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_rwsem: don't care 143 */ 144 struct posix_acl * 145 ext4_get_acl(struct inode *inode, int type, bool rcu) 146 { 147 int name_index; 148 char *value = NULL; 149 struct posix_acl *acl; 150 int retval; 151 152 if (rcu) 153 return ERR_PTR(-ECHILD); 154 155 switch (type) { 156 case ACL_TYPE_ACCESS: 157 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; 158 break; 159 case ACL_TYPE_DEFAULT: 160 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; 161 break; 162 default: 163 BUG(); 164 } 165 retval = ext4_xattr_get(inode, name_index, "", NULL, 0); 166 if (retval > 0) { 167 value = kmalloc(retval, GFP_NOFS); 168 if (!value) 169 return ERR_PTR(-ENOMEM); 170 retval = ext4_xattr_get(inode, name_index, "", value, retval); 171 } 172 if (retval > 0) 173 acl = ext4_acl_from_disk(value, retval); 174 else if (retval == -ENODATA || retval == -ENOSYS) 175 acl = NULL; 176 else 177 acl = ERR_PTR(retval); 178 kfree(value); 179 180 return acl; 181 } 182 183 /* 184 * Set the access or default ACL of an inode. 185 * 186 * inode->i_rwsem: down unless called from ext4_new_inode 187 */ 188 static int 189 __ext4_set_acl(handle_t *handle, struct inode *inode, int type, 190 struct posix_acl *acl, int xattr_flags) 191 { 192 int name_index; 193 void *value = NULL; 194 size_t size = 0; 195 int error; 196 197 switch (type) { 198 case ACL_TYPE_ACCESS: 199 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; 200 break; 201 202 case ACL_TYPE_DEFAULT: 203 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; 204 if (!S_ISDIR(inode->i_mode)) 205 return acl ? -EACCES : 0; 206 break; 207 208 default: 209 return -EINVAL; 210 } 211 if (acl) { 212 value = ext4_acl_to_disk(acl, &size); 213 if (IS_ERR(value)) 214 return (int)PTR_ERR(value); 215 } 216 217 error = ext4_xattr_set_handle(handle, inode, name_index, "", 218 value, size, xattr_flags); 219 220 kfree(value); 221 if (!error) 222 set_cached_acl(inode, type, acl); 223 224 return error; 225 } 226 227 int 228 ext4_set_acl(struct user_namespace *mnt_userns, struct inode *inode, 229 struct posix_acl *acl, int type) 230 { 231 handle_t *handle; 232 int error, credits, retries = 0; 233 size_t acl_size = acl ? ext4_acl_size(acl->a_count) : 0; 234 umode_t mode = inode->i_mode; 235 int update_mode = 0; 236 237 error = dquot_initialize(inode); 238 if (error) 239 return error; 240 retry: 241 error = ext4_xattr_set_credits(inode, acl_size, false /* is_create */, 242 &credits); 243 if (error) 244 return error; 245 246 handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits); 247 if (IS_ERR(handle)) 248 return PTR_ERR(handle); 249 250 if ((type == ACL_TYPE_ACCESS) && acl) { 251 error = posix_acl_update_mode(mnt_userns, inode, &mode, &acl); 252 if (error) 253 goto out_stop; 254 if (mode != inode->i_mode) 255 update_mode = 1; 256 } 257 258 error = __ext4_set_acl(handle, inode, type, acl, 0 /* xattr_flags */); 259 if (!error && update_mode) { 260 inode->i_mode = mode; 261 inode->i_ctime = current_time(inode); 262 error = ext4_mark_inode_dirty(handle, inode); 263 } 264 out_stop: 265 ext4_journal_stop(handle); 266 if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) 267 goto retry; 268 return error; 269 } 270 271 /* 272 * Initialize the ACLs of a new inode. Called from ext4_new_inode. 273 * 274 * dir->i_rwsem: down 275 * inode->i_rwsem: up (access to inode is still exclusive) 276 */ 277 int 278 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir) 279 { 280 struct posix_acl *default_acl, *acl; 281 int error; 282 283 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl); 284 if (error) 285 return error; 286 287 if (default_acl) { 288 error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT, 289 default_acl, XATTR_CREATE); 290 posix_acl_release(default_acl); 291 } else { 292 inode->i_default_acl = NULL; 293 } 294 if (acl) { 295 if (!error) 296 error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, 297 acl, XATTR_CREATE); 298 posix_acl_release(acl); 299 } else { 300 inode->i_acl = NULL; 301 } 302 return error; 303 } 304