![Nicolai Stange](/assets/img/avatar_default.png)
Within the copying loop in mpi_read_raw_from_sgl(), the last input SGE's
byte count gets artificially extended as follows:
if (sg_is_last(sg) && (len % BYTES_PER_MPI_LIMB))
len += BYTES_PER_MPI_LIMB - (len % BYTES_PER_MPI_LIMB);
Within the following byte copying loop, this causes reads beyond that
SGE's allocated buffer:
BUG: KASAN: slab-out-of-bounds in mpi_read_raw_from_sgl+0x331/0x650
at addr ffff8801e168d4d8
Read of size 1 by task systemd-udevd/721
[...]
Call Trace:
[<ffffffff818c4d35>] dump_stack+0xbc/0x117
[<ffffffff818c4c79>] ? _atomic_dec_and_lock+0x169/0x169
[<ffffffff814af5d1>] ? print_section+0x61/0xb0
[<ffffffff814b1109>] print_trailer+0x179/0x2c0
[<ffffffff814bc524>] object_err+0x34/0x40
[<ffffffff814bfdc7>] kasan_report_error+0x307/0x8c0
[<ffffffff814bf315>] ? kasan_unpoison_shadow+0x35/0x50
[<ffffffff814bf38e>] ? kasan_kmalloc+0x5e/0x70
[<ffffffff814c0ad1>] kasan_report+0x71/0xa0
[<ffffffff81938171>] ? mpi_read_raw_from_sgl+0x331/0x650
[<ffffffff814bf1a6>] __asan_load1+0x46/0x50
[<ffffffff81938171>] mpi_read_raw_from_sgl+0x331/0x650
[<ffffffff817f41b6>] rsa_verify+0x106/0x260
[<ffffffff817f40b0>] ? rsa_set_pub_key+0xf0/0xf0
[<ffffffff818edc79>] ? sg_init_table+0x29/0x50
[<ffffffff817f4d22>] ? pkcs1pad_sg_set_buf+0xb2/0x2e0
[<ffffffff817f5b74>] pkcs1pad_verify+0x1f4/0x2b0
[<ffffffff81831057>] public_key_verify_signature+0x3a7/0x5e0
[<ffffffff81830cb0>] ? public_key_describe+0x80/0x80
[<ffffffff817830f0>] ? keyring_search_aux+0x150/0x150
[<ffffffff818334a4>] ? x509_request_asymmetric_key+0x114/0x370
[<ffffffff814b83f0>] ? kfree+0x220/0x370
[<ffffffff818312c2>] public_key_verify_signature_2+0x32/0x50
[<ffffffff81830b5c>] verify_signature+0x7c/0xb0
[<ffffffff81835d0c>] pkcs7_validate_trust+0x42c/0x5f0
[<ffffffff813c391a>] system_verify_data+0xca/0x170
[<ffffffff813c3850>] ? top_trace_array+0x9b/0x9b
[<ffffffff81510b29>] ? __vfs_read+0x279/0x3d0
[<ffffffff8129372f>] mod_verify_sig+0x1ff/0x290
[...]
The exact purpose of the len extension isn't clear to me, but due to
its form, I suspect that it's a leftover somehow accounting for leading
zero bytes within the most significant output limb.
Note however that without that len adjustement, the total number of bytes
ever processed by the inner loop equals nbytes and thus, the last output
limb gets written at this point. Thus the net effect of the len adjustement
cited above is just to keep the inner loop running for some more
iterations, namely < BYTES_PER_MPI_LIMB ones, reading some extra bytes from
beyond the last SGE's buffer and discarding them afterwards.
Fix this issue by purging the extension of len beyond the last input SGE's
buffer length.
Fixes: 2d4d1eea54
("lib/mpi: Add mpi sgl helpers")
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
501 lines
11 KiB
C
501 lines
11 KiB
C
/* mpicoder.c - Coder for the external representation of MPIs
|
|
* Copyright (C) 1998, 1999 Free Software Foundation, Inc.
|
|
*
|
|
* This file is part of GnuPG.
|
|
*
|
|
* GnuPG is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* GnuPG is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
|
|
*/
|
|
|
|
#include <linux/bitops.h>
|
|
#include <linux/count_zeros.h>
|
|
#include <linux/byteorder/generic.h>
|
|
#include <linux/string.h>
|
|
#include "mpi-internal.h"
|
|
|
|
#define MAX_EXTERN_MPI_BITS 16384
|
|
|
|
/**
|
|
* mpi_read_raw_data - Read a raw byte stream as a positive integer
|
|
* @xbuffer: The data to read
|
|
* @nbytes: The amount of data to read
|
|
*/
|
|
MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes)
|
|
{
|
|
const uint8_t *buffer = xbuffer;
|
|
int i, j;
|
|
unsigned nbits, nlimbs;
|
|
mpi_limb_t a;
|
|
MPI val = NULL;
|
|
|
|
while (nbytes > 0 && buffer[0] == 0) {
|
|
buffer++;
|
|
nbytes--;
|
|
}
|
|
|
|
nbits = nbytes * 8;
|
|
if (nbits > MAX_EXTERN_MPI_BITS) {
|
|
pr_info("MPI: mpi too large (%u bits)\n", nbits);
|
|
return NULL;
|
|
}
|
|
if (nbytes > 0)
|
|
nbits -= count_leading_zeros(buffer[0]);
|
|
else
|
|
nbits = 0;
|
|
|
|
nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
|
|
val = mpi_alloc(nlimbs);
|
|
if (!val)
|
|
return NULL;
|
|
val->nbits = nbits;
|
|
val->sign = 0;
|
|
val->nlimbs = nlimbs;
|
|
|
|
if (nbytes > 0) {
|
|
i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
|
|
i %= BYTES_PER_MPI_LIMB;
|
|
for (j = nlimbs; j > 0; j--) {
|
|
a = 0;
|
|
for (; i < BYTES_PER_MPI_LIMB; i++) {
|
|
a <<= 8;
|
|
a |= *buffer++;
|
|
}
|
|
i = 0;
|
|
val->d[j - 1] = a;
|
|
}
|
|
}
|
|
return val;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_read_raw_data);
|
|
|
|
MPI mpi_read_from_buffer(const void *xbuffer, unsigned *ret_nread)
|
|
{
|
|
const uint8_t *buffer = xbuffer;
|
|
int i, j;
|
|
unsigned nbits, nbytes, nlimbs, nread = 0;
|
|
mpi_limb_t a;
|
|
MPI val = NULL;
|
|
|
|
if (*ret_nread < 2)
|
|
goto leave;
|
|
nbits = buffer[0] << 8 | buffer[1];
|
|
|
|
if (nbits > MAX_EXTERN_MPI_BITS) {
|
|
pr_info("MPI: mpi too large (%u bits)\n", nbits);
|
|
goto leave;
|
|
}
|
|
buffer += 2;
|
|
nread = 2;
|
|
|
|
nbytes = DIV_ROUND_UP(nbits, 8);
|
|
nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
|
|
val = mpi_alloc(nlimbs);
|
|
if (!val)
|
|
return NULL;
|
|
i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
|
|
i %= BYTES_PER_MPI_LIMB;
|
|
val->nbits = nbits;
|
|
j = val->nlimbs = nlimbs;
|
|
val->sign = 0;
|
|
for (; j > 0; j--) {
|
|
a = 0;
|
|
for (; i < BYTES_PER_MPI_LIMB; i++) {
|
|
if (++nread > *ret_nread) {
|
|
printk
|
|
("MPI: mpi larger than buffer nread=%d ret_nread=%d\n",
|
|
nread, *ret_nread);
|
|
goto leave;
|
|
}
|
|
a <<= 8;
|
|
a |= *buffer++;
|
|
}
|
|
i = 0;
|
|
val->d[j - 1] = a;
|
|
}
|
|
|
|
leave:
|
|
*ret_nread = nread;
|
|
return val;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_read_from_buffer);
|
|
|
|
static int count_lzeros(MPI a)
|
|
{
|
|
mpi_limb_t alimb;
|
|
int i, lzeros = 0;
|
|
|
|
for (i = a->nlimbs - 1; i >= 0; i--) {
|
|
alimb = a->d[i];
|
|
if (alimb == 0) {
|
|
lzeros += sizeof(mpi_limb_t);
|
|
} else {
|
|
lzeros += count_leading_zeros(alimb) / 8;
|
|
break;
|
|
}
|
|
}
|
|
return lzeros;
|
|
}
|
|
|
|
/**
|
|
* mpi_read_buffer() - read MPI to a bufer provided by user (msb first)
|
|
*
|
|
* @a: a multi precision integer
|
|
* @buf: bufer to which the output will be written to. Needs to be at
|
|
* leaset mpi_get_size(a) long.
|
|
* @buf_len: size of the buf.
|
|
* @nbytes: receives the actual length of the data written on success and
|
|
* the data to-be-written on -EOVERFLOW in case buf_len was too
|
|
* small.
|
|
* @sign: if not NULL, it will be set to the sign of a.
|
|
*
|
|
* Return: 0 on success or error code in case of error
|
|
*/
|
|
int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
|
|
int *sign)
|
|
{
|
|
uint8_t *p;
|
|
#if BYTES_PER_MPI_LIMB == 4
|
|
__be32 alimb;
|
|
#elif BYTES_PER_MPI_LIMB == 8
|
|
__be64 alimb;
|
|
#else
|
|
#error please implement for this limb size.
|
|
#endif
|
|
unsigned int n = mpi_get_size(a);
|
|
int i, lzeros;
|
|
|
|
if (!buf || !nbytes)
|
|
return -EINVAL;
|
|
|
|
if (sign)
|
|
*sign = a->sign;
|
|
|
|
lzeros = count_lzeros(a);
|
|
|
|
if (buf_len < n - lzeros) {
|
|
*nbytes = n - lzeros;
|
|
return -EOVERFLOW;
|
|
}
|
|
|
|
p = buf;
|
|
*nbytes = n - lzeros;
|
|
|
|
for (i = a->nlimbs - 1 - lzeros / BYTES_PER_MPI_LIMB,
|
|
lzeros %= BYTES_PER_MPI_LIMB;
|
|
i >= 0; i--) {
|
|
#if BYTES_PER_MPI_LIMB == 4
|
|
alimb = cpu_to_be32(a->d[i]);
|
|
#elif BYTES_PER_MPI_LIMB == 8
|
|
alimb = cpu_to_be64(a->d[i]);
|
|
#else
|
|
#error please implement for this limb size.
|
|
#endif
|
|
memcpy(p, (u8 *)&alimb + lzeros, BYTES_PER_MPI_LIMB - lzeros);
|
|
p += BYTES_PER_MPI_LIMB - lzeros;
|
|
lzeros = 0;
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_read_buffer);
|
|
|
|
/*
|
|
* mpi_get_buffer() - Returns an allocated buffer with the MPI (msb first).
|
|
* Caller must free the return string.
|
|
* This function does return a 0 byte buffer with nbytes set to zero if the
|
|
* value of A is zero.
|
|
*
|
|
* @a: a multi precision integer.
|
|
* @nbytes: receives the length of this buffer.
|
|
* @sign: if not NULL, it will be set to the sign of the a.
|
|
*
|
|
* Return: Pointer to MPI buffer or NULL on error
|
|
*/
|
|
void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign)
|
|
{
|
|
uint8_t *buf;
|
|
unsigned int n;
|
|
int ret;
|
|
|
|
if (!nbytes)
|
|
return NULL;
|
|
|
|
n = mpi_get_size(a);
|
|
|
|
if (!n)
|
|
n++;
|
|
|
|
buf = kmalloc(n, GFP_KERNEL);
|
|
|
|
if (!buf)
|
|
return NULL;
|
|
|
|
ret = mpi_read_buffer(a, buf, n, nbytes, sign);
|
|
|
|
if (ret) {
|
|
kfree(buf);
|
|
return NULL;
|
|
}
|
|
return buf;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_get_buffer);
|
|
|
|
/****************
|
|
* Use BUFFER to update MPI.
|
|
*/
|
|
int mpi_set_buffer(MPI a, const void *xbuffer, unsigned nbytes, int sign)
|
|
{
|
|
const uint8_t *buffer = xbuffer, *p;
|
|
mpi_limb_t alimb;
|
|
int nlimbs;
|
|
int i;
|
|
|
|
nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
|
|
if (RESIZE_IF_NEEDED(a, nlimbs) < 0)
|
|
return -ENOMEM;
|
|
a->sign = sign;
|
|
|
|
for (i = 0, p = buffer + nbytes - 1; p >= buffer + BYTES_PER_MPI_LIMB;) {
|
|
#if BYTES_PER_MPI_LIMB == 4
|
|
alimb = (mpi_limb_t) *p--;
|
|
alimb |= (mpi_limb_t) *p-- << 8;
|
|
alimb |= (mpi_limb_t) *p-- << 16;
|
|
alimb |= (mpi_limb_t) *p-- << 24;
|
|
#elif BYTES_PER_MPI_LIMB == 8
|
|
alimb = (mpi_limb_t) *p--;
|
|
alimb |= (mpi_limb_t) *p-- << 8;
|
|
alimb |= (mpi_limb_t) *p-- << 16;
|
|
alimb |= (mpi_limb_t) *p-- << 24;
|
|
alimb |= (mpi_limb_t) *p-- << 32;
|
|
alimb |= (mpi_limb_t) *p-- << 40;
|
|
alimb |= (mpi_limb_t) *p-- << 48;
|
|
alimb |= (mpi_limb_t) *p-- << 56;
|
|
#else
|
|
#error please implement for this limb size.
|
|
#endif
|
|
a->d[i++] = alimb;
|
|
}
|
|
if (p >= buffer) {
|
|
#if BYTES_PER_MPI_LIMB == 4
|
|
alimb = *p--;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 8;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 16;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 24;
|
|
#elif BYTES_PER_MPI_LIMB == 8
|
|
alimb = (mpi_limb_t) *p--;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 8;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 16;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 24;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 32;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 40;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 48;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 56;
|
|
#else
|
|
#error please implement for this limb size.
|
|
#endif
|
|
a->d[i++] = alimb;
|
|
}
|
|
a->nlimbs = i;
|
|
|
|
if (i != nlimbs) {
|
|
pr_emerg("MPI: mpi_set_buffer: Assertion failed (%d != %d)", i,
|
|
nlimbs);
|
|
BUG();
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_set_buffer);
|
|
|
|
/**
|
|
* mpi_write_to_sgl() - Funnction exports MPI to an sgl (msb first)
|
|
*
|
|
* This function works in the same way as the mpi_read_buffer, but it
|
|
* takes an sgl instead of u8 * buf.
|
|
*
|
|
* @a: a multi precision integer
|
|
* @sgl: scatterlist to write to. Needs to be at least
|
|
* mpi_get_size(a) long.
|
|
* @nbytes: in/out param - it has the be set to the maximum number of
|
|
* bytes that can be written to sgl. This has to be at least
|
|
* the size of the integer a. On return it receives the actual
|
|
* length of the data written on success or the data that would
|
|
* be written if buffer was too small.
|
|
* @sign: if not NULL, it will be set to the sign of a.
|
|
*
|
|
* Return: 0 on success or error code in case of error
|
|
*/
|
|
int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes,
|
|
int *sign)
|
|
{
|
|
u8 *p, *p2;
|
|
#if BYTES_PER_MPI_LIMB == 4
|
|
__be32 alimb;
|
|
#elif BYTES_PER_MPI_LIMB == 8
|
|
__be64 alimb;
|
|
#else
|
|
#error please implement for this limb size.
|
|
#endif
|
|
unsigned int n = mpi_get_size(a);
|
|
int i, x, y = 0, lzeros, buf_len;
|
|
|
|
if (!nbytes)
|
|
return -EINVAL;
|
|
|
|
if (sign)
|
|
*sign = a->sign;
|
|
|
|
lzeros = count_lzeros(a);
|
|
|
|
if (*nbytes < n - lzeros) {
|
|
*nbytes = n - lzeros;
|
|
return -EOVERFLOW;
|
|
}
|
|
|
|
*nbytes = n - lzeros;
|
|
buf_len = sgl->length;
|
|
p2 = sg_virt(sgl);
|
|
|
|
for (i = a->nlimbs - 1 - lzeros / BYTES_PER_MPI_LIMB,
|
|
lzeros %= BYTES_PER_MPI_LIMB;
|
|
i >= 0; i--) {
|
|
#if BYTES_PER_MPI_LIMB == 4
|
|
alimb = cpu_to_be32(a->d[i]);
|
|
#elif BYTES_PER_MPI_LIMB == 8
|
|
alimb = cpu_to_be64(a->d[i]);
|
|
#else
|
|
#error please implement for this limb size.
|
|
#endif
|
|
if (lzeros) {
|
|
y = lzeros;
|
|
lzeros = 0;
|
|
}
|
|
|
|
p = (u8 *)&alimb + y;
|
|
|
|
for (x = 0; x < sizeof(alimb) - y; x++) {
|
|
if (!buf_len) {
|
|
sgl = sg_next(sgl);
|
|
if (!sgl)
|
|
return -EINVAL;
|
|
buf_len = sgl->length;
|
|
p2 = sg_virt(sgl);
|
|
}
|
|
*p2++ = *p++;
|
|
buf_len--;
|
|
}
|
|
y = 0;
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_write_to_sgl);
|
|
|
|
/*
|
|
* mpi_read_raw_from_sgl() - Function allocates an MPI and populates it with
|
|
* data from the sgl
|
|
*
|
|
* This function works in the same way as the mpi_read_raw_data, but it
|
|
* takes an sgl instead of void * buffer. i.e. it allocates
|
|
* a new MPI and reads the content of the sgl to the MPI.
|
|
*
|
|
* @sgl: scatterlist to read from
|
|
* @nbytes: number of bytes to read
|
|
*
|
|
* Return: Pointer to a new MPI or NULL on error
|
|
*/
|
|
MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int nbytes)
|
|
{
|
|
struct scatterlist *sg;
|
|
int x, i, j, z, lzeros, ents;
|
|
unsigned int nbits, nlimbs;
|
|
mpi_limb_t a;
|
|
MPI val = NULL;
|
|
|
|
lzeros = 0;
|
|
ents = sg_nents(sgl);
|
|
|
|
for_each_sg(sgl, sg, ents, i) {
|
|
const u8 *buff = sg_virt(sg);
|
|
int len = sg->length;
|
|
|
|
while (len && !*buff) {
|
|
lzeros++;
|
|
len--;
|
|
buff++;
|
|
}
|
|
|
|
if (len && *buff)
|
|
break;
|
|
|
|
ents--;
|
|
nbytes -= lzeros;
|
|
lzeros = 0;
|
|
}
|
|
|
|
sgl = sg;
|
|
nbytes -= lzeros;
|
|
nbits = nbytes * 8;
|
|
if (nbits > MAX_EXTERN_MPI_BITS) {
|
|
pr_info("MPI: mpi too large (%u bits)\n", nbits);
|
|
return NULL;
|
|
}
|
|
|
|
if (nbytes > 0)
|
|
nbits -= count_leading_zeros(*(u8 *)(sg_virt(sgl) + lzeros)) -
|
|
(BITS_PER_LONG - 8);
|
|
|
|
nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
|
|
val = mpi_alloc(nlimbs);
|
|
if (!val)
|
|
return NULL;
|
|
|
|
val->nbits = nbits;
|
|
val->sign = 0;
|
|
val->nlimbs = nlimbs;
|
|
|
|
if (nbytes == 0)
|
|
return val;
|
|
|
|
j = nlimbs - 1;
|
|
a = 0;
|
|
z = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
|
|
z %= BYTES_PER_MPI_LIMB;
|
|
|
|
for_each_sg(sgl, sg, ents, i) {
|
|
const u8 *buffer = sg_virt(sg) + lzeros;
|
|
int len = sg->length - lzeros;
|
|
|
|
for (x = 0; x < len; x++) {
|
|
a <<= 8;
|
|
a |= *buffer++;
|
|
if (((z + x + 1) % BYTES_PER_MPI_LIMB) == 0) {
|
|
val->d[j--] = a;
|
|
a = 0;
|
|
}
|
|
}
|
|
z += x;
|
|
lzeros = 0;
|
|
}
|
|
return val;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_read_raw_from_sgl);
|