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, 56 insertions, 0 deletions

diff --git a/drivers/crypto/qce/cipher.h b/drivers/crypto/qce/cipher.h
new file mode 100644
index 000000000..850f257d0
--- /dev/null
+++ b/drivers/crypto/qce/cipher.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2010-2014, The Linux Foundation. All rights reserved.
+ */
+
+#ifndef _CIPHER_H_
+#define _CIPHER_H_
+
+#include "common.h"
+#include "core.h"
+
+#define QCE_MAX_KEY_SIZE	64
+
+struct qce_cipher_ctx {
+	u8 enc_key[QCE_MAX_KEY_SIZE];
+	unsigned int enc_keylen;
+	struct crypto_skcipher *fallback;
+};
+
+/**
+ * struct qce_cipher_reqctx - holds private cipher objects per request
+ * @flags: operation flags
+ * @iv: pointer to the IV
+ * @ivsize: IV size
+ * @src_nents: source entries
+ * @dst_nents: destination entries
+ * @result_sg: scatterlist used for result buffer
+ * @dst_tbl: destination sg table
+ * @dst_sg: destination sg pointer table beginning
+ * @src_tbl: source sg table
+ * @src_sg: source sg pointer table beginning;
+ * @cryptlen: crypto length
+ */
+struct qce_cipher_reqctx {
+	unsigned long flags;
+	u8 *iv;
+	unsigned int ivsize;
+	int src_nents;
+	int dst_nents;
+	struct scatterlist result_sg;
+	struct sg_table dst_tbl;
+	struct scatterlist *dst_sg;
+	struct scatterlist *src_sg;
+	unsigned int cryptlen;
+	struct skcipher_request fallback_req;	// keep at the end
+};
+
+static inline struct qce_alg_template *to_cipher_tmpl(struct crypto_skcipher *tfm)
+{
+	struct skcipher_alg *alg = crypto_skcipher_alg(tfm);
+	return container_of(alg, struct qce_alg_template, alg.skcipher);
+}
+
+extern const struct qce_algo_ops skcipher_ops;
+
+#endif /* _CIPHER_H_ */