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, 24 insertions, 0 deletions

diff --git a/security/integrity/Makefile b/security/integrity/Makefile
new file mode 100644
index 000000000..45dfdedbd
--- /dev/null
+++ b/security/integrity/Makefile
@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for caching inode integrity data (iint)
+#
+
+obj-$(CONFIG_INTEGRITY) += integrity.o
+
+integrity-y := iint.o
+integrity-$(CONFIG_INTEGRITY_AUDIT) += integrity_audit.o
+integrity-$(CONFIG_INTEGRITY_SIGNATURE) += digsig.o
+integrity-$(CONFIG_INTEGRITY_ASYMMETRIC_KEYS) += digsig_asymmetric.o
+integrity-$(CONFIG_INTEGRITY_PLATFORM_KEYRING) += platform_certs/platform_keyring.o
+integrity-$(CONFIG_INTEGRITY_MACHINE_KEYRING) += platform_certs/machine_keyring.o
+integrity-$(CONFIG_LOAD_UEFI_KEYS) += platform_certs/efi_parser.o \
+				      platform_certs/load_uefi.o \
+				      platform_certs/keyring_handler.o
+integrity-$(CONFIG_LOAD_IPL_KEYS) += platform_certs/load_ipl_s390.o
+integrity-$(CONFIG_LOAD_PPC_KEYS) += platform_certs/efi_parser.o \
+                                     platform_certs/load_powerpc.o \
+                                     platform_certs/keyring_handler.o
+integrity-$(CONFIG_EFI) += efi_secureboot.o
+# The relative order of the 'ima' and 'evm' LSMs depends on the order below.
+obj-$(CONFIG_IMA)			+= ima/
+obj-$(CONFIG_EVM)			+= evm/