linux/crypto/dh_helper.c

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (c) 2016, Intel Corporation
* Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
*/
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/err.h>
#include <linux/string.h>
#include <crypto/dh.h>
#include <crypto/kpp.h>
#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 3 * sizeof(int))
static inline u8 *dh_pack_data(u8 *dst, u8 *end, const void *src, size_t size)
{
if (!dst || size > end - dst)
return NULL;
memcpy(dst, src, size);
return dst + size;
}
static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size)
{
memcpy(dst, src, size);
return src + size;
}
static inline unsigned int dh_data_size(const struct dh *p)
{
return p->key_size + p->p_size + p->g_size;
}
unsigned int crypto_dh_key_len(const struct dh *p)
{
return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p);
}
EXPORT_SYMBOL_GPL(crypto_dh_key_len);
int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params)
{
u8 *ptr = buf;
u8 * const end = ptr + len;
struct kpp_secret secret = {
.type = CRYPTO_KPP_SECRET_TYPE_DH,
.len = len
};
if (unlikely(!len))
return -EINVAL;
ptr = dh_pack_data(ptr, end, &secret, sizeof(secret));
ptr = dh_pack_data(ptr, end, &params->key_size,
sizeof(params->key_size));
ptr = dh_pack_data(ptr, end, &params->p_size, sizeof(params->p_size));
ptr = dh_pack_data(ptr, end, &params->g_size, sizeof(params->g_size));
ptr = dh_pack_data(ptr, end, params->key, params->key_size);
ptr = dh_pack_data(ptr, end, params->p, params->p_size);
ptr = dh_pack_data(ptr, end, params->g, params->g_size);
if (ptr != end)
return -EINVAL;
return 0;
}
EXPORT_SYMBOL_GPL(crypto_dh_encode_key);
crypto: dh - split out deserialization code from crypto_dh_decode() A subsequent commit will introduce "dh" wrapping templates of the form "ffdhe2048(dh)", "ffdhe3072(dh)" and so on in order to provide built-in support for the well-known safe-prime ffdhe group parameters specified in RFC 7919. Those templates' ->set_secret() will wrap the inner "dh" implementation's ->set_secret() and set the ->p and ->g group parameters as appropriate on the way inwards. More specifically, - A ffdheXYZ(dh) user would call crypto_dh_encode() on a struct dh instance having ->p == ->g == NULL as well as ->p_size == ->g_size == 0 and pass the resulting buffer to the outer ->set_secret(). - This outer ->set_secret() would then decode the struct dh via crypto_dh_decode_key(), set ->p, ->g, ->p_size as well as ->g_size as appropriate for the group in question and encode the struct dh again before passing it further down to the inner "dh"'s ->set_secret(). The problem is that crypto_dh_decode_key() implements some basic checks which would reject parameter sets with ->p_size == 0 and thus, the ffdheXYZ templates' ->set_secret() cannot use it as-is for decoding the passed buffer. As the inner "dh"'s ->set_secret() will eventually conduct said checks on the final parameter set anyway, the outer ->set_secret() really only needs the decoding functionality. Split out the pure struct dh decoding part from crypto_dh_decode_key() into the new __crypto_dh_decode_key(). __crypto_dh_decode_key() gets defined in crypto/dh_helper.c, but will have to get called from crypto/dh.c and thus, its declaration must be somehow made available to the latter. Strictly speaking, __crypto_dh_decode_key() is internal to the dh_generic module, yet it would be a bit over the top to introduce a new header like e.g. include/crypto/internal/dh.h containing just a single prototype. Add the __crypto_dh_decode_key() declaration to include/crypto/dh.h instead. Provide a proper kernel-doc annotation, even though __crypto_dh_decode_key() is purposedly not on the function list specified in Documentation/crypto/api-kpp.rst. Signed-off-by: Nicolai Stange <nstange@suse.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-02-21 12:10:51 +00:00
int __crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
{
const u8 *ptr = buf;
struct kpp_secret secret;
if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE))
return -EINVAL;
ptr = dh_unpack_data(&secret, ptr, sizeof(secret));
if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH)
return -EINVAL;
ptr = dh_unpack_data(&params->key_size, ptr, sizeof(params->key_size));
ptr = dh_unpack_data(&params->p_size, ptr, sizeof(params->p_size));
ptr = dh_unpack_data(&params->g_size, ptr, sizeof(params->g_size));
if (secret.len != crypto_dh_key_len(params))
return -EINVAL;
crypto: dh - split out deserialization code from crypto_dh_decode() A subsequent commit will introduce "dh" wrapping templates of the form "ffdhe2048(dh)", "ffdhe3072(dh)" and so on in order to provide built-in support for the well-known safe-prime ffdhe group parameters specified in RFC 7919. Those templates' ->set_secret() will wrap the inner "dh" implementation's ->set_secret() and set the ->p and ->g group parameters as appropriate on the way inwards. More specifically, - A ffdheXYZ(dh) user would call crypto_dh_encode() on a struct dh instance having ->p == ->g == NULL as well as ->p_size == ->g_size == 0 and pass the resulting buffer to the outer ->set_secret(). - This outer ->set_secret() would then decode the struct dh via crypto_dh_decode_key(), set ->p, ->g, ->p_size as well as ->g_size as appropriate for the group in question and encode the struct dh again before passing it further down to the inner "dh"'s ->set_secret(). The problem is that crypto_dh_decode_key() implements some basic checks which would reject parameter sets with ->p_size == 0 and thus, the ffdheXYZ templates' ->set_secret() cannot use it as-is for decoding the passed buffer. As the inner "dh"'s ->set_secret() will eventually conduct said checks on the final parameter set anyway, the outer ->set_secret() really only needs the decoding functionality. Split out the pure struct dh decoding part from crypto_dh_decode_key() into the new __crypto_dh_decode_key(). __crypto_dh_decode_key() gets defined in crypto/dh_helper.c, but will have to get called from crypto/dh.c and thus, its declaration must be somehow made available to the latter. Strictly speaking, __crypto_dh_decode_key() is internal to the dh_generic module, yet it would be a bit over the top to introduce a new header like e.g. include/crypto/internal/dh.h containing just a single prototype. Add the __crypto_dh_decode_key() declaration to include/crypto/dh.h instead. Provide a proper kernel-doc annotation, even though __crypto_dh_decode_key() is purposedly not on the function list specified in Documentation/crypto/api-kpp.rst. Signed-off-by: Nicolai Stange <nstange@suse.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-02-21 12:10:51 +00:00
/* Don't allocate memory. Set pointers to data within
* the given buffer
*/
params->key = (void *)ptr;
params->p = (void *)(ptr + params->key_size);
params->g = (void *)(ptr + params->key_size + params->p_size);
return 0;
}
int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
{
int err;
err = __crypto_dh_decode_key(buf, len, params);
if (err)
return err;
/*
* Don't permit the buffer for 'key' or 'g' to be larger than 'p', since
* some drivers assume otherwise.
*/
if (params->key_size > params->p_size ||
params->g_size > params->p_size)
return -EINVAL;
crypto: dh - Don't permit 'p' to be 0 If 'p' is 0 for the software Diffie-Hellman implementation, then dh_max_size() returns 0. In the case of KEYCTL_DH_COMPUTE, this causes ZERO_SIZE_PTR to be passed to sg_init_one(), which with CONFIG_DEBUG_SG=y triggers the 'BUG_ON(!virt_addr_valid(buf));' in sg_set_buf(). Fix this by making crypto_dh_decode_key() reject 0 for 'p'. p=0 makes no sense for any DH implementation because 'p' is supposed to be a prime number. Moreover, 'mod 0' is not mathematically defined. Bug report: kernel BUG at ./include/linux/scatterlist.h:140! invalid opcode: 0000 [#1] SMP KASAN CPU: 0 PID: 27112 Comm: syz-executor2 Not tainted 4.14.0-rc7-00010-gf5dbb5d0ce32-dirty #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.3-20171021_125229-anatol 04/01/2014 task: ffff88006caac0c0 task.stack: ffff88006c7c8000 RIP: 0010:sg_set_buf include/linux/scatterlist.h:140 [inline] RIP: 0010:sg_init_one+0x1b3/0x240 lib/scatterlist.c:156 RSP: 0018:ffff88006c7cfb08 EFLAGS: 00010216 RAX: 0000000000010000 RBX: ffff88006c7cfe30 RCX: 00000000000064ee RDX: ffffffff81cf64c3 RSI: ffffc90000d72000 RDI: ffffffff92e937e0 RBP: ffff88006c7cfb30 R08: ffffed000d8f9fab R09: ffff88006c7cfd30 R10: 0000000000000005 R11: ffffed000d8f9faa R12: ffff88006c7cfd30 R13: 0000000000000000 R14: 0000000000000010 R15: ffff88006c7cfc50 FS: 00007fce190fa700(0000) GS:ffff88003ea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fffc6b33db8 CR3: 000000003cf64000 CR4: 00000000000006f0 Call Trace: __keyctl_dh_compute+0xa95/0x19b0 security/keys/dh.c:360 keyctl_dh_compute+0xac/0x100 security/keys/dh.c:434 SYSC_keyctl security/keys/keyctl.c:1745 [inline] SyS_keyctl+0x72/0x2c0 security/keys/keyctl.c:1641 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x4585c9 RSP: 002b:00007fce190f9bd8 EFLAGS: 00000216 ORIG_RAX: 00000000000000fa RAX: ffffffffffffffda RBX: 0000000000738020 RCX: 00000000004585c9 RDX: 000000002000d000 RSI: 0000000020000ff4 RDI: 0000000000000017 RBP: 0000000000000046 R08: 0000000020008000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000216 R12: 00007fff6e610cde R13: 00007fff6e610cdf R14: 00007fce190fa700 R15: 0000000000000000 Code: 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 33 5b 45 89 6c 24 14 41 5c 41 5d 41 5e 41 5f 5d c3 e8 fd 8f 68 ff <0f> 0b e8 f6 8f 68 ff 0f 0b e8 ef 8f 68 ff 0f 0b e8 e8 8f 68 ff 20 RIP: sg_set_buf include/linux/scatterlist.h:140 [inline] RSP: ffff88006c7cfb08 RIP: sg_init_one+0x1b3/0x240 lib/scatterlist.c:156 RSP: ffff88006c7cfb08 Fixes: 802c7f1c84e4 ("crypto: dh - Add DH software implementation") Cc: <stable@vger.kernel.org> # v4.8+ Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-11-06 02:30:45 +00:00
/*
* Don't permit 'p' to be 0. It's not a prime number, and it's subject
* to corner cases such as 'mod 0' being undefined or
* crypto_kpp_maxsize() returning 0.
*/
if (memchr_inv(params->p, 0, params->p_size) == NULL)
return -EINVAL;
return 0;
}
EXPORT_SYMBOL_GPL(crypto_dh_decode_key);