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, 159 insertions, 0 deletions

diff --git a/include/net/llc.h b/include/net/llc.h
new file mode 100644
index 000000000..029ba8a22
--- /dev/null
+++ b/include/net/llc.h
@@ -0,0 +1,159 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef LLC_H
+#define LLC_H
+/*
+ * Copyright (c) 1997 by Procom Technology, Inc.
+ * 		 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ */
+
+#include <linux/if.h>
+#include <linux/if_ether.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/rculist_nulls.h>
+#include <linux/hash.h>
+#include <linux/jhash.h>
+
+#include <linux/atomic.h>
+
+struct net_device;
+struct packet_type;
+struct sk_buff;
+
+struct llc_addr {
+	unsigned char lsap;
+	unsigned char mac[IFHWADDRLEN];
+};
+
+#define LLC_SAP_STATE_INACTIVE	1
+#define LLC_SAP_STATE_ACTIVE	2
+
+#define LLC_SK_DEV_HASH_BITS 6
+#define LLC_SK_DEV_HASH_ENTRIES (1<<LLC_SK_DEV_HASH_BITS)
+
+#define LLC_SK_LADDR_HASH_BITS 6
+#define LLC_SK_LADDR_HASH_ENTRIES (1<<LLC_SK_LADDR_HASH_BITS)
+
+/**
+ * struct llc_sap - Defines the SAP component
+ *
+ * @station - station this sap belongs to
+ * @state - sap state
+ * @p_bit - only lowest-order bit used
+ * @f_bit - only lowest-order bit used
+ * @laddr - SAP value in this 'lsap'
+ * @node - entry in station sap_list
+ * @sk_list - LLC sockets this one manages
+ */
+struct llc_sap {
+	unsigned char	 state;
+	unsigned char	 p_bit;
+	unsigned char	 f_bit;
+	refcount_t		 refcnt;
+	int		 (*rcv_func)(struct sk_buff *skb,
+				     struct net_device *dev,
+				     struct packet_type *pt,
+				     struct net_device *orig_dev);
+	struct llc_addr	 laddr;
+	struct list_head node;
+	spinlock_t sk_lock;
+	int sk_count;
+	struct hlist_nulls_head sk_laddr_hash[LLC_SK_LADDR_HASH_ENTRIES];
+	struct hlist_head sk_dev_hash[LLC_SK_DEV_HASH_ENTRIES];
+	struct rcu_head rcu;
+};
+
+static inline
+struct hlist_head *llc_sk_dev_hash(struct llc_sap *sap, int ifindex)
+{
+	u32 bucket = hash_32(ifindex, LLC_SK_DEV_HASH_BITS);
+
+	return &sap->sk_dev_hash[bucket];
+}
+
+static inline
+u32 llc_sk_laddr_hashfn(struct llc_sap *sap, const struct llc_addr *laddr)
+{
+	return hash_32(jhash(laddr->mac, sizeof(laddr->mac), 0),
+		       LLC_SK_LADDR_HASH_BITS);
+}
+
+static inline
+struct hlist_nulls_head *llc_sk_laddr_hash(struct llc_sap *sap,
+					   const struct llc_addr *laddr)
+{
+	return &sap->sk_laddr_hash[llc_sk_laddr_hashfn(sap, laddr)];
+}
+
+#define LLC_DEST_INVALID         0      /* Invalid LLC PDU type */
+#define LLC_DEST_SAP             1      /* Type 1 goes here */
+#define LLC_DEST_CONN            2      /* Type 2 goes here */
+
+extern struct list_head llc_sap_list;
+
+int llc_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt,
+	    struct net_device *orig_dev);
+
+int llc_mac_hdr_init(struct sk_buff *skb, const unsigned char *sa,
+		     const unsigned char *da);
+
+void llc_add_pack(int type,
+		  void (*handler)(struct llc_sap *sap, struct sk_buff *skb));
+void llc_remove_pack(int type);
+
+void llc_set_station_handler(void (*handler)(struct sk_buff *skb));
+
+struct llc_sap *llc_sap_open(unsigned char lsap,
+			     int (*rcv)(struct sk_buff *skb,
+					struct net_device *dev,
+					struct packet_type *pt,
+					struct net_device *orig_dev));
+static inline void llc_sap_hold(struct llc_sap *sap)
+{
+	refcount_inc(&sap->refcnt);
+}
+
+static inline bool llc_sap_hold_safe(struct llc_sap *sap)
+{
+	return refcount_inc_not_zero(&sap->refcnt);
+}
+
+void llc_sap_close(struct llc_sap *sap);
+
+static inline void llc_sap_put(struct llc_sap *sap)
+{
+	if (refcount_dec_and_test(&sap->refcnt))
+		llc_sap_close(sap);
+}
+
+struct llc_sap *llc_sap_find(unsigned char sap_value);
+
+int llc_build_and_send_ui_pkt(struct llc_sap *sap, struct sk_buff *skb,
+			      const unsigned char *dmac, unsigned char dsap);
+
+void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb);
+void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb);
+
+void llc_station_init(void);
+void llc_station_exit(void);
+
+#ifdef CONFIG_PROC_FS
+int llc_proc_init(void);
+void llc_proc_exit(void);
+#else
+#define llc_proc_init()	(0)
+#define llc_proc_exit()	do { } while(0)
+#endif /* CONFIG_PROC_FS */
+#ifdef CONFIG_SYSCTL
+int llc_sysctl_init(void);
+void llc_sysctl_exit(void);
+
+extern int sysctl_llc2_ack_timeout;
+extern int sysctl_llc2_busy_timeout;
+extern int sysctl_llc2_p_timeout;
+extern int sysctl_llc2_rej_timeout;
+#else
+#define llc_sysctl_init() (0)
+#define llc_sysctl_exit() do { } while(0)
+#endif /* CONFIG_SYSCTL */
+#endif /* LLC_H */