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>

2 files changed, 103 insertions, 0 deletions

diff --git a/drivers/net/wireguard/generated/netlink.c b/drivers/net/wireguard/generated/netlink.c
new file mode 100644
index 000000000..3ef8c2990
--- /dev/null
+++ b/drivers/net/wireguard/generated/netlink.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+/* Do not edit directly, auto-generated from: */
+/*	Documentation/netlink/specs/wireguard.yaml */
+/* YNL-GEN kernel source */
+/* YNL-ARG --function-prefix wg */
+/* To regenerate run: tools/net/ynl/ynl-regen.sh */
+
+#include <net/netlink.h>
+#include <net/genetlink.h>
+
+#include "netlink.h"
+
+#include <uapi/linux/wireguard.h>
+#include <linux/time_types.h>
+
+/* Common nested types */
+const struct nla_policy wireguard_wgallowedip_nl_policy[WGALLOWEDIP_A_FLAGS + 1] = {
+	[WGALLOWEDIP_A_FAMILY] = { .type = NLA_U16, },
+	[WGALLOWEDIP_A_IPADDR] = NLA_POLICY_MIN_LEN(4),
+	[WGALLOWEDIP_A_CIDR_MASK] = { .type = NLA_U8, },
+	[WGALLOWEDIP_A_FLAGS] = NLA_POLICY_MASK(NLA_U32, 0x1),
+};
+
+const struct nla_policy wireguard_wgpeer_nl_policy[WGPEER_A_PROTOCOL_VERSION + 1] = {
+	[WGPEER_A_PUBLIC_KEY] = NLA_POLICY_EXACT_LEN(WG_KEY_LEN),
+	[WGPEER_A_PRESHARED_KEY] = NLA_POLICY_EXACT_LEN(WG_KEY_LEN),
+	[WGPEER_A_FLAGS] = NLA_POLICY_MASK(NLA_U32, 0x7),
+	[WGPEER_A_ENDPOINT] = NLA_POLICY_MIN_LEN(16),
+	[WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL] = { .type = NLA_U16, },
+	[WGPEER_A_LAST_HANDSHAKE_TIME] = NLA_POLICY_EXACT_LEN(16),
+	[WGPEER_A_RX_BYTES] = { .type = NLA_U64, },
+	[WGPEER_A_TX_BYTES] = { .type = NLA_U64, },
+	[WGPEER_A_ALLOWEDIPS] = NLA_POLICY_NESTED_ARRAY(wireguard_wgallowedip_nl_policy),
+	[WGPEER_A_PROTOCOL_VERSION] = { .type = NLA_U32, },
+};
+
+/* WG_CMD_GET_DEVICE - dump */
+static const struct nla_policy wireguard_get_device_nl_policy[WGDEVICE_A_IFNAME + 1] = {
+	[WGDEVICE_A_IFINDEX] = { .type = NLA_U32, },
+	[WGDEVICE_A_IFNAME] = { .type = NLA_NUL_STRING, .len = 15, },
+};
+
+/* WG_CMD_SET_DEVICE - do */
+static const struct nla_policy wireguard_set_device_nl_policy[WGDEVICE_A_PEERS + 1] = {
+	[WGDEVICE_A_IFINDEX] = { .type = NLA_U32, },
+	[WGDEVICE_A_IFNAME] = { .type = NLA_NUL_STRING, .len = 15, },
+	[WGDEVICE_A_PRIVATE_KEY] = NLA_POLICY_EXACT_LEN(WG_KEY_LEN),
+	[WGDEVICE_A_PUBLIC_KEY] = NLA_POLICY_EXACT_LEN(WG_KEY_LEN),
+	[WGDEVICE_A_FLAGS] = NLA_POLICY_MASK(NLA_U32, 0x1),
+	[WGDEVICE_A_LISTEN_PORT] = { .type = NLA_U16, },
+	[WGDEVICE_A_FWMARK] = { .type = NLA_U32, },
+	[WGDEVICE_A_PEERS] = NLA_POLICY_NESTED_ARRAY(wireguard_wgpeer_nl_policy),
+};
+
+/* Ops table for wireguard */
+const struct genl_split_ops wireguard_nl_ops[2] = {
+	{
+		.cmd		= WG_CMD_GET_DEVICE,
+		.start		= wg_get_device_start,
+		.dumpit		= wg_get_device_dumpit,
+		.done		= wg_get_device_done,
+		.policy		= wireguard_get_device_nl_policy,
+		.maxattr	= WGDEVICE_A_IFNAME,
+		.flags		= GENL_UNS_ADMIN_PERM | GENL_CMD_CAP_DUMP,
+	},
+	{
+		.cmd		= WG_CMD_SET_DEVICE,
+		.doit		= wg_set_device_doit,
+		.policy		= wireguard_set_device_nl_policy,
+		.maxattr	= WGDEVICE_A_PEERS,
+		.flags		= GENL_UNS_ADMIN_PERM | GENL_CMD_CAP_DO,
+	},
+};
diff --git a/drivers/net/wireguard/generated/netlink.h b/drivers/net/wireguard/generated/netlink.h
new file mode 100644
index 000000000..5dc977ee9
--- /dev/null
+++ b/drivers/net/wireguard/generated/netlink.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */
+/* Do not edit directly, auto-generated from: */
+/*	Documentation/netlink/specs/wireguard.yaml */
+/* YNL-GEN kernel header */
+/* YNL-ARG --function-prefix wg */
+/* To regenerate run: tools/net/ynl/ynl-regen.sh */
+
+#ifndef _LINUX_WIREGUARD_GEN_H
+#define _LINUX_WIREGUARD_GEN_H
+
+#include <net/netlink.h>
+#include <net/genetlink.h>
+
+#include <uapi/linux/wireguard.h>
+#include <linux/time_types.h>
+
+/* Common nested types */
+extern const struct nla_policy wireguard_wgallowedip_nl_policy[WGALLOWEDIP_A_FLAGS + 1];
+extern const struct nla_policy wireguard_wgpeer_nl_policy[WGPEER_A_PROTOCOL_VERSION + 1];
+
+/* Ops table for wireguard */
+extern const struct genl_split_ops wireguard_nl_ops[2];
+
+int wg_get_device_start(struct netlink_callback *cb);
+int wg_get_device_done(struct netlink_callback *cb);
+
+int wg_get_device_dumpit(struct sk_buff *skb, struct netlink_callback *cb);
+int wg_set_device_doit(struct sk_buff *skb, struct genl_info *info);
+
+#endif /* _LINUX_WIREGUARD_GEN_H */