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, 57 insertions, 0 deletions

diff --git a/include/crypto/des.h b/include/crypto/des.h
new file mode 100644
index 000000000..73eec617f
--- /dev/null
+++ b/include/crypto/des.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* 
+ * DES & Triple DES EDE Cipher Algorithms.
+ */
+
+#ifndef __CRYPTO_DES_H
+#define __CRYPTO_DES_H
+
+#include <linux/types.h>
+
+#define DES_KEY_SIZE		8
+#define DES_EXPKEY_WORDS	32
+#define DES_BLOCK_SIZE		8
+
+#define DES3_EDE_KEY_SIZE	(3 * DES_KEY_SIZE)
+#define DES3_EDE_EXPKEY_WORDS	(3 * DES_EXPKEY_WORDS)
+#define DES3_EDE_BLOCK_SIZE	DES_BLOCK_SIZE
+
+struct des_ctx {
+	u32 expkey[DES_EXPKEY_WORDS];
+};
+
+struct des3_ede_ctx {
+	u32 expkey[DES3_EDE_EXPKEY_WORDS];
+};
+
+void des_encrypt(const struct des_ctx *ctx, u8 *dst, const u8 *src);
+void des_decrypt(const struct des_ctx *ctx, u8 *dst, const u8 *src);
+
+void des3_ede_encrypt(const struct des3_ede_ctx *dctx, u8 *dst, const u8 *src);
+void des3_ede_decrypt(const struct des3_ede_ctx *dctx, u8 *dst, const u8 *src);
+
+/**
+ * des_expand_key - Expand a DES input key into a key schedule
+ * @ctx: the key schedule
+ * @key: buffer containing the input key
+ * @keylen: size of the buffer contents
+ *
+ * Returns: 0 on success, -EINVAL if the input key is rejected and -ENOKEY if
+ * the key is accepted but has been found to be weak.
+ */
+int des_expand_key(struct des_ctx *ctx, const u8 *key, unsigned int keylen);
+
+/**
+ * des3_ede_expand_key - Expand a triple DES input key into a key schedule
+ * @ctx: the key schedule
+ * @key: buffer containing the input key
+ * @keylen: size of the buffer contents
+ *
+ * Returns: 0 on success, -EINVAL if the input key is rejected and -ENOKEY if
+ * the key is accepted but has been found to be weak. Note that weak keys will
+ * be rejected (and -EINVAL will be returned) when running in FIPS mode.
+ */
+int des3_ede_expand_key(struct des3_ede_ctx *ctx, const u8 *key,
+			unsigned int keylen);
+
+#endif /* __CRYPTO_DES_H */