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/drivers/crypto/bcm/util.h b/drivers/crypto/bcm/util.h
new file mode 100644
index 000000000..61c256384
--- /dev/null
+++ b/drivers/crypto/bcm/util.h
@@ -0,0 +1,113 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2016 Broadcom
+ */
+
+#ifndef _UTIL_H
+#define _UTIL_H
+
+#include <linux/kernel.h>
+#include <linux/delay.h>
+
+#include "spu.h"
+
+extern int flow_debug_logging;
+extern int packet_debug_logging;
+extern int debug_logging_sleep;
+
+#ifdef DEBUG
+#define flow_log(...)	                \
+	do {	                              \
+		if (flow_debug_logging) {	        \
+			printk(__VA_ARGS__);	          \
+			if (debug_logging_sleep)	      \
+				msleep(debug_logging_sleep);	\
+		}	                                \
+	} while (0)
+#define flow_dump(msg, var, var_len)	   \
+	do {	                                 \
+		if (flow_debug_logging) {	           \
+			print_hex_dump(KERN_ALERT, msg, DUMP_PREFIX_NONE,  \
+					16, 1, var, var_len, false); \
+				if (debug_logging_sleep)	       \
+					msleep(debug_logging_sleep);   \
+		}                                    \
+	} while (0)
+
+#define packet_log(...)               \
+	do {                                \
+		if (packet_debug_logging) {       \
+			printk(__VA_ARGS__);            \
+			if (debug_logging_sleep)        \
+				msleep(debug_logging_sleep);  \
+		}                                 \
+	} while (0)
+#define packet_dump(msg, var, var_len)   \
+	do {                                   \
+		if (packet_debug_logging) {          \
+			print_hex_dump(KERN_ALERT, msg, DUMP_PREFIX_NONE,  \
+					16, 1, var, var_len, false); \
+			if (debug_logging_sleep)           \
+				msleep(debug_logging_sleep);     \
+		}                                    \
+	} while (0)
+
+void __dump_sg(struct scatterlist *sg, unsigned int skip, unsigned int len);
+
+#define dump_sg(sg, skip, len)     __dump_sg(sg, skip, len)
+
+#else /* !DEBUG_ON */
+
+static inline void flow_log(const char *format, ...)
+{
+}
+
+static inline void flow_dump(const char *msg, const void *var, size_t var_len)
+{
+}
+
+static inline void packet_log(const char *format, ...)
+{
+}
+
+static inline void packet_dump(const char *msg, const void *var, size_t var_len)
+{
+}
+
+static inline void dump_sg(struct scatterlist *sg, unsigned int skip,
+			   unsigned int len)
+{
+}
+
+#endif /* DEBUG_ON */
+
+int spu_sg_at_offset(struct scatterlist *sg, unsigned int skip,
+		     struct scatterlist **sge, unsigned int *sge_offset);
+
+/* Copy sg data, from skip, length len, to dest */
+void sg_copy_part_to_buf(struct scatterlist *src, u8 *dest,
+			 unsigned int len, unsigned int skip);
+/* Copy src into scatterlist from offset, length len */
+void sg_copy_part_from_buf(struct scatterlist *dest, u8 *src,
+			   unsigned int len, unsigned int skip);
+
+int spu_sg_count(struct scatterlist *sg_list, unsigned int skip, int nbytes);
+u32 spu_msg_sg_add(struct scatterlist **to_sg,
+		   struct scatterlist **from_sg, u32 *skip,
+		   u8 from_nents, u32 tot_len);
+
+void add_to_ctr(u8 *ctr_pos, unsigned int increment);
+
+/* produce a message digest from data of length n bytes */
+int do_shash(unsigned char *name, unsigned char *result,
+	     const u8 *data1, unsigned int data1_len,
+	     const u8 *data2, unsigned int data2_len,
+	     const u8 *key, unsigned int key_len);
+
+char *spu_alg_name(enum spu_cipher_alg alg, enum spu_cipher_mode mode);
+
+void spu_setup_debugfs(void);
+void spu_free_debugfs(void);
+void format_value_ccm(unsigned int val, u8 *buf, u8 len);
+
+#endif