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 return error; 222 } 223 224 int 225 ext4_set_acl(struct user_namespace *mnt_userns, struct inode *inode, 226 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 ext4_fc_start_update(inode); 247 248 if ((type == ACL_TYPE_ACCESS) && acl) { 249 error = posix_acl_update_mode(mnt_userns, inode, &mode, &acl); 250 if (error) 251 goto out_stop; 252 if (mode != inode->i_mode) 253 update_mode = 1; 254 } 255 256 error = __ext4_set_acl(handle, inode, type, acl, 0 /* xattr_flags */); 257 if (!error && update_mode) { 258 inode->i_mode = mode; 259 inode->i_ctime = current_time(inode); 260 error = ext4_mark_inode_dirty(handle, inode); 261 } 262 out_stop: 263 ext4_journal_stop(handle); 264 ext4_fc_stop_update(inode); 265 if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) 266 goto retry; 267 return error; 268 } 269 270 /* 271 * Initialize the ACLs of a new inode. Called from ext4_new_inode. 272 * 273 * dir->i_mutex: down 274 * inode->i_mutex: up (access to inode is still exclusive) 275 */ 276 int 277 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir) 278 { 279 struct posix_acl *default_acl, *acl; 280 int error; 281 282 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl); 283 if (error) 284 return error; 285 286 if (default_acl) { 287 error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT, 288 default_acl, XATTR_CREATE); 289 posix_acl_release(default_acl); 290 } else { 291 inode->i_default_acl = NULL; 292 } 293 if (acl) { 294 if (!error) 295 error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, 296 acl, XATTR_CREATE); 297 posix_acl_release(acl); 298 } else { 299 inode->i_acl = NULL; 300 } 301 return error; 302 } 303