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>

6 files changed, 0 insertions, 10 deletions

diff --git a/security/apparmor/crypto.c b/security/apparmor/crypto.c
index af03d98c7552..baba63bc66b1 100644
--- a/security/apparmor/crypto.c
+++ b/security/apparmor/crypto.c
@@ -43,7 +43,6 @@ char *aa_calc_hash(void *data, size_t len)
                 goto fail;
 
         desc->tfm = apparmor_tfm;
-        desc->flags = 0;
 
         error = crypto_shash_init(desc);
         if (error)
@@ -81,7 +80,6 @@ int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start,
                 goto fail;
 
         desc->tfm = apparmor_tfm;
-        desc->flags = 0;
 
         error = crypto_shash_init(desc);
         if (error)
diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index c37d08118af5..e11564eb645b 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -124,7 +124,6 @@ out:
                 return ERR_PTR(-ENOMEM);
 
         desc->tfm = *tfm;
-        desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 
         rc = crypto_shash_init(desc);
         if (rc) {
diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index 16a4f45863b1..a32878e10ebc 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -333,7 +333,6 @@ static int ima_calc_file_hash_tfm(struct file *file,
         SHASH_DESC_ON_STACK(shash, tfm);
 
         shash->tfm = tfm;
-        shash->flags = 0;
 
         hash->length = crypto_shash_digestsize(tfm);
 
@@ -469,7 +468,6 @@ static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
         int rc, i;
 
         shash->tfm = tfm;
-        shash->flags = 0;
 
         hash->length = crypto_shash_digestsize(tfm);
 
@@ -591,7 +589,6 @@ static int calc_buffer_shash_tfm(const void *buf, loff_t size,
         int rc;
 
         shash->tfm = tfm;
-        shash->flags = 0;
 
         hash->length = crypto_shash_digestsize(tfm);
 
@@ -664,7 +661,6 @@ static int __init ima_calc_boot_aggregate_tfm(char *digest,
         SHASH_DESC_ON_STACK(shash, tfm);
 
         shash->tfm = tfm;
-        shash->flags = 0;
 
         rc = crypto_shash_init(shash);
         if (rc != 0)
diff --git a/security/keys/dh.c b/security/keys/dh.c
index 711e89d8c415..23f95dec771b 100644
--- a/security/keys/dh.c
+++ b/security/keys/dh.c
@@ -112,7 +112,6 @@ static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *hashname)
         if (!sdesc)
                 goto out_free_tfm;
         sdesc->shash.tfm = tfm;
-        sdesc->shash.flags = 0x0;
 
         *sdesc_ret = sdesc;
 
diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c
index 347108f660a1..1b1456b21a93 100644
--- a/security/keys/encrypted-keys/encrypted.c
+++ b/security/keys/encrypted-keys/encrypted.c
@@ -333,7 +333,6 @@ static int calc_hash(struct crypto_shash *tfm, u8 *digest,
         int err;
 
         desc->tfm = tfm;
-        desc->flags = 0;
 
         err = crypto_shash_digest(desc, buf, buflen, digest);
         shash_desc_zero(desc);
diff --git a/security/keys/trusted.c b/security/keys/trusted.c
index bcc9c6ead7fd..45ffd9e53937 100644
--- a/security/keys/trusted.c
+++ b/security/keys/trusted.c
@@ -55,7 +55,6 @@ static struct sdesc *init_sdesc(struct crypto_shash *alg)
         if (!sdesc)
                 return ERR_PTR(-ENOMEM);
         sdesc->shash.tfm = alg;
-        sdesc->shash.flags = 0x0;
         return sdesc;
 }