4 * Read and write the per-WIM-image table of security descriptors.
8 * Copyright (C) 2012, 2013, 2014 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/.
30 #include "wimlib/assert.h"
31 #include "wimlib/avl_tree.h"
32 #include "wimlib/endianness.h"
33 #include "wimlib/error.h"
34 #include "wimlib/security.h"
35 #include "wimlib/sha1.h"
36 #include "wimlib/util.h"
38 struct wim_security_data_disk {
44 struct wim_security_data *
45 new_wim_security_data(void)
47 return CALLOC(1, sizeof(struct wim_security_data));
51 * Reads the security data from the metadata resource of a WIM image.
53 * @metadata_resource: An array that contains the uncompressed metadata
54 * resource for the WIM image.
55 * @metadata_resource_len: The length of @metadata_resource.
56 * @sd_ret: A pointer to a pointer to a wim_security_data structure that
57 * will be filled in with a pointer to a new wim_security_data
58 * structure containing the security data on success.
60 * Note: There is no `offset' argument because the security data is located at
61 * the beginning of the metadata resource.
64 * WIMLIB_ERR_SUCCESS (0)
65 * WIMLIB_ERR_INVALID_METADATA_RESOURCE
69 read_wim_security_data(const u8 metadata_resource[], size_t metadata_resource_len,
70 struct wim_security_data **sd_ret)
72 struct wim_security_data *sd;
76 u64 size_no_descriptors;
77 const struct wim_security_data_disk *sd_disk;
80 if (metadata_resource_len < 8)
81 return WIMLIB_ERR_INVALID_METADATA_RESOURCE;
83 sd = new_wim_security_data();
87 sd_disk = (const struct wim_security_data_disk*)metadata_resource;
88 sd->total_length = le32_to_cpu(sd_disk->total_length);
89 sd->num_entries = le32_to_cpu(sd_disk->num_entries);
91 DEBUG("Reading security data: num_entries=%u, total_length=%u",
92 sd->num_entries, sd->total_length);
94 /* Length field of 0 is a special case that really means length
96 if (sd->total_length == 0)
99 /* The security_id field of each dentry is a signed 32-bit integer, so
100 * the possible indices into the security descriptors table are 0
101 * through 0x7fffffff. Which means 0x80000000 security descriptors
102 * maximum. Not like you should ever have anywhere close to that many
103 * security descriptors! */
104 if (sd->num_entries > 0x80000000)
107 /* Verify the listed total length of the security data is big enough to
108 * include the sizes array, verify that the file data is big enough to
109 * include it as well, then allocate the array of sizes.
111 * Note: The total length of the security data must fit in a 32-bit
112 * integer, even though each security descriptor size is a 64-bit
113 * integer. This is stupid, and we need to be careful not to actually
114 * let the security descriptor sizes be over 0xffffffff. */
115 if (sd->total_length > metadata_resource_len)
118 sizes_size = (u64)sd->num_entries * sizeof(u64);
119 size_no_descriptors = 8 + sizes_size;
120 if (size_no_descriptors > sd->total_length)
123 total_len = size_no_descriptors;
125 /* Return immediately if no security descriptors. */
126 if (sd->num_entries == 0)
127 goto out_align_total_length;
129 /* Allocate a new buffer for the sizes array */
130 sd->sizes = MALLOC(sizes_size);
134 /* Copy the sizes array into the new buffer */
135 for (u32 i = 0; i < sd->num_entries; i++) {
136 sd->sizes[i] = le64_to_cpu(sd_disk->sizes[i]);
137 if (sd->sizes[i] > 0xffffffff)
141 p = (const u8*)sd_disk + size_no_descriptors;
143 /* Allocate the array of pointers to the security descriptors, then read
144 * them into separate buffers. */
145 sd->descriptors = CALLOC(sd->num_entries, sizeof(sd->descriptors[0]));
146 if (!sd->descriptors)
149 for (u32 i = 0; i < sd->num_entries; i++) {
150 if (sd->sizes[i] == 0)
152 total_len += sd->sizes[i];
153 if (total_len > (u64)sd->total_length)
155 sd->descriptors[i] = memdup(p, sd->sizes[i]);
156 if (!sd->descriptors[i])
160 out_align_total_length:
161 total_len = (total_len + 7) & ~7;
162 sd->total_length = (sd->total_length + 7) & ~7;
163 if (total_len != sd->total_length) {
164 WARNING("Expected WIM security data total length of "
165 "%u bytes, but calculated %u bytes",
166 sd->total_length, (unsigned)total_len);
172 ERROR("WIM security data is invalid!");
173 ret = WIMLIB_ERR_INVALID_METADATA_RESOURCE;
176 ERROR("Out of memory while reading WIM security data!");
177 ret = WIMLIB_ERR_NOMEM;
179 free_wim_security_data(sd);
185 * Writes the security data for a WIM image to an in-memory buffer.
188 write_wim_security_data(const struct wim_security_data * restrict sd,
191 DEBUG("Writing security data (total_length = %"PRIu32", num_entries "
192 "= %"PRIu32")", sd->total_length, sd->num_entries);
195 struct wim_security_data_disk *sd_disk = (struct wim_security_data_disk*)p;
196 u32 num_entries = sd->num_entries;
198 sd_disk->total_length = cpu_to_le32(sd->total_length);
199 sd_disk->num_entries = cpu_to_le32(num_entries);
201 for (u32 i = 0; i < num_entries; i++)
202 sd_disk->sizes[i] = cpu_to_le64(sd->sizes[i]);
204 p = (u8*)&sd_disk->sizes[num_entries];
206 for (u32 i = 0; i < num_entries; i++)
207 p = mempcpy(p, sd->descriptors[i], sd->sizes[i]);
209 while ((uintptr_t)p & 7)
212 wimlib_assert(p - orig_p == sd->total_length);
214 DEBUG("Successfully wrote security data.");
219 free_wim_security_data(struct wim_security_data *sd)
222 u8 **descriptors = sd->descriptors;
223 u32 num_entries = sd->num_entries;
225 while (num_entries--)
226 FREE(*descriptors++);
228 FREE(sd->descriptors);
235 u8 hash[SHA1_HASH_SIZE];
236 struct avl_tree_node index_node;
239 #define SD_NODE(avl_node) \
240 avl_tree_entry(avl_node, struct sd_node, index_node)
243 free_sd_tree(struct avl_tree_node *node)
246 free_sd_tree(node->left);
247 free_sd_tree(node->right);
253 rollback_new_security_descriptors(struct wim_sd_set *sd_set)
255 struct wim_security_data *sd = sd_set->sd;
256 u8 **descriptors = sd->descriptors + sd_set->orig_num_entries;
257 u32 num_entries = sd->num_entries - sd_set->orig_num_entries;
258 while (num_entries--)
259 FREE(*descriptors++);
260 sd->num_entries = sd_set->orig_num_entries;
263 /* Frees a security descriptor index set. */
265 destroy_sd_set(struct wim_sd_set *sd_set)
267 free_sd_tree(sd_set->root);
271 _avl_cmp_nodes_by_hash(const struct avl_tree_node *n1,
272 const struct avl_tree_node *n2)
274 return hashes_cmp(SD_NODE(n1)->hash, SD_NODE(n2)->hash);
277 /* Inserts a a new node into the security descriptor index tree. Returns true
278 * if successful (not a duplicate). */
280 insert_sd_node(struct wim_sd_set *set, struct sd_node *new)
282 return NULL == avl_tree_insert(&set->root, &new->index_node,
283 _avl_cmp_nodes_by_hash);
286 /* Returns the index of the security descriptor having a SHA1 message digest of
287 * @hash. If not found, return -1. */
289 lookup_sd(struct wim_sd_set *set, const u8 hash[SHA1_HASH_SIZE])
291 struct avl_tree_node *res;
292 struct sd_node dummy;
294 copy_hash(dummy.hash, hash);
295 res = avl_tree_lookup_node(set->root, &dummy.index_node,
296 _avl_cmp_nodes_by_hash);
299 return SD_NODE(res)->security_id;
303 * Adds a security descriptor to the indexed security descriptor set as well as
304 * the corresponding `struct wim_security_data', and returns the new security
305 * ID; or, if there is an existing security descriptor that is the same, return
306 * the security ID for it. If a new security descriptor cannot be allocated,
310 sd_set_add_sd(struct wim_sd_set *sd_set, const char *descriptor, size_t size)
312 u8 hash[SHA1_HASH_SIZE];
318 struct wim_security_data *sd;
321 sha1_buffer(descriptor, size, hash);
323 security_id = lookup_sd(sd_set, hash);
324 if (security_id >= 0) /* Identical descriptor already exists */
327 /* Need to add a new security descriptor */
330 new = MALLOC(sizeof(*new));
334 descr_copy = memdup(descriptor, size);
339 new->security_id = sd->num_entries;
340 copy_hash(new->hash, hash);
342 /* There typically are only a few dozen security descriptors in a
343 * directory tree, so expanding the array of security descriptors by
344 * only 1 extra space each time should not be a problem. */
345 descriptors = REALLOC(sd->descriptors,
346 (sd->num_entries + 1) * sizeof(sd->descriptors[0]));
349 sd->descriptors = descriptors;
350 sizes = REALLOC(sd->sizes,
351 (sd->num_entries + 1) * sizeof(sd->sizes[0]));
355 sd->descriptors[sd->num_entries] = descr_copy;
356 sd->sizes[sd->num_entries] = size;
358 DEBUG("There are now %u security descriptors", sd->num_entries);
359 bret = insert_sd_node(sd_set, new);
361 security_id = new->security_id;
371 /* Initialize a `struct sd_set' mapping from SHA1 message digests of security
372 * descriptors to indices into the security descriptors table of the WIM image
375 init_sd_set(struct wim_sd_set *sd_set, struct wim_security_data *sd)
382 /* Remember the original number of security descriptors so that newly
383 * added ones can be rolled back if needed. */
384 sd_set->orig_num_entries = sd->num_entries;
385 for (u32 i = 0; i < sd->num_entries; i++) {
388 new = MALLOC(sizeof(struct sd_node));
390 ret = WIMLIB_ERR_NOMEM;
391 goto out_destroy_sd_set;
393 sha1_buffer(sd->descriptors[i], sd->sizes[i], new->hash);
394 new->security_id = i;
395 if (!insert_sd_node(sd_set, new))
396 FREE(new); /* Ignore duplicate security descriptor */
401 destroy_sd_set(sd_set);