| 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * linux/fs/ext4/acl.c |
| 4 | * |
| 5 | * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de> |
| 6 | */ |
| 7 | |
| 8 | #include <linux/quotaops.h> |
| 9 | #include "ext4_jbd2.h" |
| 10 | #include "ext4.h" |
| 11 | #include "xattr.h" |
| 12 | #include "acl.h" |
| 13 | |
| 14 | /* |
| 15 | * Convert from filesystem to in-memory representation. |
| 16 | */ |
| 17 | static struct posix_acl * |
| 18 | ext4_acl_from_disk(const void *value, size_t size) |
| 19 | { |
| 20 | const char *end = (char *)value + size; |
| 21 | int n, count; |
| 22 | struct posix_acl *acl; |
| 23 | |
| 24 | if (!value) |
| 25 | return NULL; |
| 26 | if (size < sizeof(ext4_acl_header)) |
| 27 | return ERR_PTR(-EINVAL); |
| 28 | if (((ext4_acl_header *)value)->a_version != |
| 29 | cpu_to_le32(EXT4_ACL_VERSION)) |
| 30 | return ERR_PTR(-EINVAL); |
| 31 | value = (char *)value + sizeof(ext4_acl_header); |
| 32 | count = ext4_acl_count(size); |
| 33 | if (count < 0) |
| 34 | return ERR_PTR(-EINVAL); |
| 35 | if (count == 0) |
| 36 | return NULL; |
| 37 | acl = posix_acl_alloc(count, GFP_NOFS); |
| 38 | if (!acl) |
| 39 | return ERR_PTR(-ENOMEM); |
| 40 | for (n = 0; n < count; n++) { |
| 41 | ext4_acl_entry *entry = |
| 42 | (ext4_acl_entry *)value; |
| 43 | if ((char *)value + sizeof(ext4_acl_entry_short) > end) |
| 44 | goto fail; |
| 45 | acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag); |
| 46 | acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm); |
| 47 | |
| 48 | switch (acl->a_entries[n].e_tag) { |
| 49 | case ACL_USER_OBJ: |
| 50 | case ACL_GROUP_OBJ: |
| 51 | case ACL_MASK: |
| 52 | case ACL_OTHER: |
| 53 | value = (char *)value + |
| 54 | sizeof(ext4_acl_entry_short); |
| 55 | break; |
| 56 | |
| 57 | case ACL_USER: |
| 58 | value = (char *)value + sizeof(ext4_acl_entry); |
| 59 | if ((char *)value > end) |
| 60 | goto fail; |
| 61 | acl->a_entries[n].e_uid = |
| 62 | make_kuid(&init_user_ns, |
| 63 | le32_to_cpu(entry->e_id)); |
| 64 | break; |
| 65 | case ACL_GROUP: |
| 66 | value = (char *)value + sizeof(ext4_acl_entry); |
| 67 | if ((char *)value > end) |
| 68 | goto fail; |
| 69 | acl->a_entries[n].e_gid = |
| 70 | make_kgid(&init_user_ns, |
| 71 | le32_to_cpu(entry->e_id)); |
| 72 | break; |
| 73 | |
| 74 | default: |
| 75 | goto fail; |
| 76 | } |
| 77 | } |
| 78 | if (value != end) |
| 79 | goto fail; |
| 80 | return acl; |
| 81 | |
| 82 | fail: |
| 83 | posix_acl_release(acl); |
| 84 | return ERR_PTR(-EINVAL); |
| 85 | } |
| 86 | |
| 87 | /* |
| 88 | * Convert from in-memory to filesystem representation. |
| 89 | */ |
| 90 | static void * |
| 91 | ext4_acl_to_disk(const struct posix_acl *acl, size_t *size) |
| 92 | { |
| 93 | ext4_acl_header *ext_acl; |
| 94 | char *e; |
| 95 | size_t n; |
| 96 | |
| 97 | *size = ext4_acl_size(acl->a_count); |
| 98 | ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count * |
| 99 | sizeof(ext4_acl_entry), GFP_NOFS); |
| 100 | if (!ext_acl) |
| 101 | return ERR_PTR(-ENOMEM); |
| 102 | ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION); |
| 103 | e = (char *)ext_acl + sizeof(ext4_acl_header); |
| 104 | for (n = 0; n < acl->a_count; n++) { |
| 105 | const struct posix_acl_entry *acl_e = &acl->a_entries[n]; |
| 106 | ext4_acl_entry *entry = (ext4_acl_entry *)e; |
| 107 | entry->e_tag = cpu_to_le16(acl_e->e_tag); |
| 108 | entry->e_perm = cpu_to_le16(acl_e->e_perm); |
| 109 | switch (acl_e->e_tag) { |
| 110 | case ACL_USER: |
| 111 | entry->e_id = cpu_to_le32( |
| 112 | from_kuid(&init_user_ns, acl_e->e_uid)); |
| 113 | e += sizeof(ext4_acl_entry); |
| 114 | break; |
| 115 | case ACL_GROUP: |
| 116 | entry->e_id = cpu_to_le32( |
| 117 | from_kgid(&init_user_ns, acl_e->e_gid)); |
| 118 | e += sizeof(ext4_acl_entry); |
| 119 | break; |
| 120 | |
| 121 | case ACL_USER_OBJ: |
| 122 | case ACL_GROUP_OBJ: |
| 123 | case ACL_MASK: |
| 124 | case ACL_OTHER: |
| 125 | e += sizeof(ext4_acl_entry_short); |
| 126 | break; |
| 127 | |
| 128 | default: |
| 129 | goto fail; |
| 130 | } |
| 131 | } |
| 132 | return (char *)ext_acl; |
| 133 | |
| 134 | fail: |
| 135 | kfree(ext_acl); |
| 136 | return ERR_PTR(-EINVAL); |
| 137 | } |
| 138 | |
| 139 | /* |
| 140 | * Inode operation get_posix_acl(). |
| 141 | * |
| 142 | * inode->i_mutex: don't care |
| 143 | */ |
| 144 | struct posix_acl * |
| 145 | ext4_get_acl(struct inode *inode, int type) |
| 146 | { |
| 147 | int name_index; |
| 148 | char *value = NULL; |
| 149 | struct posix_acl *acl; |
| 150 | int retval; |
| 151 | |
| 152 | switch (type) { |
| 153 | case ACL_TYPE_ACCESS: |
| 154 | name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; |
| 155 | break; |
| 156 | case ACL_TYPE_DEFAULT: |
| 157 | name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; |
| 158 | break; |
| 159 | default: |
| 160 | BUG(); |
| 161 | } |
| 162 | retval = ext4_xattr_get(inode, name_index, "", NULL, 0); |
| 163 | if (retval > 0) { |
| 164 | value = kmalloc(retval, GFP_NOFS); |
| 165 | if (!value) |
| 166 | return ERR_PTR(-ENOMEM); |
| 167 | retval = ext4_xattr_get(inode, name_index, "", value, retval); |
| 168 | } |
| 169 | if (retval > 0) |
| 170 | acl = ext4_acl_from_disk(value, retval); |
| 171 | else if (retval == -ENODATA || retval == -ENOSYS) |
| 172 | acl = NULL; |
| 173 | else |
| 174 | acl = ERR_PTR(retval); |
| 175 | kfree(value); |
| 176 | |
| 177 | return acl; |
| 178 | } |
| 179 | |
| 180 | /* |
| 181 | * Set the access or default ACL of an inode. |
| 182 | * |
| 183 | * inode->i_mutex: down unless called from ext4_new_inode |
| 184 | */ |
| 185 | static int |
| 186 | __ext4_set_acl(handle_t *handle, struct inode *inode, int type, |
| 187 | struct posix_acl *acl, int xattr_flags) |
| 188 | { |
| 189 | int name_index; |
| 190 | void *value = NULL; |
| 191 | size_t size = 0; |
| 192 | int error; |
| 193 | |
| 194 | switch (type) { |
| 195 | case ACL_TYPE_ACCESS: |
| 196 | name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; |
| 197 | break; |
| 198 | |
| 199 | case ACL_TYPE_DEFAULT: |
| 200 | name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; |
| 201 | if (!S_ISDIR(inode->i_mode)) |
| 202 | return acl ? -EACCES : 0; |
| 203 | break; |
| 204 | |
| 205 | default: |
| 206 | return -EINVAL; |
| 207 | } |
| 208 | if (acl) { |
| 209 | value = ext4_acl_to_disk(acl, &size); |
| 210 | if (IS_ERR(value)) |
| 211 | return (int)PTR_ERR(value); |
| 212 | } |
| 213 | |
| 214 | error = ext4_xattr_set_handle(handle, inode, name_index, "", |
| 215 | value, size, xattr_flags); |
| 216 | |
| 217 | kfree(value); |
| 218 | if (!error) { |
| 219 | set_cached_acl(inode, type, acl); |
| 220 | } |
| 221 | |
| 222 | return error; |
| 223 | } |
| 224 | |
| 225 | int |
| 226 | ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type) |
| 227 | { |
| 228 | handle_t *handle; |
| 229 | int error, credits, retries = 0; |
| 230 | size_t acl_size = acl ? ext4_acl_size(acl->a_count) : 0; |
| 231 | umode_t mode = inode->i_mode; |
| 232 | int update_mode = 0; |
| 233 | |
| 234 | error = dquot_initialize(inode); |
| 235 | if (error) |
| 236 | return error; |
| 237 | retry: |
| 238 | error = ext4_xattr_set_credits(inode, acl_size, false /* is_create */, |
| 239 | &credits); |
| 240 | if (error) |
| 241 | return error; |
| 242 | |
| 243 | handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits); |
| 244 | if (IS_ERR(handle)) |
| 245 | return PTR_ERR(handle); |
| 246 | |
| 247 | if ((type == ACL_TYPE_ACCESS) && acl) { |
| 248 | error = posix_acl_update_mode(inode, &mode, &acl); |
| 249 | if (error) |
| 250 | goto out_stop; |
| 251 | update_mode = 1; |
| 252 | } |
| 253 | |
| 254 | error = __ext4_set_acl(handle, inode, type, acl, 0 /* xattr_flags */); |
| 255 | if (!error && update_mode) { |
| 256 | inode->i_mode = mode; |
| 257 | inode->i_ctime = current_time(inode); |
| 258 | ext4_mark_inode_dirty(handle, inode); |
| 259 | } |
| 260 | out_stop: |
| 261 | ext4_journal_stop(handle); |
| 262 | if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) |
| 263 | goto retry; |
| 264 | return error; |
| 265 | } |
| 266 | |
| 267 | /* |
| 268 | * Initialize the ACLs of a new inode. Called from ext4_new_inode. |
| 269 | * |
| 270 | * dir->i_mutex: down |
| 271 | * inode->i_mutex: up (access to inode is still exclusive) |
| 272 | */ |
| 273 | int |
| 274 | ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir) |
| 275 | { |
| 276 | struct posix_acl *default_acl, *acl; |
| 277 | int error; |
| 278 | |
| 279 | error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl); |
| 280 | if (error) |
| 281 | return error; |
| 282 | |
| 283 | if (default_acl) { |
| 284 | error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT, |
| 285 | default_acl, XATTR_CREATE); |
| 286 | posix_acl_release(default_acl); |
| 287 | } |
| 288 | if (acl) { |
| 289 | if (!error) |
| 290 | error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, |
| 291 | acl, XATTR_CREATE); |
| 292 | posix_acl_release(acl); |
| 293 | } |
| 294 | return error; |
| 295 | } |