Limit allocation of crypto mechanisms to dialect which requires

Updated patch to try to prevent allocation of cifs, smb2 or smb3 crypto
secmech structures unless needed.  Currently cifs allocates all crypto
mechanisms when the first session is established (4 functions and
4 contexts), rather than only allocating these when needed (smb3 needs
two, the rest of the dialects only need one).

Acked-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 85 insertions, 110 deletions

diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
index 3d8bf941d12..45e57cc3820 100644
--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -1,7 +1,7 @@
 /*
  *   fs/cifs/cifsencrypt.c
  *
- *   Copyright (C) International Business Machines  Corp., 2005,2006
+ *   Copyright (C) International Business Machines  Corp., 2005,2013
  *   Author(s): Steve French (sfrench@us.ibm.com)
  *
  *   This library is free software; you can redistribute it and/or modify
@@ -31,6 +31,36 @@
 #include <linux/random.h>
 #include <linux/highmem.h>
 
+static int
+cifs_crypto_shash_md5_allocate(struct TCP_Server_Info *server)
+{
+	int rc;
+	unsigned int size;
+
+	if (server->secmech.sdescmd5 != NULL)
+		return 0; /* already allocated */
+
+	server->secmech.md5 = crypto_alloc_shash("md5", 0, 0);
+	if (IS_ERR(server->secmech.md5)) {
+		cifs_dbg(VFS, "could not allocate crypto md5\n");
+		return PTR_ERR(server->secmech.md5);
+	}
+
+	size = sizeof(struct shash_desc) +
+			crypto_shash_descsize(server->secmech.md5);
+	server->secmech.sdescmd5 = kmalloc(size, GFP_KERNEL);
+	if (!server->secmech.sdescmd5) {
+		rc = -ENOMEM;
+		crypto_free_shash(server->secmech.md5);
+		server->secmech.md5 = NULL;
+		return rc;
+	}
+	server->secmech.sdescmd5->shash.tfm = server->secmech.md5;
+	server->secmech.sdescmd5->shash.flags = 0x0;
+
+	return 0;
+}
+
 /*
  * Calculate and return the CIFS signature based on the mac key and SMB PDU.
  * The 16 byte signature must be allocated by the caller. Note we only use the
@@ -50,8 +80,11 @@ static int cifs_calc_signature(struct smb_rqst *rqst,
 		return -EINVAL;
 
 	if (!server->secmech.sdescmd5) {
-		cifs_dbg(VFS, "%s: Can't generate signature\n", __func__);
-		return -1;
+		rc = cifs_crypto_shash_md5_allocate(server);
+		if (rc) {
+			cifs_dbg(VFS, "%s: Can't alloc md5 crypto\n", __func__);
+			return -1;
+		}
 	}
 
 	rc = crypto_shash_init(&server->secmech.sdescmd5->shash);
@@ -556,6 +589,33 @@ CalcNTLMv2_response(const struct cifs_ses *ses, char *ntlmv2_hash)
 	return rc;
 }
 
+static int crypto_hmacmd5_alloc(struct TCP_Server_Info *server)
+{
+	unsigned int size;
+
+	/* check if already allocated */
+	if (server->secmech.sdeschmacmd5)
+		return 0;
+
+	server->secmech.hmacmd5 = crypto_alloc_shash("hmac(md5)", 0, 0);
+	if (IS_ERR(server->secmech.hmacmd5)) {
+		cifs_dbg(VFS, "could not allocate crypto hmacmd5\n");
+		return PTR_ERR(server->secmech.hmacmd5);
+	}
+
+	size = sizeof(struct shash_desc) +
+			crypto_shash_descsize(server->secmech.hmacmd5);
+	server->secmech.sdeschmacmd5 = kmalloc(size, GFP_KERNEL);
+	if (!server->secmech.sdeschmacmd5) {
+		crypto_free_shash(server->secmech.hmacmd5);
+		server->secmech.hmacmd5 = NULL;
+		return -ENOMEM;
+	}
+	server->secmech.sdeschmacmd5->shash.tfm = server->secmech.hmacmd5;
+	server->secmech.sdeschmacmd5->shash.flags = 0x0;
+
+	return 0;
+}
 
 int
 setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
@@ -606,6 +666,12 @@ setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
 
 	memcpy(ses->auth_key.response + baselen, tiblob, tilen);
 
+	rc = crypto_hmacmd5_alloc(ses->server);
+	if (rc) {
+		cifs_dbg(VFS, "could not crypto alloc hmacmd5 rc %d\n", rc);
+		goto setup_ntlmv2_rsp_ret;
+	}
+
 	/* calculate ntlmv2_hash */
 	rc = calc_ntlmv2_hash(ses, ntlmv2_hash, nls_cp);
 	if (rc) {
@@ -705,123 +771,32 @@ calc_seckey(struct cifs_ses *ses)
 void
 cifs_crypto_shash_release(struct TCP_Server_Info *server)
 {
-	if (server->secmech.cmacaes)
+	if (server->secmech.cmacaes) {
 		crypto_free_shash(server->secmech.cmacaes);
+		server->secmech.cmacaes = NULL;
+	}
 
-	if (server->secmech.hmacsha256)
+	if (server->secmech.hmacsha256) {
 		crypto_free_shash(server->secmech.hmacsha256);
+		server->secmech.hmacsha256 = NULL;
+	}
 
-	if (server->secmech.md5)
+	if (server->secmech.md5) {
 		crypto_free_shash(server->secmech.md5);
+		server->secmech.md5 = NULL;
+	}
 
-	if (server->secmech.hmacmd5)
+	if (server->secmech.hmacmd5) {
 		crypto_free_shash(server->secmech.hmacmd5);
+		server->secmech.hmacmd5 = NULL;
+	}
 
 	kfree(server->secmech.sdesccmacaes);
-
+	server->secmech.sdesccmacaes = NULL;
 	kfree(server->secmech.sdeschmacsha256);
-
+	server->secmech.sdeschmacsha256 = NULL;
 	kfree(server->secmech.sdeschmacmd5);
-
+	server->secmech.sdeschmacmd5 = NULL;
 	kfree(server->secmech.sdescmd5);
-}
-
-int
-cifs_crypto_shash_allocate(struct TCP_Server_Info *server)
-{
-	int rc;
-	unsigned int size;
-
-	server->secmech.hmacmd5 = crypto_alloc_shash("hmac(md5)", 0, 0);
-	if (IS_ERR(server->secmech.hmacmd5)) {
-		cifs_dbg(VFS, "could not allocate crypto hmacmd5\n");
-		return PTR_ERR(server->secmech.hmacmd5);
-	}
-
-	server->secmech.md5 = crypto_alloc_shash("md5", 0, 0);
-	if (IS_ERR(server->secmech.md5)) {
-		cifs_dbg(VFS, "could not allocate crypto md5\n");
-		rc = PTR_ERR(server->secmech.md5);
-		goto crypto_allocate_md5_fail;
-	}
-
-	server->secmech.hmacsha256 = crypto_alloc_shash("hmac(sha256)", 0, 0);
-	if (IS_ERR(server->secmech.hmacsha256)) {
-		cifs_dbg(VFS, "could not allocate crypto hmacsha256\n");
-		rc = PTR_ERR(server->secmech.hmacsha256);
-		goto crypto_allocate_hmacsha256_fail;
-	}
-
-	server->secmech.cmacaes = crypto_alloc_shash("cmac(aes)", 0, 0);
-	if (IS_ERR(server->secmech.cmacaes)) {
-		cifs_dbg(VFS, "could not allocate crypto cmac-aes");
-		rc = PTR_ERR(server->secmech.cmacaes);
-		goto crypto_allocate_cmacaes_fail;
-	}
-
-	size = sizeof(struct shash_desc) +
-			crypto_shash_descsize(server->secmech.hmacmd5);
-	server->secmech.sdeschmacmd5 = kmalloc(size, GFP_KERNEL);
-	if (!server->secmech.sdeschmacmd5) {
-		rc = -ENOMEM;
-		goto crypto_allocate_hmacmd5_sdesc_fail;
-	}
-	server->secmech.sdeschmacmd5->shash.tfm = server->secmech.hmacmd5;
-	server->secmech.sdeschmacmd5->shash.flags = 0x0;
-
-	size = sizeof(struct shash_desc) +
-			crypto_shash_descsize(server->secmech.md5);
-	server->secmech.sdescmd5 = kmalloc(size, GFP_KERNEL);
-	if (!server->secmech.sdescmd5) {
-		rc = -ENOMEM;
-		goto crypto_allocate_md5_sdesc_fail;
-	}
-	server->secmech.sdescmd5->shash.tfm = server->secmech.md5;
-	server->secmech.sdescmd5->shash.flags = 0x0;
-
-	size = sizeof(struct shash_desc) +
-			crypto_shash_descsize(server->secmech.hmacsha256);
-	server->secmech.sdeschmacsha256 = kmalloc(size, GFP_KERNEL);
-	if (!server->secmech.sdeschmacsha256) {
-		rc = -ENOMEM;
-		goto crypto_allocate_hmacsha256_sdesc_fail;
-	}
-	server->secmech.sdeschmacsha256->shash.tfm = server->secmech.hmacsha256;
-	server->secmech.sdeschmacsha256->shash.flags = 0x0;
-
-	size = sizeof(struct shash_desc) +
-			crypto_shash_descsize(server->secmech.cmacaes);
-	server->secmech.sdesccmacaes = kmalloc(size, GFP_KERNEL);
-	if (!server->secmech.sdesccmacaes) {
-		cifs_dbg(VFS, "%s: Can't alloc cmacaes\n", __func__);
-		rc = -ENOMEM;
-		goto crypto_allocate_cmacaes_sdesc_fail;
-	}
-	server->secmech.sdesccmacaes->shash.tfm = server->secmech.cmacaes;
-	server->secmech.sdesccmacaes->shash.flags = 0x0;
-
-	return 0;
-
-crypto_allocate_cmacaes_sdesc_fail:
-	kfree(server->secmech.sdeschmacsha256);
-
-crypto_allocate_hmacsha256_sdesc_fail:
-	kfree(server->secmech.sdescmd5);
-
-crypto_allocate_md5_sdesc_fail:
-	kfree(server->secmech.sdeschmacmd5);
-
-crypto_allocate_hmacmd5_sdesc_fail:
-	crypto_free_shash(server->secmech.cmacaes);
-
-crypto_allocate_cmacaes_fail:
-	crypto_free_shash(server->secmech.hmacsha256);
-
-crypto_allocate_hmacsha256_fail:
-	crypto_free_shash(server->secmech.md5);
-
-crypto_allocate_md5_fail:
-	crypto_free_shash(server->secmech.hmacmd5);
-
-	return rc;
+	server->secmech.sdescmd5 = NULL;
 }