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PG-1455 Change xlog base IVs to use addition

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This way they can eventually be made more similar to using OpenSSL
for encrypting and decrypting the CTR stream.
This commit is contained in:
Andreas Karlsson 2025-04-01 16:33:09 +02:00 committed by Andreas Karlsson
parent 72050ff258
commit 36bc82d6c0
1 changed files with 37 additions and 24 deletions
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61
contrib/pg_tde/src/access/pg_tde_xlog_encrypt.c
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@ -359,34 +359,47 @@ tdeheap_xlog_seg_read(int fd, void *buf, size_t count, off_t offset,
return readsz;
}
/* IV: (TLI(uint32) + XLogRecPtr(uint64)) XOR BaseIV(uint8[12]) */
union u128cast
{
char a[16];
unsigned __int128 i;
};
/*
* Calculate the start IV for an XLog segmenet.
*
* IV: (TLI(uint32) + XLogRecPtr(uint64)) + BaseIV(uint8[12])
*
* TODO: Make the calculation more like OpenSSL's CTR withot any gaps and
* preferrably without zeroing the lowest bytes for the base IV.
*
* TODO: This code vectorizes poorly in both gcc and clang.
*/
static void
CalcXLogPageIVPrefix(TimeLineID tli, XLogRecPtr lsn, const unsigned char *base_iv, char *iv_prefix)
{
/* Temporary variables to make GCC vectorize it */
char a[16],
b[16];
memset(a, 0, 16);
a[0] = tli >> 24;
a[1] = tli >> 16;
a[2] = tli >> 8;
a[3] = tli;
memset(b, 0, 16);
b[4] = lsn >> 56;
b[5] = lsn >> 48;
b[6] = lsn >> 40;
b[7] = lsn >> 32;
b[8] = lsn >> 24;
b[9] = lsn >> 16;
b[10] = lsn >> 8;
b[11] = lsn;
union u128cast base;
union u128cast iv;
unsigned __int128 offset;
for (int i = 0; i < 16; i++)
iv_prefix[i] = (a[i] | b[i]) ^ base_iv[i];
#ifdef WORDS_BIGENDIAN
base.a[i] = base_iv[i];
#else
base.a[i] = base_iv[15 - i];
#endif
/* Zero lowest 4 bytes */
for (int i = 12; i < 16; i++)
iv_prefix[i] = 0;
/* We do not support wrapping addition in Aes128EncryptedZeroBlocks() */
base.i &= ~(((unsigned __int128) 1) << 32);
offset = (((unsigned __int128) tli) << 112) | (((unsigned __int128) lsn) << 32);
iv.i = base.i + offset;
for (int i = 0; i < 16; i++)
#ifdef WORDS_BIGENDIAN
iv_prefix[i] = iv.a[i];
#else
iv_prefix[i] = iv.a[15 - i];
#endif
}