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, 97 insertions, 0 deletions

diff --git a/net/sunrpc/netlink.c b/net/sunrpc/netlink.c
new file mode 100644
index 000000000..ce09ecc0f
--- /dev/null
+++ b/net/sunrpc/netlink.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+/* Do not edit directly, auto-generated from: */
+/*	Documentation/netlink/specs/sunrpc_cache.yaml */
+/* YNL-GEN kernel source */
+/* To regenerate run: tools/net/ynl/ynl-regen.sh */
+
+#include <net/netlink.h>
+#include <net/genetlink.h>
+
+#include "netlink.h"
+
+#include <uapi/linux/sunrpc_netlink.h>
+
+/* Common nested types */
+const struct nla_policy sunrpc_ip_map_nl_policy[SUNRPC_A_IP_MAP_EXPIRY + 1] = {
+	[SUNRPC_A_IP_MAP_SEQNO] = { .type = NLA_U64, },
+	[SUNRPC_A_IP_MAP_CLASS] = { .type = NLA_NUL_STRING, },
+	[SUNRPC_A_IP_MAP_ADDR] = { .type = NLA_NUL_STRING, },
+	[SUNRPC_A_IP_MAP_DOMAIN] = { .type = NLA_NUL_STRING, },
+	[SUNRPC_A_IP_MAP_NEGATIVE] = { .type = NLA_FLAG, },
+	[SUNRPC_A_IP_MAP_EXPIRY] = { .type = NLA_U64, },
+};
+
+const struct nla_policy sunrpc_unix_gid_nl_policy[SUNRPC_A_UNIX_GID_EXPIRY + 1] = {
+	[SUNRPC_A_UNIX_GID_SEQNO] = { .type = NLA_U64, },
+	[SUNRPC_A_UNIX_GID_UID] = { .type = NLA_U32, },
+	[SUNRPC_A_UNIX_GID_GIDS] = { .type = NLA_U32, },
+	[SUNRPC_A_UNIX_GID_NEGATIVE] = { .type = NLA_FLAG, },
+	[SUNRPC_A_UNIX_GID_EXPIRY] = { .type = NLA_U64, },
+};
+
+/* SUNRPC_CMD_IP_MAP_SET_REQS - do */
+static const struct nla_policy sunrpc_ip_map_set_reqs_nl_policy[SUNRPC_A_IP_MAP_REQS_REQUESTS + 1] = {
+	[SUNRPC_A_IP_MAP_REQS_REQUESTS] = NLA_POLICY_NESTED(sunrpc_ip_map_nl_policy),
+};
+
+/* SUNRPC_CMD_UNIX_GID_SET_REQS - do */
+static const struct nla_policy sunrpc_unix_gid_set_reqs_nl_policy[SUNRPC_A_UNIX_GID_REQS_REQUESTS + 1] = {
+	[SUNRPC_A_UNIX_GID_REQS_REQUESTS] = NLA_POLICY_NESTED(sunrpc_unix_gid_nl_policy),
+};
+
+/* SUNRPC_CMD_CACHE_FLUSH - do */
+static const struct nla_policy sunrpc_cache_flush_nl_policy[SUNRPC_A_CACHE_FLUSH_MASK + 1] = {
+	[SUNRPC_A_CACHE_FLUSH_MASK] = NLA_POLICY_MASK(NLA_U32, 0x3),
+};
+
+/* Ops table for sunrpc */
+static const struct genl_split_ops sunrpc_nl_ops[] = {
+	{
+		.cmd	= SUNRPC_CMD_IP_MAP_GET_REQS,
+		.dumpit	= sunrpc_nl_ip_map_get_reqs_dumpit,
+		.flags	= GENL_ADMIN_PERM | GENL_CMD_CAP_DUMP,
+	},
+	{
+		.cmd		= SUNRPC_CMD_IP_MAP_SET_REQS,
+		.doit		= sunrpc_nl_ip_map_set_reqs_doit,
+		.policy		= sunrpc_ip_map_set_reqs_nl_policy,
+		.maxattr	= SUNRPC_A_IP_MAP_REQS_REQUESTS,
+		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
+	},
+	{
+		.cmd	= SUNRPC_CMD_UNIX_GID_GET_REQS,
+		.dumpit	= sunrpc_nl_unix_gid_get_reqs_dumpit,
+		.flags	= GENL_ADMIN_PERM | GENL_CMD_CAP_DUMP,
+	},
+	{
+		.cmd		= SUNRPC_CMD_UNIX_GID_SET_REQS,
+		.doit		= sunrpc_nl_unix_gid_set_reqs_doit,
+		.policy		= sunrpc_unix_gid_set_reqs_nl_policy,
+		.maxattr	= SUNRPC_A_UNIX_GID_REQS_REQUESTS,
+		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
+	},
+	{
+		.cmd		= SUNRPC_CMD_CACHE_FLUSH,
+		.doit		= sunrpc_nl_cache_flush_doit,
+		.policy		= sunrpc_cache_flush_nl_policy,
+		.maxattr	= SUNRPC_A_CACHE_FLUSH_MASK,
+		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
+	},
+};
+
+static const struct genl_multicast_group sunrpc_nl_mcgrps[] = {
+	[SUNRPC_NLGRP_NONE] = { "none", },
+	[SUNRPC_NLGRP_EXPORTD] = { "exportd", },
+};
+
+struct genl_family sunrpc_nl_family __ro_after_init = {
+	.name		= SUNRPC_FAMILY_NAME,
+	.version	= SUNRPC_FAMILY_VERSION,
+	.netnsok	= true,
+	.parallel_ops	= true,
+	.module		= THIS_MODULE,
+	.split_ops	= sunrpc_nl_ops,
+	.n_split_ops	= ARRAY_SIZE(sunrpc_nl_ops),
+	.mcgrps		= sunrpc_nl_mcgrps,
+	.n_mcgrps	= ARRAY_SIZE(sunrpc_nl_mcgrps),
+};