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, 34 insertions, 0 deletions

diff --git a/drivers/crypto/omap-crypto.h b/drivers/crypto/omap-crypto.h
new file mode 100644
index 000000000..506ccde6f
--- /dev/null
+++ b/drivers/crypto/omap-crypto.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * OMAP Crypto driver common support routines.
+ *
+ * Copyright (c) 2017 Texas Instruments Incorporated
+ *   Tero Kristo <t-kristo@ti.com>
+ */
+
+#ifndef __CRYPTO_OMAP_CRYPTO_H
+#define __CRYPTO_OMAP_CRYPTO_H
+
+enum {
+	OMAP_CRYPTO_NOT_ALIGNED = 1,
+	OMAP_CRYPTO_BAD_DATA_LENGTH,
+};
+
+#define OMAP_CRYPTO_DATA_COPIED		BIT(0)
+#define OMAP_CRYPTO_SG_COPIED		BIT(1)
+
+#define OMAP_CRYPTO_COPY_MASK		0x3
+
+#define OMAP_CRYPTO_COPY_DATA		BIT(0)
+#define OMAP_CRYPTO_FORCE_COPY		BIT(1)
+#define OMAP_CRYPTO_ZERO_BUF		BIT(2)
+#define OMAP_CRYPTO_FORCE_SINGLE_ENTRY	BIT(3)
+
+int omap_crypto_align_sg(struct scatterlist **sg, int total, int bs,
+			 struct scatterlist *new_sg, u16 flags,
+			 u8 flags_shift, unsigned long *dd_flags);
+void omap_crypto_cleanup(struct scatterlist *sg, struct scatterlist *orig,
+			 int offset, int len, u8 flags_shift,
+			 unsigned long flags);
+
+#endif