Revision 35a9393c95b31870a74f51a3e7455f33f5657b6f authored by Peter Zijlstra on 26 February 2015, 15:23:11 UTC, committed by Ingo Molnar on 23 March 2015, 09:49:07 UTC
Module unload calls lockdep_free_key_range(), which removes entries
from the data structures. Most of the lockdep code OTOH assumes the
data structures are append only; in specific see the comments in
add_lock_to_list() and look_up_lock_class().

Clearly this has only worked by accident; make it work proper. The
actual scenario to make it go boom would involve the memory freed by
the module unlock being re-allocated and re-used for a lock inside of
a rcu-sched grace period. This is a very unlikely scenario, still
better plug the hole.

Use RCU list iteration in all places and ammend the comments.

Change lockdep_free_key_range() to issue a sync_sched() between
removal from the lists and returning -- which results in the memory
being freed. Further ensure the callers are placed correctly and
comment the requirements.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Tsyvarev <tsyvarev@ispras.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 parent bc465aa
Raw File
cipher.c
/*
 * Cryptographic API.
 *
 * Cipher operations.
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */

#include <linux/kernel.h>
#include <linux/crypto.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/string.h>
#include "internal.h"

static int setkey_unaligned(struct crypto_tfm *tfm, const u8 *key,
			    unsigned int keylen)
{
	struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
	unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
	int ret;
	u8 *buffer, *alignbuffer;
	unsigned long absize;

	absize = keylen + alignmask;
	buffer = kmalloc(absize, GFP_ATOMIC);
	if (!buffer)
		return -ENOMEM;

	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
	memcpy(alignbuffer, key, keylen);
	ret = cia->cia_setkey(tfm, alignbuffer, keylen);
	memset(alignbuffer, 0, keylen);
	kfree(buffer);
	return ret;

}

static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
{
	struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
	unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);

	tfm->crt_flags &= ~CRYPTO_TFM_RES_MASK;
	if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
		tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
		return -EINVAL;
	}

	if ((unsigned long)key & alignmask)
		return setkey_unaligned(tfm, key, keylen);

	return cia->cia_setkey(tfm, key, keylen);
}

static void cipher_crypt_unaligned(void (*fn)(struct crypto_tfm *, u8 *,
					      const u8 *),
				   struct crypto_tfm *tfm,
				   u8 *dst, const u8 *src)
{
	unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
	unsigned int size = crypto_tfm_alg_blocksize(tfm);
	u8 buffer[size + alignmask];
	u8 *tmp = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);

	memcpy(tmp, src, size);
	fn(tfm, tmp, tmp);
	memcpy(dst, tmp, size);
}

static void cipher_encrypt_unaligned(struct crypto_tfm *tfm,
				     u8 *dst, const u8 *src)
{
	unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;

	if (unlikely(((unsigned long)dst | (unsigned long)src) & alignmask)) {
		cipher_crypt_unaligned(cipher->cia_encrypt, tfm, dst, src);
		return;
	}

	cipher->cia_encrypt(tfm, dst, src);
}

static void cipher_decrypt_unaligned(struct crypto_tfm *tfm,
				     u8 *dst, const u8 *src)
{
	unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;

	if (unlikely(((unsigned long)dst | (unsigned long)src) & alignmask)) {
		cipher_crypt_unaligned(cipher->cia_decrypt, tfm, dst, src);
		return;
	}

	cipher->cia_decrypt(tfm, dst, src);
}

int crypto_init_cipher_ops(struct crypto_tfm *tfm)
{
	struct cipher_tfm *ops = &tfm->crt_cipher;
	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;

	ops->cit_setkey = setkey;
	ops->cit_encrypt_one = crypto_tfm_alg_alignmask(tfm) ?
		cipher_encrypt_unaligned : cipher->cia_encrypt;
	ops->cit_decrypt_one = crypto_tfm_alg_alignmask(tfm) ?
		cipher_decrypt_unaligned : cipher->cia_decrypt;

	return 0;
}

void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
{
}
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