
181 |
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