linux/crypto/scompress.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

326 lines
7.4 KiB
C

/*
* Synchronous Compression operations
*
* Copyright 2015 LG Electronics Inc.
* Copyright (c) 2016, Intel Corporation
* Author: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
*
* 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/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/crypto.h>
#include <linux/compiler.h>
#include <linux/vmalloc.h>
#include <crypto/algapi.h>
#include <linux/cryptouser.h>
#include <net/netlink.h>
#include <linux/scatterlist.h>
#include <crypto/scatterwalk.h>
#include <crypto/internal/acompress.h>
#include <crypto/internal/scompress.h>
#include "internal.h"
static const struct crypto_type crypto_scomp_type;
static void * __percpu *scomp_src_scratches;
static void * __percpu *scomp_dst_scratches;
static int scomp_scratch_users;
static DEFINE_MUTEX(scomp_lock);
#ifdef CONFIG_NET
static int crypto_scomp_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_comp rscomp;
memset(&rscomp, 0, sizeof(rscomp));
strscpy(rscomp.type, "scomp", sizeof(rscomp.type));
return nla_put(skb, CRYPTOCFGA_REPORT_COMPRESS,
sizeof(rscomp), &rscomp);
}
#else
static int crypto_scomp_report(struct sk_buff *skb, struct crypto_alg *alg)
{
return -ENOSYS;
}
#endif
static void crypto_scomp_show(struct seq_file *m, struct crypto_alg *alg)
__maybe_unused;
static void crypto_scomp_show(struct seq_file *m, struct crypto_alg *alg)
{
seq_puts(m, "type : scomp\n");
}
static void crypto_scomp_free_scratches(void * __percpu *scratches)
{
int i;
if (!scratches)
return;
for_each_possible_cpu(i)
vfree(*per_cpu_ptr(scratches, i));
free_percpu(scratches);
}
static void * __percpu *crypto_scomp_alloc_scratches(void)
{
void * __percpu *scratches;
int i;
scratches = alloc_percpu(void *);
if (!scratches)
return NULL;
for_each_possible_cpu(i) {
void *scratch;
scratch = vmalloc_node(SCOMP_SCRATCH_SIZE, cpu_to_node(i));
if (!scratch)
goto error;
*per_cpu_ptr(scratches, i) = scratch;
}
return scratches;
error:
crypto_scomp_free_scratches(scratches);
return NULL;
}
static void crypto_scomp_free_all_scratches(void)
{
if (!--scomp_scratch_users) {
crypto_scomp_free_scratches(scomp_src_scratches);
crypto_scomp_free_scratches(scomp_dst_scratches);
scomp_src_scratches = NULL;
scomp_dst_scratches = NULL;
}
}
static int crypto_scomp_alloc_all_scratches(void)
{
if (!scomp_scratch_users++) {
scomp_src_scratches = crypto_scomp_alloc_scratches();
if (!scomp_src_scratches)
return -ENOMEM;
scomp_dst_scratches = crypto_scomp_alloc_scratches();
if (!scomp_dst_scratches) {
crypto_scomp_free_scratches(scomp_src_scratches);
scomp_src_scratches = NULL;
return -ENOMEM;
}
}
return 0;
}
static int crypto_scomp_init_tfm(struct crypto_tfm *tfm)
{
int ret;
mutex_lock(&scomp_lock);
ret = crypto_scomp_alloc_all_scratches();
mutex_unlock(&scomp_lock);
return ret;
}
static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
{
struct crypto_acomp *tfm = crypto_acomp_reqtfm(req);
void **tfm_ctx = acomp_tfm_ctx(tfm);
struct crypto_scomp *scomp = *tfm_ctx;
void **ctx = acomp_request_ctx(req);
const int cpu = get_cpu();
u8 *scratch_src = *per_cpu_ptr(scomp_src_scratches, cpu);
u8 *scratch_dst = *per_cpu_ptr(scomp_dst_scratches, cpu);
int ret;
if (!req->src || !req->slen || req->slen > SCOMP_SCRATCH_SIZE) {
ret = -EINVAL;
goto out;
}
if (req->dst && !req->dlen) {
ret = -EINVAL;
goto out;
}
if (!req->dlen || req->dlen > SCOMP_SCRATCH_SIZE)
req->dlen = SCOMP_SCRATCH_SIZE;
scatterwalk_map_and_copy(scratch_src, req->src, 0, req->slen, 0);
if (dir)
ret = crypto_scomp_compress(scomp, scratch_src, req->slen,
scratch_dst, &req->dlen, *ctx);
else
ret = crypto_scomp_decompress(scomp, scratch_src, req->slen,
scratch_dst, &req->dlen, *ctx);
if (!ret) {
if (!req->dst) {
req->dst = sgl_alloc(req->dlen, GFP_ATOMIC, NULL);
if (!req->dst)
goto out;
}
scatterwalk_map_and_copy(scratch_dst, req->dst, 0, req->dlen,
1);
}
out:
put_cpu();
return ret;
}
static int scomp_acomp_compress(struct acomp_req *req)
{
return scomp_acomp_comp_decomp(req, 1);
}
static int scomp_acomp_decompress(struct acomp_req *req)
{
return scomp_acomp_comp_decomp(req, 0);
}
static void crypto_exit_scomp_ops_async(struct crypto_tfm *tfm)
{
struct crypto_scomp **ctx = crypto_tfm_ctx(tfm);
crypto_free_scomp(*ctx);
mutex_lock(&scomp_lock);
crypto_scomp_free_all_scratches();
mutex_unlock(&scomp_lock);
}
int crypto_init_scomp_ops_async(struct crypto_tfm *tfm)
{
struct crypto_alg *calg = tfm->__crt_alg;
struct crypto_acomp *crt = __crypto_acomp_tfm(tfm);
struct crypto_scomp **ctx = crypto_tfm_ctx(tfm);
struct crypto_scomp *scomp;
if (!crypto_mod_get(calg))
return -EAGAIN;
scomp = crypto_create_tfm(calg, &crypto_scomp_type);
if (IS_ERR(scomp)) {
crypto_mod_put(calg);
return PTR_ERR(scomp);
}
*ctx = scomp;
tfm->exit = crypto_exit_scomp_ops_async;
crt->compress = scomp_acomp_compress;
crt->decompress = scomp_acomp_decompress;
crt->dst_free = sgl_free;
crt->reqsize = sizeof(void *);
return 0;
}
struct acomp_req *crypto_acomp_scomp_alloc_ctx(struct acomp_req *req)
{
struct crypto_acomp *acomp = crypto_acomp_reqtfm(req);
struct crypto_tfm *tfm = crypto_acomp_tfm(acomp);
struct crypto_scomp **tfm_ctx = crypto_tfm_ctx(tfm);
struct crypto_scomp *scomp = *tfm_ctx;
void *ctx;
ctx = crypto_scomp_alloc_ctx(scomp);
if (IS_ERR(ctx)) {
kfree(req);
return NULL;
}
*req->__ctx = ctx;
return req;
}
void crypto_acomp_scomp_free_ctx(struct acomp_req *req)
{
struct crypto_acomp *acomp = crypto_acomp_reqtfm(req);
struct crypto_tfm *tfm = crypto_acomp_tfm(acomp);
struct crypto_scomp **tfm_ctx = crypto_tfm_ctx(tfm);
struct crypto_scomp *scomp = *tfm_ctx;
void *ctx = *req->__ctx;
if (ctx)
crypto_scomp_free_ctx(scomp, ctx);
}
static const struct crypto_type crypto_scomp_type = {
.extsize = crypto_alg_extsize,
.init_tfm = crypto_scomp_init_tfm,
#ifdef CONFIG_PROC_FS
.show = crypto_scomp_show,
#endif
.report = crypto_scomp_report,
.maskclear = ~CRYPTO_ALG_TYPE_MASK,
.maskset = CRYPTO_ALG_TYPE_MASK,
.type = CRYPTO_ALG_TYPE_SCOMPRESS,
.tfmsize = offsetof(struct crypto_scomp, base),
};
int crypto_register_scomp(struct scomp_alg *alg)
{
struct crypto_alg *base = &alg->base;
base->cra_type = &crypto_scomp_type;
base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
base->cra_flags |= CRYPTO_ALG_TYPE_SCOMPRESS;
return crypto_register_alg(base);
}
EXPORT_SYMBOL_GPL(crypto_register_scomp);
int crypto_unregister_scomp(struct scomp_alg *alg)
{
return crypto_unregister_alg(&alg->base);
}
EXPORT_SYMBOL_GPL(crypto_unregister_scomp);
int crypto_register_scomps(struct scomp_alg *algs, int count)
{
int i, ret;
for (i = 0; i < count; i++) {
ret = crypto_register_scomp(&algs[i]);
if (ret)
goto err;
}
return 0;
err:
for (--i; i >= 0; --i)
crypto_unregister_scomp(&algs[i]);
return ret;
}
EXPORT_SYMBOL_GPL(crypto_register_scomps);
void crypto_unregister_scomps(struct scomp_alg *algs, int count)
{
int i;
for (i = count - 1; i >= 0; --i)
crypto_unregister_scomp(&algs[i]);
}
EXPORT_SYMBOL_GPL(crypto_unregister_scomps);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Synchronous compression type");