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, 64 insertions, 0 deletions

diff --git a/include/net/icmp.h b/include/net/icmp.h
new file mode 100644
index 000000000..935ee13d9
--- /dev/null
+++ b/include/net/icmp.h
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the  BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ *		Definitions for the ICMP module.
+ *
+ * Version:	@(#)icmp.h	1.0.4	05/13/93
+ *
+ * Authors:	Ross Biro
+ *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ */
+#ifndef _ICMP_H
+#define	_ICMP_H
+
+#include <linux/icmp.h>
+
+#include <net/inet_sock.h>
+#include <net/snmp.h>
+#include <net/ip.h>
+
+struct icmp_err {
+  int		errno;
+  unsigned int	fatal:1;
+};
+
+extern const struct icmp_err icmp_err_convert[];
+#define ICMP_INC_STATS(net, field)	SNMP_INC_STATS((net)->mib.icmp_statistics, field)
+#define __ICMP_INC_STATS(net, field)	__SNMP_INC_STATS((net)->mib.icmp_statistics, field)
+#define ICMPMSGOUT_INC_STATS(net, field)	SNMP_INC_STATS_ATOMIC_LONG((net)->mib.icmpmsg_statistics, field+256)
+#define ICMPMSGIN_INC_STATS(net, field)		SNMP_INC_STATS_ATOMIC_LONG((net)->mib.icmpmsg_statistics, field)
+
+struct dst_entry;
+struct net_proto_family;
+struct sk_buff;
+struct net;
+
+void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
+		 const struct inet_skb_parm *parm);
+static inline void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
+{
+	__icmp_send(skb_in, type, code, info, IPCB(skb_in));
+}
+
+#if IS_ENABLED(CONFIG_NF_NAT)
+void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info);
+#else
+static inline void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
+{
+	struct inet_skb_parm parm;
+
+	memset(&parm, 0, sizeof(parm));
+	__icmp_send(skb_in, type, code, info, &parm);
+}
+#endif
+
+int icmp_rcv(struct sk_buff *skb);
+int icmp_err(struct sk_buff *skb, u32 info);
+int icmp_init(void);
+void icmp_out_count(struct net *net, unsigned char type);
+bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr);
+
+#endif	/* _ICMP_H */