X-Git-Url: https://wimlib.net/git/?p=wimlib;a=blobdiff_plain;f=src%2Fsecurity.c;h=e6a7e93a84d6001ed47f55afdfdfd8d3e2c1f395;hp=c955050054be0662c5fa95bef9a8524e95568e4c;hb=76b57cc8cf113194136a7e264644a37515650ccc;hpb=7231431086332de22b2556477bcc5fc2c3e4bdcf diff --git a/src/security.c b/src/security.c index c9550500..e6a7e93a 100644 --- a/src/security.c +++ b/src/security.c @@ -1,13 +1,11 @@ /* * security.c * - * Read and write the WIM security data. The security data is a table of - * security descriptors. Each WIM image has its own security data, but it's - * possible that an image's security data have no security descriptors. + * Read and write the per-WIM-image table of security descriptors. */ /* - * Copyright (C) 2012 Eric Biggers + * Copyright (C) 2012, 2013, 2014 Eric Biggers * * This file is part of wimlib, a library for working with WIM files. * @@ -25,82 +23,87 @@ * along with wimlib; if not, see http://www.gnu.org/licenses/. */ -#include "wimlib_internal.h" -#include "io.h" -#include "security.h" +#ifdef HAVE_CONFIG_H +# include "config.h" +#endif -/* - * This is a hack to work around a problem in libntfs-3g. libntfs-3g validates - * security descriptors with a function named ntfs_valid_descr(). - * ntfs_valid_descr() considers a security descriptor that ends in a SACL - * (Sysetm Access Control List) with no ACE's (Access Control Entries) to be - * invalid. However, a security descriptor like this exists in the Windows 7 - * install.wim. Here, security descriptors matching this pattern are modified - * to have no SACL. This should make no difference since the SACL had no - * entries anyway; however this ensures that that the security descriptors pass - * the validation in libntfs-3g. - */ -static void empty_sacl_fixup(u8 *descr, u64 *size_p) +#include "wimlib/assert.h" +#include "wimlib/avl_tree.h" +#include "wimlib/endianness.h" +#include "wimlib/error.h" +#include "wimlib/security.h" +#include "wimlib/sha1.h" +#include "wimlib/util.h" + +struct wim_security_data_disk { + le32 total_length; + le32 num_entries; + le64 sizes[]; +} _packed_attribute; + +struct wim_security_data * +new_wim_security_data(void) { - if (*size_p >= sizeof(SecurityDescriptor)) { - SecurityDescriptor *sd = (SecurityDescriptor*)descr; - u32 sacl_offset = le32_to_cpu(sd->sacl_offset); - if (sacl_offset == *size_p - sizeof(ACL)) { - sd->sacl_offset = cpu_to_le32(0); - *size_p -= sizeof(ACL); - } - } + return CALLOC(1, sizeof(struct wim_security_data)); } /* - * Reads the security data from the metadata resource. + * Reads the security data from the metadata resource of a WIM image. * - * @metadata_resource: An array that contains the uncompressed metadata - * resource for the WIM file. - * @metadata_resource_len: The length of @metadata_resource. It MUST be at - * least 8 bytes. - * @sd_p: A pointer to a pointer to a wim_security_data structure that - * will be filled in with a pointer to a new wim_security_data - * structure on success. + * @buf + * Buffer containing an uncompressed WIM metadata resource. + * @buf_len + * Length of the uncompressed metadata resource, in bytes. + * @sd_ret + * On success, a pointer to the resulting security data structure will be + * returned here. * * Note: There is no `offset' argument because the security data is located at * the beginning of the metadata resource. + * + * Return values: + * WIMLIB_ERR_SUCCESS (0) + * WIMLIB_ERR_INVALID_METADATA_RESOURCE + * WIMLIB_ERR_NOMEM */ -int read_security_data(const u8 metadata_resource[], u64 metadata_resource_len, - struct wim_security_data **sd_p) +int +read_wim_security_data(const u8 *buf, size_t buf_len, + struct wim_security_data **sd_ret) { struct wim_security_data *sd; - const u8 *p; int ret; u64 total_len; + u64 sizes_size; + u64 size_no_descriptors; + const struct wim_security_data_disk *sd_disk; + const u8 *p; - /* - * Sorry this function is excessively complicated--- I'm just being - * extremely careful about integer overflows. - */ + if (buf_len < 8) + return WIMLIB_ERR_INVALID_METADATA_RESOURCE; - sd = MALLOC(sizeof(struct wim_security_data)); - if (!sd) { - ERROR("Out of memory"); - return WIMLIB_ERR_NOMEM; - } - sd->sizes = NULL; - sd->descriptors = NULL; - sd->refcnt = 1; + sd = new_wim_security_data(); + if (!sd) + goto out_of_memory; + + sd_disk = (const struct wim_security_data_disk *)buf; + sd->total_length = le32_to_cpu(sd_disk->total_length); + sd->num_entries = le32_to_cpu(sd_disk->num_entries); - p = metadata_resource; - p = get_u32(p, &sd->total_length); - p = get_u32(p, (u32*)&sd->num_entries); + DEBUG("Reading security data: num_entries=%u, total_length=%u", + sd->num_entries, sd->total_length); + + /* Length field of 0 is a special case that really means length + * of 8. */ + if (sd->total_length == 0) + sd->total_length = 8; /* The security_id field of each dentry is a signed 32-bit integer, so * the possible indices into the security descriptors table are 0 * through 0x7fffffff. Which means 0x80000000 security descriptors * maximum. Not like you should ever have anywhere close to that many * security descriptors! */ - if (sd->num_entries > 0x80000000) { - ERROR("Security data has too many entries!"); + if (sd->num_entries > 0x80000000) goto out_invalid_sd; - } /* Verify the listed total length of the security data is big enough to * include the sizes array, verify that the file data is big enough to @@ -110,235 +113,293 @@ int read_security_data(const u8 metadata_resource[], u64 metadata_resource_len, * integer, even though each security descriptor size is a 64-bit * integer. This is stupid, and we need to be careful not to actually * let the security descriptor sizes be over 0xffffffff. */ - if ((u64)sd->total_length > metadata_resource_len) { - ERROR("Security data total length (%u) is bigger than the " - "metadata resource length (%"PRIu64")", - sd->total_length, metadata_resource_len); + if (sd->total_length > buf_len) goto out_invalid_sd; - } - DEBUG("Reading security data: %u entries, length = %u", - sd->num_entries, sd->total_length); + sizes_size = (u64)sd->num_entries * sizeof(u64); + size_no_descriptors = 8 + sizes_size; + if (size_no_descriptors > sd->total_length) + goto out_invalid_sd; - if (sd->num_entries == 0) { - /* No security descriptors. */ - if (sd->total_length != 0 && sd->total_length != 8) { - ERROR("Invalid security data length (%u): expected 0 or 8", - sd->total_length); - goto out_invalid_sd; - } - sd->total_length = 8; - goto out_return_sd; - } + total_len = size_no_descriptors; - u64 sizes_size = (u64)sd->num_entries * sizeof(u64); - u64 size_no_descriptors = 8 + sizes_size; - if (size_no_descriptors > (u64)sd->total_length) { - ERROR("Security data total length of %u is too short because " - "there must be at least %"PRIu64" bytes of security data", - sd->total_length, 8 + sizes_size); - goto out_invalid_sd; - } - if (sizeof(size_t) < 8 && sizes_size > 0xffffffff) { - ERROR("Too many security descriptors!"); - goto out_invalid_sd; - } + /* Return immediately if no security descriptors. */ + if (sd->num_entries == 0) + goto out_align_total_length; + + /* Allocate a new buffer for the sizes array */ sd->sizes = MALLOC(sizes_size); - if (!sd->sizes) { - ret = WIMLIB_ERR_NOMEM; - goto out_free_sd; - } + if (!sd->sizes) + goto out_of_memory; - /* Copy the sizes array in from the file data. */ - p = get_bytes(p, sizes_size, sd->sizes); - array_le64_to_cpu(sd->sizes, sd->num_entries); - - /* Allocate the array of pointers to descriptors, and read them in. */ - sd->descriptors = CALLOC(sd->num_entries, sizeof(u8*)); - if (!sd->descriptors) { - ERROR("Out of memory while allocating security " - "descriptors"); - ret = WIMLIB_ERR_NOMEM; - goto out_free_sd; + /* Copy the sizes array into the new buffer */ + for (u32 i = 0; i < sd->num_entries; i++) { + sd->sizes[i] = le64_to_cpu(sd_disk->sizes[i]); + if (sd->sizes[i] > 0xffffffff) + goto out_invalid_sd; } - total_len = size_no_descriptors; + + p = (const u8*)sd_disk + size_no_descriptors; + + /* Allocate the array of pointers to the security descriptors, then read + * them into separate buffers. */ + sd->descriptors = CALLOC(sd->num_entries, sizeof(sd->descriptors[0])); + if (!sd->descriptors) + goto out_of_memory; for (u32 i = 0; i < sd->num_entries; i++) { - /* Watch out for huge security descriptor sizes that could - * overflow the total length and wrap it around. */ - if (total_len + sd->sizes[i] < total_len) { - ERROR("Caught overflow in security descriptor lengths " - "(current total length = %"PRIu64", security " - "descriptor size = %"PRIu64")", - total_len, sd->sizes[i]); - goto out_invalid_sd; - } + if (sd->sizes[i] == 0) + continue; total_len += sd->sizes[i]; - /* This check assures that the descriptor size fits in a 32 bit - * integer. Because if it didn't, the total length would come - * out bigger than sd->total_length, which is a 32 bit integer. - * */ - if (total_len > (u64)sd->total_length) { - ERROR("Security data total length of %u is too short " - "because there are at least %"PRIu64" bytes of " - "security data", sd->total_length, total_len); + if (total_len > (u64)sd->total_length) goto out_invalid_sd; - } - sd->descriptors[i] = MALLOC(sd->sizes[i]); - if (!sd->descriptors[i]) { - ERROR("Out of memory while allocating security " - "descriptors"); - ret = WIMLIB_ERR_NOMEM; - goto out_free_sd; - } - p = get_bytes(p, sd->sizes[i], sd->descriptors[i]); - empty_sacl_fixup(sd->descriptors[i], &sd->sizes[i]); + sd->descriptors[i] = memdup(p, sd->sizes[i]); + if (!sd->descriptors[i]) + goto out_of_memory; + p += sd->sizes[i]; } - wimlib_assert(total_len <= 0xffffffff); - if (((total_len + 7) & ~7) != ((sd->total_length + 7) & ~7)) { - ERROR("Expected security data total length = %u, but " - "calculated %u", sd->total_length, (unsigned)total_len); - goto out_invalid_sd; +out_align_total_length: + total_len = (total_len + 7) & ~7; + sd->total_length = (sd->total_length + 7) & ~7; + if (total_len != sd->total_length) { + WARNING("Expected WIM security data total length of " + "%u bytes, but calculated %u bytes", + sd->total_length, (unsigned)total_len); } - sd->total_length = total_len; -out_return_sd: - *sd_p = sd; - return 0; + *sd_ret = sd; + ret = 0; + goto out; out_invalid_sd: - ret = WIMLIB_ERR_INVALID_SECURITY_DATA; + ERROR("WIM security data is invalid!"); + ret = WIMLIB_ERR_INVALID_METADATA_RESOURCE; + goto out_free_sd; +out_of_memory: + ERROR("Out of memory while reading WIM security data!"); + ret = WIMLIB_ERR_NOMEM; out_free_sd: - free_security_data(sd); + free_wim_security_data(sd); +out: return ret; } /* - * Writes security data to an in-memory buffer. + * Writes the security data for a WIM image to an in-memory buffer. */ -u8 *write_security_data(const struct wim_security_data *sd, u8 *p) +u8 * +write_wim_security_data(const struct wim_security_data * restrict sd, + u8 * restrict p) { DEBUG("Writing security data (total_length = %"PRIu32", num_entries " "= %"PRIu32")", sd->total_length, sd->num_entries); - u32 aligned_length = (sd->total_length + 7) & ~7; - u8 *orig_p = p; - p = put_u32(p, aligned_length); - p = put_u32(p, sd->num_entries); + struct wim_security_data_disk *sd_disk = (struct wim_security_data_disk*)p; + u32 num_entries = sd->num_entries; - for (u32 i = 0; i < sd->num_entries; i++) - p = put_u64(p, sd->sizes[i]); + sd_disk->total_length = cpu_to_le32(sd->total_length); + sd_disk->num_entries = cpu_to_le32(num_entries); - for (u32 i = 0; i < sd->num_entries; i++) - p = put_bytes(p, sd->sizes[i], sd->descriptors[i]); + for (u32 i = 0; i < num_entries; i++) + sd_disk->sizes[i] = cpu_to_le64(sd->sizes[i]); + + p = (u8*)&sd_disk->sizes[num_entries]; + + for (u32 i = 0; i < num_entries; i++) + p = mempcpy(p, sd->descriptors[i], sd->sizes[i]); + + while ((uintptr_t)p & 7) + *p++ = 0; wimlib_assert(p - orig_p == sd->total_length); - p = put_zeroes(p, aligned_length - sd->total_length); DEBUG("Successfully wrote security data."); return p; } -static void print_acl(const u8 *p, const char *type) +void +free_wim_security_data(struct wim_security_data *sd) +{ + if (sd) { + u8 **descriptors = sd->descriptors; + u32 num_entries = sd->num_entries; + if (descriptors) + while (num_entries--) + FREE(*descriptors++); + FREE(sd->sizes); + FREE(sd->descriptors); + FREE(sd); + } +} + +struct sd_node { + int32_t security_id; + u8 hash[SHA1_HASH_SIZE]; + struct avl_tree_node index_node; +}; + +#define SD_NODE(avl_node) \ + avl_tree_entry(avl_node, struct sd_node, index_node) + +static void +free_sd_tree(struct avl_tree_node *node) { - const ACL *acl = (const ACL*)p; - u8 revision = acl->revision; - u16 acl_size = le16_to_cpu(acl->acl_size); - u16 ace_count = le16_to_cpu(acl->ace_count); - printf(" [%s ACL]\n", type); - printf(" Revision = %u\n", revision); - printf(" ACL Size = %u\n", acl_size); - printf(" ACE Count = %u\n", ace_count); - - p += sizeof(ACL); - for (uint i = 0; i < acl->ace_count; i++) { - const ACEHeader *hdr = (const ACEHeader*)p; - printf(" [ACE]\n"); - printf(" ACE type = %d\n", hdr->type); - printf(" ACE flags = 0x%x\n", hdr->flags); - printf(" ACE size = %u\n", hdr->size); - const AccessAllowedACE *aaa = (const AccessAllowedACE*)hdr; - printf(" ACE mask = %x\n", le32_to_cpu(aaa->mask)); - printf(" SID start = %u\n", le32_to_cpu(aaa->sid_start)); - p += hdr->size; + if (node) { + free_sd_tree(node->left); + free_sd_tree(node->right); + FREE(SD_NODE(node)); } - putchar('\n'); } -static void print_sid(const u8 *p, const char *type) +void +rollback_new_security_descriptors(struct wim_sd_set *sd_set) { - const SID *sid = (const SID*)p; - printf(" [%s SID]\n", type); - printf(" Revision = %u\n", sid->revision); - printf(" Subauthority count = %u\n", sid->sub_authority_count); - printf(" Identifier authority = "); - print_byte_field(sid->identifier_authority, - sizeof(sid->identifier_authority)); - putchar('\n'); - for (uint i = 0; i < sid->sub_authority_count; i++) - printf(" Subauthority %u = %u\n", - i, le32_to_cpu(sid->sub_authority[i])); - putchar('\n'); + struct wim_security_data *sd = sd_set->sd; + u8 **descriptors = sd->descriptors + sd_set->orig_num_entries; + u32 num_entries = sd->num_entries - sd_set->orig_num_entries; + while (num_entries--) + FREE(*descriptors++); + sd->num_entries = sd_set->orig_num_entries; } -static void print_security_descriptor(const u8 *p, u64 size) +/* Frees a security descriptor index set. */ +void +destroy_sd_set(struct wim_sd_set *sd_set) { - const SecurityDescriptor *sd = (const SecurityDescriptor*)p; - u8 revision = sd->revision; - u16 control = le16_to_cpu(sd->security_descriptor_control); - u32 owner_offset = le32_to_cpu(sd->owner_offset); - u32 group_offset = le32_to_cpu(sd->group_offset); - u32 sacl_offset = le32_to_cpu(sd->sacl_offset); - u32 dacl_offset = le32_to_cpu(sd->dacl_offset); - printf("Revision = %u\n", revision); - printf("Security Descriptor Control = %#x\n", control); - printf("Owner offset = %u\n", owner_offset); - printf("Group offset = %u\n", group_offset); - printf("System ACL offset = %u\n", sacl_offset); - printf("Discretionary ACL offset = %u\n", dacl_offset); - - if (sd->owner_offset != 0) - print_sid(p + owner_offset, "Owner"); - if (sd->group_offset != 0) - print_sid(p + group_offset, "Group"); - if (sd->sacl_offset != 0) - print_acl(p + sacl_offset, "System"); - if (sd->dacl_offset != 0) - print_acl(p + dacl_offset, "Discretionary"); + free_sd_tree(sd_set->root); +} + +static int +_avl_cmp_nodes_by_hash(const struct avl_tree_node *n1, + const struct avl_tree_node *n2) +{ + return hashes_cmp(SD_NODE(n1)->hash, SD_NODE(n2)->hash); +} + +/* Inserts a new node into the security descriptor index tree. Returns true + * if successful (not a duplicate). */ +static bool +insert_sd_node(struct wim_sd_set *set, struct sd_node *new) +{ + return NULL == avl_tree_insert(&set->root, &new->index_node, + _avl_cmp_nodes_by_hash); +} + +/* Returns the index of the security descriptor having a SHA1 message digest of + * @hash. If not found, return -1. */ +static int32_t +lookup_sd(struct wim_sd_set *set, const u8 hash[SHA1_HASH_SIZE]) +{ + struct avl_tree_node *res; + struct sd_node dummy; + + copy_hash(dummy.hash, hash); + res = avl_tree_lookup_node(set->root, &dummy.index_node, + _avl_cmp_nodes_by_hash); + if (!res) + return -1; + return SD_NODE(res)->security_id; } /* - * Prints the security data for a WIM file. + * Adds a security descriptor to the indexed security descriptor set as well as + * the corresponding `struct wim_security_data', and returns the new security + * ID; or, if there is an existing security descriptor that is the same, return + * the security ID for it. If a new security descriptor cannot be allocated, + * return -1. */ -void print_security_data(const struct wim_security_data *sd) +int32_t +sd_set_add_sd(struct wim_sd_set *sd_set, const char *descriptor, size_t size) { - wimlib_assert(sd != NULL); + u8 hash[SHA1_HASH_SIZE]; + int32_t security_id; + struct sd_node *new; + u8 **descriptors; + u64 *sizes; + u8 *descr_copy; + struct wim_security_data *sd; + bool bret; - puts("[SECURITY DATA]"); - printf("Length = %"PRIu32" bytes\n", sd->total_length); - printf("Number of Entries = %"PRIu32"\n", sd->num_entries); + sha1_buffer(descriptor, size, hash); - for (u32 i = 0; i < sd->num_entries; i++) { - printf("[SecurityDescriptor %"PRIu32", length = %"PRIu64"]\n", - i, sd->sizes[i]); - print_security_descriptor(sd->descriptors[i], sd->sizes[i]); - putchar('\n'); - } - putchar('\n'); + security_id = lookup_sd(sd_set, hash); + if (security_id >= 0) /* Identical descriptor already exists */ + goto out; + + /* Need to add a new security descriptor */ + security_id = -1; + + new = MALLOC(sizeof(*new)); + if (!new) + goto out; + + descr_copy = memdup(descriptor, size); + if (!descr_copy) + goto out_free_node; + + sd = sd_set->sd; + new->security_id = sd->num_entries; + copy_hash(new->hash, hash); + + /* There typically are only a few dozen security descriptors in a + * directory tree, so expanding the array of security descriptors by + * only 1 extra space each time should not be a problem. */ + descriptors = REALLOC(sd->descriptors, + (sd->num_entries + 1) * sizeof(sd->descriptors[0])); + if (!descriptors) + goto out_free_descr; + sd->descriptors = descriptors; + sizes = REALLOC(sd->sizes, + (sd->num_entries + 1) * sizeof(sd->sizes[0])); + if (!sizes) + goto out_free_descr; + sd->sizes = sizes; + sd->descriptors[sd->num_entries] = descr_copy; + sd->sizes[sd->num_entries] = size; + sd->num_entries++; + DEBUG("There are now %u security descriptors", sd->num_entries); + bret = insert_sd_node(sd_set, new); + wimlib_assert(bret); + security_id = new->security_id; + goto out; +out_free_descr: + FREE(descr_copy); +out_free_node: + FREE(new); +out: + return security_id; } -void free_security_data(struct wim_security_data *sd) +/* Initialize a `struct sd_set' mapping from SHA1 message digests of security + * descriptors to indices into the security descriptors table of the WIM image + * (security IDs). */ +int +init_sd_set(struct wim_sd_set *sd_set, struct wim_security_data *sd) { - if (!sd) - return; - wimlib_assert(sd->refcnt != 0); - if (--sd->refcnt == 0) { - u8 **descriptors = sd->descriptors; - u32 num_entries = sd->num_entries; - if (descriptors) - while (num_entries--) - FREE(*descriptors++); - FREE(sd->sizes); - FREE(sd->descriptors); - FREE(sd); + int ret; + + sd_set->sd = sd; + sd_set->root = NULL; + + /* Remember the original number of security descriptors so that newly + * added ones can be rolled back if needed. */ + sd_set->orig_num_entries = sd->num_entries; + for (u32 i = 0; i < sd->num_entries; i++) { + struct sd_node *new; + + new = MALLOC(sizeof(struct sd_node)); + if (!new) { + ret = WIMLIB_ERR_NOMEM; + goto out_destroy_sd_set; + } + sha1_buffer(sd->descriptors[i], sd->sizes[i], new->hash); + new->security_id = i; + if (!insert_sd_node(sd_set, new)) + FREE(new); /* Ignore duplicate security descriptor */ } + ret = 0; + goto out; +out_destroy_sd_set: + destroy_sd_set(sd_set); +out: + return ret; }