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, 76 insertions, 0 deletions

diff --git a/security/integrity/evm/Kconfig b/security/integrity/evm/Kconfig
new file mode 100644
index 000000000..861b3baca
--- /dev/null
+++ b/security/integrity/evm/Kconfig
@@ -0,0 +1,76 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config EVM
+	bool "EVM support"
+	select KEYS
+	select ENCRYPTED_KEYS
+	select CRYPTO_HMAC
+	select CRYPTO_SHA1
+	select CRYPTO_HASH_INFO
+	select SECURITY_PATH
+	default n
+	help
+	  EVM protects a file's security extended attributes against
+	  integrity attacks.
+
+	  If you are unsure how to answer this question, answer N.
+
+config EVM_ATTR_FSUUID
+	bool "FSUUID (version 2)"
+	default y
+	depends on EVM
+	help
+	  Include filesystem UUID for HMAC calculation.
+
+	  Default value is 'selected', which is former version 2.
+	  if 'not selected', it is former version 1
+
+	  WARNING: changing the HMAC calculation method or adding
+	  additional info to the calculation, requires existing EVM
+	  labeled file systems to be relabeled.
+
+config EVM_EXTRA_SMACK_XATTRS
+	bool "Additional SMACK xattrs"
+	depends on EVM && SECURITY_SMACK
+	default n
+	help
+	  Include additional SMACK xattrs for HMAC calculation.
+
+	  In addition to the original security xattrs (eg. security.selinux,
+	  security.SMACK64, security.capability, and security.ima) included
+	  in the HMAC calculation, enabling this option includes newly defined
+	  Smack xattrs: security.SMACK64EXEC, security.SMACK64TRANSMUTE and
+	  security.SMACK64MMAP.
+
+	  WARNING: changing the HMAC calculation method or adding
+	  additional info to the calculation, requires existing EVM
+	  labeled file systems to be relabeled.
+
+config EVM_ADD_XATTRS
+	bool "Add additional EVM extended attributes at runtime"
+	depends on EVM
+	default n
+	help
+	  Allow userland to provide additional xattrs for HMAC calculation.
+
+	  When this option is enabled, root can add additional xattrs to the
+	  list used by EVM by writing them into
+	  /sys/kernel/security/integrity/evm/evm_xattrs.
+
+config EVM_LOAD_X509
+	bool "Load an X509 certificate onto the '.evm' trusted keyring"
+	depends on EVM && INTEGRITY_TRUSTED_KEYRING
+	default n
+	help
+	   Load an X509 certificate onto the '.evm' trusted keyring.
+
+	   This option enables X509 certificate loading from the kernel
+	   onto the '.evm' trusted keyring.  A public key can be used to
+	   verify EVM integrity starting from the 'init' process. The
+	   key must have digitalSignature usage set.
+
+config EVM_X509_PATH
+	string "EVM X509 certificate path"
+	depends on EVM_LOAD_X509
+	default "/etc/keys/x509_evm.der"
+	help
+	   This option defines X509 certificate path.