leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity
e316f7179b
linux/crypto/rsa-pkcs1pad.c
Eric Biggers e316f7179b crypto: rsa-pkcs1pad - correctly get hash from source scatterlist 
Commit c7381b0128 ("crypto: akcipher - new verify API for public key
algorithms") changed akcipher_alg::verify to take in both the signature
and the actual hash and do the signature verification, rather than just
return the hash expected by the signature as was the case before.  To do
this, it implemented a hack where the signature and hash are
concatenated with each other in one scatterlist.

Obviously, for this to work correctly, akcipher_alg::verify needs to
correctly extract the two items from the scatterlist it is given.
Unfortunately, it doesn't correctly extract the hash in the case where
the signature is longer than the RSA key size, as it assumes that the
signature's length is equal to the RSA key size.  This causes a prefix
of the hash, or even the entire hash, to be taken from the *signature*.

(Note, the case of a signature longer than the RSA key size should not
be allowed in the first place; a separate patch will fix that.)

It is unclear whether the resulting scheme has any useful security
properties.

Fix this by correctly extracting the hash from the scatterlist.

Fixes: c7381b0128 ("crypto: akcipher - new verify API for public key algorithms")
Cc: <stable@vger.kernel.org> # v5.2+
Reviewed-by: Vitaly Chikunov <vt@altlinux.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-01-31 11:21:44 +11:00

691 lines
17 KiB
C
Raw Blame History

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* RSA padding templates.
*
* Copyright (c) 2015 Intel Corporation
*/
#include <crypto/algapi.h>
#include <crypto/akcipher.h>
#include <crypto/internal/akcipher.h>
#include <crypto/internal/rsa.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/scatterlist.h>
/*
* Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
*/
static const u8 rsa_digest_info_md5[] = {
0x30, 0x20, 0x30, 0x0c, 0x06, 0x08,
0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, /* OID */
0x05, 0x00, 0x04, 0x10
};
static const u8 rsa_digest_info_sha1[] = {
0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
0x2b, 0x0e, 0x03, 0x02, 0x1a,
0x05, 0x00, 0x04, 0x14
};
static const u8 rsa_digest_info_rmd160[] = {
0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
0x2b, 0x24, 0x03, 0x02, 0x01,
0x05, 0x00, 0x04, 0x14
};
static const u8 rsa_digest_info_sha224[] = {
0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
0x05, 0x00, 0x04, 0x1c
};
static const u8 rsa_digest_info_sha256[] = {
0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
0x05, 0x00, 0x04, 0x20
};
static const u8 rsa_digest_info_sha384[] = {
0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
0x05, 0x00, 0x04, 0x30
};
static const u8 rsa_digest_info_sha512[] = {
0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
0x05, 0x00, 0x04, 0x40
};
static const struct rsa_asn1_template {
const char *name;
const u8 *data;
size_t size;
} rsa_asn1_templates[] = {
#define _(X) { #X, rsa_digest_info_##X, sizeof(rsa_digest_info_##X) }
_(md5),
_(sha1),
_(rmd160),
_(sha256),
_(sha384),
_(sha512),
_(sha224),
{ NULL }
#undef _
};
static const struct rsa_asn1_template *rsa_lookup_asn1(const char *name)
{
const struct rsa_asn1_template *p;
for (p = rsa_asn1_templates; p->name; p++)
if (strcmp(name, p->name) == 0)
return p;
return NULL;
}
struct pkcs1pad_ctx {
struct crypto_akcipher *child;
unsigned int key_size;
};
struct pkcs1pad_inst_ctx {
struct crypto_akcipher_spawn spawn;
const struct rsa_asn1_template *digest_info;
};
struct pkcs1pad_request {
struct scatterlist in_sg[2], out_sg[1];
uint8_t *in_buf, *out_buf;
struct akcipher_request child_req;
};
static int pkcs1pad_set_pub_key(struct crypto_akcipher *tfm, const void *key,
unsigned int keylen)
{
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
int err;
ctx->key_size = 0;
err = crypto_akcipher_set_pub_key(ctx->child, key, keylen);
if (err)
return err;
/* Find out new modulus size from rsa implementation */
err = crypto_akcipher_maxsize(ctx->child);
if (err > PAGE_SIZE)
return -ENOTSUPP;
ctx->key_size = err;
return 0;
}
static int pkcs1pad_set_priv_key(struct crypto_akcipher *tfm, const void *key,
unsigned int keylen)
{
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
int err;
ctx->key_size = 0;
err = crypto_akcipher_set_priv_key(ctx->child, key, keylen);
if (err)
return err;
/* Find out new modulus size from rsa implementation */
err = crypto_akcipher_maxsize(ctx->child);
if (err > PAGE_SIZE)
return -ENOTSUPP;
ctx->key_size = err;
return 0;
}
static unsigned int pkcs1pad_get_max_size(struct crypto_akcipher *tfm)
{
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
/*
* The maximum destination buffer size for the encrypt/sign operations
* will be the same as for RSA, even though it's smaller for
* decrypt/verify.
*/
return ctx->key_size;
}
static void pkcs1pad_sg_set_buf(struct scatterlist *sg, void *buf, size_t len,
struct scatterlist *next)
{
int nsegs = next ? 2 : 1;
sg_init_table(sg, nsegs);
sg_set_buf(sg, buf, len);
if (next)
sg_chain(sg, nsegs, next);
}
static int pkcs1pad_encrypt_sign_complete(struct akcipher_request *req, int err)
{
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
unsigned int pad_len;
unsigned int len;
u8 *out_buf;
if (err)
goto out;
len = req_ctx->child_req.dst_len;
pad_len = ctx->key_size - len;
/* Four billion to one */
if (likely(!pad_len))
goto out;
out_buf = kzalloc(ctx->key_size, GFP_KERNEL);
err = -ENOMEM;
if (!out_buf)
goto out;
sg_copy_to_buffer(req->dst, sg_nents_for_len(req->dst, len),
out_buf + pad_len, len);
sg_copy_from_buffer(req->dst,
sg_nents_for_len(req->dst, ctx->key_size),
out_buf, ctx->key_size);
kfree_sensitive(out_buf);
out:
req->dst_len = ctx->key_size;
kfree(req_ctx->in_buf);
return err;
}
static void pkcs1pad_encrypt_sign_complete_cb(
struct crypto_async_request *child_async_req, int err)
{
struct akcipher_request *req = child_async_req->data;
struct crypto_async_request async_req;
if (err == -EINPROGRESS)
return;
async_req.data = req->base.data;
async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
async_req.flags = child_async_req->flags;
req->base.complete(&async_req,
pkcs1pad_encrypt_sign_complete(req, err));
}
static int pkcs1pad_encrypt(struct akcipher_request *req)
{
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
int err;
unsigned int i, ps_end;
if (!ctx->key_size)
return -EINVAL;
if (req->src_len > ctx->key_size - 11)
return -EOVERFLOW;
if (req->dst_len < ctx->key_size) {
req->dst_len = ctx->key_size;
return -EOVERFLOW;
}
req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
GFP_KERNEL);
if (!req_ctx->in_buf)
return -ENOMEM;
ps_end = ctx->key_size - req->src_len - 2;
req_ctx->in_buf[0] = 0x02;
for (i = 1; i < ps_end; i++)
req_ctx->in_buf[i] = 1 + prandom_u32_max(255);
req_ctx->in_buf[ps_end] = 0x00;
pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
ctx->key_size - 1 - req->src_len, req->src);
akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
pkcs1pad_encrypt_sign_complete_cb, req);
/* Reuse output buffer */
akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
req->dst, ctx->key_size - 1, req->dst_len);
err = crypto_akcipher_encrypt(&req_ctx->child_req);
if (err != -EINPROGRESS && err != -EBUSY)
return pkcs1pad_encrypt_sign_complete(req, err);
return err;
}
static int pkcs1pad_decrypt_complete(struct akcipher_request *req, int err)
{
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
unsigned int dst_len;
unsigned int pos;
u8 *out_buf;
if (err)
goto done;
err = -EINVAL;
dst_len = req_ctx->child_req.dst_len;
if (dst_len < ctx->key_size - 1)
goto done;
out_buf = req_ctx->out_buf;
if (dst_len == ctx->key_size) {
if (out_buf[0] != 0x00)
/* Decrypted value had no leading 0 byte */
goto done;
dst_len--;
out_buf++;
}
if (out_buf[0] != 0x02)
goto done;
for (pos = 1; pos < dst_len; pos++)
if (out_buf[pos] == 0x00)
break;
if (pos < 9 || pos == dst_len)
goto done;
pos++;
err = 0;
if (req->dst_len < dst_len - pos)
err = -EOVERFLOW;
req->dst_len = dst_len - pos;
if (!err)
sg_copy_from_buffer(req->dst,
sg_nents_for_len(req->dst, req->dst_len),
out_buf + pos, req->dst_len);
done:
kfree_sensitive(req_ctx->out_buf);
return err;
}
static void pkcs1pad_decrypt_complete_cb(
struct crypto_async_request *child_async_req, int err)
{
struct akcipher_request *req = child_async_req->data;
struct crypto_async_request async_req;
if (err == -EINPROGRESS)
return;
async_req.data = req->base.data;
async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
async_req.flags = child_async_req->flags;
req->base.complete(&async_req, pkcs1pad_decrypt_complete(req, err));
}
static int pkcs1pad_decrypt(struct akcipher_request *req)
{
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
int err;
if (!ctx->key_size || req->src_len != ctx->key_size)
return -EINVAL;
req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
if (!req_ctx->out_buf)
return -ENOMEM;
pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
ctx->key_size, NULL);
akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
pkcs1pad_decrypt_complete_cb, req);
/* Reuse input buffer, output to a new buffer */
akcipher_request_set_crypt(&req_ctx->child_req, req->src,
req_ctx->out_sg, req->src_len,
ctx->key_size);
err = crypto_akcipher_decrypt(&req_ctx->child_req);
if (err != -EINPROGRESS && err != -EBUSY)
return pkcs1pad_decrypt_complete(req, err);
return err;
}
static int pkcs1pad_sign(struct akcipher_request *req)
{
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
struct akcipher_instance *inst = akcipher_alg_instance(tfm);
struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
const struct rsa_asn1_template *digest_info = ictx->digest_info;
int err;
unsigned int ps_end, digest_size = 0;
if (!ctx->key_size)
return -EINVAL;
if (digest_info)
digest_size = digest_info->size;
if (req->src_len + digest_size > ctx->key_size - 11)
return -EOVERFLOW;
if (req->dst_len < ctx->key_size) {
req->dst_len = ctx->key_size;
return -EOVERFLOW;
}
req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
GFP_KERNEL);
if (!req_ctx->in_buf)
return -ENOMEM;
ps_end = ctx->key_size - digest_size - req->src_len - 2;
req_ctx->in_buf[0] = 0x01;
memset(req_ctx->in_buf + 1, 0xff, ps_end - 1);
req_ctx->in_buf[ps_end] = 0x00;
if (digest_info)
memcpy(req_ctx->in_buf + ps_end + 1, digest_info->data,
digest_info->size);
pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
ctx->key_size - 1 - req->src_len, req->src);
akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
pkcs1pad_encrypt_sign_complete_cb, req);
/* Reuse output buffer */
akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
req->dst, ctx->key_size - 1, req->dst_len);
err = crypto_akcipher_decrypt(&req_ctx->child_req);
if (err != -EINPROGRESS && err != -EBUSY)
return pkcs1pad_encrypt_sign_complete(req, err);
return err;
}
static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
{
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
struct akcipher_instance *inst = akcipher_alg_instance(tfm);
struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
const struct rsa_asn1_template *digest_info = ictx->digest_info;
unsigned int dst_len;
unsigned int pos;
u8 *out_buf;
if (err)
goto done;
err = -EINVAL;
dst_len = req_ctx->child_req.dst_len;
if (dst_len < ctx->key_size - 1)
goto done;
out_buf = req_ctx->out_buf;
if (dst_len == ctx->key_size) {
if (out_buf[0] != 0x00)
/* Decrypted value had no leading 0 byte */
goto done;
dst_len--;
out_buf++;
}
err = -EBADMSG;
if (out_buf[0] != 0x01)
goto done;
for (pos = 1; pos < dst_len; pos++)
if (out_buf[pos] != 0xff)
break;
if (pos < 9 || pos == dst_len || out_buf[pos] != 0x00)
goto done;
pos++;
if (digest_info) {
if (crypto_memneq(out_buf + pos, digest_info->data,
digest_info->size))
goto done;
pos += digest_info->size;
}
err = 0;
if (req->dst_len != dst_len - pos) {
err = -EKEYREJECTED;
req->dst_len = dst_len - pos;
goto done;
}
/* Extract appended digest. */
sg_pcopy_to_buffer(req->src,
sg_nents_for_len(req->src,
req->src_len + req->dst_len),
req_ctx->out_buf + ctx->key_size,
req->dst_len, req->src_len);
/* Do the actual verification step. */
if (memcmp(req_ctx->out_buf + ctx->key_size, out_buf + pos,
req->dst_len) != 0)
err = -EKEYREJECTED;
done:
kfree_sensitive(req_ctx->out_buf);
return err;
}
static void pkcs1pad_verify_complete_cb(
struct crypto_async_request *child_async_req, int err)
{
struct akcipher_request *req = child_async_req->data;
struct crypto_async_request async_req;
if (err == -EINPROGRESS)
return;
async_req.data = req->base.data;
async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
async_req.flags = child_async_req->flags;
req->base.complete(&async_req, pkcs1pad_verify_complete(req, err));
}
/*
* The verify operation is here for completeness similar to the verification
* defined in RFC2313 section 10.2 except that block type 0 is not accepted,
* as in RFC2437. RFC2437 section 9.2 doesn't define any operation to
* retrieve the DigestInfo from a signature, instead the user is expected
* to call the sign operation to generate the expected signature and compare
* signatures instead of the message-digests.
*/
static int pkcs1pad_verify(struct akcipher_request *req)
{
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
int err;
if (WARN_ON(req->dst) ||
WARN_ON(!req->dst_len) ||
!ctx->key_size || req->src_len < ctx->key_size)
return -EINVAL;
req_ctx->out_buf = kmalloc(ctx->key_size + req->dst_len, GFP_KERNEL);
if (!req_ctx->out_buf)
return -ENOMEM;
pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
ctx->key_size, NULL);
akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
pkcs1pad_verify_complete_cb, req);
/* Reuse input buffer, output to a new buffer */
akcipher_request_set_crypt(&req_ctx->child_req, req->src,
req_ctx->out_sg, req->src_len,
ctx->key_size);
err = crypto_akcipher_encrypt(&req_ctx->child_req);
if (err != -EINPROGRESS && err != -EBUSY)
return pkcs1pad_verify_complete(req, err);
return err;
}
static int pkcs1pad_init_tfm(struct crypto_akcipher *tfm)
{
struct akcipher_instance *inst = akcipher_alg_instance(tfm);
struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
struct crypto_akcipher *child_tfm;
child_tfm = crypto_spawn_akcipher(&ictx->spawn);
if (IS_ERR(child_tfm))
return PTR_ERR(child_tfm);
ctx->child = child_tfm;
return 0;
}
static void pkcs1pad_exit_tfm(struct crypto_akcipher *tfm)
{
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
crypto_free_akcipher(ctx->child);
}
static void pkcs1pad_free(struct akcipher_instance *inst)
{
struct pkcs1pad_inst_ctx *ctx = akcipher_instance_ctx(inst);
struct crypto_akcipher_spawn *spawn = &ctx->spawn;
crypto_drop_akcipher(spawn);
kfree(inst);
}
static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
{
u32 mask;
struct akcipher_instance *inst;
struct pkcs1pad_inst_ctx *ctx;
struct akcipher_alg *rsa_alg;
const char *hash_name;
int err;
err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AKCIPHER, &mask);
if (err)
return err;
inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
if (!inst)
return -ENOMEM;
ctx = akcipher_instance_ctx(inst);
err = crypto_grab_akcipher(&ctx->spawn, akcipher_crypto_instance(inst),
crypto_attr_alg_name(tb[1]), 0, mask);
if (err)
goto err_free_inst;
rsa_alg = crypto_spawn_akcipher_alg(&ctx->spawn);
if (strcmp(rsa_alg->base.cra_name, "rsa") != 0) {
err = -EINVAL;
goto err_free_inst;
}
err = -ENAMETOOLONG;
hash_name = crypto_attr_alg_name(tb[2]);
if (IS_ERR(hash_name)) {
if (snprintf(inst->alg.base.cra_name,
CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
rsa_alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
goto err_free_inst;
if (snprintf(inst->alg.base.cra_driver_name,
CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
rsa_alg->base.cra_driver_name) >=
CRYPTO_MAX_ALG_NAME)
goto err_free_inst;
} else {
ctx->digest_info = rsa_lookup_asn1(hash_name);
if (!ctx->digest_info) {
err = -EINVAL;
goto err_free_inst;
}
if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
"pkcs1pad(%s,%s)", rsa_alg->base.cra_name,
hash_name) >= CRYPTO_MAX_ALG_NAME)
goto err_free_inst;
if (snprintf(inst->alg.base.cra_driver_name,
CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s,%s)",
rsa_alg->base.cra_driver_name,
hash_name) >= CRYPTO_MAX_ALG_NAME)
goto err_free_inst;
}
inst->alg.base.cra_priority = rsa_alg->base.cra_priority;
inst->alg.base.cra_ctxsize = sizeof(struct pkcs1pad_ctx);
inst->alg.init = pkcs1pad_init_tfm;
inst->alg.exit = pkcs1pad_exit_tfm;
inst->alg.encrypt = pkcs1pad_encrypt;
inst->alg.decrypt = pkcs1pad_decrypt;
inst->alg.sign = pkcs1pad_sign;
inst->alg.verify = pkcs1pad_verify;
inst->alg.set_pub_key = pkcs1pad_set_pub_key;
inst->alg.set_priv_key = pkcs1pad_set_priv_key;
inst->alg.max_size = pkcs1pad_get_max_size;
inst->alg.reqsize = sizeof(struct pkcs1pad_request) + rsa_alg->reqsize;
inst->free = pkcs1pad_free;
err = akcipher_register_instance(tmpl, inst);
if (err) {
err_free_inst:
pkcs1pad_free(inst);
}
return err;
}
struct crypto_template rsa_pkcs1pad_tmpl = {
.name = "pkcs1pad",
.create = pkcs1pad_create,
.module = THIS_MODULE,
};
Reference in New Issue View Git Blame Copy Permalink