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![Herbert Xu](/assets/img/avatar_default.png)
The cbc template should not be applied on stream ciphers, especially
ones that have internal state. Enforce this by checking the state
size when the instance is created.
Reported-by: syzbot+050eeedd6c285d8c42f2@syzkaller.appspotmail.com
Fixes: 47309ea135
("crypto: arc4 - Add internal state")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
188 lines
4.2 KiB
C
188 lines
4.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* CBC: Cipher Block Chaining mode
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*
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* Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au>
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*/
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#include <crypto/internal/skcipher.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/log2.h>
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#include <linux/module.h>
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static int crypto_cbc_encrypt_segment(struct crypto_lskcipher *tfm,
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const u8 *src, u8 *dst, unsigned nbytes,
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u8 *iv)
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{
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unsigned int bsize = crypto_lskcipher_blocksize(tfm);
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for (; nbytes >= bsize; src += bsize, dst += bsize, nbytes -= bsize) {
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crypto_xor(iv, src, bsize);
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crypto_lskcipher_encrypt(tfm, iv, dst, bsize, NULL);
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memcpy(iv, dst, bsize);
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}
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return nbytes;
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}
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static int crypto_cbc_encrypt_inplace(struct crypto_lskcipher *tfm,
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u8 *src, unsigned nbytes, u8 *oiv)
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{
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unsigned int bsize = crypto_lskcipher_blocksize(tfm);
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u8 *iv = oiv;
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if (nbytes < bsize)
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goto out;
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do {
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crypto_xor(src, iv, bsize);
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crypto_lskcipher_encrypt(tfm, src, src, bsize, NULL);
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iv = src;
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src += bsize;
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} while ((nbytes -= bsize) >= bsize);
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memcpy(oiv, iv, bsize);
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out:
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return nbytes;
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}
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static int crypto_cbc_encrypt(struct crypto_lskcipher *tfm, const u8 *src,
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u8 *dst, unsigned len, u8 *iv, u32 flags)
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{
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struct crypto_lskcipher **ctx = crypto_lskcipher_ctx(tfm);
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bool final = flags & CRYPTO_LSKCIPHER_FLAG_FINAL;
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struct crypto_lskcipher *cipher = *ctx;
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int rem;
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if (src == dst)
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rem = crypto_cbc_encrypt_inplace(cipher, dst, len, iv);
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else
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rem = crypto_cbc_encrypt_segment(cipher, src, dst, len, iv);
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return rem && final ? -EINVAL : rem;
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}
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static int crypto_cbc_decrypt_segment(struct crypto_lskcipher *tfm,
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const u8 *src, u8 *dst, unsigned nbytes,
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u8 *oiv)
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{
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unsigned int bsize = crypto_lskcipher_blocksize(tfm);
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const u8 *iv = oiv;
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if (nbytes < bsize)
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goto out;
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do {
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crypto_lskcipher_decrypt(tfm, src, dst, bsize, NULL);
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crypto_xor(dst, iv, bsize);
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iv = src;
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src += bsize;
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dst += bsize;
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} while ((nbytes -= bsize) >= bsize);
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memcpy(oiv, iv, bsize);
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out:
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return nbytes;
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}
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static int crypto_cbc_decrypt_inplace(struct crypto_lskcipher *tfm,
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u8 *src, unsigned nbytes, u8 *iv)
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{
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unsigned int bsize = crypto_lskcipher_blocksize(tfm);
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u8 last_iv[MAX_CIPHER_BLOCKSIZE];
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if (nbytes < bsize)
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goto out;
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/* Start of the last block. */
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src += nbytes - (nbytes & (bsize - 1)) - bsize;
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memcpy(last_iv, src, bsize);
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for (;;) {
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crypto_lskcipher_decrypt(tfm, src, src, bsize, NULL);
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if ((nbytes -= bsize) < bsize)
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break;
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crypto_xor(src, src - bsize, bsize);
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src -= bsize;
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}
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crypto_xor(src, iv, bsize);
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memcpy(iv, last_iv, bsize);
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out:
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return nbytes;
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}
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static int crypto_cbc_decrypt(struct crypto_lskcipher *tfm, const u8 *src,
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u8 *dst, unsigned len, u8 *iv, u32 flags)
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{
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struct crypto_lskcipher **ctx = crypto_lskcipher_ctx(tfm);
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bool final = flags & CRYPTO_LSKCIPHER_FLAG_FINAL;
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struct crypto_lskcipher *cipher = *ctx;
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int rem;
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if (src == dst)
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rem = crypto_cbc_decrypt_inplace(cipher, dst, len, iv);
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else
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rem = crypto_cbc_decrypt_segment(cipher, src, dst, len, iv);
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return rem && final ? -EINVAL : rem;
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}
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static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
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{
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struct lskcipher_instance *inst;
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int err;
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inst = lskcipher_alloc_instance_simple(tmpl, tb);
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if (IS_ERR(inst))
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return PTR_ERR(inst);
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err = -EINVAL;
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if (!is_power_of_2(inst->alg.co.base.cra_blocksize))
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goto out_free_inst;
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if (inst->alg.co.statesize)
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goto out_free_inst;
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inst->alg.encrypt = crypto_cbc_encrypt;
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inst->alg.decrypt = crypto_cbc_decrypt;
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err = lskcipher_register_instance(tmpl, inst);
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if (err) {
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out_free_inst:
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inst->free(inst);
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}
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return err;
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}
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static struct crypto_template crypto_cbc_tmpl = {
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.name = "cbc",
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.create = crypto_cbc_create,
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.module = THIS_MODULE,
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};
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static int __init crypto_cbc_module_init(void)
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{
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return crypto_register_template(&crypto_cbc_tmpl);
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}
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static void __exit crypto_cbc_module_exit(void)
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{
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crypto_unregister_template(&crypto_cbc_tmpl);
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}
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subsys_initcall(crypto_cbc_module_init);
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module_exit(crypto_cbc_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("CBC block cipher mode of operation");
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MODULE_ALIAS_CRYPTO("cbc");
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