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, 117 insertions, 0 deletions

diff --git a/fs/ceph/cache.h b/fs/ceph/cache.h
new file mode 100644
index 000000000..20efac020
--- /dev/null
+++ b/fs/ceph/cache.h
@@ -0,0 +1,117 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Ceph cache definitions.
+ *
+ *  Copyright (C) 2013 by Adfin Solutions, Inc. All Rights Reserved.
+ *  Written by Milosz Tanski (milosz@adfin.com)
+ */
+
+#ifndef _CEPH_CACHE_H
+#define _CEPH_CACHE_H
+
+#include <linux/netfs.h>
+
+#ifdef CONFIG_CEPH_FSCACHE
+#include <linux/fscache.h>
+
+int ceph_fscache_register_fs(struct ceph_fs_client* fsc, struct fs_context *fc);
+void ceph_fscache_unregister_fs(struct ceph_fs_client* fsc);
+
+void ceph_fscache_register_inode_cookie(struct inode *inode);
+void ceph_fscache_unregister_inode_cookie(struct ceph_inode_info* ci);
+
+void ceph_fscache_use_cookie(struct inode *inode, bool will_modify);
+void ceph_fscache_unuse_cookie(struct inode *inode, bool update);
+
+void ceph_fscache_update(struct inode *inode);
+void ceph_fscache_invalidate(struct inode *inode, bool dio_write);
+
+static inline struct fscache_cookie *ceph_fscache_cookie(struct ceph_inode_info *ci)
+{
+	return netfs_i_cookie(&ci->netfs);
+}
+
+static inline void ceph_fscache_resize(struct inode *inode, loff_t to)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct fscache_cookie *cookie = ceph_fscache_cookie(ci);
+
+	if (cookie) {
+		ceph_fscache_use_cookie(inode, true);
+		fscache_resize_cookie(cookie, to);
+		ceph_fscache_unuse_cookie(inode, true);
+	}
+}
+
+static inline int ceph_fscache_unpin_writeback(struct inode *inode,
+						struct writeback_control *wbc)
+{
+	return netfs_unpin_writeback(inode, wbc);
+}
+
+#define ceph_fscache_dirty_folio netfs_dirty_folio
+
+static inline bool ceph_is_cache_enabled(struct inode *inode)
+{
+	return fscache_cookie_enabled(ceph_fscache_cookie(ceph_inode(inode)));
+}
+
+#else /* CONFIG_CEPH_FSCACHE */
+static inline int ceph_fscache_register_fs(struct ceph_fs_client* fsc,
+					   struct fs_context *fc)
+{
+	return 0;
+}
+
+static inline void ceph_fscache_unregister_fs(struct ceph_fs_client* fsc)
+{
+}
+
+static inline void ceph_fscache_register_inode_cookie(struct inode *inode)
+{
+}
+
+static inline void ceph_fscache_unregister_inode_cookie(struct ceph_inode_info* ci)
+{
+}
+
+static inline void ceph_fscache_use_cookie(struct inode *inode, bool will_modify)
+{
+}
+
+static inline void ceph_fscache_unuse_cookie(struct inode *inode, bool update)
+{
+}
+
+static inline void ceph_fscache_update(struct inode *inode)
+{
+}
+
+static inline void ceph_fscache_invalidate(struct inode *inode, bool dio_write)
+{
+}
+
+static inline struct fscache_cookie *ceph_fscache_cookie(struct ceph_inode_info *ci)
+{
+	return NULL;
+}
+
+static inline void ceph_fscache_resize(struct inode *inode, loff_t to)
+{
+}
+
+static inline int ceph_fscache_unpin_writeback(struct inode *inode,
+					       struct writeback_control *wbc)
+{
+	return 0;
+}
+
+#define ceph_fscache_dirty_folio filemap_dirty_folio
+
+static inline bool ceph_is_cache_enabled(struct inode *inode)
+{
+	return false;
+}
+#endif /* CONFIG_CEPH_FSCACHE */
+
+#endif