linux/crypto/shash.c

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/*
* Synchronous Cryptographic Hash operations.
*
* Copyright (c) 2008 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/scatterwalk.h>
#include <crypto/internal/hash.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/cryptouser.h>
#include <net/netlink.h>
#include <linux/compiler.h>
#include "internal.h"
static const struct crypto_type crypto_shash_type;
crypto: hmac - require that the underlying hash algorithm is unkeyed Because the HMAC template didn't check that its underlying hash algorithm is unkeyed, trying to use "hmac(hmac(sha3-512-generic))" through AF_ALG or through KEYCTL_DH_COMPUTE resulted in the inner HMAC being used without having been keyed, resulting in sha3_update() being called without sha3_init(), causing a stack buffer overflow. This is a very old bug, but it seems to have only started causing real problems when SHA-3 support was added (requires CONFIG_CRYPTO_SHA3) because the innermost hash's state is ->import()ed from a zeroed buffer, and it just so happens that other hash algorithms are fine with that, but SHA-3 is not. However, there could be arch or hardware-dependent hash algorithms also affected; I couldn't test everything. Fix the bug by introducing a function crypto_shash_alg_has_setkey() which tests whether a shash algorithm is keyed. Then update the HMAC template to require that its underlying hash algorithm is unkeyed. Here is a reproducer: #include <linux/if_alg.h> #include <sys/socket.h> int main() { int algfd; struct sockaddr_alg addr = { .salg_type = "hash", .salg_name = "hmac(hmac(sha3-512-generic))", }; char key[4096] = { 0 }; algfd = socket(AF_ALG, SOCK_SEQPACKET, 0); bind(algfd, (const struct sockaddr *)&addr, sizeof(addr)); setsockopt(algfd, SOL_ALG, ALG_SET_KEY, key, sizeof(key)); } Here was the KASAN report from syzbot: BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:341 [inline] BUG: KASAN: stack-out-of-bounds in sha3_update+0xdf/0x2e0 crypto/sha3_generic.c:161 Write of size 4096 at addr ffff8801cca07c40 by task syzkaller076574/3044 CPU: 1 PID: 3044 Comm: syzkaller076574 Not tainted 4.14.0-mm1+ #25 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 print_address_description+0x73/0x250 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x25b/0x340 mm/kasan/report.c:409 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x137/0x190 mm/kasan/kasan.c:267 memcpy+0x37/0x50 mm/kasan/kasan.c:303 memcpy include/linux/string.h:341 [inline] sha3_update+0xdf/0x2e0 crypto/sha3_generic.c:161 crypto_shash_update+0xcb/0x220 crypto/shash.c:109 shash_finup_unaligned+0x2a/0x60 crypto/shash.c:151 crypto_shash_finup+0xc4/0x120 crypto/shash.c:165 hmac_finup+0x182/0x330 crypto/hmac.c:152 crypto_shash_finup+0xc4/0x120 crypto/shash.c:165 shash_digest_unaligned+0x9e/0xd0 crypto/shash.c:172 crypto_shash_digest+0xc4/0x120 crypto/shash.c:186 hmac_setkey+0x36a/0x690 crypto/hmac.c:66 crypto_shash_setkey+0xad/0x190 crypto/shash.c:64 shash_async_setkey+0x47/0x60 crypto/shash.c:207 crypto_ahash_setkey+0xaf/0x180 crypto/ahash.c:200 hash_setkey+0x40/0x90 crypto/algif_hash.c:446 alg_setkey crypto/af_alg.c:221 [inline] alg_setsockopt+0x2a1/0x350 crypto/af_alg.c:254 SYSC_setsockopt net/socket.c:1851 [inline] SyS_setsockopt+0x189/0x360 net/socket.c:1830 entry_SYSCALL_64_fastpath+0x1f/0x96 Reported-by: syzbot <syzkaller@googlegroups.com> Cc: <stable@vger.kernel.org> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-11-29 02:01:38 +00:00
int shash_no_setkey(struct crypto_shash *tfm, const u8 *key,
unsigned int keylen)
{
return -ENOSYS;
}
crypto: hmac - require that the underlying hash algorithm is unkeyed Because the HMAC template didn't check that its underlying hash algorithm is unkeyed, trying to use "hmac(hmac(sha3-512-generic))" through AF_ALG or through KEYCTL_DH_COMPUTE resulted in the inner HMAC being used without having been keyed, resulting in sha3_update() being called without sha3_init(), causing a stack buffer overflow. This is a very old bug, but it seems to have only started causing real problems when SHA-3 support was added (requires CONFIG_CRYPTO_SHA3) because the innermost hash's state is ->import()ed from a zeroed buffer, and it just so happens that other hash algorithms are fine with that, but SHA-3 is not. However, there could be arch or hardware-dependent hash algorithms also affected; I couldn't test everything. Fix the bug by introducing a function crypto_shash_alg_has_setkey() which tests whether a shash algorithm is keyed. Then update the HMAC template to require that its underlying hash algorithm is unkeyed. Here is a reproducer: #include <linux/if_alg.h> #include <sys/socket.h> int main() { int algfd; struct sockaddr_alg addr = { .salg_type = "hash", .salg_name = "hmac(hmac(sha3-512-generic))", }; char key[4096] = { 0 }; algfd = socket(AF_ALG, SOCK_SEQPACKET, 0); bind(algfd, (const struct sockaddr *)&addr, sizeof(addr)); setsockopt(algfd, SOL_ALG, ALG_SET_KEY, key, sizeof(key)); } Here was the KASAN report from syzbot: BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:341 [inline] BUG: KASAN: stack-out-of-bounds in sha3_update+0xdf/0x2e0 crypto/sha3_generic.c:161 Write of size 4096 at addr ffff8801cca07c40 by task syzkaller076574/3044 CPU: 1 PID: 3044 Comm: syzkaller076574 Not tainted 4.14.0-mm1+ #25 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 print_address_description+0x73/0x250 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x25b/0x340 mm/kasan/report.c:409 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x137/0x190 mm/kasan/kasan.c:267 memcpy+0x37/0x50 mm/kasan/kasan.c:303 memcpy include/linux/string.h:341 [inline] sha3_update+0xdf/0x2e0 crypto/sha3_generic.c:161 crypto_shash_update+0xcb/0x220 crypto/shash.c:109 shash_finup_unaligned+0x2a/0x60 crypto/shash.c:151 crypto_shash_finup+0xc4/0x120 crypto/shash.c:165 hmac_finup+0x182/0x330 crypto/hmac.c:152 crypto_shash_finup+0xc4/0x120 crypto/shash.c:165 shash_digest_unaligned+0x9e/0xd0 crypto/shash.c:172 crypto_shash_digest+0xc4/0x120 crypto/shash.c:186 hmac_setkey+0x36a/0x690 crypto/hmac.c:66 crypto_shash_setkey+0xad/0x190 crypto/shash.c:64 shash_async_setkey+0x47/0x60 crypto/shash.c:207 crypto_ahash_setkey+0xaf/0x180 crypto/ahash.c:200 hash_setkey+0x40/0x90 crypto/algif_hash.c:446 alg_setkey crypto/af_alg.c:221 [inline] alg_setsockopt+0x2a1/0x350 crypto/af_alg.c:254 SYSC_setsockopt net/socket.c:1851 [inline] SyS_setsockopt+0x189/0x360 net/socket.c:1830 entry_SYSCALL_64_fastpath+0x1f/0x96 Reported-by: syzbot <syzkaller@googlegroups.com> Cc: <stable@vger.kernel.org> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-11-29 02:01:38 +00:00
EXPORT_SYMBOL_GPL(shash_no_setkey);
static int shash_setkey_unaligned(struct crypto_shash *tfm, const u8 *key,
unsigned int keylen)
{
struct shash_alg *shash = crypto_shash_alg(tfm);
unsigned long alignmask = crypto_shash_alignmask(tfm);
unsigned long absize;
u8 *buffer, *alignbuffer;
int err;
absize = keylen + (alignmask & ~(crypto_tfm_ctx_alignment() - 1));
buffer = kmalloc(absize, GFP_ATOMIC);
if (!buffer)
return -ENOMEM;
alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
memcpy(alignbuffer, key, keylen);
err = shash->setkey(tfm, alignbuffer, keylen);
kzfree(buffer);
return err;
}
int crypto_shash_setkey(struct crypto_shash *tfm, const u8 *key,
unsigned int keylen)
{
struct shash_alg *shash = crypto_shash_alg(tfm);
unsigned long alignmask = crypto_shash_alignmask(tfm);
crypto: hash - prevent using keyed hashes without setting key Currently, almost none of the keyed hash algorithms check whether a key has been set before proceeding. Some algorithms are okay with this and will effectively just use a key of all 0's or some other bogus default. However, others will severely break, as demonstrated using "hmac(sha3-512-generic)", the unkeyed use of which causes a kernel crash via a (potentially exploitable) stack buffer overflow. A while ago, this problem was solved for AF_ALG by pairing each hash transform with a 'has_key' bool. However, there are still other places in the kernel where userspace can specify an arbitrary hash algorithm by name, and the kernel uses it as unkeyed hash without checking whether it is really unkeyed. Examples of this include: - KEYCTL_DH_COMPUTE, via the KDF extension - dm-verity - dm-crypt, via the ESSIV support - dm-integrity, via the "internal hash" mode with no key given - drbd (Distributed Replicated Block Device) This bug is especially bad for KEYCTL_DH_COMPUTE as that requires no privileges to call. Fix the bug for all users by adding a flag CRYPTO_TFM_NEED_KEY to the ->crt_flags of each hash transform that indicates whether the transform still needs to be keyed or not. Then, make the hash init, import, and digest functions return -ENOKEY if the key is still needed. The new flag also replaces the 'has_key' bool which algif_hash was previously using, thereby simplifying the algif_hash implementation. Reported-by: syzbot <syzkaller@googlegroups.com> Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-01-03 19:16:27 +00:00
int err;
if ((unsigned long)key & alignmask)
crypto: hash - prevent using keyed hashes without setting key Currently, almost none of the keyed hash algorithms check whether a key has been set before proceeding. Some algorithms are okay with this and will effectively just use a key of all 0's or some other bogus default. However, others will severely break, as demonstrated using "hmac(sha3-512-generic)", the unkeyed use of which causes a kernel crash via a (potentially exploitable) stack buffer overflow. A while ago, this problem was solved for AF_ALG by pairing each hash transform with a 'has_key' bool. However, there are still other places in the kernel where userspace can specify an arbitrary hash algorithm by name, and the kernel uses it as unkeyed hash without checking whether it is really unkeyed. Examples of this include: - KEYCTL_DH_COMPUTE, via the KDF extension - dm-verity - dm-crypt, via the ESSIV support - dm-integrity, via the "internal hash" mode with no key given - drbd (Distributed Replicated Block Device) This bug is especially bad for KEYCTL_DH_COMPUTE as that requires no privileges to call. Fix the bug for all users by adding a flag CRYPTO_TFM_NEED_KEY to the ->crt_flags of each hash transform that indicates whether the transform still needs to be keyed or not. Then, make the hash init, import, and digest functions return -ENOKEY if the key is still needed. The new flag also replaces the 'has_key' bool which algif_hash was previously using, thereby simplifying the algif_hash implementation. Reported-by: syzbot <syzkaller@googlegroups.com> Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-01-03 19:16:27 +00:00
err = shash_setkey_unaligned(tfm, key, keylen);
else
err = shash->setkey(tfm, key, keylen);
if (err)
return err;
crypto: hash - prevent using keyed hashes without setting key Currently, almost none of the keyed hash algorithms check whether a key has been set before proceeding. Some algorithms are okay with this and will effectively just use a key of all 0's or some other bogus default. However, others will severely break, as demonstrated using "hmac(sha3-512-generic)", the unkeyed use of which causes a kernel crash via a (potentially exploitable) stack buffer overflow. A while ago, this problem was solved for AF_ALG by pairing each hash transform with a 'has_key' bool. However, there are still other places in the kernel where userspace can specify an arbitrary hash algorithm by name, and the kernel uses it as unkeyed hash without checking whether it is really unkeyed. Examples of this include: - KEYCTL_DH_COMPUTE, via the KDF extension - dm-verity - dm-crypt, via the ESSIV support - dm-integrity, via the "internal hash" mode with no key given - drbd (Distributed Replicated Block Device) This bug is especially bad for KEYCTL_DH_COMPUTE as that requires no privileges to call. Fix the bug for all users by adding a flag CRYPTO_TFM_NEED_KEY to the ->crt_flags of each hash transform that indicates whether the transform still needs to be keyed or not. Then, make the hash init, import, and digest functions return -ENOKEY if the key is still needed. The new flag also replaces the 'has_key' bool which algif_hash was previously using, thereby simplifying the algif_hash implementation. Reported-by: syzbot <syzkaller@googlegroups.com> Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-01-03 19:16:27 +00:00
crypto_shash_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
return 0;
}
EXPORT_SYMBOL_GPL(crypto_shash_setkey);
static int shash_update_unaligned(struct shash_desc *desc, const u8 *data,
unsigned int len)
{
struct crypto_shash *tfm = desc->tfm;
struct shash_alg *shash = crypto_shash_alg(tfm);
unsigned long alignmask = crypto_shash_alignmask(tfm);
unsigned int unaligned_len = alignmask + 1 -
((unsigned long)data & alignmask);
/*
* We cannot count on __aligned() working for large values:
* https://patchwork.kernel.org/patch/9507697/
*/
u8 ubuf[MAX_ALGAPI_ALIGNMASK * 2];
u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1);
int err;
if (WARN_ON(buf + unaligned_len > ubuf + sizeof(ubuf)))
return -EINVAL;
if (unaligned_len > len)
unaligned_len = len;
memcpy(buf, data, unaligned_len);
err = shash->update(desc, buf, unaligned_len);
memset(buf, 0, unaligned_len);
return err ?:
shash->update(desc, data + unaligned_len, len - unaligned_len);
}
int crypto_shash_update(struct shash_desc *desc, const u8 *data,
unsigned int len)
{
struct crypto_shash *tfm = desc->tfm;
struct shash_alg *shash = crypto_shash_alg(tfm);
unsigned long alignmask = crypto_shash_alignmask(tfm);
if ((unsigned long)data & alignmask)
return shash_update_unaligned(desc, data, len);
return shash->update(desc, data, len);
}
EXPORT_SYMBOL_GPL(crypto_shash_update);
static int shash_final_unaligned(struct shash_desc *desc, u8 *out)
{
struct crypto_shash *tfm = desc->tfm;
unsigned long alignmask = crypto_shash_alignmask(tfm);
struct shash_alg *shash = crypto_shash_alg(tfm);
unsigned int ds = crypto_shash_digestsize(tfm);
/*
* We cannot count on __aligned() working for large values:
* https://patchwork.kernel.org/patch/9507697/
*/
u8 ubuf[MAX_ALGAPI_ALIGNMASK + HASH_MAX_DIGESTSIZE];
u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1);
int err;
if (WARN_ON(buf + ds > ubuf + sizeof(ubuf)))
return -EINVAL;
err = shash->final(desc, buf);
if (err)
goto out;
memcpy(out, buf, ds);
out:
memset(buf, 0, ds);
return err;
}
int crypto_shash_final(struct shash_desc *desc, u8 *out)
{
struct crypto_shash *tfm = desc->tfm;
struct shash_alg *shash = crypto_shash_alg(tfm);
unsigned long alignmask = crypto_shash_alignmask(tfm);
if ((unsigned long)out & alignmask)
return shash_final_unaligned(desc, out);
return shash->final(desc, out);
}
EXPORT_SYMBOL_GPL(crypto_shash_final);
static int shash_finup_unaligned(struct shash_desc *desc, const u8 *data,
unsigned int len, u8 *out)
{
return crypto_shash_update(desc, data, len) ?:
crypto_shash_final(desc, out);
}
int crypto_shash_finup(struct shash_desc *desc, const u8 *data,
unsigned int len, u8 *out)
{
struct crypto_shash *tfm = desc->tfm;
struct shash_alg *shash = crypto_shash_alg(tfm);
unsigned long alignmask = crypto_shash_alignmask(tfm);
if (((unsigned long)data | (unsigned long)out) & alignmask)
return shash_finup_unaligned(desc, data, len, out);
return shash->finup(desc, data, len, out);
}
EXPORT_SYMBOL_GPL(crypto_shash_finup);
static int shash_digest_unaligned(struct shash_desc *desc, const u8 *data,
unsigned int len, u8 *out)
{
return crypto_shash_init(desc) ?:
crypto_shash_finup(desc, data, len, out);
}
int crypto_shash_digest(struct shash_desc *desc, const u8 *data,
unsigned int len, u8 *out)
{
struct crypto_shash *tfm = desc->tfm;
struct shash_alg *shash = crypto_shash_alg(tfm);
unsigned long alignmask = crypto_shash_alignmask(tfm);
crypto: hash - prevent using keyed hashes without setting key Currently, almost none of the keyed hash algorithms check whether a key has been set before proceeding. Some algorithms are okay with this and will effectively just use a key of all 0's or some other bogus default. However, others will severely break, as demonstrated using "hmac(sha3-512-generic)", the unkeyed use of which causes a kernel crash via a (potentially exploitable) stack buffer overflow. A while ago, this problem was solved for AF_ALG by pairing each hash transform with a 'has_key' bool. However, there are still other places in the kernel where userspace can specify an arbitrary hash algorithm by name, and the kernel uses it as unkeyed hash without checking whether it is really unkeyed. Examples of this include: - KEYCTL_DH_COMPUTE, via the KDF extension - dm-verity - dm-crypt, via the ESSIV support - dm-integrity, via the "internal hash" mode with no key given - drbd (Distributed Replicated Block Device) This bug is especially bad for KEYCTL_DH_COMPUTE as that requires no privileges to call. Fix the bug for all users by adding a flag CRYPTO_TFM_NEED_KEY to the ->crt_flags of each hash transform that indicates whether the transform still needs to be keyed or not. Then, make the hash init, import, and digest functions return -ENOKEY if the key is still needed. The new flag also replaces the 'has_key' bool which algif_hash was previously using, thereby simplifying the algif_hash implementation. Reported-by: syzbot <syzkaller@googlegroups.com> Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-01-03 19:16:27 +00:00
if (crypto_shash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
return -ENOKEY;
if (((unsigned long)data | (unsigned long)out) & alignmask)
return shash_digest_unaligned(desc, data, len, out);
return shash->digest(desc, data, len, out);
}
EXPORT_SYMBOL_GPL(crypto_shash_digest);
static int shash_default_export(struct shash_desc *desc, void *out)
{
memcpy(out, shash_desc_ctx(desc), crypto_shash_descsize(desc->tfm));
return 0;
}
static int shash_default_import(struct shash_desc *desc, const void *in)
{
memcpy(shash_desc_ctx(desc), in, crypto_shash_descsize(desc->tfm));
return 0;
}
static int shash_async_setkey(struct crypto_ahash *tfm, const u8 *key,
unsigned int keylen)
{
struct crypto_shash **ctx = crypto_ahash_ctx(tfm);
return crypto_shash_setkey(*ctx, key, keylen);
}
static int shash_async_init(struct ahash_request *req)
{
struct crypto_shash **ctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
struct shash_desc *desc = ahash_request_ctx(req);
desc->tfm = *ctx;
desc->flags = req->base.flags;
return crypto_shash_init(desc);
}
int shash_ahash_update(struct ahash_request *req, struct shash_desc *desc)
{
struct crypto_hash_walk walk;
int nbytes;
for (nbytes = crypto_hash_walk_first(req, &walk); nbytes > 0;
nbytes = crypto_hash_walk_done(&walk, nbytes))
nbytes = crypto_shash_update(desc, walk.data, nbytes);
return nbytes;
}
EXPORT_SYMBOL_GPL(shash_ahash_update);
static int shash_async_update(struct ahash_request *req)
{
return shash_ahash_update(req, ahash_request_ctx(req));
}
static int shash_async_final(struct ahash_request *req)
{
return crypto_shash_final(ahash_request_ctx(req), req->result);
}
int shash_ahash_finup(struct ahash_request *req, struct shash_desc *desc)
{
struct crypto_hash_walk walk;
int nbytes;
nbytes = crypto_hash_walk_first(req, &walk);
if (!nbytes)
return crypto_shash_final(desc, req->result);
do {
nbytes = crypto_hash_walk_last(&walk) ?
crypto_shash_finup(desc, walk.data, nbytes,
req->result) :
crypto_shash_update(desc, walk.data, nbytes);
nbytes = crypto_hash_walk_done(&walk, nbytes);
} while (nbytes > 0);
return nbytes;
}
EXPORT_SYMBOL_GPL(shash_ahash_finup);
static int shash_async_finup(struct ahash_request *req)
{
struct crypto_shash **ctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
struct shash_desc *desc = ahash_request_ctx(req);
desc->tfm = *ctx;
desc->flags = req->base.flags;
return shash_ahash_finup(req, desc);
}
int shash_ahash_digest(struct ahash_request *req, struct shash_desc *desc)
{
unsigned int nbytes = req->nbytes;
struct scatterlist *sg;
unsigned int offset;
int err;
if (nbytes &&
(sg = req->src, offset = sg->offset,
nbytes < min(sg->length, ((unsigned int)(PAGE_SIZE)) - offset))) {
void *data;
data = kmap_atomic(sg_page(sg));
err = crypto_shash_digest(desc, data + offset, nbytes,
req->result);
kunmap_atomic(data);
crypto_yield(desc->flags);
} else
err = crypto_shash_init(desc) ?:
shash_ahash_finup(req, desc);
return err;
}
EXPORT_SYMBOL_GPL(shash_ahash_digest);
static int shash_async_digest(struct ahash_request *req)
{
struct crypto_shash **ctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
struct shash_desc *desc = ahash_request_ctx(req);
desc->tfm = *ctx;
desc->flags = req->base.flags;
return shash_ahash_digest(req, desc);
}
static int shash_async_export(struct ahash_request *req, void *out)
{
return crypto_shash_export(ahash_request_ctx(req), out);
}
static int shash_async_import(struct ahash_request *req, const void *in)
{
struct crypto_shash **ctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
struct shash_desc *desc = ahash_request_ctx(req);
desc->tfm = *ctx;
desc->flags = req->base.flags;
return crypto_shash_import(desc, in);
}
static void crypto_exit_shash_ops_async(struct crypto_tfm *tfm)
{
struct crypto_shash **ctx = crypto_tfm_ctx(tfm);
crypto_free_shash(*ctx);
}
int crypto_init_shash_ops_async(struct crypto_tfm *tfm)
{
struct crypto_alg *calg = tfm->__crt_alg;
struct shash_alg *alg = __crypto_shash_alg(calg);
struct crypto_ahash *crt = __crypto_ahash_cast(tfm);
struct crypto_shash **ctx = crypto_tfm_ctx(tfm);
struct crypto_shash *shash;
if (!crypto_mod_get(calg))
return -EAGAIN;
shash = crypto_create_tfm(calg, &crypto_shash_type);
if (IS_ERR(shash)) {
crypto_mod_put(calg);
return PTR_ERR(shash);
}
*ctx = shash;
tfm->exit = crypto_exit_shash_ops_async;
crt->init = shash_async_init;
crt->update = shash_async_update;
crt->final = shash_async_final;
crt->finup = shash_async_finup;
crt->digest = shash_async_digest;
crt->setkey = shash_async_setkey;
crypto: hash - prevent using keyed hashes without setting key Currently, almost none of the keyed hash algorithms check whether a key has been set before proceeding. Some algorithms are okay with this and will effectively just use a key of all 0's or some other bogus default. However, others will severely break, as demonstrated using "hmac(sha3-512-generic)", the unkeyed use of which causes a kernel crash via a (potentially exploitable) stack buffer overflow. A while ago, this problem was solved for AF_ALG by pairing each hash transform with a 'has_key' bool. However, there are still other places in the kernel where userspace can specify an arbitrary hash algorithm by name, and the kernel uses it as unkeyed hash without checking whether it is really unkeyed. Examples of this include: - KEYCTL_DH_COMPUTE, via the KDF extension - dm-verity - dm-crypt, via the ESSIV support - dm-integrity, via the "internal hash" mode with no key given - drbd (Distributed Replicated Block Device) This bug is especially bad for KEYCTL_DH_COMPUTE as that requires no privileges to call. Fix the bug for all users by adding a flag CRYPTO_TFM_NEED_KEY to the ->crt_flags of each hash transform that indicates whether the transform still needs to be keyed or not. Then, make the hash init, import, and digest functions return -ENOKEY if the key is still needed. The new flag also replaces the 'has_key' bool which algif_hash was previously using, thereby simplifying the algif_hash implementation. Reported-by: syzbot <syzkaller@googlegroups.com> Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-01-03 19:16:27 +00:00
crypto_ahash_set_flags(crt, crypto_shash_get_flags(shash) &
CRYPTO_TFM_NEED_KEY);
if (alg->export)
crt->export = shash_async_export;
if (alg->import)
crt->import = shash_async_import;
crt->reqsize = sizeof(struct shash_desc) + crypto_shash_descsize(shash);
return 0;
}
static int crypto_shash_init_tfm(struct crypto_tfm *tfm)
{
struct crypto_shash *hash = __crypto_shash_cast(tfm);
crypto: hash - prevent using keyed hashes without setting key Currently, almost none of the keyed hash algorithms check whether a key has been set before proceeding. Some algorithms are okay with this and will effectively just use a key of all 0's or some other bogus default. However, others will severely break, as demonstrated using "hmac(sha3-512-generic)", the unkeyed use of which causes a kernel crash via a (potentially exploitable) stack buffer overflow. A while ago, this problem was solved for AF_ALG by pairing each hash transform with a 'has_key' bool. However, there are still other places in the kernel where userspace can specify an arbitrary hash algorithm by name, and the kernel uses it as unkeyed hash without checking whether it is really unkeyed. Examples of this include: - KEYCTL_DH_COMPUTE, via the KDF extension - dm-verity - dm-crypt, via the ESSIV support - dm-integrity, via the "internal hash" mode with no key given - drbd (Distributed Replicated Block Device) This bug is especially bad for KEYCTL_DH_COMPUTE as that requires no privileges to call. Fix the bug for all users by adding a flag CRYPTO_TFM_NEED_KEY to the ->crt_flags of each hash transform that indicates whether the transform still needs to be keyed or not. Then, make the hash init, import, and digest functions return -ENOKEY if the key is still needed. The new flag also replaces the 'has_key' bool which algif_hash was previously using, thereby simplifying the algif_hash implementation. Reported-by: syzbot <syzkaller@googlegroups.com> Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-01-03 19:16:27 +00:00
struct shash_alg *alg = crypto_shash_alg(hash);
hash->descsize = alg->descsize;
if (crypto_shash_alg_has_setkey(alg) &&
!(alg->base.cra_flags & CRYPTO_ALG_OPTIONAL_KEY))
crypto_shash_set_flags(hash, CRYPTO_TFM_NEED_KEY);
return 0;
}
#ifdef CONFIG_NET
static int crypto_shash_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_hash rhash;
struct shash_alg *salg = __crypto_shash_alg(alg);
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 4473710df1f8 ("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 cac5818c25d0 ("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>
2018-11-03 21:56:03 +00:00
memset(&rhash, 0, sizeof(rhash));
strscpy(rhash.type, "shash", sizeof(rhash.type));
rhash.blocksize = alg->cra_blocksize;
rhash.digestsize = salg->digestsize;
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 4473710df1f8 ("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 cac5818c25d0 ("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>
2018-11-03 21:56:03 +00:00
return nla_put(skb, CRYPTOCFGA_REPORT_HASH, sizeof(rhash), &rhash);
}
#else
static int crypto_shash_report(struct sk_buff *skb, struct crypto_alg *alg)
{
return -ENOSYS;
}
#endif
static void crypto_shash_show(struct seq_file *m, struct crypto_alg *alg)
__maybe_unused;
static void crypto_shash_show(struct seq_file *m, struct crypto_alg *alg)
{
struct shash_alg *salg = __crypto_shash_alg(alg);
seq_printf(m, "type : shash\n");
seq_printf(m, "blocksize : %u\n", alg->cra_blocksize);
seq_printf(m, "digestsize : %u\n", salg->digestsize);
}
static const struct crypto_type crypto_shash_type = {
.extsize = crypto_alg_extsize,
.init_tfm = crypto_shash_init_tfm,
#ifdef CONFIG_PROC_FS
.show = crypto_shash_show,
#endif
.report = crypto_shash_report,
.maskclear = ~CRYPTO_ALG_TYPE_MASK,
.maskset = CRYPTO_ALG_TYPE_MASK,
.type = CRYPTO_ALG_TYPE_SHASH,
.tfmsize = offsetof(struct crypto_shash, base),
};
struct crypto_shash *crypto_alloc_shash(const char *alg_name, u32 type,
u32 mask)
{
return crypto_alloc_tfm(alg_name, &crypto_shash_type, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_alloc_shash);
static int shash_prepare_alg(struct shash_alg *alg)
{
struct crypto_alg *base = &alg->base;
if (alg->digestsize > HASH_MAX_DIGESTSIZE ||
alg->descsize > HASH_MAX_DESCSIZE ||
alg->statesize > HASH_MAX_STATESIZE)
return -EINVAL;
base->cra_type = &crypto_shash_type;
base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
base->cra_flags |= CRYPTO_ALG_TYPE_SHASH;
if (!alg->finup)
alg->finup = shash_finup_unaligned;
if (!alg->digest)
alg->digest = shash_digest_unaligned;
if (!alg->export) {
alg->export = shash_default_export;
alg->import = shash_default_import;
alg->statesize = alg->descsize;
}
if (!alg->setkey)
alg->setkey = shash_no_setkey;
return 0;
}
int crypto_register_shash(struct shash_alg *alg)
{
struct crypto_alg *base = &alg->base;
int err;
err = shash_prepare_alg(alg);
if (err)
return err;
return crypto_register_alg(base);
}
EXPORT_SYMBOL_GPL(crypto_register_shash);
int crypto_unregister_shash(struct shash_alg *alg)
{
return crypto_unregister_alg(&alg->base);
}
EXPORT_SYMBOL_GPL(crypto_unregister_shash);
int crypto_register_shashes(struct shash_alg *algs, int count)
{
int i, ret;
for (i = 0; i < count; i++) {
ret = crypto_register_shash(&algs[i]);
if (ret)
goto err;
}
return 0;
err:
for (--i; i >= 0; --i)
crypto_unregister_shash(&algs[i]);
return ret;
}
EXPORT_SYMBOL_GPL(crypto_register_shashes);
int crypto_unregister_shashes(struct shash_alg *algs, int count)
{
int i, ret;
for (i = count - 1; i >= 0; --i) {
ret = crypto_unregister_shash(&algs[i]);
if (ret)
pr_err("Failed to unregister %s %s: %d\n",
algs[i].base.cra_driver_name,
algs[i].base.cra_name, ret);
}
return 0;
}
EXPORT_SYMBOL_GPL(crypto_unregister_shashes);
int shash_register_instance(struct crypto_template *tmpl,
struct shash_instance *inst)
{
int err;
err = shash_prepare_alg(&inst->alg);
if (err)
return err;
return crypto_register_instance(tmpl, shash_crypto_instance(inst));
}
EXPORT_SYMBOL_GPL(shash_register_instance);
void shash_free_instance(struct crypto_instance *inst)
{
crypto_drop_spawn(crypto_instance_ctx(inst));
kfree(shash_instance(inst));
}
EXPORT_SYMBOL_GPL(shash_free_instance);
int crypto_init_shash_spawn(struct crypto_shash_spawn *spawn,
struct shash_alg *alg,
struct crypto_instance *inst)
{
return crypto_init_spawn2(&spawn->base, &alg->base, inst,
&crypto_shash_type);
}
EXPORT_SYMBOL_GPL(crypto_init_shash_spawn);
struct shash_alg *shash_attr_alg(struct rtattr *rta, u32 type, u32 mask)
{
struct crypto_alg *alg;
alg = crypto_attr_alg2(rta, &crypto_shash_type, type, mask);
return IS_ERR(alg) ? ERR_CAST(alg) :
container_of(alg, struct shash_alg, base);
}
EXPORT_SYMBOL_GPL(shash_attr_alg);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Synchronous cryptographic hash type");