openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 113 insertions, 0 deletions

diff --git a/net/mac80211/aead_api.c b/net/mac80211/aead_api.c
new file mode 100644
index 000000000..b00d6f5b3
--- /dev/null
+++ b/net/mac80211/aead_api.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2003-2004, Instant802 Networks, Inc.
+ * Copyright 2005-2006, Devicescape Software, Inc.
+ * Copyright 2014-2015, Qualcomm Atheros, Inc.
+ *
+ * Rewrite: Copyright (C) 2013 Linaro Ltd <ard.biesheuvel@linaro.org>
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/err.h>
+#include <linux/scatterlist.h>
+#include <crypto/aead.h>
+
+#include "aead_api.h"
+
+int aead_encrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad, size_t aad_len,
+		 u8 *data, size_t data_len, u8 *mic)
+{
+	size_t mic_len = crypto_aead_authsize(tfm);
+	struct scatterlist sg[3];
+	struct aead_request *aead_req;
+	int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);
+	u8 *__aad;
+	int ret;
+
+	aead_req = kzalloc(reqsize + aad_len, GFP_ATOMIC);
+	if (!aead_req)
+		return -ENOMEM;
+
+	__aad = (u8 *)aead_req + reqsize;
+	memcpy(__aad, aad, aad_len);
+
+	sg_init_table(sg, 3);
+	sg_set_buf(&sg[0], __aad, aad_len);
+	sg_set_buf(&sg[1], data, data_len);
+	sg_set_buf(&sg[2], mic, mic_len);
+
+	aead_request_set_tfm(aead_req, tfm);
+	aead_request_set_crypt(aead_req, sg, sg, data_len, b_0);
+	aead_request_set_ad(aead_req, sg[0].length);
+
+	ret = crypto_aead_encrypt(aead_req);
+	kfree_sensitive(aead_req);
+
+	return ret;
+}
+
+int aead_decrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad, size_t aad_len,
+		 u8 *data, size_t data_len, u8 *mic)
+{
+	size_t mic_len = crypto_aead_authsize(tfm);
+	struct scatterlist sg[3];
+	struct aead_request *aead_req;
+	int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);
+	u8 *__aad;
+	int err;
+
+	if (data_len == 0)
+		return -EINVAL;
+
+	aead_req = kzalloc(reqsize + aad_len, GFP_ATOMIC);
+	if (!aead_req)
+		return -ENOMEM;
+
+	__aad = (u8 *)aead_req + reqsize;
+	memcpy(__aad, aad, aad_len);
+
+	sg_init_table(sg, 3);
+	sg_set_buf(&sg[0], __aad, aad_len);
+	sg_set_buf(&sg[1], data, data_len);
+	sg_set_buf(&sg[2], mic, mic_len);
+
+	aead_request_set_tfm(aead_req, tfm);
+	aead_request_set_crypt(aead_req, sg, sg, data_len + mic_len, b_0);
+	aead_request_set_ad(aead_req, sg[0].length);
+
+	err = crypto_aead_decrypt(aead_req);
+	kfree_sensitive(aead_req);
+
+	return err;
+}
+
+struct crypto_aead *
+aead_key_setup_encrypt(const char *alg, const u8 key[],
+		       size_t key_len, size_t mic_len)
+{
+	struct crypto_aead *tfm;
+	int err;
+
+	tfm = crypto_alloc_aead(alg, 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(tfm))
+		return tfm;
+
+	err = crypto_aead_setkey(tfm, key, key_len);
+	if (err)
+		goto free_aead;
+	err = crypto_aead_setauthsize(tfm, mic_len);
+	if (err)
+		goto free_aead;
+
+	return tfm;
+
+free_aead:
+	crypto_free_aead(tfm);
+	return ERR_PTR(err);
+}
+
+void aead_key_free(struct crypto_aead *tfm)
+{
+	crypto_free_aead(tfm);
+}