4 * Read and write the per-WIM-image table of security descriptors.
8 * Copyright (C) 2012, 2013 Eric Biggers
10 * This file is part of wimlib, a library for working with WIM files.
12 * wimlib is free software; you can redistribute it and/or modify it under the
13 * terms of the GNU General Public License as published by the Free
14 * Software Foundation; either version 3 of the License, or (at your option)
17 * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
18 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
19 * A PARTICULAR PURPOSE. See the GNU General Public License for more
22 * You should have received a copy of the GNU General Public License
23 * along with wimlib; if not, see http://www.gnu.org/licenses/.
26 #include "wimlib_internal.h"
27 #include "buffer_io.h"
30 /* At the start of each type of access control entry. */
32 /* enum ace_type, specifies what type of ACE this is. */
35 /* bitwise OR of the inherit ACE flags #defined above */
38 /* Size of the access control entry. */
42 /* Grants rights to a user or group */
49 /* Denies rights to a user or group */
63 /* Header of an access control list. */
65 /* ACL_REVISION or ACL_REVISION_DS */
71 /* Total size of the ACL, including all access control entries */
74 /* Number of access control entry structures that follow the ACL
82 /* A structure used to identify users or groups. */
87 u8 sub_authority_count;
89 /* Identifies the authority that issued the SID. Can be, but does not
90 * have to be, one of enum sid_authority_value */
91 u8 identifier_authority[6];
102 /* Example: 0x4149 */
103 u16 security_descriptor_control;
105 /* Offset of a SID structure in the security descriptor. */
109 /* Offset of a SID structure in the security descriptor. */
113 /* Offset of an ACL structure in the security descriptor. */
118 /* Offset of an ACL structure in the security descriptor. */
119 /* Discretionary ACL. */
122 } SecurityDescriptor;
125 * This is a hack to work around a problem in libntfs-3g. libntfs-3g validates
126 * security descriptors with a function named ntfs_valid_descr().
127 * ntfs_valid_descr() considers a security descriptor that ends in a SACL
128 * (Sysetm Access Control List) with no ACE's (Access Control Entries) to be
129 * invalid. However, a security descriptor like this exists in the Windows 7
130 * install.wim. Here, security descriptors matching this pattern are modified
131 * to have no SACL. This should make no difference since the SACL had no
132 * entries anyway; however this ensures that that the security descriptors pass
133 * the validation in libntfs-3g.
136 empty_sacl_fixup(u8 *descr, u64 *size_p)
138 /* No-op if no NTFS-3g support, or if NTFS-3g is version 2013 or later
140 #if defined(WITH_NTFS_3G) && !defined(HAVE_NTFS_MNT_RDONLY)
141 if (*size_p >= sizeof(SecurityDescriptor)) {
142 SecurityDescriptor *sd = (SecurityDescriptor*)descr;
143 u32 sacl_offset = le32_to_cpu(sd->sacl_offset);
144 if (sacl_offset == *size_p - sizeof(ACL)) {
145 sd->sacl_offset = cpu_to_le32(0);
146 *size_p -= sizeof(ACL);
152 struct wim_security_data *
153 new_wim_security_data()
155 return CALLOC(1, sizeof(struct wim_security_data));
159 * Reads the security data from the metadata resource.
161 * @metadata_resource: An array that contains the uncompressed metadata
162 * resource for the WIM file.
163 * @metadata_resource_len: The length of @metadata_resource. It must be at
165 * @sd_p: A pointer to a pointer to a wim_security_data structure that
166 * will be filled in with a pointer to a new wim_security_data
167 * structure on success.
169 * Note: There is no `offset' argument because the security data is located at
170 * the beginning of the metadata resource.
173 read_security_data(const u8 metadata_resource[], u64 metadata_resource_len,
174 struct wim_security_data **sd_p)
176 struct wim_security_data *sd;
181 wimlib_assert(metadata_resource_len >= 8);
184 * Sorry this function is excessively complicated--- I'm just being
185 * extremely careful about integer overflows.
188 sd = MALLOC(sizeof(struct wim_security_data));
190 ERROR("Out of memory");
191 return WIMLIB_ERR_NOMEM;
194 sd->descriptors = NULL;
196 p = metadata_resource;
197 p = get_u32(p, &sd->total_length);
198 p = get_u32(p, (u32*)&sd->num_entries);
200 /* The security_id field of each dentry is a signed 32-bit integer, so
201 * the possible indices into the security descriptors table are 0
202 * through 0x7fffffff. Which means 0x80000000 security descriptors
203 * maximum. Not like you should ever have anywhere close to that many
204 * security descriptors! */
205 if (sd->num_entries > 0x80000000) {
206 ERROR("Security data has too many entries!");
210 /* Verify the listed total length of the security data is big enough to
211 * include the sizes array, verify that the file data is big enough to
212 * include it as well, then allocate the array of sizes.
214 * Note: The total length of the security data must fit in a 32-bit
215 * integer, even though each security descriptor size is a 64-bit
216 * integer. This is stupid, and we need to be careful not to actually
217 * let the security descriptor sizes be over 0xffffffff. */
218 if ((u64)sd->total_length > metadata_resource_len) {
219 ERROR("Security data total length (%u) is bigger than the "
220 "metadata resource length (%"PRIu64")",
221 sd->total_length, metadata_resource_len);
225 DEBUG("Reading security data: %u entries, length = %u",
226 sd->num_entries, sd->total_length);
228 if (sd->num_entries == 0) {
229 /* No security descriptors. We allow the total_length field to
230 * be either 8 (which is correct, since there are always 2
231 * 32-bit integers) or 0. */
232 if (sd->total_length != 0 && sd->total_length != 8) {
233 ERROR("Invalid security data length (%u): expected 0 or 8",
237 sd->total_length = 8;
241 u64 sizes_size = (u64)sd->num_entries * sizeof(u64);
242 u64 size_no_descriptors = 8 + sizes_size;
243 if (size_no_descriptors > (u64)sd->total_length) {
244 ERROR("Security data total length of %u is too short because "
245 "there seem to be at least %"PRIu64" bytes of security data",
246 sd->total_length, 8 + sizes_size);
250 sd->sizes = MALLOC(sizes_size);
252 ret = WIMLIB_ERR_NOMEM;
256 /* Copy the sizes array in from the file data. */
257 p = get_bytes(p, sizes_size, sd->sizes);
258 array_le64_to_cpu(sd->sizes, sd->num_entries);
260 /* Allocate the array of pointers to descriptors, and read them in. */
261 sd->descriptors = CALLOC(sd->num_entries, sizeof(u8*));
262 if (!sd->descriptors) {
263 ERROR("Out of memory while allocating security "
265 ret = WIMLIB_ERR_NOMEM;
268 total_len = size_no_descriptors;
270 for (u32 i = 0; i < sd->num_entries; i++) {
271 /* Watch out for huge security descriptor sizes that could
272 * overflow the total length and wrap it around. */
273 if (total_len + sd->sizes[i] < total_len) {
274 ERROR("Caught overflow in security descriptor lengths "
275 "(current total length = %"PRIu64", security "
276 "descriptor size = %"PRIu64")",
277 total_len, sd->sizes[i]);
280 total_len += sd->sizes[i];
281 /* This check ensures that the descriptor size fits in a 32 bit
282 * integer. Because if it didn't, the total length would come
283 * out bigger than sd->total_length, which is a 32 bit integer.
285 if (total_len > (u64)sd->total_length) {
286 ERROR("Security data total length of %u is too short "
287 "because there seem to be at least %"PRIu64" "
288 "bytes of security data",
289 sd->total_length, total_len);
292 sd->descriptors[i] = MALLOC(sd->sizes[i]);
293 if (!sd->descriptors[i]) {
294 ERROR("Out of memory while allocating security "
296 ret = WIMLIB_ERR_NOMEM;
299 p = get_bytes(p, sd->sizes[i], sd->descriptors[i]);
300 empty_sacl_fixup(sd->descriptors[i], &sd->sizes[i]);
302 wimlib_assert(total_len <= 0xffffffff);
303 if (((total_len + 7) & ~7) != ((sd->total_length + 7) & ~7)) {
304 ERROR("Expected security data total length = %u, but "
305 "calculated %u", sd->total_length, (unsigned)total_len);
308 sd->total_length = total_len;
313 ret = WIMLIB_ERR_INVALID_SECURITY_DATA;
315 free_security_data(sd);
320 * Writes security data to an in-memory buffer.
323 write_security_data(const struct wim_security_data *sd, u8 *p)
325 DEBUG("Writing security data (total_length = %"PRIu32", num_entries "
326 "= %"PRIu32")", sd->total_length, sd->num_entries);
328 u32 aligned_length = (sd->total_length + 7) & ~7;
331 p = put_u32(p, aligned_length);
332 p = put_u32(p, sd->num_entries);
334 for (u32 i = 0; i < sd->num_entries; i++)
335 p = put_u64(p, sd->sizes[i]);
337 for (u32 i = 0; i < sd->num_entries; i++)
338 p = put_bytes(p, sd->sizes[i], sd->descriptors[i]);
340 wimlib_assert(p - orig_p == sd->total_length);
341 p = put_zeroes(p, aligned_length - sd->total_length);
343 DEBUG("Successfully wrote security data.");
348 print_acl(const void *p, const tchar *type)
351 u8 revision = acl->revision;
352 u16 acl_size = le16_to_cpu(acl->acl_size);
353 u16 ace_count = le16_to_cpu(acl->ace_count);
354 tprintf(T(" [%"TS" ACL]\n"), type);
355 tprintf(T(" Revision = %u\n"), revision);
356 tprintf(T(" ACL Size = %u\n"), acl_size);
357 tprintf(T(" ACE Count = %u\n"), ace_count);
360 for (u16 i = 0; i < ace_count; i++) {
361 const ACEHeader *hdr = p;
362 tprintf(T(" [ACE]\n"));
363 tprintf(T(" ACE type = %d\n"), hdr->type);
364 tprintf(T(" ACE flags = 0x%x\n"), hdr->flags);
365 tprintf(T(" ACE size = %u\n"), hdr->size);
366 const AccessAllowedACE *aaa = (const AccessAllowedACE*)hdr;
367 tprintf(T(" ACE mask = %x\n"), le32_to_cpu(aaa->mask));
368 tprintf(T(" SID start = %u\n"), le32_to_cpu(aaa->sid_start));
375 print_sid(const void *p, const tchar *type)
378 tprintf(T(" [%"TS" SID]\n"), type);
379 tprintf(T(" Revision = %u\n"), sid->revision);
380 tprintf(T(" Subauthority count = %u\n"), sid->sub_authority_count);
381 tprintf(T(" Identifier authority = "));
382 print_byte_field(sid->identifier_authority,
383 sizeof(sid->identifier_authority), stdout);
385 for (u8 i = 0; i < sid->sub_authority_count; i++) {
386 tprintf(T(" Subauthority %u = %u\n"),
387 i, le32_to_cpu(sid->sub_authority[i]));
393 print_security_descriptor(const void *p, u64 size)
395 const SecurityDescriptor *sd = p;
397 u8 revision = sd->revision;
398 u16 control = le16_to_cpu(sd->security_descriptor_control);
399 u32 owner_offset = le32_to_cpu(sd->owner_offset);
400 u32 group_offset = le32_to_cpu(sd->group_offset);
401 u32 sacl_offset = le32_to_cpu(sd->sacl_offset);
402 u32 dacl_offset = le32_to_cpu(sd->dacl_offset);
403 tprintf(T("Revision = %u\n"), revision);
404 tprintf(T("Security Descriptor Control = %#x\n"), control);
405 tprintf(T("Owner offset = %u\n"), owner_offset);
406 tprintf(T("Group offset = %u\n"), group_offset);
407 tprintf(T("System ACL offset = %u\n"), sacl_offset);
408 tprintf(T("Discretionary ACL offset = %u\n"), dacl_offset);
410 if (sd->owner_offset != 0)
411 print_sid(p + owner_offset, T("Owner"));
412 if (sd->group_offset != 0)
413 print_sid(p + group_offset, T("Group"));
414 if (sd->sacl_offset != 0)
415 print_acl(p + sacl_offset, T("System"));
416 if (sd->dacl_offset != 0)
417 print_acl(p + dacl_offset, T("Discretionary"));
421 * Prints the security data for a WIM file.
424 print_security_data(const struct wim_security_data *sd)
426 wimlib_assert(sd != NULL);
428 tputs(T("[SECURITY DATA]"));
429 tprintf(T("Length = %"PRIu32" bytes\n"), sd->total_length);
430 tprintf(T("Number of Entries = %"PRIu32"\n"), sd->num_entries);
432 for (u32 i = 0; i < sd->num_entries; i++) {
433 tprintf(T("[SecurityDescriptor %"PRIu32", length = %"PRIu64"]\n"),
435 print_security_descriptor(sd->descriptors[i], sd->sizes[i]);
442 free_security_data(struct wim_security_data *sd)
445 u8 **descriptors = sd->descriptors;
446 u32 num_entries = sd->num_entries;
448 while (num_entries--)
449 FREE(*descriptors++);
451 FREE(sd->descriptors);
458 u8 hash[SHA1_HASH_SIZE];
459 struct rb_node rb_node;
463 free_sd_tree(struct rb_node *node)
466 free_sd_tree(node->rb_left);
467 free_sd_tree(node->rb_right);
468 FREE(container_of(node, struct sd_node, rb_node));
472 /* Frees a security descriptor index set. */
474 destroy_sd_set(struct sd_set *sd_set, bool rollback)
477 struct wim_security_data *sd = sd_set->sd;
479 for (i = sd_set->orig_num_entries; i < sd->num_entries; i++)
480 FREE(sd->descriptors[i]);
481 sd->num_entries = sd_set->orig_num_entries;
483 free_sd_tree(sd_set->rb_root.rb_node);
486 /* Inserts a a new node into the security descriptor index tree. */
488 insert_sd_node(struct sd_set *set, struct sd_node *new)
490 struct rb_root *root = &set->rb_root;
491 struct rb_node **p = &(root->rb_node);
492 struct rb_node *rb_parent = NULL;
495 struct sd_node *this = container_of(*p, struct sd_node, rb_node);
496 int cmp = hashes_cmp(new->hash, this->hash);
500 p = &((*p)->rb_left);
502 p = &((*p)->rb_right);
504 return false; /* Duplicate SHA1 message digest */
506 rb_link_node(&new->rb_node, rb_parent, p);
507 rb_insert_color(&new->rb_node, root);
511 /* Returns the index of the security descriptor having a SHA1 message digest of
512 * @hash. If not found, return -1. */
514 lookup_sd(struct sd_set *set, const u8 hash[SHA1_HASH_SIZE])
516 struct rb_node *node = set->rb_root.rb_node;
519 struct sd_node *sd_node = container_of(node, struct sd_node, rb_node);
520 int cmp = hashes_cmp(hash, sd_node->hash);
522 node = node->rb_left;
524 node = node->rb_right;
526 return sd_node->security_id;
532 * Adds a security descriptor to the indexed security descriptor set as well as
533 * the corresponding `struct wim_security_data', and returns the new security
534 * ID; or, if there is an existing security descriptor that is the same, return
535 * the security ID for it. If a new security descriptor cannot be allocated,
539 sd_set_add_sd(struct sd_set *sd_set, const char descriptor[], size_t size)
541 u8 hash[SHA1_HASH_SIZE];
547 struct wim_security_data *sd;
550 sha1_buffer((const u8*)descriptor, size, hash);
552 security_id = lookup_sd(sd_set, hash);
553 if (security_id >= 0) /* Identical descriptor already exists */
556 /* Need to add a new security descriptor */
557 new = MALLOC(sizeof(*new));
560 descr_copy = MALLOC(size);
566 memcpy(descr_copy, descriptor, size);
567 new->security_id = sd->num_entries;
568 copy_hash(new->hash, hash);
570 /* There typically are only a few dozen security descriptors in a
571 * directory tree, so expanding the array of security descriptors by
572 * only 1 extra space each time should not be a problem. */
573 descriptors = REALLOC(sd->descriptors,
574 (sd->num_entries + 1) * sizeof(sd->descriptors[0]));
577 sd->descriptors = descriptors;
578 sizes = REALLOC(sd->sizes,
579 (sd->num_entries + 1) * sizeof(sd->sizes[0]));
583 sd->descriptors[sd->num_entries] = descr_copy;
584 sd->sizes[sd->num_entries] = size;
586 DEBUG("There are now %d security descriptors", sd->num_entries);
587 sd->total_length += size + sizeof(sd->sizes[0]);
588 bret = insert_sd_node(sd_set, new);
590 return new->security_id;
600 init_sd_set(struct sd_set *sd_set, struct wim_security_data *sd)
605 sd_set->rb_root.rb_node = NULL;
606 sd_set->orig_num_entries = sd->num_entries;
607 for (int32_t i = 0; i < sd->num_entries; i++) {
610 new = MALLOC(sizeof(struct sd_node));
612 ret = WIMLIB_ERR_NOMEM;
613 goto out_destroy_sd_set;
615 sha1_buffer(sd->descriptors[i], sd->sizes[i], new->hash);
616 new->security_id = i;
617 if (!insert_sd_node(sd_set, new))
618 FREE(new); /* Ignore duplicate security descriptor */
623 destroy_sd_set(sd_set, false);