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/security/ipe/Kconfig b/security/ipe/Kconfig
new file mode 100644
index 000000000..a110a6cd8
--- /dev/null
+++ b/security/ipe/Kconfig
@@ -0,0 +1,117 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Integrity Policy Enforcement (IPE) configuration
+#
+
+menuconfig SECURITY_IPE
+	bool "Integrity Policy Enforcement (IPE)"
+	depends on SECURITY && SECURITYFS && AUDIT && AUDITSYSCALL
+	select CRYPTO_LIB_SHA256
+	select PKCS7_MESSAGE_PARSER
+	select SYSTEM_DATA_VERIFICATION
+	select IPE_PROP_DM_VERITY if DM_VERITY
+	select IPE_PROP_DM_VERITY_SIGNATURE if DM_VERITY && DM_VERITY_VERIFY_ROOTHASH_SIG
+	select IPE_PROP_FS_VERITY if FS_VERITY
+	select IPE_PROP_FS_VERITY_BUILTIN_SIG if FS_VERITY && FS_VERITY_BUILTIN_SIGNATURES
+	help
+	  This option enables the Integrity Policy Enforcement LSM
+	  allowing users to define a policy to enforce a trust-based access
+	  control. A key feature of IPE is a customizable policy to allow
+	  admins to reconfigure trust requirements on the fly.
+
+	  If unsure, answer N.
+
+if SECURITY_IPE
+config IPE_BOOT_POLICY
+	string "Integrity policy to apply on system startup"
+	help
+	  This option specifies a filepath to an IPE policy that is compiled
+	  into the kernel. This policy will be enforced until a policy update
+	  is deployed via the $securityfs/ipe/policies/$policy_name/active
+	  interface.
+
+	  If unsure, leave blank.
+
+config IPE_POLICY_SIG_SECONDARY_KEYRING
+	bool "IPE policy update verification with secondary keyring"
+	default y
+	depends on SECONDARY_TRUSTED_KEYRING
+	help
+	  Also allow the secondary trusted keyring to verify IPE policy
+	  updates.
+
+	  If unsure, answer Y.
+
+config IPE_POLICY_SIG_PLATFORM_KEYRING
+	bool "IPE policy update verification with platform keyring"
+	default y
+	depends on INTEGRITY_PLATFORM_KEYRING
+	help
+	  Also allow the platform keyring to verify IPE policy updates.
+
+	  If unsure, answer Y.
+
+menu "IPE Trust Providers"
+
+config IPE_PROP_DM_VERITY
+	bool "Enable support for dm-verity based on root hash"
+	depends on DM_VERITY
+	help
+	  This option enables the 'dmverity_roothash' property within IPE
+	  policies. The property evaluates to TRUE when a file from a dm-verity
+	  volume is evaluated, and the volume's root hash matches the value
+	  supplied in the policy.
+
+config IPE_PROP_DM_VERITY_SIGNATURE
+	bool "Enable support for dm-verity based on root hash signature"
+	depends on DM_VERITY && DM_VERITY_VERIFY_ROOTHASH_SIG
+	help
+	  This option enables the 'dmverity_signature' property within IPE
+	  policies. The property evaluates to TRUE when a file from a dm-verity
+	  volume, which has been mounted with a valid signed root hash,
+	  is evaluated.
+
+	  If unsure, answer Y.
+
+config IPE_PROP_FS_VERITY
+	bool "Enable support for fs-verity based on file digest"
+	depends on FS_VERITY
+	help
+	  This option enables the 'fsverity_digest' property within IPE
+	  policies. The property evaluates to TRUE when a file is fsverity
+	  enabled and its digest matches the supplied digest value in the
+	  policy.
+
+	  if unsure, answer Y.
+
+config IPE_PROP_FS_VERITY_BUILTIN_SIG
+	bool "Enable support for fs-verity based on builtin signature"
+	depends on FS_VERITY && FS_VERITY_BUILTIN_SIGNATURES
+	help
+	  This option enables the 'fsverity_signature' property within IPE
+	  policies. The property evaluates to TRUE when a file is fsverity
+	  enabled and it has a valid builtin signature whose signing cert
+	  is in the .fs-verity keyring.
+
+	  if unsure, answer Y.
+
+endmenu
+
+config SECURITY_IPE_KUNIT_TEST
+	bool "Build KUnit tests for IPE" if !KUNIT_ALL_TESTS
+	depends on KUNIT=y
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the IPE KUnit tests.
+
+	  KUnit tests run during boot and output the results to the debug log
+	  in TAP format (https://testanything.org/). Only useful for kernel devs
+	  running KUnit test harness and are not for inclusion into a
+	  production build.
+
+	  For more information on KUnit and unit tests in general please refer
+	  to the KUnit documentation in Documentation/dev-tools/kunit/.
+
+	  If unsure, say N.
+
+endif