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authorStephan Müller <smueller@chronox.de>2021-11-19 09:58:44 +0300
committerHerbert Xu <herbert@gondor.apana.org.au>2021-11-26 08:25:17 +0300
commitd7921344234d15ce24a151d932aa0748797fc502 (patch)
treeb7b53707a46d11005c9f391949734c720d8178bb /security/keys
parent026a733e66592e743a0905c7fd6b5d3bf89b2d7e (diff)
downloadlinux-d7921344234d15ce24a151d932aa0748797fc502.tar.xz
security: DH - remove dead code for zero padding
Remove the specific code that adds a zero padding that was intended to be invoked when the DH operation result was smaller than the modulus. However, this cannot occur any more these days because the function mpi_write_to_sgl is used in the code path that calculates the shared secret in dh_compute_value. This MPI service function guarantees that leading zeros are introduced as needed to ensure the resulting data is exactly as long as the modulus. This implies that the specific code to add zero padding is dead code which can be safely removed. Signed-off-by: Stephan Mueller <smueller@chronox.de> Acked-by: Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'security/keys')
-rw-r--r--security/keys/dh.c25
1 files changed, 4 insertions, 21 deletions
diff --git a/security/keys/dh.c b/security/keys/dh.c
index 1abfa70ed6e1..56e12dae4534 100644
--- a/security/keys/dh.c
+++ b/security/keys/dh.c
@@ -141,7 +141,7 @@ static void kdf_dealloc(struct kdf_sdesc *sdesc)
* 'dlen' must be a multiple of the digest size.
*/
static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
- u8 *dst, unsigned int dlen, unsigned int zlen)
+ u8 *dst, unsigned int dlen)
{
struct shash_desc *desc = &sdesc->shash;
unsigned int h = crypto_shash_digestsize(desc->tfm);
@@ -158,22 +158,6 @@ static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
if (err)
goto err;
- if (zlen && h) {
- u8 tmpbuffer[32];
- size_t chunk = min_t(size_t, zlen, sizeof(tmpbuffer));
- memset(tmpbuffer, 0, chunk);
-
- do {
- err = crypto_shash_update(desc, tmpbuffer,
- chunk);
- if (err)
- goto err;
-
- zlen -= chunk;
- chunk = min_t(size_t, zlen, sizeof(tmpbuffer));
- } while (zlen);
- }
-
if (src && slen) {
err = crypto_shash_update(desc, src, slen);
if (err)
@@ -198,7 +182,7 @@ err:
static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc,
char __user *buffer, size_t buflen,
- uint8_t *kbuf, size_t kbuflen, size_t lzero)
+ uint8_t *kbuf, size_t kbuflen)
{
uint8_t *outbuf = NULL;
int ret;
@@ -211,7 +195,7 @@ static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc,
goto err;
}
- ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, outbuf_len, lzero);
+ ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, outbuf_len);
if (ret)
goto err;
@@ -384,8 +368,7 @@ long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
}
ret = keyctl_dh_compute_kdf(sdesc, buffer, buflen, outbuf,
- req->dst_len + kdfcopy->otherinfolen,
- outlen - req->dst_len);
+ req->dst_len + kdfcopy->otherinfolen);
} else if (copy_to_user(buffer, outbuf, req->dst_len) == 0) {
ret = req->dst_len;
} else {