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, 100 insertions, 0 deletions

diff --git a/include/net/raw.h b/include/net/raw.h
new file mode 100644
index 000000000..66c0ffead
--- /dev/null
+++ b/include/net/raw.h
@@ -0,0 +1,100 @@
+/* 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 RAW-IP module.
+ *
+ * Version:	@(#)raw.h	1.0.2	05/07/93
+ *
+ * Author:	Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ */
+#ifndef _RAW_H
+#define _RAW_H
+
+#include <net/inet_sock.h>
+#include <net/protocol.h>
+#include <net/netns/hash.h>
+#include <linux/hash.h>
+#include <linux/icmp.h>
+
+extern struct proto raw_prot;
+
+extern struct raw_hashinfo raw_v4_hashinfo;
+bool raw_v4_match(struct net *net, const struct sock *sk, unsigned short num,
+		  __be32 raddr, __be32 laddr, int dif, int sdif);
+
+int raw_abort(struct sock *sk, int err);
+void raw_icmp_error(struct sk_buff *, int, u32);
+int raw_local_deliver(struct sk_buff *, int);
+
+int raw_rcv(struct sock *, struct sk_buff *);
+
+#define RAW_HTABLE_LOG	8
+#define RAW_HTABLE_SIZE	(1U << RAW_HTABLE_LOG)
+
+struct raw_hashinfo {
+	spinlock_t lock;
+
+	struct hlist_head ht[RAW_HTABLE_SIZE] ____cacheline_aligned;
+};
+
+static inline u32 raw_hashfunc(const struct net *net, u32 proto)
+{
+	return hash_32(net_hash_mix(net) ^ proto, RAW_HTABLE_LOG);
+}
+
+static inline void raw_hashinfo_init(struct raw_hashinfo *hashinfo)
+{
+	int i;
+
+	spin_lock_init(&hashinfo->lock);
+	for (i = 0; i < RAW_HTABLE_SIZE; i++)
+		INIT_HLIST_HEAD(&hashinfo->ht[i]);
+}
+
+#ifdef CONFIG_PROC_FS
+int raw_proc_init(void);
+void raw_proc_exit(void);
+
+struct raw_iter_state {
+	struct seq_net_private p;
+	int bucket;
+};
+
+static inline struct raw_iter_state *raw_seq_private(struct seq_file *seq)
+{
+	return seq->private;
+}
+void *raw_seq_start(struct seq_file *seq, loff_t *pos);
+void *raw_seq_next(struct seq_file *seq, void *v, loff_t *pos);
+void raw_seq_stop(struct seq_file *seq, void *v);
+#endif
+
+int raw_hash_sk(struct sock *sk);
+void raw_unhash_sk(struct sock *sk);
+void raw_init(void);
+
+struct raw_sock {
+	/* inet_sock has to be the first member */
+	struct inet_sock   inet;
+	struct icmp_filter filter;
+	u32		   ipmr_table;
+	struct numa_drop_counters drop_counters;
+};
+
+#define raw_sk(ptr) container_of_const(ptr, struct raw_sock, inet.sk)
+
+static inline bool raw_sk_bound_dev_eq(struct net *net, int bound_dev_if,
+				       int dif, int sdif)
+{
+#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
+	return inet_bound_dev_eq(READ_ONCE(net->ipv4.sysctl_raw_l3mdev_accept),
+				 bound_dev_if, dif, sdif);
+#else
+	return inet_bound_dev_eq(true, bound_dev_if, dif, sdif);
+#endif
+}
+
+#endif	/* _RAW_H */