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/smack/Kconfig b/security/smack/Kconfig
new file mode 100644
index 000000000..5a8dfad46
--- /dev/null
+++ b/security/smack/Kconfig
@@ -0,0 +1,55 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config SECURITY_SMACK
+	bool "Simplified Mandatory Access Control Kernel Support"
+	depends on NET
+	depends on INET
+	depends on SECURITY
+	select NETLABEL
+	select SECURITY_NETWORK
+	default n
+	help
+	  This selects the Simplified Mandatory Access Control Kernel.
+	  Smack is useful for sensitivity, integrity, and a variety
+	  of other mandatory security schemes.
+	  If you are unsure how to answer this question, answer N.
+
+config SECURITY_SMACK_BRINGUP
+	bool "Reporting on access granted by Smack rules"
+	depends on SECURITY_SMACK
+	default n
+	help
+	  Enable the bring-up ("b") access mode in Smack rules.
+	  When access is granted by a rule with the "b" mode a
+	  message about the access requested is generated. The
+	  intention is that a process can be granted a wide set
+	  of access initially with the bringup mode set on the
+	  rules. The developer can use the information to
+	  identify which rules are necessary and what accesses
+	  may be inappropriate. The developer can reduce the
+	  access rule set once the behavior is well understood.
+	  This is a superior mechanism to the oft abused
+	  "permissive" mode of other systems.
+	  If you are unsure how to answer this question, answer N.
+
+config SECURITY_SMACK_NETFILTER
+	bool "Packet marking using secmarks for netfilter"
+	depends on SECURITY_SMACK
+	depends on NETWORK_SECMARK
+	depends on NETFILTER
+	default n
+	help
+	  This enables security marking of network packets using
+	  Smack labels.
+	  If you are unsure how to answer this question, answer N.
+
+config SECURITY_SMACK_APPEND_SIGNALS
+	bool "Treat delivering signals as an append operation"
+	depends on SECURITY_SMACK
+	default n
+	help
+	  Sending a signal has been treated as a write operation to the
+	  receiving process. If this option is selected, the delivery
+	  will be an append operation instead. This makes it possible
+	  to differentiate between delivering a network packet and
+	  delivering a signal in the Smack rules.
+	  If you are unsure how to answer this question, answer N.