From 97a5fee2bd70df9e48cdfdbbacc15d45089228a3 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Wed, 12 Jun 2019 18:19:59 +0200 Subject: [PATCH] fs: cifs: switch to RC4 library interface The CIFS code uses the sync skcipher API to invoke the ecb(arc4) skcipher, of which only a single generic C code implementation exists. This means that going through all the trouble of using scatterlists etc buys us very little, and we're better off just invoking the arc4 library directly. This also reverts commit 5f4b55699aaf ("CIFS: Fix BUG() in calc_seckey()"), since it is no longer necessary to allocate sec_key on the heap. Cc: linux-cifs@vger.kernel.org Cc: Steve French Signed-off-by: Ard Biesheuvel Acked-by: Steve French Signed-off-by: Herbert Xu --- fs/cifs/Kconfig | 2 +- fs/cifs/cifsencrypt.c | 62 +++++++++++-------------------------------- fs/cifs/cifsfs.c | 1 - 3 files changed, 17 insertions(+), 48 deletions(-) diff --git a/fs/cifs/Kconfig b/fs/cifs/Kconfig index 76724efc831c..3da294231dcc 100644 --- a/fs/cifs/Kconfig +++ b/fs/cifs/Kconfig @@ -9,7 +9,7 @@ config CIFS select CRYPTO_SHA512 select CRYPTO_CMAC select CRYPTO_HMAC - select CRYPTO_ARC4 + select CRYPTO_LIB_ARC4 select CRYPTO_AEAD2 select CRYPTO_CCM select CRYPTO_ECB diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c index d2a05e46d6f5..97b7497c13ef 100644 --- a/fs/cifs/cifsencrypt.c +++ b/fs/cifs/cifsencrypt.c @@ -33,7 +33,8 @@ #include #include #include -#include +#include +#include #include int __cifs_calc_signature(struct smb_rqst *rqst, @@ -772,63 +773,32 @@ setup_ntlmv2_rsp_ret: int calc_seckey(struct cifs_ses *ses) { - int rc; - struct crypto_skcipher *tfm_arc4; - struct scatterlist sgin, sgout; - struct skcipher_request *req; - unsigned char *sec_key; + unsigned char sec_key[CIFS_SESS_KEY_SIZE]; /* a nonce */ + struct arc4_ctx *ctx_arc4; - sec_key = kmalloc(CIFS_SESS_KEY_SIZE, GFP_KERNEL); - if (sec_key == NULL) - return -ENOMEM; + if (fips_enabled) + return -ENODEV; get_random_bytes(sec_key, CIFS_SESS_KEY_SIZE); - tfm_arc4 = crypto_alloc_skcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC); - if (IS_ERR(tfm_arc4)) { - rc = PTR_ERR(tfm_arc4); - cifs_dbg(VFS, "could not allocate crypto API arc4\n"); - goto out; - } - - rc = crypto_skcipher_setkey(tfm_arc4, ses->auth_key.response, - CIFS_SESS_KEY_SIZE); - if (rc) { - cifs_dbg(VFS, "%s: Could not set response as a key\n", - __func__); - goto out_free_cipher; - } - - req = skcipher_request_alloc(tfm_arc4, GFP_KERNEL); - if (!req) { - rc = -ENOMEM; - cifs_dbg(VFS, "could not allocate crypto API arc4 request\n"); - goto out_free_cipher; + ctx_arc4 = kmalloc(sizeof(*ctx_arc4), GFP_KERNEL); + if (!ctx_arc4) { + cifs_dbg(VFS, "could not allocate arc4 context\n"); + return -ENOMEM; } - sg_init_one(&sgin, sec_key, CIFS_SESS_KEY_SIZE); - sg_init_one(&sgout, ses->ntlmssp->ciphertext, CIFS_CPHTXT_SIZE); - - skcipher_request_set_callback(req, 0, NULL, NULL); - skcipher_request_set_crypt(req, &sgin, &sgout, CIFS_CPHTXT_SIZE, NULL); - - rc = crypto_skcipher_encrypt(req); - skcipher_request_free(req); - if (rc) { - cifs_dbg(VFS, "could not encrypt session key rc: %d\n", rc); - goto out_free_cipher; - } + arc4_setkey(ctx_arc4, ses->auth_key.response, CIFS_SESS_KEY_SIZE); + arc4_crypt(ctx_arc4, ses->ntlmssp->ciphertext, sec_key, + CIFS_CPHTXT_SIZE); /* make secondary_key/nonce as session key */ memcpy(ses->auth_key.response, sec_key, CIFS_SESS_KEY_SIZE); /* and make len as that of session key only */ ses->auth_key.len = CIFS_SESS_KEY_SIZE; -out_free_cipher: - crypto_free_skcipher(tfm_arc4); -out: - kfree(sec_key); - return rc; + memzero_explicit(sec_key, CIFS_SESS_KEY_SIZE); + kzfree(ctx_arc4); + return 0; } void diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c index f5fcd6360056..e55afaf9e5a3 100644 --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -1590,7 +1590,6 @@ MODULE_DESCRIPTION ("VFS to access SMB3 servers e.g. Samba, Macs, Azure and Windows (and " "also older servers complying with the SNIA CIFS Specification)"); MODULE_VERSION(CIFS_VERSION); -MODULE_SOFTDEP("pre: arc4"); MODULE_SOFTDEP("pre: des"); MODULE_SOFTDEP("pre: ecb"); MODULE_SOFTDEP("pre: hmac"); -- 2.30.2