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Modernize crypt-des.c a bit, avoiding dubious casts.

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The header comment for this file says it assumes that "the CPU is not
picky about alignment", which we wouldn't really accept for Postgres.
The two functions that have alignment requirements have been hacked in
ways that are inconsistent and yet both ugly.  des_setkey just casts
its "const char *" argument to "const uint32 *", relying on the caller
to ensure that that pointer is actually word-aligned, which the caller
does by declaring the buffer as uint32[] and then casting to "char *".
Meanwhile des_cipher carefully memcpy's to and from an internal
uint32[] buffer, which is pretty silly given that what it's passed
must be word-aligned for the benefit of des_setkey.  And on top of
that we have a bunch of ugly casting and oddly-written pointer
arithmetic in the caller px_crypt_des.  The odd pointer arithmetic
causes warnings about possible buffer overrun when using recent gcc
at -O3 or higher.

Let's clean this up by converting the buffer variable into a union
of a uint8 array and a uint32 array, so that we can remove all these
casts, and also replace the strange loop logic with a simple subscript
variable to satisfy gcc.

Reported-by: Andres Freund <andres@anarazel.de>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Co-authored-by: Ayush Tiwari <ayushtiwari.slg01@gmail.com>
Discussion: https://postgr.es/m/2005885.1790359097@sss.pgh.pa.us
Discussion: https://postgr.es/m/3nuudxv365kjnmwjhnygdakhxuktpdjvf26rt26eb44esgqdrj@y2x3vomkrfoo
Backpatch-through: 14
This commit is contained in:
Tom Lane
2026-09-25 15:34:38 -04:00
parent 3e9bc39c5d
commit 87762cbaa4
1 changed files with 21 additions and 32 deletions
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53
contrib/pgcrypto/crypt-des.c
View File

@@ -53,11 +53,6 @@
* pbox, and final permutations are inverted (this has been brought to the
* attention of the author). A list of errata for this book has been
* posted to the sci.crypt newsgroup by the author and is available for FTP.
*
* ARCHITECTURE ASSUMPTIONS:
* It is assumed that the 8-byte arrays passed by reference can be
* addressed as arrays of uint32's (ie. the CPU is not picky about
* alignment).
*/
#include "postgres.h"
@@ -393,7 +388,7 @@ setup_salt(long salt)
}
static int
des_setkey(const char *key)
des_setkey(const uint32 *key)
{
uint32 k0,
k1,
@@ -405,8 +400,8 @@ des_setkey(const char *key)
if (!des_initialised)
des_init();
rawkey0 = pg_ntoh32(*(const uint32 *) key);
rawkey1 = pg_ntoh32(*(const uint32 *) (key + 4));
rawkey0 = pg_ntoh32(key[0]);
rawkey1 = pg_ntoh32(key[1]);
if ((rawkey0 | rawkey1)
&& rawkey0 == old_rawkey0
@@ -614,9 +609,8 @@ do_des(uint32 l_in, uint32 r_in, uint32 *l_out, uint32 *r_out, int count)
}
static int
des_cipher(const char *in, char *out, long salt, int count)
des_cipher(const uint32 *in, uint32 *out, long salt, int count)
{
uint32 buffer[2];
uint32 l_out,
r_out,
rawl,
@@ -628,21 +622,15 @@ des_cipher(const char *in, char *out, long salt, int count)
setup_salt(salt);
/* copy data to avoid assuming input is word-aligned */
memcpy(buffer, in, sizeof(buffer));
rawl = pg_ntoh32(buffer[0]);
rawr = pg_ntoh32(buffer[1]);
rawl = pg_ntoh32(in[0]);
rawr = pg_ntoh32(in[1]);
retval = do_des(rawl, rawr, &l_out, &r_out, count);
if (retval)
return retval;
buffer[0] = pg_hton32(l_out);
buffer[1] = pg_hton32(r_out);
/* copy data to avoid assuming output is word-aligned */
memcpy(out, buffer, sizeof(buffer));
out[0] = pg_hton32(l_out);
out[1] = pg_hton32(r_out);
return retval;
}
@@ -655,10 +643,13 @@ px_crypt_des(const char *key, const char *setting)
salt,
l,
r0,
r1,
keybuf[2];
r1;
union
{
uint8 bytes[8];
uint32 ints[2];
} keybuf;
char *p;
uint8 *q;
static char output[21];
if (!des_initialised)
@@ -669,14 +660,13 @@ px_crypt_des(const char *key, const char *setting)
* Copy the key, shifting each character up by one bit and padding with
* zeros.
*/
q = (uint8 *) keybuf;
while (q - (uint8 *) keybuf - 8)
for (size_t q = 0; q < lengthof(keybuf.bytes); q++)
{
*q++ = *key << 1;
keybuf.bytes[q] = *key << 1;
if (*key != '\0')
key++;
}
if (des_setkey((char *) keybuf))
if (des_setkey(keybuf.ints))
return NULL;
#ifndef DISABLE_XDES
@@ -707,17 +697,16 @@ px_crypt_des(const char *key, const char *setting)
/*
* Encrypt the key with itself.
*/
if (des_cipher((char *) keybuf, (char *) keybuf, 0L, 1))
if (des_cipher(keybuf.ints, keybuf.ints, 0L, 1))
return NULL;
/*
* And XOR with the next 8 characters of the key.
*/
q = (uint8 *) keybuf;
while (q - (uint8 *) keybuf - 8 && *key)
*q++ ^= *key++ << 1;
for (size_t q = 0; q < lengthof(keybuf.bytes) && *key; q++)
keybuf.bytes[q] ^= *key++ << 1;
if (des_setkey((char *) keybuf))
if (des_setkey(keybuf.ints))
return NULL;
}
strlcpy(output, setting, 10);