[PATCH] crypto: rsassa-pkcs1 - Copy source data for SG list

Herbert Xu
2024-11-29T09:53:21Z

As virtual addresses in general may not be suitable for DMA, always
perform a copy before using them in an SG list.

Fixes: 1e562deacecc ("crypto: rsassa-pkcs1 - Migrate to sig_alg backend")
Reported-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/rsassa-pkcs1.c b/crypto/rsassa-pkcs1.c
index 4d077fc96076..f68ffd338f48 100644
--- a/crypto/rsassa-pkcs1.c
+++ b/crypto/rsassa-pkcs1.c
@@ -163,10 +163,6 @@ static int rsassa_pkcs1_sign(struct crypto_sig *tfm,
struct rsassa_pkcs1_inst_ctx *ictx = sig_instance_ctx(inst);
const struct hash_prefix *hash_prefix = ictx->hash_prefix;
struct rsassa_pkcs1_ctx *ctx = crypto_sig_ctx(tfm);
- unsigned int child_reqsize = crypto_akcipher_reqsize(ctx->child);
- struct akcipher_request *child_req __free(kfree_sensitive) = NULL;
- struct scatterlist in_sg[3], out_sg;
- struct crypto_wait cwait;
unsigned int pad_len;
unsigned int ps_end;
unsigned int len;
@@ -187,37 +183,25 @@ static int rsassa_pkcs1_sign(struct crypto_sig *tfm,

pad_len = ctx->key_size - slen - hash_prefix->size - 1;

- child_req = kmalloc(sizeof(*child_req) + child_reqsize + pad_len,
- GFP_KERNEL);
- if (!child_req)
- return -ENOMEM;
-
/* RFC 8017 sec 8.2.1 step 1 - EMSA-PKCS1-v1_5 encoding generation */
- in_buf = (u8 *)(child_req + 1) + child_reqsize;
+ in_buf = dst;
+ memmove(in_buf + pad_len + hash_prefix->size, src, slen);
+ memcpy(in_buf + pad_len, hash_prefix->data, hash_prefix->size);
+
ps_end = pad_len - 1;
in_buf[0] = 0x01;
memset(in_buf + 1, 0xff, ps_end - 1);
in_buf[ps_end] = 0x00;

- /* RFC 8017 sec 8.2.1 step 2 - RSA signature */
- crypto_init_wait(&cwait);
- sg_init_table(in_sg, 3);
- sg_set_buf(&in_sg[0], in_buf, pad_len);
- sg_set_buf(&in_sg[1], hash_prefix->data, hash_prefix->size);
- sg_set_buf(&in_sg[2], src, slen);
- sg_init_one(&out_sg, dst, dlen);
- akcipher_request_set_tfm(child_req, ctx->child);
- akcipher_request_set_crypt(child_req, in_sg, &out_sg,
- ctx->key_size - 1, dlen);
- akcipher_request_set_callback(child_req, CRYPTO_TFM_REQ_MAY_SLEEP,
- crypto_req_done, &cwait);

- err = crypto_akcipher_decrypt(child_req);
- err = crypto_wait_req(err, &cwait);
- if (err)
+ /* RFC 8017 sec 8.2.1 step 2 - RSA signature */
+ err = crypto_akcipher_sync_decrypt(ctx->child, in_buf,
+ ctx->key_size - 1, in_buf,
+ ctx->key_size);
+ if (err < 0)
return err;

- len = child_req->dst_len;
+ len = err;
pad_len = ctx->key_size - len;

/* Four billion to one */
@@ -239,8 +223,8 @@ static int rsassa_pkcs1_verify(struct crypto_sig *tfm,
struct rsassa_pkcs1_ctx *ctx = crypto_sig_ctx(tfm);
unsigned int child_reqsize = crypto_akcipher_reqsize(ctx->child);
struct akcipher_request *child_req __free(kfree_sensitive) = NULL;
- struct scatterlist in_sg, out_sg;
struct crypto_wait cwait;
+ struct scatterlist sg;
unsigned int dst_len;
unsigned int pos;
u8 *out_buf;
@@ -259,13 +243,12 @@ static int rsassa_pkcs1_verify(struct crypto_sig *tfm,
return -ENOMEM;

out_buf = (u8 *)(child_req + 1) + child_reqsize;
+ memcpy(out_buf, src, slen);

crypto_init_wait(&cwait);
- sg_init_one(&in_sg, src, slen);
- sg_init_one(&out_sg, out_buf, ctx->key_size);
+ sg_init_one(&sg, out_buf, slen);
akcipher_request_set_tfm(child_req, ctx->child);
- akcipher_request_set_crypt(child_req, &in_sg, &out_sg,
- slen, ctx->key_size);
+ akcipher_request_set_crypt(child_req, &sg, &sg, slen, slen);
akcipher_request_set_callback(child_req, CRYPTO_TFM_REQ_MAY_SLEEP,
crypto_req_done, &cwait);