Revision 472e5b056f000a778abb41f1e443de58eb259783 authored by Linus Torvalds on 02 October 2020, 02:14:36 UTC, committed by Linus Torvalds on 02 October 2020, 02:14:36 UTC
The pipe splice code still used the old model of waiting for pipe IO by using a non-specific "pipe_wait()" that waited for any pipe event to happen, which depended on all pipe IO being entirely serialized by the pipe lock. So by checking the state you were waiting for, and then adding yourself to the wait queue before dropping the lock, you were guaranteed to see all the wakeups. Strictly speaking, the actual wakeups were not done under the lock, but the pipe_wait() model still worked, because since the waiter held the lock when checking whether it should sleep, it would always see the current state, and the wakeup was always done after updating the state. However, commit 0ddad21d3e99 ("pipe: use exclusive waits when reading or writing") split the single wait-queue into two, and in the process also made the "wait for event" code wait for _two_ wait queues, and that then showed a race with the wakers that were not serialized by the pipe lock. It's only splice that used that "pipe_wait()" model, so the problem wasn't obvious, but Josef Bacik reports: "I hit a hang with fstest btrfs/187, which does a btrfs send into /dev/null. This works by creating a pipe, the write side is given to the kernel to write into, and the read side is handed to a thread that splices into a file, in this case /dev/null. The box that was hung had the write side stuck here [pipe_write] and the read side stuck here [splice_from_pipe_next -> pipe_wait]. [ more details about pipe_wait() scenario ] The problem is we're doing the prepare_to_wait, which sets our state each time, however we can be woken up either with reads or writes. In the case above we race with the WRITER waking us up, and re-set our state to INTERRUPTIBLE, and thus never break out of schedule" Josef had a patch that avoided the issue in pipe_wait() by just making it set the state only once, but the deeper problem is that pipe_wait() depends on a level of synchonization by the pipe mutex that it really shouldn't. And the whole "wait for any pipe state change" model really isn't very good to begin with. So rather than trying to work around things in pipe_wait(), remove that legacy model of "wait for arbitrary pipe event" entirely, and actually create functions that wait for the pipe actually being readable or writable, and can do so without depending on the pipe lock serializing everything. Fixes: 0ddad21d3e99 ("pipe: use exclusive waits when reading or writing") Link: https://lore.kernel.org/linux-fsdevel/bfa88b5ad6f069b2b679316b9e495a970130416c.1601567868.git.josef@toxicpanda.com/ Reported-by: Josef Bacik <josef@toxicpanda.com> Reviewed-and-tested-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 44b6e23
ecc.c
/*
* Copyright (c) 2013, 2014 Kenneth MacKay. All rights reserved.
* Copyright (c) 2019 Vitaly Chikunov <vt@altlinux.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <linux/module.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/swab.h>
#include <linux/fips.h>
#include <crypto/ecdh.h>
#include <crypto/rng.h>
#include <asm/unaligned.h>
#include <linux/ratelimit.h>
#include "ecc.h"
#include "ecc_curve_defs.h"
typedef struct {
u64 m_low;
u64 m_high;
} uint128_t;
static inline const struct ecc_curve *ecc_get_curve(unsigned int curve_id)
{
switch (curve_id) {
/* In FIPS mode only allow P256 and higher */
case ECC_CURVE_NIST_P192:
return fips_enabled ? NULL : &nist_p192;
case ECC_CURVE_NIST_P256:
return &nist_p256;
default:
return NULL;
}
}
static u64 *ecc_alloc_digits_space(unsigned int ndigits)
{
size_t len = ndigits * sizeof(u64);
if (!len)
return NULL;
return kmalloc(len, GFP_KERNEL);
}
static void ecc_free_digits_space(u64 *space)
{
kfree_sensitive(space);
}
static struct ecc_point *ecc_alloc_point(unsigned int ndigits)
{
struct ecc_point *p = kmalloc(sizeof(*p), GFP_KERNEL);
if (!p)
return NULL;
p->x = ecc_alloc_digits_space(ndigits);
if (!p->x)
goto err_alloc_x;
p->y = ecc_alloc_digits_space(ndigits);
if (!p->y)
goto err_alloc_y;
p->ndigits = ndigits;
return p;
err_alloc_y:
ecc_free_digits_space(p->x);
err_alloc_x:
kfree(p);
return NULL;
}
static void ecc_free_point(struct ecc_point *p)
{
if (!p)
return;
kfree_sensitive(p->x);
kfree_sensitive(p->y);
kfree_sensitive(p);
}
static void vli_clear(u64 *vli, unsigned int ndigits)
{
int i;
for (i = 0; i < ndigits; i++)
vli[i] = 0;
}
/* Returns true if vli == 0, false otherwise. */
bool vli_is_zero(const u64 *vli, unsigned int ndigits)
{
int i;
for (i = 0; i < ndigits; i++) {
if (vli[i])
return false;
}
return true;
}
EXPORT_SYMBOL(vli_is_zero);
/* Returns nonzero if bit bit of vli is set. */
static u64 vli_test_bit(const u64 *vli, unsigned int bit)
{
return (vli[bit / 64] & ((u64)1 << (bit % 64)));
}
static bool vli_is_negative(const u64 *vli, unsigned int ndigits)
{
return vli_test_bit(vli, ndigits * 64 - 1);
}
/* Counts the number of 64-bit "digits" in vli. */
static unsigned int vli_num_digits(const u64 *vli, unsigned int ndigits)
{
int i;
/* Search from the end until we find a non-zero digit.
* We do it in reverse because we expect that most digits will
* be nonzero.
*/
for (i = ndigits - 1; i >= 0 && vli[i] == 0; i--);
return (i + 1);
}
/* Counts the number of bits required for vli. */
static unsigned int vli_num_bits(const u64 *vli, unsigned int ndigits)
{
unsigned int i, num_digits;
u64 digit;
num_digits = vli_num_digits(vli, ndigits);
if (num_digits == 0)
return 0;
digit = vli[num_digits - 1];
for (i = 0; digit; i++)
digit >>= 1;
return ((num_digits - 1) * 64 + i);
}
/* Set dest from unaligned bit string src. */
void vli_from_be64(u64 *dest, const void *src, unsigned int ndigits)
{
int i;
const u64 *from = src;
for (i = 0; i < ndigits; i++)
dest[i] = get_unaligned_be64(&from[ndigits - 1 - i]);
}
EXPORT_SYMBOL(vli_from_be64);
void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits)
{
int i;
const u64 *from = src;
for (i = 0; i < ndigits; i++)
dest[i] = get_unaligned_le64(&from[i]);
}
EXPORT_SYMBOL(vli_from_le64);
/* Sets dest = src. */
static void vli_set(u64 *dest, const u64 *src, unsigned int ndigits)
{
int i;
for (i = 0; i < ndigits; i++)
dest[i] = src[i];
}
/* Returns sign of left - right. */
int vli_cmp(const u64 *left, const u64 *right, unsigned int ndigits)
{
int i;
for (i = ndigits - 1; i >= 0; i--) {
if (left[i] > right[i])
return 1;
else if (left[i] < right[i])
return -1;
}
return 0;
}
EXPORT_SYMBOL(vli_cmp);
/* Computes result = in << c, returning carry. Can modify in place
* (if result == in). 0 < shift < 64.
*/
static u64 vli_lshift(u64 *result, const u64 *in, unsigned int shift,
unsigned int ndigits)
{
u64 carry = 0;
int i;
for (i = 0; i < ndigits; i++) {
u64 temp = in[i];
result[i] = (temp << shift) | carry;
carry = temp >> (64 - shift);
}
return carry;
}
/* Computes vli = vli >> 1. */
static void vli_rshift1(u64 *vli, unsigned int ndigits)
{
u64 *end = vli;
u64 carry = 0;
vli += ndigits;
while (vli-- > end) {
u64 temp = *vli;
*vli = (temp >> 1) | carry;
carry = temp << 63;
}
}
/* Computes result = left + right, returning carry. Can modify in place. */
static u64 vli_add(u64 *result, const u64 *left, const u64 *right,
unsigned int ndigits)
{
u64 carry = 0;
int i;
for (i = 0; i < ndigits; i++) {
u64 sum;
sum = left[i] + right[i] + carry;
if (sum != left[i])
carry = (sum < left[i]);
result[i] = sum;
}
return carry;
}
/* Computes result = left + right, returning carry. Can modify in place. */
static u64 vli_uadd(u64 *result, const u64 *left, u64 right,
unsigned int ndigits)
{
u64 carry = right;
int i;
for (i = 0; i < ndigits; i++) {
u64 sum;
sum = left[i] + carry;
if (sum != left[i])
carry = (sum < left[i]);
else
carry = !!carry;
result[i] = sum;
}
return carry;
}
/* Computes result = left - right, returning borrow. Can modify in place. */
u64 vli_sub(u64 *result, const u64 *left, const u64 *right,
unsigned int ndigits)
{
u64 borrow = 0;
int i;
for (i = 0; i < ndigits; i++) {
u64 diff;
diff = left[i] - right[i] - borrow;
if (diff != left[i])
borrow = (diff > left[i]);
result[i] = diff;
}
return borrow;
}
EXPORT_SYMBOL(vli_sub);
/* Computes result = left - right, returning borrow. Can modify in place. */
static u64 vli_usub(u64 *result, const u64 *left, u64 right,
unsigned int ndigits)
{
u64 borrow = right;
int i;
for (i = 0; i < ndigits; i++) {
u64 diff;
diff = left[i] - borrow;
if (diff != left[i])
borrow = (diff > left[i]);
result[i] = diff;
}
return borrow;
}
static uint128_t mul_64_64(u64 left, u64 right)
{
uint128_t result;
#if defined(CONFIG_ARCH_SUPPORTS_INT128)
unsigned __int128 m = (unsigned __int128)left * right;
result.m_low = m;
result.m_high = m >> 64;
#else
u64 a0 = left & 0xffffffffull;
u64 a1 = left >> 32;
u64 b0 = right & 0xffffffffull;
u64 b1 = right >> 32;
u64 m0 = a0 * b0;
u64 m1 = a0 * b1;
u64 m2 = a1 * b0;
u64 m3 = a1 * b1;
m2 += (m0 >> 32);
m2 += m1;
/* Overflow */
if (m2 < m1)
m3 += 0x100000000ull;
result.m_low = (m0 & 0xffffffffull) | (m2 << 32);
result.m_high = m3 + (m2 >> 32);
#endif
return result;
}
static uint128_t add_128_128(uint128_t a, uint128_t b)
{
uint128_t result;
result.m_low = a.m_low + b.m_low;
result.m_high = a.m_high + b.m_high + (result.m_low < a.m_low);
return result;
}
static void vli_mult(u64 *result, const u64 *left, const u64 *right,
unsigned int ndigits)
{
uint128_t r01 = { 0, 0 };
u64 r2 = 0;
unsigned int i, k;
/* Compute each digit of result in sequence, maintaining the
* carries.
*/
for (k = 0; k < ndigits * 2 - 1; k++) {
unsigned int min;
if (k < ndigits)
min = 0;
else
min = (k + 1) - ndigits;
for (i = min; i <= k && i < ndigits; i++) {
uint128_t product;
product = mul_64_64(left[i], right[k - i]);
r01 = add_128_128(r01, product);
r2 += (r01.m_high < product.m_high);
}
result[k] = r01.m_low;
r01.m_low = r01.m_high;
r01.m_high = r2;
r2 = 0;
}
result[ndigits * 2 - 1] = r01.m_low;
}
/* Compute product = left * right, for a small right value. */
static void vli_umult(u64 *result, const u64 *left, u32 right,
unsigned int ndigits)
{
uint128_t r01 = { 0 };
unsigned int k;
for (k = 0; k < ndigits; k++) {
uint128_t product;
product = mul_64_64(left[k], right);
r01 = add_128_128(r01, product);
/* no carry */
result[k] = r01.m_low;
r01.m_low = r01.m_high;
r01.m_high = 0;
}
result[k] = r01.m_low;
for (++k; k < ndigits * 2; k++)
result[k] = 0;
}
static void vli_square(u64 *result, const u64 *left, unsigned int ndigits)
{
uint128_t r01 = { 0, 0 };
u64 r2 = 0;
int i, k;
for (k = 0; k < ndigits * 2 - 1; k++) {
unsigned int min;
if (k < ndigits)
min = 0;
else
min = (k + 1) - ndigits;
for (i = min; i <= k && i <= k - i; i++) {
uint128_t product;
product = mul_64_64(left[i], left[k - i]);
if (i < k - i) {
r2 += product.m_high >> 63;
product.m_high = (product.m_high << 1) |
(product.m_low >> 63);
product.m_low <<= 1;
}
r01 = add_128_128(r01, product);
r2 += (r01.m_high < product.m_high);
}
result[k] = r01.m_low;
r01.m_low = r01.m_high;
r01.m_high = r2;
r2 = 0;
}
result[ndigits * 2 - 1] = r01.m_low;
}
/* Computes result = (left + right) % mod.
* Assumes that left < mod and right < mod, result != mod.
*/
static void vli_mod_add(u64 *result, const u64 *left, const u64 *right,
const u64 *mod, unsigned int ndigits)
{
u64 carry;
carry = vli_add(result, left, right, ndigits);
/* result > mod (result = mod + remainder), so subtract mod to
* get remainder.
*/
if (carry || vli_cmp(result, mod, ndigits) >= 0)
vli_sub(result, result, mod, ndigits);
}
/* Computes result = (left - right) % mod.
* Assumes that left < mod and right < mod, result != mod.
*/
static void vli_mod_sub(u64 *result, const u64 *left, const u64 *right,
const u64 *mod, unsigned int ndigits)
{
u64 borrow = vli_sub(result, left, right, ndigits);
/* In this case, p_result == -diff == (max int) - diff.
* Since -x % d == d - x, we can get the correct result from
* result + mod (with overflow).
*/
if (borrow)
vli_add(result, result, mod, ndigits);
}
/*
* Computes result = product % mod
* for special form moduli: p = 2^k-c, for small c (note the minus sign)
*
* References:
* R. Crandall, C. Pomerance. Prime Numbers: A Computational Perspective.
* 9 Fast Algorithms for Large-Integer Arithmetic. 9.2.3 Moduli of special form
* Algorithm 9.2.13 (Fast mod operation for special-form moduli).
*/
static void vli_mmod_special(u64 *result, const u64 *product,
const u64 *mod, unsigned int ndigits)
{
u64 c = -mod[0];
u64 t[ECC_MAX_DIGITS * 2];
u64 r[ECC_MAX_DIGITS * 2];
vli_set(r, product, ndigits * 2);
while (!vli_is_zero(r + ndigits, ndigits)) {
vli_umult(t, r + ndigits, c, ndigits);
vli_clear(r + ndigits, ndigits);
vli_add(r, r, t, ndigits * 2);
}
vli_set(t, mod, ndigits);
vli_clear(t + ndigits, ndigits);
while (vli_cmp(r, t, ndigits * 2) >= 0)
vli_sub(r, r, t, ndigits * 2);
vli_set(result, r, ndigits);
}
/*
* Computes result = product % mod
* for special form moduli: p = 2^{k-1}+c, for small c (note the plus sign)
* where k-1 does not fit into qword boundary by -1 bit (such as 255).
* References (loosely based on):
* A. Menezes, P. van Oorschot, S. Vanstone. Handbook of Applied Cryptography.
* 14.3.4 Reduction methods for moduli of special form. Algorithm 14.47.
* URL: http://cacr.uwaterloo.ca/hac/about/chap14.pdf
*
* H. Cohen, G. Frey, R. Avanzi, C. Doche, T. Lange, K. Nguyen, F. Vercauteren.
* Handbook of Elliptic and Hyperelliptic Curve Cryptography.
* Algorithm 10.25 Fast reduction for special form moduli
*/
static void vli_mmod_special2(u64 *result, const u64 *product,
const u64 *mod, unsigned int ndigits)
{
u64 c2 = mod[0] * 2;
u64 q[ECC_MAX_DIGITS];
u64 r[ECC_MAX_DIGITS * 2];
u64 m[ECC_MAX_DIGITS * 2]; /* expanded mod */
int carry; /* last bit that doesn't fit into q */
int i;
vli_set(m, mod, ndigits);
vli_clear(m + ndigits, ndigits);
vli_set(r, product, ndigits);
/* q and carry are top bits */
vli_set(q, product + ndigits, ndigits);
vli_clear(r + ndigits, ndigits);
carry = vli_is_negative(r, ndigits);
if (carry)
r[ndigits - 1] &= (1ull << 63) - 1;
for (i = 1; carry || !vli_is_zero(q, ndigits); i++) {
u64 qc[ECC_MAX_DIGITS * 2];
vli_umult(qc, q, c2, ndigits);
if (carry)
vli_uadd(qc, qc, mod[0], ndigits * 2);
vli_set(q, qc + ndigits, ndigits);
vli_clear(qc + ndigits, ndigits);
carry = vli_is_negative(qc, ndigits);
if (carry)
qc[ndigits - 1] &= (1ull << 63) - 1;
if (i & 1)
vli_sub(r, r, qc, ndigits * 2);
else
vli_add(r, r, qc, ndigits * 2);
}
while (vli_is_negative(r, ndigits * 2))
vli_add(r, r, m, ndigits * 2);
while (vli_cmp(r, m, ndigits * 2) >= 0)
vli_sub(r, r, m, ndigits * 2);
vli_set(result, r, ndigits);
}
/*
* Computes result = product % mod, where product is 2N words long.
* Reference: Ken MacKay's micro-ecc.
* Currently only designed to work for curve_p or curve_n.
*/
static void vli_mmod_slow(u64 *result, u64 *product, const u64 *mod,
unsigned int ndigits)
{
u64 mod_m[2 * ECC_MAX_DIGITS];
u64 tmp[2 * ECC_MAX_DIGITS];
u64 *v[2] = { tmp, product };
u64 carry = 0;
unsigned int i;
/* Shift mod so its highest set bit is at the maximum position. */
int shift = (ndigits * 2 * 64) - vli_num_bits(mod, ndigits);
int word_shift = shift / 64;
int bit_shift = shift % 64;
vli_clear(mod_m, word_shift);
if (bit_shift > 0) {
for (i = 0; i < ndigits; ++i) {
mod_m[word_shift + i] = (mod[i] << bit_shift) | carry;
carry = mod[i] >> (64 - bit_shift);
}
} else
vli_set(mod_m + word_shift, mod, ndigits);
for (i = 1; shift >= 0; --shift) {
u64 borrow = 0;
unsigned int j;
for (j = 0; j < ndigits * 2; ++j) {
u64 diff = v[i][j] - mod_m[j] - borrow;
if (diff != v[i][j])
borrow = (diff > v[i][j]);
v[1 - i][j] = diff;
}
i = !(i ^ borrow); /* Swap the index if there was no borrow */
vli_rshift1(mod_m, ndigits);
mod_m[ndigits - 1] |= mod_m[ndigits] << (64 - 1);
vli_rshift1(mod_m + ndigits, ndigits);
}
vli_set(result, v[i], ndigits);
}
/* Computes result = product % mod using Barrett's reduction with precomputed
* value mu appended to the mod after ndigits, mu = (2^{2w} / mod) and have
* length ndigits + 1, where mu * (2^w - 1) should not overflow ndigits
* boundary.
*
* Reference:
* R. Brent, P. Zimmermann. Modern Computer Arithmetic. 2010.
* 2.4.1 Barrett's algorithm. Algorithm 2.5.
*/
static void vli_mmod_barrett(u64 *result, u64 *product, const u64 *mod,
unsigned int ndigits)
{
u64 q[ECC_MAX_DIGITS * 2];
u64 r[ECC_MAX_DIGITS * 2];
const u64 *mu = mod + ndigits;
vli_mult(q, product + ndigits, mu, ndigits);
if (mu[ndigits])
vli_add(q + ndigits, q + ndigits, product + ndigits, ndigits);
vli_mult(r, mod, q + ndigits, ndigits);
vli_sub(r, product, r, ndigits * 2);
while (!vli_is_zero(r + ndigits, ndigits) ||
vli_cmp(r, mod, ndigits) != -1) {
u64 carry;
carry = vli_sub(r, r, mod, ndigits);
vli_usub(r + ndigits, r + ndigits, carry, ndigits);
}
vli_set(result, r, ndigits);
}
/* Computes p_result = p_product % curve_p.
* See algorithm 5 and 6 from
* http://www.isys.uni-klu.ac.at/PDF/2001-0126-MT.pdf
*/
static void vli_mmod_fast_192(u64 *result, const u64 *product,
const u64 *curve_prime, u64 *tmp)
{
const unsigned int ndigits = 3;
int carry;
vli_set(result, product, ndigits);
vli_set(tmp, &product[3], ndigits);
carry = vli_add(result, result, tmp, ndigits);
tmp[0] = 0;
tmp[1] = product[3];
tmp[2] = product[4];
carry += vli_add(result, result, tmp, ndigits);
tmp[0] = tmp[1] = product[5];
tmp[2] = 0;
carry += vli_add(result, result, tmp, ndigits);
while (carry || vli_cmp(curve_prime, result, ndigits) != 1)
carry -= vli_sub(result, result, curve_prime, ndigits);
}
/* Computes result = product % curve_prime
* from http://www.nsa.gov/ia/_files/nist-routines.pdf
*/
static void vli_mmod_fast_256(u64 *result, const u64 *product,
const u64 *curve_prime, u64 *tmp)
{
int carry;
const unsigned int ndigits = 4;
/* t */
vli_set(result, product, ndigits);
/* s1 */
tmp[0] = 0;
tmp[1] = product[5] & 0xffffffff00000000ull;
tmp[2] = product[6];
tmp[3] = product[7];
carry = vli_lshift(tmp, tmp, 1, ndigits);
carry += vli_add(result, result, tmp, ndigits);
/* s2 */
tmp[1] = product[6] << 32;
tmp[2] = (product[6] >> 32) | (product[7] << 32);
tmp[3] = product[7] >> 32;
carry += vli_lshift(tmp, tmp, 1, ndigits);
carry += vli_add(result, result, tmp, ndigits);
/* s3 */
tmp[0] = product[4];
tmp[1] = product[5] & 0xffffffff;
tmp[2] = 0;
tmp[3] = product[7];
carry += vli_add(result, result, tmp, ndigits);
/* s4 */
tmp[0] = (product[4] >> 32) | (product[5] << 32);
tmp[1] = (product[5] >> 32) | (product[6] & 0xffffffff00000000ull);
tmp[2] = product[7];
tmp[3] = (product[6] >> 32) | (product[4] << 32);
carry += vli_add(result, result, tmp, ndigits);
/* d1 */
tmp[0] = (product[5] >> 32) | (product[6] << 32);
tmp[1] = (product[6] >> 32);
tmp[2] = 0;
tmp[3] = (product[4] & 0xffffffff) | (product[5] << 32);
carry -= vli_sub(result, result, tmp, ndigits);
/* d2 */
tmp[0] = product[6];
tmp[1] = product[7];
tmp[2] = 0;
tmp[3] = (product[4] >> 32) | (product[5] & 0xffffffff00000000ull);
carry -= vli_sub(result, result, tmp, ndigits);
/* d3 */
tmp[0] = (product[6] >> 32) | (product[7] << 32);
tmp[1] = (product[7] >> 32) | (product[4] << 32);
tmp[2] = (product[4] >> 32) | (product[5] << 32);
tmp[3] = (product[6] << 32);
carry -= vli_sub(result, result, tmp, ndigits);
/* d4 */
tmp[0] = product[7];
tmp[1] = product[4] & 0xffffffff00000000ull;
tmp[2] = product[5];
tmp[3] = product[6] & 0xffffffff00000000ull;
carry -= vli_sub(result, result, tmp, ndigits);
if (carry < 0) {
do {
carry += vli_add(result, result, curve_prime, ndigits);
} while (carry < 0);
} else {
while (carry || vli_cmp(curve_prime, result, ndigits) != 1)
carry -= vli_sub(result, result, curve_prime, ndigits);
}
}
/* Computes result = product % curve_prime for different curve_primes.
*
* Note that curve_primes are distinguished just by heuristic check and
* not by complete conformance check.
*/
static bool vli_mmod_fast(u64 *result, u64 *product,
const u64 *curve_prime, unsigned int ndigits)
{
u64 tmp[2 * ECC_MAX_DIGITS];
/* Currently, both NIST primes have -1 in lowest qword. */
if (curve_prime[0] != -1ull) {
/* Try to handle Pseudo-Marsenne primes. */
if (curve_prime[ndigits - 1] == -1ull) {
vli_mmod_special(result, product, curve_prime,
ndigits);
return true;
} else if (curve_prime[ndigits - 1] == 1ull << 63 &&
curve_prime[ndigits - 2] == 0) {
vli_mmod_special2(result, product, curve_prime,
ndigits);
return true;
}
vli_mmod_barrett(result, product, curve_prime, ndigits);
return true;
}
switch (ndigits) {
case 3:
vli_mmod_fast_192(result, product, curve_prime, tmp);
break;
case 4:
vli_mmod_fast_256(result, product, curve_prime, tmp);
break;
default:
pr_err_ratelimited("ecc: unsupported digits size!\n");
return false;
}
return true;
}
/* Computes result = (left * right) % mod.
* Assumes that mod is big enough curve order.
*/
void vli_mod_mult_slow(u64 *result, const u64 *left, const u64 *right,
const u64 *mod, unsigned int ndigits)
{
u64 product[ECC_MAX_DIGITS * 2];
vli_mult(product, left, right, ndigits);
vli_mmod_slow(result, product, mod, ndigits);
}
EXPORT_SYMBOL(vli_mod_mult_slow);
/* Computes result = (left * right) % curve_prime. */
static void vli_mod_mult_fast(u64 *result, const u64 *left, const u64 *right,
const u64 *curve_prime, unsigned int ndigits)
{
u64 product[2 * ECC_MAX_DIGITS];
vli_mult(product, left, right, ndigits);
vli_mmod_fast(result, product, curve_prime, ndigits);
}
/* Computes result = left^2 % curve_prime. */
static void vli_mod_square_fast(u64 *result, const u64 *left,
const u64 *curve_prime, unsigned int ndigits)
{
u64 product[2 * ECC_MAX_DIGITS];
vli_square(product, left, ndigits);
vli_mmod_fast(result, product, curve_prime, ndigits);
}
#define EVEN(vli) (!(vli[0] & 1))
/* Computes result = (1 / p_input) % mod. All VLIs are the same size.
* See "From Euclid's GCD to Montgomery Multiplication to the Great Divide"
* https://labs.oracle.com/techrep/2001/smli_tr-2001-95.pdf
*/
void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod,
unsigned int ndigits)
{
u64 a[ECC_MAX_DIGITS], b[ECC_MAX_DIGITS];
u64 u[ECC_MAX_DIGITS], v[ECC_MAX_DIGITS];
u64 carry;
int cmp_result;
if (vli_is_zero(input, ndigits)) {
vli_clear(result, ndigits);
return;
}
vli_set(a, input, ndigits);
vli_set(b, mod, ndigits);
vli_clear(u, ndigits);
u[0] = 1;
vli_clear(v, ndigits);
while ((cmp_result = vli_cmp(a, b, ndigits)) != 0) {
carry = 0;
if (EVEN(a)) {
vli_rshift1(a, ndigits);
if (!EVEN(u))
carry = vli_add(u, u, mod, ndigits);
vli_rshift1(u, ndigits);
if (carry)
u[ndigits - 1] |= 0x8000000000000000ull;
} else if (EVEN(b)) {
vli_rshift1(b, ndigits);
if (!EVEN(v))
carry = vli_add(v, v, mod, ndigits);
vli_rshift1(v, ndigits);
if (carry)
v[ndigits - 1] |= 0x8000000000000000ull;
} else if (cmp_result > 0) {
vli_sub(a, a, b, ndigits);
vli_rshift1(a, ndigits);
if (vli_cmp(u, v, ndigits) < 0)
vli_add(u, u, mod, ndigits);
vli_sub(u, u, v, ndigits);
if (!EVEN(u))
carry = vli_add(u, u, mod, ndigits);
vli_rshift1(u, ndigits);
if (carry)
u[ndigits - 1] |= 0x8000000000000000ull;
} else {
vli_sub(b, b, a, ndigits);
vli_rshift1(b, ndigits);
if (vli_cmp(v, u, ndigits) < 0)
vli_add(v, v, mod, ndigits);
vli_sub(v, v, u, ndigits);
if (!EVEN(v))
carry = vli_add(v, v, mod, ndigits);
vli_rshift1(v, ndigits);
if (carry)
v[ndigits - 1] |= 0x8000000000000000ull;
}
}
vli_set(result, u, ndigits);
}
EXPORT_SYMBOL(vli_mod_inv);
/* ------ Point operations ------ */
/* Returns true if p_point is the point at infinity, false otherwise. */
static bool ecc_point_is_zero(const struct ecc_point *point)
{
return (vli_is_zero(point->x, point->ndigits) &&
vli_is_zero(point->y, point->ndigits));
}
/* Point multiplication algorithm using Montgomery's ladder with co-Z
* coordinates. From https://eprint.iacr.org/2011/338.pdf
*/
/* Double in place */
static void ecc_point_double_jacobian(u64 *x1, u64 *y1, u64 *z1,
u64 *curve_prime, unsigned int ndigits)
{
/* t1 = x, t2 = y, t3 = z */
u64 t4[ECC_MAX_DIGITS];
u64 t5[ECC_MAX_DIGITS];
if (vli_is_zero(z1, ndigits))
return;
/* t4 = y1^2 */
vli_mod_square_fast(t4, y1, curve_prime, ndigits);
/* t5 = x1*y1^2 = A */
vli_mod_mult_fast(t5, x1, t4, curve_prime, ndigits);
/* t4 = y1^4 */
vli_mod_square_fast(t4, t4, curve_prime, ndigits);
/* t2 = y1*z1 = z3 */
vli_mod_mult_fast(y1, y1, z1, curve_prime, ndigits);
/* t3 = z1^2 */
vli_mod_square_fast(z1, z1, curve_prime, ndigits);
/* t1 = x1 + z1^2 */
vli_mod_add(x1, x1, z1, curve_prime, ndigits);
/* t3 = 2*z1^2 */
vli_mod_add(z1, z1, z1, curve_prime, ndigits);
/* t3 = x1 - z1^2 */
vli_mod_sub(z1, x1, z1, curve_prime, ndigits);
/* t1 = x1^2 - z1^4 */
vli_mod_mult_fast(x1, x1, z1, curve_prime, ndigits);
/* t3 = 2*(x1^2 - z1^4) */
vli_mod_add(z1, x1, x1, curve_prime, ndigits);
/* t1 = 3*(x1^2 - z1^4) */
vli_mod_add(x1, x1, z1, curve_prime, ndigits);
if (vli_test_bit(x1, 0)) {
u64 carry = vli_add(x1, x1, curve_prime, ndigits);
vli_rshift1(x1, ndigits);
x1[ndigits - 1] |= carry << 63;
} else {
vli_rshift1(x1, ndigits);
}
/* t1 = 3/2*(x1^2 - z1^4) = B */
/* t3 = B^2 */
vli_mod_square_fast(z1, x1, curve_prime, ndigits);
/* t3 = B^2 - A */
vli_mod_sub(z1, z1, t5, curve_prime, ndigits);
/* t3 = B^2 - 2A = x3 */
vli_mod_sub(z1, z1, t5, curve_prime, ndigits);
/* t5 = A - x3 */
vli_mod_sub(t5, t5, z1, curve_prime, ndigits);
/* t1 = B * (A - x3) */
vli_mod_mult_fast(x1, x1, t5, curve_prime, ndigits);
/* t4 = B * (A - x3) - y1^4 = y3 */
vli_mod_sub(t4, x1, t4, curve_prime, ndigits);
vli_set(x1, z1, ndigits);
vli_set(z1, y1, ndigits);
vli_set(y1, t4, ndigits);
}
/* Modify (x1, y1) => (x1 * z^2, y1 * z^3) */
static void apply_z(u64 *x1, u64 *y1, u64 *z, u64 *curve_prime,
unsigned int ndigits)
{
u64 t1[ECC_MAX_DIGITS];
vli_mod_square_fast(t1, z, curve_prime, ndigits); /* z^2 */
vli_mod_mult_fast(x1, x1, t1, curve_prime, ndigits); /* x1 * z^2 */
vli_mod_mult_fast(t1, t1, z, curve_prime, ndigits); /* z^3 */
vli_mod_mult_fast(y1, y1, t1, curve_prime, ndigits); /* y1 * z^3 */
}
/* P = (x1, y1) => 2P, (x2, y2) => P' */
static void xycz_initial_double(u64 *x1, u64 *y1, u64 *x2, u64 *y2,
u64 *p_initial_z, u64 *curve_prime,
unsigned int ndigits)
{
u64 z[ECC_MAX_DIGITS];
vli_set(x2, x1, ndigits);
vli_set(y2, y1, ndigits);
vli_clear(z, ndigits);
z[0] = 1;
if (p_initial_z)
vli_set(z, p_initial_z, ndigits);
apply_z(x1, y1, z, curve_prime, ndigits);
ecc_point_double_jacobian(x1, y1, z, curve_prime, ndigits);
apply_z(x2, y2, z, curve_prime, ndigits);
}
/* Input P = (x1, y1, Z), Q = (x2, y2, Z)
* Output P' = (x1', y1', Z3), P + Q = (x3, y3, Z3)
* or P => P', Q => P + Q
*/
static void xycz_add(u64 *x1, u64 *y1, u64 *x2, u64 *y2, u64 *curve_prime,
unsigned int ndigits)
{
/* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */
u64 t5[ECC_MAX_DIGITS];
/* t5 = x2 - x1 */
vli_mod_sub(t5, x2, x1, curve_prime, ndigits);
/* t5 = (x2 - x1)^2 = A */
vli_mod_square_fast(t5, t5, curve_prime, ndigits);
/* t1 = x1*A = B */
vli_mod_mult_fast(x1, x1, t5, curve_prime, ndigits);
/* t3 = x2*A = C */
vli_mod_mult_fast(x2, x2, t5, curve_prime, ndigits);
/* t4 = y2 - y1 */
vli_mod_sub(y2, y2, y1, curve_prime, ndigits);
/* t5 = (y2 - y1)^2 = D */
vli_mod_square_fast(t5, y2, curve_prime, ndigits);
/* t5 = D - B */
vli_mod_sub(t5, t5, x1, curve_prime, ndigits);
/* t5 = D - B - C = x3 */
vli_mod_sub(t5, t5, x2, curve_prime, ndigits);
/* t3 = C - B */
vli_mod_sub(x2, x2, x1, curve_prime, ndigits);
/* t2 = y1*(C - B) */
vli_mod_mult_fast(y1, y1, x2, curve_prime, ndigits);
/* t3 = B - x3 */
vli_mod_sub(x2, x1, t5, curve_prime, ndigits);
/* t4 = (y2 - y1)*(B - x3) */
vli_mod_mult_fast(y2, y2, x2, curve_prime, ndigits);
/* t4 = y3 */
vli_mod_sub(y2, y2, y1, curve_prime, ndigits);
vli_set(x2, t5, ndigits);
}
/* Input P = (x1, y1, Z), Q = (x2, y2, Z)
* Output P + Q = (x3, y3, Z3), P - Q = (x3', y3', Z3)
* or P => P - Q, Q => P + Q
*/
static void xycz_add_c(u64 *x1, u64 *y1, u64 *x2, u64 *y2, u64 *curve_prime,
unsigned int ndigits)
{
/* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */
u64 t5[ECC_MAX_DIGITS];
u64 t6[ECC_MAX_DIGITS];
u64 t7[ECC_MAX_DIGITS];
/* t5 = x2 - x1 */
vli_mod_sub(t5, x2, x1, curve_prime, ndigits);
/* t5 = (x2 - x1)^2 = A */
vli_mod_square_fast(t5, t5, curve_prime, ndigits);
/* t1 = x1*A = B */
vli_mod_mult_fast(x1, x1, t5, curve_prime, ndigits);
/* t3 = x2*A = C */
vli_mod_mult_fast(x2, x2, t5, curve_prime, ndigits);
/* t4 = y2 + y1 */
vli_mod_add(t5, y2, y1, curve_prime, ndigits);
/* t4 = y2 - y1 */
vli_mod_sub(y2, y2, y1, curve_prime, ndigits);
/* t6 = C - B */
vli_mod_sub(t6, x2, x1, curve_prime, ndigits);
/* t2 = y1 * (C - B) */
vli_mod_mult_fast(y1, y1, t6, curve_prime, ndigits);
/* t6 = B + C */
vli_mod_add(t6, x1, x2, curve_prime, ndigits);
/* t3 = (y2 - y1)^2 */
vli_mod_square_fast(x2, y2, curve_prime, ndigits);
/* t3 = x3 */
vli_mod_sub(x2, x2, t6, curve_prime, ndigits);
/* t7 = B - x3 */
vli_mod_sub(t7, x1, x2, curve_prime, ndigits);
/* t4 = (y2 - y1)*(B - x3) */
vli_mod_mult_fast(y2, y2, t7, curve_prime, ndigits);
/* t4 = y3 */
vli_mod_sub(y2, y2, y1, curve_prime, ndigits);
/* t7 = (y2 + y1)^2 = F */
vli_mod_square_fast(t7, t5, curve_prime, ndigits);
/* t7 = x3' */
vli_mod_sub(t7, t7, t6, curve_prime, ndigits);
/* t6 = x3' - B */
vli_mod_sub(t6, t7, x1, curve_prime, ndigits);
/* t6 = (y2 + y1)*(x3' - B) */
vli_mod_mult_fast(t6, t6, t5, curve_prime, ndigits);
/* t2 = y3' */
vli_mod_sub(y1, t6, y1, curve_prime, ndigits);
vli_set(x1, t7, ndigits);
}
static void ecc_point_mult(struct ecc_point *result,
const struct ecc_point *point, const u64 *scalar,
u64 *initial_z, const struct ecc_curve *curve,
unsigned int ndigits)
{
/* R0 and R1 */
u64 rx[2][ECC_MAX_DIGITS];
u64 ry[2][ECC_MAX_DIGITS];
u64 z[ECC_MAX_DIGITS];
u64 sk[2][ECC_MAX_DIGITS];
u64 *curve_prime = curve->p;
int i, nb;
int num_bits;
int carry;
carry = vli_add(sk[0], scalar, curve->n, ndigits);
vli_add(sk[1], sk[0], curve->n, ndigits);
scalar = sk[!carry];
num_bits = sizeof(u64) * ndigits * 8 + 1;
vli_set(rx[1], point->x, ndigits);
vli_set(ry[1], point->y, ndigits);
xycz_initial_double(rx[1], ry[1], rx[0], ry[0], initial_z, curve_prime,
ndigits);
for (i = num_bits - 2; i > 0; i--) {
nb = !vli_test_bit(scalar, i);
xycz_add_c(rx[1 - nb], ry[1 - nb], rx[nb], ry[nb], curve_prime,
ndigits);
xycz_add(rx[nb], ry[nb], rx[1 - nb], ry[1 - nb], curve_prime,
ndigits);
}
nb = !vli_test_bit(scalar, 0);
xycz_add_c(rx[1 - nb], ry[1 - nb], rx[nb], ry[nb], curve_prime,
ndigits);
/* Find final 1/Z value. */
/* X1 - X0 */
vli_mod_sub(z, rx[1], rx[0], curve_prime, ndigits);
/* Yb * (X1 - X0) */
vli_mod_mult_fast(z, z, ry[1 - nb], curve_prime, ndigits);
/* xP * Yb * (X1 - X0) */
vli_mod_mult_fast(z, z, point->x, curve_prime, ndigits);
/* 1 / (xP * Yb * (X1 - X0)) */
vli_mod_inv(z, z, curve_prime, point->ndigits);
/* yP / (xP * Yb * (X1 - X0)) */
vli_mod_mult_fast(z, z, point->y, curve_prime, ndigits);
/* Xb * yP / (xP * Yb * (X1 - X0)) */
vli_mod_mult_fast(z, z, rx[1 - nb], curve_prime, ndigits);
/* End 1/Z calculation */
xycz_add(rx[nb], ry[nb], rx[1 - nb], ry[1 - nb], curve_prime, ndigits);
apply_z(rx[0], ry[0], z, curve_prime, ndigits);
vli_set(result->x, rx[0], ndigits);
vli_set(result->y, ry[0], ndigits);
}
/* Computes R = P + Q mod p */
static void ecc_point_add(const struct ecc_point *result,
const struct ecc_point *p, const struct ecc_point *q,
const struct ecc_curve *curve)
{
u64 z[ECC_MAX_DIGITS];
u64 px[ECC_MAX_DIGITS];
u64 py[ECC_MAX_DIGITS];
unsigned int ndigits = curve->g.ndigits;
vli_set(result->x, q->x, ndigits);
vli_set(result->y, q->y, ndigits);
vli_mod_sub(z, result->x, p->x, curve->p, ndigits);
vli_set(px, p->x, ndigits);
vli_set(py, p->y, ndigits);
xycz_add(px, py, result->x, result->y, curve->p, ndigits);
vli_mod_inv(z, z, curve->p, ndigits);
apply_z(result->x, result->y, z, curve->p, ndigits);
}
/* Computes R = u1P + u2Q mod p using Shamir's trick.
* Based on: Kenneth MacKay's micro-ecc (2014).
*/
void ecc_point_mult_shamir(const struct ecc_point *result,
const u64 *u1, const struct ecc_point *p,
const u64 *u2, const struct ecc_point *q,
const struct ecc_curve *curve)
{
u64 z[ECC_MAX_DIGITS];
u64 sump[2][ECC_MAX_DIGITS];
u64 *rx = result->x;
u64 *ry = result->y;
unsigned int ndigits = curve->g.ndigits;
unsigned int num_bits;
struct ecc_point sum = ECC_POINT_INIT(sump[0], sump[1], ndigits);
const struct ecc_point *points[4];
const struct ecc_point *point;
unsigned int idx;
int i;
ecc_point_add(&sum, p, q, curve);
points[0] = NULL;
points[1] = p;
points[2] = q;
points[3] = ∑
num_bits = max(vli_num_bits(u1, ndigits),
vli_num_bits(u2, ndigits));
i = num_bits - 1;
idx = (!!vli_test_bit(u1, i)) | ((!!vli_test_bit(u2, i)) << 1);
point = points[idx];
vli_set(rx, point->x, ndigits);
vli_set(ry, point->y, ndigits);
vli_clear(z + 1, ndigits - 1);
z[0] = 1;
for (--i; i >= 0; i--) {
ecc_point_double_jacobian(rx, ry, z, curve->p, ndigits);
idx = (!!vli_test_bit(u1, i)) | ((!!vli_test_bit(u2, i)) << 1);
point = points[idx];
if (point) {
u64 tx[ECC_MAX_DIGITS];
u64 ty[ECC_MAX_DIGITS];
u64 tz[ECC_MAX_DIGITS];
vli_set(tx, point->x, ndigits);
vli_set(ty, point->y, ndigits);
apply_z(tx, ty, z, curve->p, ndigits);
vli_mod_sub(tz, rx, tx, curve->p, ndigits);
xycz_add(tx, ty, rx, ry, curve->p, ndigits);
vli_mod_mult_fast(z, z, tz, curve->p, ndigits);
}
}
vli_mod_inv(z, z, curve->p, ndigits);
apply_z(rx, ry, z, curve->p, ndigits);
}
EXPORT_SYMBOL(ecc_point_mult_shamir);
static inline void ecc_swap_digits(const u64 *in, u64 *out,
unsigned int ndigits)
{
const __be64 *src = (__force __be64 *)in;
int i;
for (i = 0; i < ndigits; i++)
out[i] = be64_to_cpu(src[ndigits - 1 - i]);
}
static int __ecc_is_key_valid(const struct ecc_curve *curve,
const u64 *private_key, unsigned int ndigits)
{
u64 one[ECC_MAX_DIGITS] = { 1, };
u64 res[ECC_MAX_DIGITS];
if (!private_key)
return -EINVAL;
if (curve->g.ndigits != ndigits)
return -EINVAL;
/* Make sure the private key is in the range [2, n-3]. */
if (vli_cmp(one, private_key, ndigits) != -1)
return -EINVAL;
vli_sub(res, curve->n, one, ndigits);
vli_sub(res, res, one, ndigits);
if (vli_cmp(res, private_key, ndigits) != 1)
return -EINVAL;
return 0;
}
int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
const u64 *private_key, unsigned int private_key_len)
{
int nbytes;
const struct ecc_curve *curve = ecc_get_curve(curve_id);
nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
if (private_key_len != nbytes)
return -EINVAL;
return __ecc_is_key_valid(curve, private_key, ndigits);
}
EXPORT_SYMBOL(ecc_is_key_valid);
/*
* ECC private keys are generated using the method of extra random bits,
* equivalent to that described in FIPS 186-4, Appendix B.4.1.
*
* d = (c mod(n–1)) + 1 where c is a string of random bits, 64 bits longer
* than requested
* 0 <= c mod(n-1) <= n-2 and implies that
* 1 <= d <= n-1
*
* This method generates a private key uniformly distributed in the range
* [1, n-1].
*/
int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey)
{
const struct ecc_curve *curve = ecc_get_curve(curve_id);
u64 priv[ECC_MAX_DIGITS];
unsigned int nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
unsigned int nbits = vli_num_bits(curve->n, ndigits);
int err;
/* Check that N is included in Table 1 of FIPS 186-4, section 6.1.1 */
if (nbits < 160 || ndigits > ARRAY_SIZE(priv))
return -EINVAL;
/*
* FIPS 186-4 recommends that the private key should be obtained from a
* RBG with a security strength equal to or greater than the security
* strength associated with N.
*
* The maximum security strength identified by NIST SP800-57pt1r4 for
* ECC is 256 (N >= 512).
*
* This condition is met by the default RNG because it selects a favored
* DRBG with a security strength of 256.
*/
if (crypto_get_default_rng())
return -EFAULT;
err = crypto_rng_get_bytes(crypto_default_rng, (u8 *)priv, nbytes);
crypto_put_default_rng();
if (err)
return err;
/* Make sure the private key is in the valid range. */
if (__ecc_is_key_valid(curve, priv, ndigits))
return -EINVAL;
ecc_swap_digits(priv, privkey, ndigits);
return 0;
}
EXPORT_SYMBOL(ecc_gen_privkey);
int ecc_make_pub_key(unsigned int curve_id, unsigned int ndigits,
const u64 *private_key, u64 *public_key)
{
int ret = 0;
struct ecc_point *pk;
u64 priv[ECC_MAX_DIGITS];
const struct ecc_curve *curve = ecc_get_curve(curve_id);
if (!private_key || !curve || ndigits > ARRAY_SIZE(priv)) {
ret = -EINVAL;
goto out;
}
ecc_swap_digits(private_key, priv, ndigits);
pk = ecc_alloc_point(ndigits);
if (!pk) {
ret = -ENOMEM;
goto out;
}
ecc_point_mult(pk, &curve->g, priv, NULL, curve, ndigits);
/* SP800-56A rev 3 5.6.2.1.3 key check */
if (ecc_is_pubkey_valid_full(curve, pk)) {
ret = -EAGAIN;
goto err_free_point;
}
ecc_swap_digits(pk->x, public_key, ndigits);
ecc_swap_digits(pk->y, &public_key[ndigits], ndigits);
err_free_point:
ecc_free_point(pk);
out:
return ret;
}
EXPORT_SYMBOL(ecc_make_pub_key);
/* SP800-56A section 5.6.2.3.4 partial verification: ephemeral keys only */
int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve,
struct ecc_point *pk)
{
u64 yy[ECC_MAX_DIGITS], xxx[ECC_MAX_DIGITS], w[ECC_MAX_DIGITS];
if (WARN_ON(pk->ndigits != curve->g.ndigits))
return -EINVAL;
/* Check 1: Verify key is not the zero point. */
if (ecc_point_is_zero(pk))
return -EINVAL;
/* Check 2: Verify key is in the range [1, p-1]. */
if (vli_cmp(curve->p, pk->x, pk->ndigits) != 1)
return -EINVAL;
if (vli_cmp(curve->p, pk->y, pk->ndigits) != 1)
return -EINVAL;
/* Check 3: Verify that y^2 == (x^3 + a·x + b) mod p */
vli_mod_square_fast(yy, pk->y, curve->p, pk->ndigits); /* y^2 */
vli_mod_square_fast(xxx, pk->x, curve->p, pk->ndigits); /* x^2 */
vli_mod_mult_fast(xxx, xxx, pk->x, curve->p, pk->ndigits); /* x^3 */
vli_mod_mult_fast(w, curve->a, pk->x, curve->p, pk->ndigits); /* a·x */
vli_mod_add(w, w, curve->b, curve->p, pk->ndigits); /* a·x + b */
vli_mod_add(w, w, xxx, curve->p, pk->ndigits); /* x^3 + a·x + b */
if (vli_cmp(yy, w, pk->ndigits) != 0) /* Equation */
return -EINVAL;
return 0;
}
EXPORT_SYMBOL(ecc_is_pubkey_valid_partial);
/* SP800-56A section 5.6.2.3.3 full verification */
int ecc_is_pubkey_valid_full(const struct ecc_curve *curve,
struct ecc_point *pk)
{
struct ecc_point *nQ;
/* Checks 1 through 3 */
int ret = ecc_is_pubkey_valid_partial(curve, pk);
if (ret)
return ret;
/* Check 4: Verify that nQ is the zero point. */
nQ = ecc_alloc_point(pk->ndigits);
if (!nQ)
return -ENOMEM;
ecc_point_mult(nQ, pk, curve->n, NULL, curve, pk->ndigits);
if (!ecc_point_is_zero(nQ))
ret = -EINVAL;
ecc_free_point(nQ);
return ret;
}
EXPORT_SYMBOL(ecc_is_pubkey_valid_full);
int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
const u64 *private_key, const u64 *public_key,
u64 *secret)
{
int ret = 0;
struct ecc_point *product, *pk;
u64 priv[ECC_MAX_DIGITS];
u64 rand_z[ECC_MAX_DIGITS];
unsigned int nbytes;
const struct ecc_curve *curve = ecc_get_curve(curve_id);
if (!private_key || !public_key || !curve ||
ndigits > ARRAY_SIZE(priv) || ndigits > ARRAY_SIZE(rand_z)) {
ret = -EINVAL;
goto out;
}
nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
get_random_bytes(rand_z, nbytes);
pk = ecc_alloc_point(ndigits);
if (!pk) {
ret = -ENOMEM;
goto out;
}
ecc_swap_digits(public_key, pk->x, ndigits);
ecc_swap_digits(&public_key[ndigits], pk->y, ndigits);
ret = ecc_is_pubkey_valid_partial(curve, pk);
if (ret)
goto err_alloc_product;
ecc_swap_digits(private_key, priv, ndigits);
product = ecc_alloc_point(ndigits);
if (!product) {
ret = -ENOMEM;
goto err_alloc_product;
}
ecc_point_mult(product, pk, priv, rand_z, curve, ndigits);
if (ecc_point_is_zero(product)) {
ret = -EFAULT;
goto err_validity;
}
ecc_swap_digits(product->x, secret, ndigits);
err_validity:
memzero_explicit(priv, sizeof(priv));
memzero_explicit(rand_z, sizeof(rand_z));
ecc_free_point(product);
err_alloc_product:
ecc_free_point(pk);
out:
return ret;
}
EXPORT_SYMBOL(crypto_ecdh_shared_secret);
MODULE_LICENSE("Dual BSD/GPL");
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