[PATCH 10/29] crypto: powerpc/p10-aes-gcm - simplify handling of linear associated data

Eric Biggers
2024-12-21T09:11:33Z

p10_aes_gcm_crypt() is abusing the scatter_walk API to get the virtual
address for the first source scatterlist element. But this code is only
built for PPC64 which is a !HIGHMEM platform, and it can read past a
page boundary from the address returned by scatterwalk_map() which means
it already assumes the address is from the kernel's direct map. Thus,
just use sg_virt() instead to get the same result in a simpler way.

Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Danny Tsen <dtsen@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
---

This patch is part of a long series touching many files, so I have
limited the Cc list on the full series. If you want the full series and
did not receive it, please retrieve it from lore.kernel.org.

arch/powerpc/crypto/aes-gcm-p10-glue.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/crypto/aes-gcm-p10-glue.c b/arch/powerpc/crypto/aes-gcm-p10-glue.c
index f37b3d13fc53..2862c3cf8e41 100644
--- a/arch/powerpc/crypto/aes-gcm-p10-glue.c
+++ b/arch/powerpc/crypto/aes-gcm-p10-glue.c
@@ -212,11 +212,10 @@ static int p10_aes_gcm_crypt(struct aead_request *req, u8 *riv,
struct p10_aes_gcm_ctx *ctx = crypto_tfm_ctx(tfm);
u8 databuf[sizeof(struct gcm_ctx) + PPC_ALIGN];
struct gcm_ctx *gctx = PTR_ALIGN((void *)databuf, PPC_ALIGN);
u8 hashbuf[sizeof(struct Hash_ctx) + PPC_ALIGN];
struct Hash_ctx *hash = PTR_ALIGN((void *)hashbuf, PPC_ALIGN);
- struct scatter_walk assoc_sg_walk;
struct skcipher_walk walk;
u8 *assocmem = NULL;
u8 *assoc;
unsigned int cryptlen = req->cryptlen;
unsigned char ivbuf[AES_BLOCK_SIZE+PPC_ALIGN];
@@ -232,12 +231,11 @@ static int p10_aes_gcm_crypt(struct aead_request *req, u8 *riv,
memset(ivbuf, 0, sizeof(ivbuf));
memcpy(iv, riv, GCM_IV_SIZE);

/* Linearize assoc, if not already linear */
if (req->src->length >= assoclen && req->src->length) {
- scatterwalk_start(&assoc_sg_walk, req->src);
- assoc = scatterwalk_map(&assoc_sg_walk);
+ assoc = sg_virt(req->src); /* ppc64 is !HIGHMEM */
} else {
gfp_t flags = (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
GFP_KERNEL : GFP_ATOMIC;

/* assoc can be any length, so must be on heap */
@@ -251,13 +249,11 @@ static int p10_aes_gcm_crypt(struct aead_request *req, u8 *riv,

vsx_begin();
gcmp10_init(gctx, iv, (unsigned char *) &ctx->enc_key, hash, assoc, assoclen);
vsx_end();

- if (!assocmem)
- scatterwalk_unmap(assoc);
- else
+ if (assocmem)
kfree(assocmem);

if (enc)
ret = skcipher_walk_aead_encrypt(&walk, req, false);
else
--
2.47.1