mtree/commoncrypto.c

   1 #include <dispatch/dispatch.h>
   2 #include <os/assumes.h>
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <string.h>
   6 #include <sys/xattr.h>
   7 #include <stdbool.h>
   8 #include <err.h>
   9 #include <errno.h>
  10 #include <stdio.h>
  11 #include <sys/attr.h>
  12 #include <unistd.h>
  13
  14 #include "commoncrypto.h"
  15
  16 const int kSHA256NullTerminatedBuffLen = 65;
  17 static const char hex[] = "0123456789abcdef";
  18
  19 /* Functions for SHA256_File_XATTRs */
  20 #define SHA256_Data(d, s, b)    Digest_Data(kCCDigestSHA256, d, s, b)
  21 char *Digest_Data(CCDigestAlg algorithm, void *data, size_t size, char *buf);
  22 void Quicksort(char **array, int num);
  23
  24 /* Generic version of libmd's *_File() functions. */
  25 char *
  26 Digest_File(CCDigestAlg algorithm, const char *filename, char *buf)
  27 {
  28         int fd;
  29         __block CCDigestCtx ctx;
  30         dispatch_queue_t queue;
  31         dispatch_semaphore_t sema;
  32         dispatch_io_t io;
  33         __block int s_error = 0;
  34         uint8_t digest[32]; // SHA256 is the biggest
  35         size_t i, length;
  36
  37         /* dispatch_io_create_with_path requires an absolute path */
  38         fd = open(filename, O_RDONLY);
  39         if (fd < 0) {
  40                 return NULL;
  41         }
  42
  43         (void)fcntl(fd, F_NOCACHE, 1);
  44
  45         (void)os_assumes_zero(CCDigestInit(algorithm, &ctx));
  46
  47         queue = dispatch_queue_create("com.apple.mtree.io", NULL);
  48         os_assert(queue);
  49         sema = dispatch_semaphore_create(0);
  50         os_assert(sema);
  51
  52         io = dispatch_io_create(DISPATCH_IO_STREAM, fd, queue, ^(int error) {
  53                 if (error != 0) {
  54                         s_error = error;
  55                 }
  56                 (void)close(fd);
  57                 (void)dispatch_semaphore_signal(sema);
  58         });
  59         os_assert(io);
  60         dispatch_io_read(io, 0, SIZE_MAX, queue, ^(__unused bool done, dispatch_data_t data, int error) {
  61                 if (data != NULL) {
  62                         (void)dispatch_data_apply(data, ^(__unused dispatch_data_t region, __unused size_t offset, const void *buffer, size_t size) {
  63                                 (void)os_assumes_zero(CCDigestUpdate(&ctx, buffer, size));
  64                                 return (bool)true;
  65                         });
  66                 }
  67
  68                 if (error != 0) {
  69                         s_error = error;
  70                 }
  71         });
  72         dispatch_release(io); // it will close on its own
  73
  74         (void)dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER);
  75
  76         dispatch_release(queue);
  77         dispatch_release(sema);
  78
  79         if (s_error != 0) {
  80                 errno = s_error;
  81                 return NULL;
  82         }
  83
  84         /* Finalize and convert to hex. */
  85         (void)os_assumes_zero(CCDigestFinal(&ctx, digest));
  86         length = CCDigestOutputSize(&ctx);
  87         os_assert(length <= sizeof(digest));
  88         for (i = 0; i < length; i++) {
  89                 buf[i+i] = hex[digest[i] >> 4];
  90                 buf[i+i+1] = hex[digest[i] & 0x0f];
  91         }
  92         buf[i+i] = '\0';
  93
  94         return buf;
  95 }
  96
  97 char *SHA256_Path_XATTRs(char *path, char *buf)
  98 {
  99         char *xattrsSummary = NULL;
 100         int options = XATTR_SHOWCOMPRESSION | XATTR_NOFOLLOW;
 101         ssize_t nameBufSize = listxattr(path, NULL, 0, options);
 102         if (nameBufSize > 0) {
 103                 char *nameBuf = malloc(nameBufSize);
 104
 105                 listxattr(path, nameBuf, nameBufSize, options);
 106
 107                 size_t xattrsLen = 1;
 108                 size_t xattrIndex = 0;
 109                 char **xattrs = malloc(xattrsLen * sizeof(char *));
 110                 char *nextName = nameBuf;
 111                 while (nextName < nameBuf + nameBufSize)
 112                 {
 113                         char *name = nextName;
 114                         if (xattrIndex == xattrsLen) {
 115                                 xattrsLen *= 2;
 116                                 xattrs = realloc(xattrs, xattrsLen * sizeof(char *));
 117                         }
 118                         xattrs[xattrIndex++] = name;
 119                         nextName += strlen(name) + 1;
 120                 }
 121
 122                 // sort the xattr array as they're not guaranteed to come in the same order
 123                 qsort_b(xattrs, xattrIndex, sizeof(char *), ^(const void *l, const void *r) {
 124                         char *left = *(char **)l;
 125                         char *right = *(char **)r;
 126                         return strcmp(left, right);
 127                 });
 128
 129                 // gather the data for the xattrs
 130                 bool didAddXATTR = false;
 131                 int xattrBufLen = kSHA256NullTerminatedBuffLen;
 132                 void *xattrBuf = malloc(xattrBufLen); // resized if necessary
 133                 char *digest;
 134                 ssize_t result = 0;
 135                 char *oldSummary = NULL;
 136                 for (int i = 0; i < xattrIndex; i++) {
 137                         char *name = xattrs[i];
 138                         ssize_t xlen = getxattr(path, name, NULL, 0, 0, options);
 139                         if (xlen > xattrBufLen) {
 140                                 xattrBufLen = xlen;
 141                                 xattrBuf = realloc(xattrBuf, xattrBufLen);
 142                         }
 143                         bzero(xattrBuf, xattrBufLen);
 144                         result = getxattr(path, name, xattrBuf, xattrBufLen, 0, options);
 145                         if (result < 0)
 146                                 err(1, "SHA256_Path_XATTRs getxattr of \"%s\" at path \"%s\" failed with error", name, path );
 147
 148                         digest = SHA256_Data(xattrBuf, xattrBufLen, buf);
 149                         if (!digest)
 150                                 err(1, "%s", xattrsSummary);
 151                         if (!didAddXATTR)
 152                         {
 153                                 didAddXATTR = true;
 154                                 asprintf(&xattrsSummary, "%s:%s", name, digest);
 155                         } else {
 156                                 oldSummary = xattrsSummary;
 157                                 asprintf(&xattrsSummary, "%s, %s:%s", oldSummary, name, digest);
 158                                 free(oldSummary);
 159                         }
 160                 }
 161
 162                 free(xattrBuf);
 163                 free(nameBuf);
 164                 free(xattrs);
 165
 166                 digest = SHA256_Data(xattrsSummary, strlen(xattrsSummary) * sizeof(char), buf);
 167                 if (!digest)
 168                         err(1, "%s", xattrsSummary);
 169
 170                 free(xattrsSummary);
 171                 return digest;
 172         }
 173         return kNone;
 174 }
 175
 176 char *SHA256_Path_ACL(char *path, char *buf)
 177 {
 178         int result              = 0;
 179         char *data              = NULL;
 180         char *digest            = NULL;
 181
 182         struct attrlist list = {
 183                 .bitmapcount    = ATTR_BIT_MAP_COUNT,
 184                 .commonattr     = ATTR_CMN_RETURNED_ATTRS | ATTR_CMN_EXTENDED_SECURITY,
 185         };
 186
 187         struct ACLBuf {
 188                 uint32_t                len;
 189                 attribute_set_t         returned_attrs;
 190                 attrreference_t         acl;
 191                 char                    buf[8192]; // current acls are up to 3116 bytes, but they may increase in the future
 192         } __attribute__((aligned(4), packed));
 193
 194         struct ACLBuf aclBuf;
 195
 196         result = getattrlist(path, &list, &aclBuf, sizeof(aclBuf), FSOPT_NOFOLLOW);
 197
 198         if (result)
 199                 err(1, "SHA256_Path_ACL: getattrlist");
 200
 201         // if the path does not have an acl, return none
 202         if ( ( ! ( aclBuf.returned_attrs.commonattr & ATTR_CMN_EXTENDED_SECURITY ) )
 203             || ( aclBuf.acl.attr_length == 0 ) ) {
 204                 return kNone;
 205         }
 206
 207         data = ((char*)&aclBuf.acl) + aclBuf.acl.attr_dataoffset;
 208
 209         digest = SHA256_Data(data, aclBuf.acl.attr_length, buf);
 210         if (!digest)
 211                 err(1, "SHA256_Path_ACL: SHA256_Data");
 212
 213         return digest;
 214 }
 215
 216 /* Functions for Digest_Path_* */
 217 char *
 218 Digest_Data(CCDigestAlg algorithm, void *data, size_t size, char *buf) {
 219
 220         uint8_t digest[32]; // SHA256 is the biggest
 221         CCDigestCtx ctx;
 222         size_t i, length;
 223
 224         (void)os_assumes_zero(CCDigestInit(algorithm, &ctx));
 225         (void)os_assumes_zero(CCDigestUpdate(&ctx, data, size));
 226
 227         /* Finalize and convert to hex. */
 228         (void)os_assumes_zero(CCDigestFinal(&ctx, digest));
 229         length = CCDigestOutputSize(&ctx);
 230         os_assert(length <= sizeof(digest));
 231         for (i = 0; i < length; i++) {
 232                 buf[i+i] = hex[digest[i] >> 4];
 233                 buf[i+i+1] = hex[digest[i] & 0x0f];
 234         }
 235         buf[i+i] = '\0';
 236
 237         return buf;
 238 }
 239