/*++ Copyright (c) 1991 Microsoft Corporation Module Name: imagedir.c Abstract: The module contains the code to translate an image directory type to the address of the data for that entry. Author: Steve Wood (stevewo) 18-Aug-1989 Environment: User Mode or Kernel Mode Revision History: --*/ #include "ntrtlp.h" // // Define forward referenced prootypes. // USHORT ChkSum( ULONG PartialSum, PUSHORT Source, ULONG Length ); #if defined(ALLOC_PRAGMA) && defined(NTOS_KERNEL_RUNTIME) #pragma alloc_text(PAGE,ChkSum) #pragma alloc_text(PAGE,LdrVerifyMappedImageMatchesChecksum) #pragma alloc_text(PAGE, RtlComputeCrc32) #endif // // This is the precomputed data table for the CRC32 algorithm as specified // in IS0 3309. See RFC-1662 and RFC-1952 for implementation details and // references. // // To calculate this table, use the following function: // // VOID // PrintCrcTable( // ) // { // ULONG32 Val; // ULONG i, k; // // for (i = 0; i < 256; i++) { // Val = (ULONG) i; // for (k = 0; k < 8; k++) { // if (Val & 1) { // Val = 0xedb88320L ^ (Val >> 1); // } else { // Val = Val >> 1; // } // } // // printf ("0x%08x, ", Val); // // if ( (i+1) % 6 == 0) { // printf ("\n"); // } // } // } // // #if defined(ALLOC_DATA_PRAGMA) && defined(NTOS_KERNEL_RUNTIME) #pragma data_seg("PAGEDATA") #pragma const_seg("PAGECONST") #endif const ULONG32 RtlCrc32Table [] = { 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d }; #if defined(ALLOC_DATA_PRAGMA) && defined(NTOS_KERNEL_RUNTIME) #pragma const_seg() #pragma data_seg() #endif USHORT ChkSum( ULONG PartialSum, PUSHORT Source, ULONG Length ) /*++ Routine Description: Compute a partial checksum on a portion of an imagefile. Arguments: PartialSum - Supplies the initial checksum value. Sources - Supplies a pointer to the array of words for which the checksum is computed. Length - Supplies the length of the array in words. Return Value: The computed checksum value is returned as the function value. --*/ { RTL_PAGED_CODE(); // // Compute the word wise checksum allowing carries to occur into the // high order half of the checksum longword. // while (Length--) { PartialSum += *Source++; PartialSum = (PartialSum >> 16) + (PartialSum & 0xffff); } // // Fold final carry into a single word result and return the resultant // value. // return (USHORT)(((PartialSum >> 16) + PartialSum) & 0xffff); } BOOLEAN LdrVerifyMappedImageMatchesChecksum ( IN PVOID BaseAddress, IN ULONG FileLength ) /*++ Routine Description: This functions computes the checksum of an image mapped as a data file. Arguments: BaseAddress - Supplies a pointer to the base of the mapped file. FileLength - Supplies the length of the file in bytes. Return Value: TRUE - The checksum stored in the image matches the checksum of the data. FALSE - The checksum in the image is not correct. --*/ { PUSHORT AdjustSum; PIMAGE_NT_HEADERS NtHeaders; USHORT PartialSum; ULONG HeaderSum; ULONG CheckSum; RTL_PAGED_CODE(); // // Compute the checksum of the file and zero the header checksum value. // HeaderSum = 0; PartialSum = ChkSum(0, (PUSHORT)BaseAddress, (FileLength + 1) >> 1); // // If the file is an image file, then subtract the two checksum words // in the optional header from the computed checksum before adding // the file length, and set the value of the header checksum. // NtHeaders = RtlImageNtHeader(BaseAddress); if (NtHeaders != NULL) { HeaderSum = NtHeaders->OptionalHeader.CheckSum; #ifndef NTOS_KERNEL_RUNTIME // // On Nt 3.1 and 3.5, we allowed printer drivers with 0 checksums into // csrss unintentionally. This means that we must allow this forever. // I don't want to allow this for kernel mode drivers, so I will only // allow 0 checksums of the high order bit is clear ? // if ( HeaderSum == 0 ) { return TRUE; } #endif // NTOS_KERNEL_RUNTIME AdjustSum = (PUSHORT)(&NtHeaders->OptionalHeader.CheckSum); PartialSum -= (PartialSum < AdjustSum[0]); PartialSum -= AdjustSum[0]; PartialSum -= (PartialSum < AdjustSum[1]); PartialSum -= AdjustSum[1]; } else { PartialSum = 0; HeaderSum = FileLength; } // // Compute the final checksum value as the sum of the paritial checksum // and the file length. // CheckSum = (ULONG)PartialSum + FileLength; return (CheckSum == HeaderSum); } ULONG32 RtlComputeCrc32( ULONG32 PartialCrc, PUCHAR Buffer, ULONG Length ) /*++ Routine Description: Compute the CRC32 as specified in in IS0 3309. See RFC-1662 and RFC-1952 for implementation details and references. Pre- and post-conditioning (one's complement) is done by this function, so it should not be done by the caller. That is, do: Crc = RtlComputeCrc32 ( 0, buffer, length ); instead of Crc = RtlComputeCrc32 ( 0xffffffff, buffer, length ); or Crc = RtlComputeCrc32 ( 0xffffffff, buffer, length) ^ 0xffffffff; Arguments: PartialCrc - A partially calculated CRC32. Buffer - The buffer you want to CRC. Length - The length of the buffer in bytes. Return Value: The updated CRC32 value. Environment: Kernel mode at IRQL of APC_LEVEL or below, User mode, or within the boot-loader. --*/ { ULONG32 Crc; ULONG i; RTL_PAGED_CODE (); // // Compute the CRC32 checksum. // Crc = PartialCrc ^ 0xffffffffL; for (i = 0; i < Length; i++) { Crc = RtlCrc32Table [(Crc ^ Buffer [ i ]) & 0xff] ^ (Crc >> 8); } return (Crc ^ 0xffffffffL); }