]> wimlib.net Git - wimlib/blobdiff - src/security.c
security.c: Rewrite some code
[wimlib] / src / security.c
index 88e6c84770b3fc840e07363146162087a90f5973..62b6e8e9eb42cd1693544ad22d593c34988881e9 100644 (file)
  * along with wimlib; if not, see http://www.gnu.org/licenses/.
  */
 
-#include "wimlib_internal.h"
-#include "buffer_io.h"
-#include "security.h"
-
-
-#define        SECURITY_DESCRIPTOR_REVISION    1
-#define        SECURITY_DESCRIPTOR_REVISION1   1
-
-/* inherit AceFlags */
-#define        OBJECT_INHERIT_ACE              0x01
-#define        CONTAINER_INHERIT_ACE           0x02
-#define        NO_PROPAGATE_INHERIT_ACE        0x04
-#define        INHERIT_ONLY_ACE                0x08
-#define        INHERITED_ACE                   0x10
-#define        VALID_INHERIT_FLAGS             0x1F
-
-#define SE_OWNER_DEFAULTED             0x00000001
-#define SE_GROUP_DEFAULTED             0x00000002
-#define SE_DACL_PRESENT                        0x00000004
-#define SE_DACL_DEFAULTED              0x00000008
-#define SE_SACL_PRESENT                        0x00000010
-#define SE_SACL_DEFAULTED              0x00000020
-#define SE_DACL_AUTO_INHERIT_REQ       0x00000100
-#define SE_SACL_AUTO_INHERIT_REQ       0x00000200
-#define SE_DACL_AUTO_INHERITED         0x00000400
-#define SE_SACL_AUTO_INHERITED         0x00000800
-#define SE_DACL_PROTECTED              0x00001000
-#define SE_SACL_PROTECTED              0x00002000
-#define SE_RM_CONTROL_VALID            0x00004000
-#define SE_SELF_RELATIVE               0x00008000
-
-/* Flags in access control entries */
-#define DELETE                     0x00010000
-#define READ_CONTROL               0x00020000
-#define WRITE_DAC                  0x00040000
-#define WRITE_OWNER                0x00080000
-#define SYNCHRONIZE                0x00100000
-#define STANDARD_RIGHTS_REQUIRED   0x000f0000
-
-#define STANDARD_RIGHTS_READ       READ_CONTROL
-#define STANDARD_RIGHTS_WRITE      READ_CONTROL
-#define STANDARD_RIGHTS_EXECUTE    READ_CONTROL
-
-#define STANDARD_RIGHTS_ALL        0x001f0000
-
-#define SPECIFIC_RIGHTS_ALL        0x0000ffff
-
-#define GENERIC_READ               0x80000000
-#define GENERIC_WRITE              0x40000000
-#define GENERIC_EXECUTE            0x20000000
-#define GENERIC_ALL                0x10000000
-
-#define MAXIMUM_ALLOWED            0x02000000
-#define ACCESS_SYSTEM_SECURITY     0x01000000
-
-#define EVENT_QUERY_STATE          0x0001
-#define EVENT_MODIFY_STATE         0x0002
-#define EVENT_ALL_ACCESS           (STANDARD_RIGHTS_REQUIRED|SYNCHRONIZE|0x3)
-
-#define SEMAPHORE_MODIFY_STATE     0x0002
-#define SEMAPHORE_ALL_ACCESS       (STANDARD_RIGHTS_REQUIRED|SYNCHRONIZE|0x3)
-
-#define MUTEX_MODIFY_STATE         0x0001
-#define MUTEX_ALL_ACCESS           (STANDARD_RIGHTS_REQUIRED|SYNCHRONIZE|0x1)
-
-#define JOB_OBJECT_ASSIGN_PROCESS           0x0001
-#define JOB_OBJECT_SET_ATTRIBUTES           0x0002
-#define JOB_OBJECT_QUERY                    0x0004
-#define JOB_OBJECT_TERMINATE                0x0008
-#define JOB_OBJECT_SET_SECURITY_ATTRIBUTES  0x0010
-#define JOB_OBJECT_ALL_ACCESS               (STANDARD_RIGHTS_REQUIRED|SYNCHRONIZE|0x1f)
-
-#define TIMER_QUERY_STATE          0x0001
-#define TIMER_MODIFY_STATE         0x0002
-#define TIMER_ALL_ACCESS           (STANDARD_RIGHTS_REQUIRED|SYNCHRONIZE|0x3)
-
-#define PROCESS_TERMINATE          0x0001
-#define PROCESS_CREATE_THREAD      0x0002
-#define PROCESS_VM_OPERATION       0x0008
-#define PROCESS_VM_READ            0x0010
-#define PROCESS_VM_WRITE           0x0020
-#define PROCESS_DUP_HANDLE         0x0040
-#define PROCESS_CREATE_PROCESS     0x0080
-#define PROCESS_SET_QUOTA          0x0100
-#define PROCESS_SET_INFORMATION    0x0200
-#define PROCESS_QUERY_INFORMATION  0x0400
-#define PROCESS_SUSPEND_RESUME     0x0800
-#define PROCESS_QUERY_LIMITED_INFORMATION 0x1000
-#define PROCESS_ALL_ACCESS         (STANDARD_RIGHTS_REQUIRED|SYNCHRONIZE|0xfff)
-
-#define THREAD_TERMINATE           0x0001
-#define THREAD_SUSPEND_RESUME      0x0002
-#define THREAD_GET_CONTEXT         0x0008
-#define THREAD_SET_CONTEXT         0x0010
-#define THREAD_SET_INFORMATION     0x0020
-#define THREAD_QUERY_INFORMATION   0x0040
-#define THREAD_SET_THREAD_TOKEN    0x0080
-#define THREAD_IMPERSONATE         0x0100
-#define THREAD_DIRECT_IMPERSONATION 0x0200
-#define THREAD_ALL_ACCESS          (STANDARD_RIGHTS_REQUIRED|SYNCHRONIZE|0x3ff)
-
-#define THREAD_BASE_PRIORITY_LOWRT  15
-#define THREAD_BASE_PRIORITY_MAX    2
-#define THREAD_BASE_PRIORITY_MIN   -2
-#define THREAD_BASE_PRIORITY_IDLE  -15
-
-/* predefined authority values for SID's (security identifiers) */
-enum sid_authority_value {
-       SECURITY_NULL_SID_AUTHORITY    = 0,
-       SECURITY_WORLD_SID_AUTHORITY   = 1,
-       SECURITY_LOCAL_SID_AUTHORITY   = 2,
-       SECURITY_CREATOR_SID_AUTHORITY = 3,
-       SECURITY_NON_UNIQUE_AUTHORITY  = 4,
-       SECURITY_NT_AUTHORITY          = 5,
-};
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
 
-/* local administrators group */
-#define SECURITY_BUILTIN_DOMAIN_RID 32
-#define DOMAIN_ALIAS_RID_ADMINS     544
-
-/* See ACEHeader. */
-enum ace_type {
-       ACCESS_ALLOWED_ACE_TYPE = 0,
-       ACCESS_DENIED_ACE_TYPE  = 1,
-       SYSTEM_AUDIT_ACE_TYPE   = 2,
-};
+#include "wimlib/assert.h"
+#include "wimlib/buffer_io.h"
+#include "wimlib/error.h"
+#include "wimlib/security.h"
+#include "wimlib/sha1.h"
+#include "wimlib/util.h"
 
 /* At the start of each type of access control entry.  */
-typedef struct {
+typedef struct _ACE_HEADER {
        /* enum ace_type, specifies what type of ACE this is.  */
        u8 type;
 
@@ -159,32 +43,32 @@ typedef struct {
        u8 flags;
 
        /* Size of the access control entry. */
-       u8 size;
-} ACEHeader;
+       le16 size;
+} _packed_attribute ACE_HEADER;
 
 /* Grants rights to a user or group */
-typedef struct {
-       ACEHeader hdr;
-       u32 mask;
-       u32 sid_start;
-} AccessAllowedACE;
+typedef struct _ACCESS_ALLOWED_ACE {
+       ACE_HEADER hdr;
+       le32 mask;
+       le32 sid_start;
+} _packed_attribute ACCESS_ALLOWED_ACE;
 
 /* Denies rights to a user or group */
-typedef struct {
-       ACEHeader hdr;
+typedef struct _ACCESS_DENIED_ACE {
+       ACE_HEADER hdr;
+       le32 mask;
+       le32 sid_start;
+} _packed_attribute ACCESS_DENIED_ACE;
+
+typedef struct _SYSTEM_AUDIT_ACE {
+       ACE_HEADER hdr;
        u32 mask;
        u32 sid_start;
-} AccessDeniedACE;
-
-typedef struct {
-       ACEHeader hdr;
-       u32 mask;
-       u32 sid_start;
-} SystemAuditACE;
+} _packed_attribute SYSTEM_AUDIT_ACE;
 
 
 /* Header of an access control list. */
-typedef struct {
+typedef struct _ACL {
        /* ACL_REVISION or ACL_REVISION_DS */
        u8 revision;
 
@@ -200,10 +84,10 @@ typedef struct {
 
        /* padding */
        u16 sbz2;
-} ACL;
+} _packed_attribute ACL;
 
 /* A structure used to identify users or groups. */
-typedef struct {
+typedef struct _SID {
 
        /* example: 0x1 */
        u8  revision;
@@ -213,11 +97,10 @@ typedef struct {
         * have to be, one of enum sid_authority_value */
        u8  identifier_authority[6];
 
-       u32 sub_authority[0];
-} SID;
-
+       u32 sub_authority[];
+} _packed_attribute SID;
 
-typedef struct {
+typedef struct _SECURITY_DESCRIPTOR_RELATIVE  {
        /* Example: 0x1 */
        u8 revision;
        /* Example: 0x0 */
@@ -242,7 +125,13 @@ typedef struct {
        /* Discretionary ACL. */
        /* Example: 0x34 */
        u32 dacl_offset;
-} SecurityDescriptor;
+} _packed_attribute SECURITY_DESCRIPTOR_RELATIVE;
+
+struct wim_security_data_disk {
+       u32 total_length;
+       u32 num_entries;
+       u64 sizes[];
+} _packed_attribute;
 
 /*
  * This is a hack to work around a problem in libntfs-3g.  libntfs-3g validates
@@ -256,74 +145,82 @@ typedef struct {
  * the validation in libntfs-3g.
  */
 static void
-empty_sacl_fixup(u8 *descr, u64 *size_p)
+empty_sacl_fixup(SECURITY_DESCRIPTOR_RELATIVE *descr, size_t *size_p)
 {
        /* No-op if no NTFS-3g support, or if NTFS-3g is version 2013 or later
         * */
 #if defined(WITH_NTFS_3G) && !defined(HAVE_NTFS_MNT_RDONLY)
-       if (*size_p >= sizeof(SecurityDescriptor)) {
-               SecurityDescriptor *sd = (SecurityDescriptor*)descr;
-               u32 sacl_offset = le32_to_cpu(sd->sacl_offset);
+       if (*size_p >= sizeof(SECURITY_DESCRIPTOR_RELATIVE)) {
+               u32 sacl_offset = le32_to_cpu(descr->sacl_offset);
                if (sacl_offset == *size_p - sizeof(ACL)) {
-                       sd->sacl_offset = cpu_to_le32(0);
+                       descr->sacl_offset = cpu_to_le32(0);
                        *size_p -= sizeof(ACL);
                }
        }
 #endif
 }
 
+struct wim_security_data *
+new_wim_security_data(void)
+{
+       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.
+ *                             resource for the WIM image.
  * @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
+ * @sd_ret:    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.
+ *             structure containing the security data on success.
  *
  * Note: There is no `offset' argument because the security data is located at
  * the beginning of the metadata resource.
+ *
+ * Possible errors include:
+ *     WIMLIB_ERR_NOMEM
+ *     WIMLIB_ERR_INVALID_SECURITY_DATA
  */
 int
-read_security_data(const u8 metadata_resource[], u64 metadata_resource_len,
-                  struct wim_security_data **sd_p)
+read_wim_security_data(const u8 metadata_resource[], size_t metadata_resource_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;
 
        wimlib_assert(metadata_resource_len >= 8);
 
-       /*
-        * Sorry this function is excessively complicated--- I'm just being
-        * extremely careful about integer overflows.
-        */
+       sd = new_wim_security_data();
+       if (!sd)
+               goto out_of_memory;
 
-       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_disk = (const struct wim_security_data_disk*)metadata_resource;
+       sd->total_length = le32_to_cpu(sd_disk->total_length);
+       sd->num_entries = le32_to_cpu(sd_disk->num_entries);
+
+       DEBUG("Reading security data: num_entries=%u, total_length=%u",
+             sd->num_entries, sd->total_length);
 
-       p = metadata_resource;
-       p = get_u32(p, &sd->total_length);
-       p = get_u32(p, (u32*)&sd->num_entries);
+       /* 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
@@ -333,242 +230,234 @@ 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 > metadata_resource_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.  We allow the total_length field to
-                * be either 8 (which is correct, since there are always 2
-                * 32-bit integers) or 0. */
-               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 seem to be at least %"PRIu64" bytes of security data",
-                     sd->total_length, 8 + sizes_size);
-               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 ensures 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 seem to be 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]);
+               if (!sd->descriptors[i])
+                       goto out_of_memory;
+               memcpy(sd->descriptors[i], p, sd->sizes[i]);
+               p += sd->sizes[i];
+               empty_sacl_fixup((SECURITY_DESCRIPTOR_RELATIVE*)sd->descriptors[i],
+                                &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:
+       ERROR("WIM security data is invalid!");
        ret = WIMLIB_ERR_INVALID_SECURITY_DATA;
+       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)
+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;
+
+       sd_disk->total_length = cpu_to_le32(sd->total_length);
+       sd_disk->num_entries = cpu_to_le32(sd->num_entries);
 
        for (u32 i = 0; i < sd->num_entries; i++)
-               p = put_u64(p, sd->sizes[i]);
+               sd_disk->sizes[i] = cpu_to_le64(sd->sizes[i]);
+
+       p = (u8*)&sd_disk->sizes[sd_disk->num_entries];
 
        for (u32 i = 0; i < sd->num_entries; i++)
-               p = put_bytes(p, sd->sizes[i], sd->descriptors[i]);
+               p = mempcpy(p, sd->descriptors[i], sd->sizes[i]);
+
+       while (p - orig_p < sd->total_length)
+               *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)
+print_acl(const ACL *acl, const tchar *type, size_t max_size)
 {
-       const ACL *acl = (const ACL*)p;
+       const u8 *p;
+
+       if (max_size < sizeof(ACL))
+               return;
+
        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);
+       tprintf(T("    [%"TS" ACL]\n"), type);
+       tprintf(T("    Revision = %u\n"), revision);
+       tprintf(T("    ACL Size = %u\n"), acl_size);
+       tprintf(T("    ACE Count = %u\n"), ace_count);
+
+       p = (const u8*)acl + sizeof(ACL);
        for (u16 i = 0; i < 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 (max_size < p + sizeof(ACCESS_ALLOWED_ACE) - (const u8*)acl)
+                       break;
+               const ACCESS_ALLOWED_ACE *aaa = (const ACCESS_ALLOWED_ACE*)p;
+               tprintf(T("        [ACE]\n"));
+               tprintf(T("        ACE type  = %d\n"), aaa->hdr.type);
+               tprintf(T("        ACE flags = 0x%x\n"), aaa->hdr.flags);
+               tprintf(T("        ACE size  = %u\n"), le16_to_cpu(aaa->hdr.size));
+               tprintf(T("        ACE mask = %x\n"), le32_to_cpu(aaa->mask));
+               tprintf(T("        SID start = %u\n"), le32_to_cpu(aaa->sid_start));
+               p += le16_to_cpu(aaa->hdr.size);
        }
-       putchar('\n');
+       tputchar(T('\n'));
 }
 
 static void
-print_sid(const u8 *p, const char *type)
+print_sid(const SID *sid, const tchar *type, size_t max_size)
 {
-       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 = ");
+       if (max_size < sizeof(SID))
+               return;
+
+       tprintf(T("    [%"TS" SID]\n"), type);
+       tprintf(T("    Revision = %u\n"), sid->revision);
+       tprintf(T("    Subauthority count = %u\n"), sid->sub_authority_count);
+       tprintf(T("    Identifier authority = "));
        print_byte_field(sid->identifier_authority,
-                        sizeof(sid->identifier_authority));
-       putchar('\n');
-       for (u8 i = 0; i < sid->sub_authority_count; i++)
-               printf("    Subauthority %u = %u\n",
-                      i, le32_to_cpu(sid->sub_authority[i]));
-       putchar('\n');
+                        sizeof(sid->identifier_authority), stdout);
+       tputchar(T('\n'));
+       if (max_size < sizeof(SID) + (size_t)sid->sub_authority_count * sizeof(u32))
+               return;
+       for (u8 i = 0; i < sid->sub_authority_count; i++) {
+               tprintf(T("    Subauthority %u = %u\n"),
+                       i, le32_to_cpu(sid->sub_authority[i]));
+       }
+       tputchar(T('\n'));
 }
 
 static void
-print_security_descriptor(const u8 *p, u64 size)
+print_security_descriptor(const SECURITY_DESCRIPTOR_RELATIVE *descr,
+                         size_t size)
 {
-       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");
+       u8 revision      = descr->revision;
+       u16 control      = le16_to_cpu(descr->security_descriptor_control);
+       u32 owner_offset = le32_to_cpu(descr->owner_offset);
+       u32 group_offset = le32_to_cpu(descr->group_offset);
+       u32 dacl_offset  = le32_to_cpu(descr->dacl_offset);
+       u32 sacl_offset  = le32_to_cpu(descr->sacl_offset);
+
+       tprintf(T("Revision = %u\n"), revision);
+       tprintf(T("Security Descriptor Control = %#x\n"), control);
+       tprintf(T("Owner offset = %u\n"), owner_offset);
+       tprintf(T("Group offset = %u\n"), group_offset);
+       tprintf(T("Discretionary ACL offset = %u\n"), dacl_offset);
+       tprintf(T("System ACL offset = %u\n"), sacl_offset);
+
+       if (owner_offset != 0 && owner_offset <= size)
+               print_sid((const SID*)((const u8*)descr + owner_offset),
+                         T("Owner"), size - owner_offset);
+
+       if (group_offset != 0 && group_offset <= size)
+               print_sid((const SID*)((const u8*)descr + group_offset),
+                         T("Group"), size - group_offset);
+
+       if (dacl_offset != 0 && dacl_offset <= size)
+               print_acl((const ACL*)((const u8*)descr + dacl_offset),
+                         T("Discretionary"), size - dacl_offset);
+
+       if (sacl_offset != 0 && sacl_offset <= size)
+               print_acl((const ACL*)((const u8*)descr + sacl_offset),
+                         T("System"), size - sacl_offset);
 }
 
 /*
  * Prints the security data for a WIM file.
  */
 void
-print_security_data(const struct wim_security_data *sd)
+print_wim_security_data(const struct wim_security_data *sd)
 {
-       wimlib_assert(sd != NULL);
-
-       puts("[SECURITY DATA]");
-       printf("Length            = %"PRIu32" bytes\n", sd->total_length);
-       printf("Number of Entries = %"PRIu32"\n", sd->num_entries);
+       tputs(T("[SECURITY DATA]"));
+       tprintf(T("Length            = %"PRIu32" bytes\n"), sd->total_length);
+       tprintf(T("Number of Entries = %"PRIu32"\n"), sd->num_entries);
 
        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');
+               tprintf(T("[SECURITY_DESCRIPTOR_RELATIVE %"PRIu32", length = %"PRIu64"]\n"),
+                       i, sd->sizes[i]);
+               print_security_descriptor((const SECURITY_DESCRIPTOR_RELATIVE*)sd->descriptors[i],
+                                         sd->sizes[i]);
+               tputchar(T('\n'));
        }
-       putchar('\n');
+       tputchar(T('\n'));
 }
 
 void
-free_security_data(struct wim_security_data *sd)
+free_wim_security_data(struct wim_security_data *sd)
 {
        if (sd) {
-               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);
-               }
+               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);
        }
 }
 
@@ -590,14 +479,22 @@ free_sd_tree(struct rb_node *node)
 
 /* Frees a security descriptor index set. */
 void
-destroy_sd_set(struct sd_set *sd_set)
+destroy_sd_set(struct wim_sd_set *sd_set, bool rollback)
 {
+       if (rollback) {
+               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;
+       }
        free_sd_tree(sd_set->rb_root.rb_node);
 }
 
 /* Inserts a a new node into the security descriptor index tree. */
-static void
-insert_sd_node(struct sd_set *set, struct sd_node *new)
+static bool
+insert_sd_node(struct wim_sd_set *set, struct sd_node *new)
 {
        struct rb_root *root = &set->rb_root;
        struct rb_node **p = &(root->rb_node);
@@ -613,16 +510,17 @@ insert_sd_node(struct sd_set *set, struct sd_node *new)
                else if (cmp > 0)
                        p = &((*p)->rb_right);
                else
-                       wimlib_assert(0); /* Duplicate SHA1 message digest */
+                       return false; /* Duplicate security descriptor */
        }
        rb_link_node(&new->rb_node, rb_parent, p);
        rb_insert_color(&new->rb_node, root);
+       return true;
 }
 
 /* Returns the index of the security descriptor having a SHA1 message digest of
  * @hash.  If not found, return -1. */
 int
-lookup_sd(struct sd_set *set, const u8 hash[SHA1_HASH_SIZE])
+lookup_sd(struct wim_sd_set *set, const u8 hash[SHA1_HASH_SIZE])
 {
        struct rb_node *node = set->rb_root.rb_node;
 
@@ -647,23 +545,26 @@ lookup_sd(struct sd_set *set, const u8 hash[SHA1_HASH_SIZE])
  * return -1.
  */
 int
-sd_set_add_sd(struct sd_set *sd_set, const char descriptor[], size_t size)
+sd_set_add_sd(struct wim_sd_set *sd_set, const char *descriptor, size_t size)
 {
        u8 hash[SHA1_HASH_SIZE];
        int security_id;
        struct sd_node *new;
        u8 **descriptors;
        u64 *sizes;
-       u8 *descr_copy;
+       char *descr_copy;
        struct wim_security_data *sd;
+       bool bret;
 
-       sha1_buffer((const u8*)descriptor, size, hash);
+       sha1_buffer(descriptor, size, hash);
 
        security_id = lookup_sd(sd_set, hash);
        if (security_id >= 0) /* Identical descriptor already exists */
-               return security_id;
+               goto out;
 
        /* Need to add a new security descriptor */
+       security_id = -1;
+
        new = MALLOC(sizeof(*new));
        if (!new)
                goto out;
@@ -677,6 +578,9 @@ sd_set_add_sd(struct sd_set *sd_set, const char descriptor[], size_t size)
        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)
@@ -690,14 +594,50 @@ sd_set_add_sd(struct sd_set *sd_set, const char descriptor[], size_t size)
        sd->descriptors[sd->num_entries] = descr_copy;
        sd->sizes[sd->num_entries] = size;
        sd->num_entries++;
-       DEBUG("There are now %d security descriptors", sd->num_entries);
-       sd->total_length += size + sizeof(sd->sizes[0]);
-       insert_sd_node(sd_set, new);
-       return new->security_id;
+       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 -1;
+       return security_id;
+}
+
+/* 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)
+{
+       int ret;
+
+       sd_set->sd = sd;
+       sd_set->rb_root.rb_node = 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, false);
+out:
+       return ret;
 }