linux/crypto/blkcipher.c
Eric Biggers 37db69e0b4 crypto: user - clean up report structure copying
There have been a pretty ridiculous number of issues with initializing
the report structures that are copied to userspace by NETLINK_CRYPTO.
Commit 4473710df1 ("crypto: user - Prepare for CRYPTO_MAX_ALG_NAME
expansion") replaced some strncpy()s with strlcpy()s, thereby
introducing information leaks.  Later two other people tried to replace
other strncpy()s with strlcpy() too, which would have introduced even
more information leaks:

    - https://lore.kernel.org/patchwork/patch/954991/
    - https://patchwork.kernel.org/patch/10434351/

Commit cac5818c25 ("crypto: user - Implement a generic crypto
statistics") also uses the buggy strlcpy() approach and therefore leaks
uninitialized memory to userspace.  A fix was proposed, but it was
originally incomplete.

Seeing as how apparently no one can get this right with the current
approach, change all the reporting functions to:

- Start by memsetting the report structure to 0.  This guarantees it's
  always initialized, regardless of what happens later.
- Initialize all strings using strscpy().  This is safe after the
  memset, ensures null termination of long strings, avoids unnecessary
  work, and avoids the -Wstringop-truncation warnings from gcc.
- Use sizeof(var) instead of sizeof(type).  This is more robust against
  copy+paste errors.

For simplicity, also reuse the -EMSGSIZE return value from nla_put().

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-11-09 17:41:39 +08:00

556 lines
15 KiB
C

/*
* Block chaining cipher operations.
*
* Generic encrypt/decrypt wrapper for ciphers, handles operations across
* multiple page boundaries by using temporary blocks. In user context,
* the kernel is given a chance to schedule us once per page.
*
* Copyright (c) 2006 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 <crypto/aead.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/cryptouser.h>
#include <linux/compiler.h>
#include <net/netlink.h>
#include "internal.h"
enum {
BLKCIPHER_WALK_PHYS = 1 << 0,
BLKCIPHER_WALK_SLOW = 1 << 1,
BLKCIPHER_WALK_COPY = 1 << 2,
BLKCIPHER_WALK_DIFF = 1 << 3,
};
static int blkcipher_walk_next(struct blkcipher_desc *desc,
struct blkcipher_walk *walk);
static int blkcipher_walk_first(struct blkcipher_desc *desc,
struct blkcipher_walk *walk);
static inline void blkcipher_map_src(struct blkcipher_walk *walk)
{
walk->src.virt.addr = scatterwalk_map(&walk->in);
}
static inline void blkcipher_map_dst(struct blkcipher_walk *walk)
{
walk->dst.virt.addr = scatterwalk_map(&walk->out);
}
static inline void blkcipher_unmap_src(struct blkcipher_walk *walk)
{
scatterwalk_unmap(walk->src.virt.addr);
}
static inline void blkcipher_unmap_dst(struct blkcipher_walk *walk)
{
scatterwalk_unmap(walk->dst.virt.addr);
}
/* Get a spot of the specified length that does not straddle a page.
* The caller needs to ensure that there is enough space for this operation.
*/
static inline u8 *blkcipher_get_spot(u8 *start, unsigned int len)
{
u8 *end_page = (u8 *)(((unsigned long)(start + len - 1)) & PAGE_MASK);
return max(start, end_page);
}
static inline void blkcipher_done_slow(struct blkcipher_walk *walk,
unsigned int bsize)
{
u8 *addr;
addr = (u8 *)ALIGN((unsigned long)walk->buffer, walk->alignmask + 1);
addr = blkcipher_get_spot(addr, bsize);
scatterwalk_copychunks(addr, &walk->out, bsize, 1);
}
static inline void blkcipher_done_fast(struct blkcipher_walk *walk,
unsigned int n)
{
if (walk->flags & BLKCIPHER_WALK_COPY) {
blkcipher_map_dst(walk);
memcpy(walk->dst.virt.addr, walk->page, n);
blkcipher_unmap_dst(walk);
} else if (!(walk->flags & BLKCIPHER_WALK_PHYS)) {
if (walk->flags & BLKCIPHER_WALK_DIFF)
blkcipher_unmap_dst(walk);
blkcipher_unmap_src(walk);
}
scatterwalk_advance(&walk->in, n);
scatterwalk_advance(&walk->out, n);
}
int blkcipher_walk_done(struct blkcipher_desc *desc,
struct blkcipher_walk *walk, int err)
{
unsigned int n; /* bytes processed */
bool more;
if (unlikely(err < 0))
goto finish;
n = walk->nbytes - err;
walk->total -= n;
more = (walk->total != 0);
if (likely(!(walk->flags & BLKCIPHER_WALK_SLOW))) {
blkcipher_done_fast(walk, n);
} else {
if (WARN_ON(err)) {
/* unexpected case; didn't process all bytes */
err = -EINVAL;
goto finish;
}
blkcipher_done_slow(walk, n);
}
scatterwalk_done(&walk->in, 0, more);
scatterwalk_done(&walk->out, 1, more);
if (more) {
crypto_yield(desc->flags);
return blkcipher_walk_next(desc, walk);
}
err = 0;
finish:
walk->nbytes = 0;
if (walk->iv != desc->info)
memcpy(desc->info, walk->iv, walk->ivsize);
if (walk->buffer != walk->page)
kfree(walk->buffer);
if (walk->page)
free_page((unsigned long)walk->page);
return err;
}
EXPORT_SYMBOL_GPL(blkcipher_walk_done);
static inline int blkcipher_next_slow(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
unsigned int bsize,
unsigned int alignmask)
{
unsigned int n;
unsigned aligned_bsize = ALIGN(bsize, alignmask + 1);
if (walk->buffer)
goto ok;
walk->buffer = walk->page;
if (walk->buffer)
goto ok;
n = aligned_bsize * 3 - (alignmask + 1) +
(alignmask & ~(crypto_tfm_ctx_alignment() - 1));
walk->buffer = kmalloc(n, GFP_ATOMIC);
if (!walk->buffer)
return blkcipher_walk_done(desc, walk, -ENOMEM);
ok:
walk->dst.virt.addr = (u8 *)ALIGN((unsigned long)walk->buffer,
alignmask + 1);
walk->dst.virt.addr = blkcipher_get_spot(walk->dst.virt.addr, bsize);
walk->src.virt.addr = blkcipher_get_spot(walk->dst.virt.addr +
aligned_bsize, bsize);
scatterwalk_copychunks(walk->src.virt.addr, &walk->in, bsize, 0);
walk->nbytes = bsize;
walk->flags |= BLKCIPHER_WALK_SLOW;
return 0;
}
static inline int blkcipher_next_copy(struct blkcipher_walk *walk)
{
u8 *tmp = walk->page;
blkcipher_map_src(walk);
memcpy(tmp, walk->src.virt.addr, walk->nbytes);
blkcipher_unmap_src(walk);
walk->src.virt.addr = tmp;
walk->dst.virt.addr = tmp;
return 0;
}
static inline int blkcipher_next_fast(struct blkcipher_desc *desc,
struct blkcipher_walk *walk)
{
unsigned long diff;
walk->src.phys.page = scatterwalk_page(&walk->in);
walk->src.phys.offset = offset_in_page(walk->in.offset);
walk->dst.phys.page = scatterwalk_page(&walk->out);
walk->dst.phys.offset = offset_in_page(walk->out.offset);
if (walk->flags & BLKCIPHER_WALK_PHYS)
return 0;
diff = walk->src.phys.offset - walk->dst.phys.offset;
diff |= walk->src.virt.page - walk->dst.virt.page;
blkcipher_map_src(walk);
walk->dst.virt.addr = walk->src.virt.addr;
if (diff) {
walk->flags |= BLKCIPHER_WALK_DIFF;
blkcipher_map_dst(walk);
}
return 0;
}
static int blkcipher_walk_next(struct blkcipher_desc *desc,
struct blkcipher_walk *walk)
{
unsigned int bsize;
unsigned int n;
int err;
n = walk->total;
if (unlikely(n < walk->cipher_blocksize)) {
desc->flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
return blkcipher_walk_done(desc, walk, -EINVAL);
}
bsize = min(walk->walk_blocksize, n);
walk->flags &= ~(BLKCIPHER_WALK_SLOW | BLKCIPHER_WALK_COPY |
BLKCIPHER_WALK_DIFF);
if (!scatterwalk_aligned(&walk->in, walk->alignmask) ||
!scatterwalk_aligned(&walk->out, walk->alignmask)) {
walk->flags |= BLKCIPHER_WALK_COPY;
if (!walk->page) {
walk->page = (void *)__get_free_page(GFP_ATOMIC);
if (!walk->page)
n = 0;
}
}
n = scatterwalk_clamp(&walk->in, n);
n = scatterwalk_clamp(&walk->out, n);
if (unlikely(n < bsize)) {
err = blkcipher_next_slow(desc, walk, bsize, walk->alignmask);
goto set_phys_lowmem;
}
walk->nbytes = n;
if (walk->flags & BLKCIPHER_WALK_COPY) {
err = blkcipher_next_copy(walk);
goto set_phys_lowmem;
}
return blkcipher_next_fast(desc, walk);
set_phys_lowmem:
if (walk->flags & BLKCIPHER_WALK_PHYS) {
walk->src.phys.page = virt_to_page(walk->src.virt.addr);
walk->dst.phys.page = virt_to_page(walk->dst.virt.addr);
walk->src.phys.offset &= PAGE_SIZE - 1;
walk->dst.phys.offset &= PAGE_SIZE - 1;
}
return err;
}
static inline int blkcipher_copy_iv(struct blkcipher_walk *walk)
{
unsigned bs = walk->walk_blocksize;
unsigned aligned_bs = ALIGN(bs, walk->alignmask + 1);
unsigned int size = aligned_bs * 2 +
walk->ivsize + max(aligned_bs, walk->ivsize) -
(walk->alignmask + 1);
u8 *iv;
size += walk->alignmask & ~(crypto_tfm_ctx_alignment() - 1);
walk->buffer = kmalloc(size, GFP_ATOMIC);
if (!walk->buffer)
return -ENOMEM;
iv = (u8 *)ALIGN((unsigned long)walk->buffer, walk->alignmask + 1);
iv = blkcipher_get_spot(iv, bs) + aligned_bs;
iv = blkcipher_get_spot(iv, bs) + aligned_bs;
iv = blkcipher_get_spot(iv, walk->ivsize);
walk->iv = memcpy(iv, walk->iv, walk->ivsize);
return 0;
}
int blkcipher_walk_virt(struct blkcipher_desc *desc,
struct blkcipher_walk *walk)
{
walk->flags &= ~BLKCIPHER_WALK_PHYS;
walk->walk_blocksize = crypto_blkcipher_blocksize(desc->tfm);
walk->cipher_blocksize = walk->walk_blocksize;
walk->ivsize = crypto_blkcipher_ivsize(desc->tfm);
walk->alignmask = crypto_blkcipher_alignmask(desc->tfm);
return blkcipher_walk_first(desc, walk);
}
EXPORT_SYMBOL_GPL(blkcipher_walk_virt);
int blkcipher_walk_phys(struct blkcipher_desc *desc,
struct blkcipher_walk *walk)
{
walk->flags |= BLKCIPHER_WALK_PHYS;
walk->walk_blocksize = crypto_blkcipher_blocksize(desc->tfm);
walk->cipher_blocksize = walk->walk_blocksize;
walk->ivsize = crypto_blkcipher_ivsize(desc->tfm);
walk->alignmask = crypto_blkcipher_alignmask(desc->tfm);
return blkcipher_walk_first(desc, walk);
}
EXPORT_SYMBOL_GPL(blkcipher_walk_phys);
static int blkcipher_walk_first(struct blkcipher_desc *desc,
struct blkcipher_walk *walk)
{
if (WARN_ON_ONCE(in_irq()))
return -EDEADLK;
walk->iv = desc->info;
walk->nbytes = walk->total;
if (unlikely(!walk->total))
return 0;
walk->buffer = NULL;
if (unlikely(((unsigned long)walk->iv & walk->alignmask))) {
int err = blkcipher_copy_iv(walk);
if (err)
return err;
}
scatterwalk_start(&walk->in, walk->in.sg);
scatterwalk_start(&walk->out, walk->out.sg);
walk->page = NULL;
return blkcipher_walk_next(desc, walk);
}
int blkcipher_walk_virt_block(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
unsigned int blocksize)
{
walk->flags &= ~BLKCIPHER_WALK_PHYS;
walk->walk_blocksize = blocksize;
walk->cipher_blocksize = crypto_blkcipher_blocksize(desc->tfm);
walk->ivsize = crypto_blkcipher_ivsize(desc->tfm);
walk->alignmask = crypto_blkcipher_alignmask(desc->tfm);
return blkcipher_walk_first(desc, walk);
}
EXPORT_SYMBOL_GPL(blkcipher_walk_virt_block);
int blkcipher_aead_walk_virt_block(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
struct crypto_aead *tfm,
unsigned int blocksize)
{
walk->flags &= ~BLKCIPHER_WALK_PHYS;
walk->walk_blocksize = blocksize;
walk->cipher_blocksize = crypto_aead_blocksize(tfm);
walk->ivsize = crypto_aead_ivsize(tfm);
walk->alignmask = crypto_aead_alignmask(tfm);
return blkcipher_walk_first(desc, walk);
}
EXPORT_SYMBOL_GPL(blkcipher_aead_walk_virt_block);
static int setkey_unaligned(struct crypto_tfm *tfm, const u8 *key,
unsigned int keylen)
{
struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;
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 = cipher->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 blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;
unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
if (keylen < cipher->min_keysize || keylen > cipher->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 cipher->setkey(tfm, key, keylen);
}
static int async_setkey(struct crypto_ablkcipher *tfm, const u8 *key,
unsigned int keylen)
{
return setkey(crypto_ablkcipher_tfm(tfm), key, keylen);
}
static int async_encrypt(struct ablkcipher_request *req)
{
struct crypto_tfm *tfm = req->base.tfm;
struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
struct blkcipher_desc desc = {
.tfm = __crypto_blkcipher_cast(tfm),
.info = req->info,
.flags = req->base.flags,
};
return alg->encrypt(&desc, req->dst, req->src, req->nbytes);
}
static int async_decrypt(struct ablkcipher_request *req)
{
struct crypto_tfm *tfm = req->base.tfm;
struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
struct blkcipher_desc desc = {
.tfm = __crypto_blkcipher_cast(tfm),
.info = req->info,
.flags = req->base.flags,
};
return alg->decrypt(&desc, req->dst, req->src, req->nbytes);
}
static unsigned int crypto_blkcipher_ctxsize(struct crypto_alg *alg, u32 type,
u32 mask)
{
struct blkcipher_alg *cipher = &alg->cra_blkcipher;
unsigned int len = alg->cra_ctxsize;
if ((mask & CRYPTO_ALG_TYPE_MASK) == CRYPTO_ALG_TYPE_MASK &&
cipher->ivsize) {
len = ALIGN(len, (unsigned long)alg->cra_alignmask + 1);
len += cipher->ivsize;
}
return len;
}
static int crypto_init_blkcipher_ops_async(struct crypto_tfm *tfm)
{
struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;
struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
crt->setkey = async_setkey;
crt->encrypt = async_encrypt;
crt->decrypt = async_decrypt;
crt->base = __crypto_ablkcipher_cast(tfm);
crt->ivsize = alg->ivsize;
return 0;
}
static int crypto_init_blkcipher_ops_sync(struct crypto_tfm *tfm)
{
struct blkcipher_tfm *crt = &tfm->crt_blkcipher;
struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
unsigned long align = crypto_tfm_alg_alignmask(tfm) + 1;
unsigned long addr;
crt->setkey = setkey;
crt->encrypt = alg->encrypt;
crt->decrypt = alg->decrypt;
addr = (unsigned long)crypto_tfm_ctx(tfm);
addr = ALIGN(addr, align);
addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
crt->iv = (void *)addr;
return 0;
}
static int crypto_init_blkcipher_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
{
struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
if (alg->ivsize > PAGE_SIZE / 8)
return -EINVAL;
if ((mask & CRYPTO_ALG_TYPE_MASK) == CRYPTO_ALG_TYPE_MASK)
return crypto_init_blkcipher_ops_sync(tfm);
else
return crypto_init_blkcipher_ops_async(tfm);
}
#ifdef CONFIG_NET
static int crypto_blkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_blkcipher rblkcipher;
memset(&rblkcipher, 0, sizeof(rblkcipher));
strscpy(rblkcipher.type, "blkcipher", sizeof(rblkcipher.type));
strscpy(rblkcipher.geniv, alg->cra_blkcipher.geniv ?: "<default>",
sizeof(rblkcipher.geniv));
rblkcipher.blocksize = alg->cra_blocksize;
rblkcipher.min_keysize = alg->cra_blkcipher.min_keysize;
rblkcipher.max_keysize = alg->cra_blkcipher.max_keysize;
rblkcipher.ivsize = alg->cra_blkcipher.ivsize;
return nla_put(skb, CRYPTOCFGA_REPORT_BLKCIPHER,
sizeof(rblkcipher), &rblkcipher);
}
#else
static int crypto_blkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
return -ENOSYS;
}
#endif
static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
__maybe_unused;
static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
{
seq_printf(m, "type : blkcipher\n");
seq_printf(m, "blocksize : %u\n", alg->cra_blocksize);
seq_printf(m, "min keysize : %u\n", alg->cra_blkcipher.min_keysize);
seq_printf(m, "max keysize : %u\n", alg->cra_blkcipher.max_keysize);
seq_printf(m, "ivsize : %u\n", alg->cra_blkcipher.ivsize);
seq_printf(m, "geniv : %s\n", alg->cra_blkcipher.geniv ?:
"<default>");
}
const struct crypto_type crypto_blkcipher_type = {
.ctxsize = crypto_blkcipher_ctxsize,
.init = crypto_init_blkcipher_ops,
#ifdef CONFIG_PROC_FS
.show = crypto_blkcipher_show,
#endif
.report = crypto_blkcipher_report,
};
EXPORT_SYMBOL_GPL(crypto_blkcipher_type);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Generic block chaining cipher type");