Revision a4aeaa06d45e90f9b279f0b09de84bd00006e733 authored by Yang Shi on 28 October 2021, 21:36:30 UTC, committed by Linus Torvalds on 29 October 2021, 00:18:55 UTC
The read-only THP for filesystems will collapse THP for files opened readonly and mapped with VM_EXEC. The intended usecase is to avoid TLB misses for large text segments. But it doesn't restrict the file types so a THP could be collapsed for a non-regular file, for example, block device, if it is opened readonly and mapped with EXEC permission. This may cause bugs, like [1] and [2]. This is definitely not the intended usecase, so just collapse THP for regular files in order to close the attack surface. [shy828301@gmail.com: fix vm_file check [3]] Link: https://lore.kernel.org/lkml/CACkBjsYwLYLRmX8GpsDpMthagWOjWWrNxqY6ZLNQVr6yx+f5vA@mail.gmail.com/ [1] Link: https://lore.kernel.org/linux-mm/000000000000c6a82505ce284e4c@google.com/ [2] Link: https://lkml.kernel.org/r/CAHbLzkqTW9U3VvTu1Ki5v_cLRC9gHW+znBukg_ycergE0JWj-A@mail.gmail.com [3] Link: https://lkml.kernel.org/r/20211027195221.3825-1-shy828301@gmail.com Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Yang Shi <shy828301@gmail.com> Reported-by: Hao Sun <sunhao.th@gmail.com> Reported-by: syzbot+aae069be1de40fb11825@syzkaller.appspotmail.com Cc: Matthew Wilcox <willy@infradead.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Song Liu <songliubraving@fb.com> Cc: Andrea Righi <andrea.righi@canonical.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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rsa.c
// SPDX-License-Identifier: GPL-2.0-or-later
/* RSA asymmetric public-key algorithm [RFC3447]
*
* Copyright (c) 2015, Intel Corporation
* Authors: Tadeusz Struk <tadeusz.struk@intel.com>
*/
#include <linux/module.h>
#include <linux/mpi.h>
#include <crypto/internal/rsa.h>
#include <crypto/internal/akcipher.h>
#include <crypto/akcipher.h>
#include <crypto/algapi.h>
struct rsa_mpi_key {
MPI n;
MPI e;
MPI d;
};
/*
* RSAEP function [RFC3447 sec 5.1.1]
* c = m^e mod n;
*/
static int _rsa_enc(const struct rsa_mpi_key *key, MPI c, MPI m)
{
/* (1) Validate 0 <= m < n */
if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0)
return -EINVAL;
/* (2) c = m^e mod n */
return mpi_powm(c, m, key->e, key->n);
}
/*
* RSADP function [RFC3447 sec 5.1.2]
* m = c^d mod n;
*/
static int _rsa_dec(const struct rsa_mpi_key *key, MPI m, MPI c)
{
/* (1) Validate 0 <= c < n */
if (mpi_cmp_ui(c, 0) < 0 || mpi_cmp(c, key->n) >= 0)
return -EINVAL;
/* (2) m = c^d mod n */
return mpi_powm(m, c, key->d, key->n);
}
static inline struct rsa_mpi_key *rsa_get_key(struct crypto_akcipher *tfm)
{
return akcipher_tfm_ctx(tfm);
}
static int rsa_enc(struct akcipher_request *req)
{
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
MPI m, c = mpi_alloc(0);
int ret = 0;
int sign;
if (!c)
return -ENOMEM;
if (unlikely(!pkey->n || !pkey->e)) {
ret = -EINVAL;
goto err_free_c;
}
ret = -ENOMEM;
m = mpi_read_raw_from_sgl(req->src, req->src_len);
if (!m)
goto err_free_c;
ret = _rsa_enc(pkey, c, m);
if (ret)
goto err_free_m;
ret = mpi_write_to_sgl(c, req->dst, req->dst_len, &sign);
if (ret)
goto err_free_m;
if (sign < 0)
ret = -EBADMSG;
err_free_m:
mpi_free(m);
err_free_c:
mpi_free(c);
return ret;
}
static int rsa_dec(struct akcipher_request *req)
{
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
MPI c, m = mpi_alloc(0);
int ret = 0;
int sign;
if (!m)
return -ENOMEM;
if (unlikely(!pkey->n || !pkey->d)) {
ret = -EINVAL;
goto err_free_m;
}
ret = -ENOMEM;
c = mpi_read_raw_from_sgl(req->src, req->src_len);
if (!c)
goto err_free_m;
ret = _rsa_dec(pkey, m, c);
if (ret)
goto err_free_c;
ret = mpi_write_to_sgl(m, req->dst, req->dst_len, &sign);
if (ret)
goto err_free_c;
if (sign < 0)
ret = -EBADMSG;
err_free_c:
mpi_free(c);
err_free_m:
mpi_free(m);
return ret;
}
static void rsa_free_mpi_key(struct rsa_mpi_key *key)
{
mpi_free(key->d);
mpi_free(key->e);
mpi_free(key->n);
key->d = NULL;
key->e = NULL;
key->n = NULL;
}
static int rsa_check_key_length(unsigned int len)
{
switch (len) {
case 512:
case 1024:
case 1536:
case 2048:
case 3072:
case 4096:
return 0;
}
return -EINVAL;
}
static int rsa_set_pub_key(struct crypto_akcipher *tfm, const void *key,
unsigned int keylen)
{
struct rsa_mpi_key *mpi_key = akcipher_tfm_ctx(tfm);
struct rsa_key raw_key = {0};
int ret;
/* Free the old MPI key if any */
rsa_free_mpi_key(mpi_key);
ret = rsa_parse_pub_key(&raw_key, key, keylen);
if (ret)
return ret;
mpi_key->e = mpi_read_raw_data(raw_key.e, raw_key.e_sz);
if (!mpi_key->e)
goto err;
mpi_key->n = mpi_read_raw_data(raw_key.n, raw_key.n_sz);
if (!mpi_key->n)
goto err;
if (rsa_check_key_length(mpi_get_size(mpi_key->n) << 3)) {
rsa_free_mpi_key(mpi_key);
return -EINVAL;
}
return 0;
err:
rsa_free_mpi_key(mpi_key);
return -ENOMEM;
}
static int rsa_set_priv_key(struct crypto_akcipher *tfm, const void *key,
unsigned int keylen)
{
struct rsa_mpi_key *mpi_key = akcipher_tfm_ctx(tfm);
struct rsa_key raw_key = {0};
int ret;
/* Free the old MPI key if any */
rsa_free_mpi_key(mpi_key);
ret = rsa_parse_priv_key(&raw_key, key, keylen);
if (ret)
return ret;
mpi_key->d = mpi_read_raw_data(raw_key.d, raw_key.d_sz);
if (!mpi_key->d)
goto err;
mpi_key->e = mpi_read_raw_data(raw_key.e, raw_key.e_sz);
if (!mpi_key->e)
goto err;
mpi_key->n = mpi_read_raw_data(raw_key.n, raw_key.n_sz);
if (!mpi_key->n)
goto err;
if (rsa_check_key_length(mpi_get_size(mpi_key->n) << 3)) {
rsa_free_mpi_key(mpi_key);
return -EINVAL;
}
return 0;
err:
rsa_free_mpi_key(mpi_key);
return -ENOMEM;
}
static unsigned int rsa_max_size(struct crypto_akcipher *tfm)
{
struct rsa_mpi_key *pkey = akcipher_tfm_ctx(tfm);
return mpi_get_size(pkey->n);
}
static void rsa_exit_tfm(struct crypto_akcipher *tfm)
{
struct rsa_mpi_key *pkey = akcipher_tfm_ctx(tfm);
rsa_free_mpi_key(pkey);
}
static struct akcipher_alg rsa = {
.encrypt = rsa_enc,
.decrypt = rsa_dec,
.set_priv_key = rsa_set_priv_key,
.set_pub_key = rsa_set_pub_key,
.max_size = rsa_max_size,
.exit = rsa_exit_tfm,
.base = {
.cra_name = "rsa",
.cra_driver_name = "rsa-generic",
.cra_priority = 100,
.cra_module = THIS_MODULE,
.cra_ctxsize = sizeof(struct rsa_mpi_key),
},
};
static int rsa_init(void)
{
int err;
err = crypto_register_akcipher(&rsa);
if (err)
return err;
err = crypto_register_template(&rsa_pkcs1pad_tmpl);
if (err) {
crypto_unregister_akcipher(&rsa);
return err;
}
return 0;
}
static void rsa_exit(void)
{
crypto_unregister_template(&rsa_pkcs1pad_tmpl);
crypto_unregister_akcipher(&rsa);
}
subsys_initcall(rsa_init);
module_exit(rsa_exit);
MODULE_ALIAS_CRYPTO("rsa");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("RSA generic algorithm");
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