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, 55 insertions, 0 deletions

diff --git a/security/ipe/hooks.h b/security/ipe/hooks.h
new file mode 100644
index 000000000..07db37332
--- /dev/null
+++ b/security/ipe/hooks.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.
+ */
+#ifndef _IPE_HOOKS_H
+#define _IPE_HOOKS_H
+
+#include <linux/fs.h>
+#include <linux/binfmts.h>
+#include <linux/security.h>
+#include <linux/blk_types.h>
+#include <linux/fsverity.h>
+
+enum ipe_hook_type {
+	IPE_HOOK_BPRM_CHECK = 0,
+	IPE_HOOK_BPRM_CREDS_FOR_EXEC,
+	IPE_HOOK_MMAP,
+	IPE_HOOK_MPROTECT,
+	IPE_HOOK_KERNEL_READ,
+	IPE_HOOK_KERNEL_LOAD,
+	__IPE_HOOK_MAX
+};
+
+#define IPE_HOOK_INVALID __IPE_HOOK_MAX
+
+int ipe_bprm_check_security(struct linux_binprm *bprm);
+
+int ipe_bprm_creds_for_exec(struct linux_binprm *bprm);
+
+int ipe_mmap_file(struct file *f, unsigned long reqprot, unsigned long prot,
+		  unsigned long flags);
+
+int ipe_file_mprotect(struct vm_area_struct *vma, unsigned long reqprot,
+		      unsigned long prot);
+
+int ipe_kernel_read_file(struct file *file, enum kernel_read_file_id id,
+			 bool contents);
+
+int ipe_kernel_load_data(enum kernel_load_data_id id, bool contents);
+
+void ipe_unpack_initramfs(void);
+
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+void ipe_bdev_free_security(struct block_device *bdev);
+
+int ipe_bdev_setintegrity(struct block_device *bdev, enum lsm_integrity_type type,
+			  const void *value, size_t len);
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
+
+#ifdef CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG
+int ipe_inode_setintegrity(const struct inode *inode, enum lsm_integrity_type type,
+			   const void *value, size_t size);
+#endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
+
+#endif /* _IPE_HOOKS_H */