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, 54 insertions, 0 deletions

diff --git a/net/ceph/auth_x.h b/net/ceph/auth_x.h
new file mode 100644
index 000000000..c03735f96
--- /dev/null
+++ b/net/ceph/auth_x.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _FS_CEPH_AUTH_X_H
+#define _FS_CEPH_AUTH_X_H
+
+#include <linux/rbtree.h>
+
+#include <linux/ceph/auth.h>
+
+#include "crypto.h"
+#include "auth_x_protocol.h"
+
+/*
+ * Handle ticket for a single service.
+ */
+struct ceph_x_ticket_handler {
+	struct rb_node node;
+	unsigned int service;
+
+	struct ceph_crypto_key session_key;
+	bool have_key;
+
+	u64 secret_id;
+	struct ceph_buffer *ticket_blob;
+
+	time64_t renew_after, expires;
+};
+
+#define CEPHX_AU_ENC_BUF_LEN	128  /* big enough for encrypted blob */
+
+struct ceph_x_authorizer {
+	struct ceph_authorizer base;
+	struct ceph_crypto_key session_key;
+	struct ceph_buffer *buf;
+	unsigned int service;
+	u64 nonce;
+	u64 secret_id;
+	char enc_buf[CEPHX_AU_ENC_BUF_LEN] __aligned(8);
+};
+
+struct ceph_x_info {
+	struct ceph_crypto_key secret;
+
+	bool starting;
+	u64 server_challenge;
+
+	unsigned int have_keys;
+	struct rb_root ticket_handlers;
+
+	struct ceph_x_authorizer auth_authorizer;
+};
+
+int ceph_x_init(struct ceph_auth_client *ac);
+
+#endif