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Subject[PATCH] cifs: Allocate crypto structures on the fly for calculating signatures of incoming packets
Date
From: Long Li <longli@microsoft.com>

CIFS uses pre-allocated crypto structures to calculate signatures for both
incoming and outgoing packets. In this way it doesn't need to allocate crypto
structures for every packet, but it requires a lock to prevent concurrent
access to crypto structures.

Remove the lock by allocating crypto structures on the fly for
incoming packets. At the same time, we can still use pre-allocated crypto
structures for outgoing packets, as they are already protected by transport
lock srv_mutex.

Signed-off-by: Long Li <longli@microsoft.com>
---
fs/cifs/cifsglob.h | 3 +-
fs/cifs/smb2proto.h | 6 ++-
fs/cifs/smb2transport.c | 87 +++++++++++++++++++++++++----------------
3 files changed, 60 insertions(+), 36 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 0d956360e984..7448e7202e7a 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -426,7 +426,8 @@ struct smb_version_operations {
/* generate new lease key */
void (*new_lease_key)(struct cifs_fid *);
int (*generate_signingkey)(struct cifs_ses *);
- int (*calc_signature)(struct smb_rqst *, struct TCP_Server_Info *);
+ int (*calc_signature)(struct smb_rqst *, struct TCP_Server_Info *,
+ bool allocate_crypto);
int (*set_integrity)(const unsigned int, struct cifs_tcon *tcon,
struct cifsFileInfo *src_file);
int (*enum_snapshots)(const unsigned int xid, struct cifs_tcon *tcon,
diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
index 4d1ff7b66fdc..087d5f14320b 100644
--- a/fs/cifs/smb2proto.h
+++ b/fs/cifs/smb2proto.h
@@ -55,9 +55,11 @@ extern struct cifs_ses *smb2_find_smb_ses(struct TCP_Server_Info *server,
extern struct cifs_tcon *smb2_find_smb_tcon(struct TCP_Server_Info *server,
__u64 ses_id, __u32 tid);
extern int smb2_calc_signature(struct smb_rqst *rqst,
- struct TCP_Server_Info *server);
+ struct TCP_Server_Info *server,
+ bool allocate_crypto);
extern int smb3_calc_signature(struct smb_rqst *rqst,
- struct TCP_Server_Info *server);
+ struct TCP_Server_Info *server,
+ bool allocate_crypto);
extern void smb2_echo_request(struct work_struct *work);
extern __le32 smb2_get_lease_state(struct cifsInodeInfo *cinode);
extern bool smb2_is_valid_oplock_break(char *buffer,
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index 08b703b7a15e..c01e19a3b112 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -40,14 +40,6 @@
#include "smb2status.h"
#include "smb2glob.h"

-static int
-smb2_crypto_shash_allocate(struct TCP_Server_Info *server)
-{
- return cifs_alloc_hash("hmac(sha256)",
- &server->secmech.hmacsha256,
- &server->secmech.sdeschmacsha256);
-}
-
static int
smb3_crypto_shash_allocate(struct TCP_Server_Info *server)
{
@@ -219,7 +211,8 @@ smb2_find_smb_tcon(struct TCP_Server_Info *server, __u64 ses_id, __u32 tid)
}

int
-smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
+smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server,
+ bool allocate_crypto)
{
int rc;
unsigned char smb2_signature[SMB2_HMACSHA256_SIZE];
@@ -228,6 +221,8 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)iov[0].iov_base;
struct cifs_ses *ses;
struct shash_desc *shash;
+ struct crypto_shash *hash;
+ struct sdesc *sdesc = NULL;
struct smb_rqst drqst;

ses = smb2_find_smb_ses(server, shdr->SessionId);
@@ -239,24 +234,32 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
memset(smb2_signature, 0x0, SMB2_HMACSHA256_SIZE);
memset(shdr->Signature, 0x0, SMB2_SIGNATURE_SIZE);

- rc = smb2_crypto_shash_allocate(server);
- if (rc) {
- cifs_server_dbg(VFS, "%s: sha256 alloc failed\n", __func__);
- return rc;
+ if (allocate_crypto) {
+ rc = cifs_alloc_hash("hmac(sha256)", &hash, &sdesc);
+ if (rc) {
+ cifs_server_dbg(VFS,
+ "%s: sha256 alloc failed\n", __func__);
+ return rc;
+ }
+ shash = &sdesc->shash;
+ } else {
+ hash = server->secmech.hmacsha256;
+ shash = &server->secmech.sdeschmacsha256->shash;
}

- rc = crypto_shash_setkey(server->secmech.hmacsha256,
- ses->auth_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
+ rc = crypto_shash_setkey(hash, ses->auth_key.response,
+ SMB2_NTLMV2_SESSKEY_SIZE);
if (rc) {
- cifs_server_dbg(VFS, "%s: Could not update with response\n", __func__);
- return rc;
+ cifs_server_dbg(VFS,
+ "%s: Could not update with response\n",
+ __func__);
+ goto out;
}

- shash = &server->secmech.sdeschmacsha256->shash;
rc = crypto_shash_init(shash);
if (rc) {
cifs_server_dbg(VFS, "%s: Could not init sha256", __func__);
- return rc;
+ goto out;
}

/*
@@ -271,9 +274,10 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
rc = crypto_shash_update(shash, iov[0].iov_base,
iov[0].iov_len);
if (rc) {
- cifs_server_dbg(VFS, "%s: Could not update with payload\n",
- __func__);
- return rc;
+ cifs_server_dbg(VFS,
+ "%s: Could not update with payload\n",
+ __func__);
+ goto out;
}
drqst.rq_iov++;
drqst.rq_nvec--;
@@ -283,6 +287,9 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
if (!rc)
memcpy(shdr->Signature, sigptr, SMB2_SIGNATURE_SIZE);

+out:
+ if (allocate_crypto)
+ cifs_free_hash(&hash, &sdesc);
return rc;
}

@@ -504,14 +511,17 @@ generate_smb311signingkey(struct cifs_ses *ses)
}

int
-smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
+smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server,
+ bool allocate_crypto)
{
int rc;
unsigned char smb3_signature[SMB2_CMACAES_SIZE];
unsigned char *sigptr = smb3_signature;
struct kvec *iov = rqst->rq_iov;
struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)iov[0].iov_base;
- struct shash_desc *shash = &server->secmech.sdesccmacaes->shash;
+ struct shash_desc *shash;
+ struct crypto_shash *hash;
+ struct sdesc *sdesc = NULL;
struct smb_rqst drqst;
u8 key[SMB3_SIGN_KEY_SIZE];

@@ -519,14 +529,24 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
if (rc)
return 0;

+ if (allocate_crypto) {
+ rc = cifs_alloc_hash("cmac(aes)", &hash, &sdesc);
+ if (rc)
+ return rc;
+
+ shash = &sdesc->shash;
+ } else {
+ hash = server->secmech.cmacaes;
+ shash = &server->secmech.sdesccmacaes->shash;
+ }
+
memset(smb3_signature, 0x0, SMB2_CMACAES_SIZE);
memset(shdr->Signature, 0x0, SMB2_SIGNATURE_SIZE);

- rc = crypto_shash_setkey(server->secmech.cmacaes,
- key, SMB2_CMACAES_SIZE);
+ rc = crypto_shash_setkey(hash, key, SMB2_CMACAES_SIZE);
if (rc) {
cifs_server_dbg(VFS, "%s: Could not set key for cmac aes\n", __func__);
- return rc;
+ goto out;
}

/*
@@ -537,7 +557,7 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
rc = crypto_shash_init(shash);
if (rc) {
cifs_server_dbg(VFS, "%s: Could not init cmac aes\n", __func__);
- return rc;
+ goto out;
}

/*
@@ -554,7 +574,7 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
if (rc) {
cifs_server_dbg(VFS, "%s: Could not update with payload\n",
__func__);
- return rc;
+ goto out;
}
drqst.rq_iov++;
drqst.rq_nvec--;
@@ -564,6 +584,9 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
if (!rc)
memcpy(shdr->Signature, sigptr, SMB2_SIGNATURE_SIZE);

+out:
+ if (allocate_crypto)
+ cifs_free_hash(&hash, &sdesc);
return rc;
}

@@ -593,7 +616,7 @@ smb2_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server)
return 0;
}

- rc = server->ops->calc_signature(rqst, server);
+ rc = server->ops->calc_signature(rqst, server, false);

return rc;
}
@@ -631,9 +654,7 @@ smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)

memset(shdr->Signature, 0, SMB2_SIGNATURE_SIZE);

- mutex_lock(&server->srv_mutex);
- rc = server->ops->calc_signature(rqst, server);
- mutex_unlock(&server->srv_mutex);
+ rc = server->ops->calc_signature(rqst, server, true);

if (rc)
return rc;
--
2.17.1
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