From 877b5691f27a1aec0d9b53095a323e45c30069e2 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Sun, 14 Apr 2019 17:37:09 -0700
Subject: [Backport 877b5691f27a] crypto: shash - remove shash_desc::flags
The flags field in 'struct shash_desc' never actually does anything.
The only ostensibly supported flag is CRYPTO_TFM_REQ_MAY_SLEEP.
However, no shash algorithm ever sleeps, making this flag a no-op.
With this being the case, inevitably some users who can't sleep wrongly
pass MAY_SLEEP. These would all need to be fixed if any shash algorithm
actually started sleeping. For example, the shash_ahash_*() functions,
which wrap a shash algorithm with the ahash API, pass through MAY_SLEEP
from the ahash API to the shash API. However, the shash functions are
called under kmap_atomic(), so actually they're assumed to never sleep.
Even if it turns out that some users do need preemption points while
hashing large buffers, we could easily provide a helper function
crypto_shash_update_large() which divides the data into smaller chunks
and calls crypto_shash_update() and cond_resched() for each chunk. It's
not necessary to have a flag in 'struct shash_desc', nor is it necessary
to make individual shash algorithms aware of this at all.
Therefore, remove shash_desc::flags, and document that the
crypto_shash_*() functions can be called from any context.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
src/crypto.c | 1 -
src/keystore.c | 1 -
2 files changed, 2 deletions(-)
diff --git a/src/crypto.c b/src/crypto.c
index f664da55234e93b18194237e9995a16c70f1334d..491cf5baa8c23b5f97254f4d5cb43d32e3339f8f 100644
--- a/src/crypto.c
+++ b/src/crypto.c
@@ -68,7 +68,6 @@ static int ecryptfs_hash_digest(struct crypto_shash *tfm,
int err;
desc->tfm = tfm;
- desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
err = crypto_shash_digest(desc, src, len, dst);
shash_desc_zero(desc);
return err;
diff --git a/src/keystore.c b/src/keystore.c
index e74fe84d0886879c04cc26297f0e8b27db8281a6..90fbac5d485b3a79728f342e81e2bcdaa8b0e552 100644
--- a/src/keystore.c
+++ b/src/keystore.c
@@ -769,7 +769,6 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
}
s->hash_desc->tfm = s->hash_tfm;
- s->hash_desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
rc = crypto_shash_digest(s->hash_desc,
(u8 *)s->auth_tok->token.password.session_key_encryption_key,
--
2.31.1