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, 41 insertions, 0 deletions

diff --git a/Documentation/crypto/api-kpp.rst b/Documentation/crypto/api-kpp.rst
new file mode 100644
index 000000000..5794e2d10
--- /dev/null
+++ b/Documentation/crypto/api-kpp.rst
@@ -0,0 +1,41 @@
+Key-agreement Protocol Primitives (KPP)
+=======================================
+
+Key-agreement Protocol Primitives (KPP) Cipher Algorithm Definitions
+--------------------------------------------------------------------
+
+.. kernel-doc:: include/crypto/kpp.h
+   :functions: kpp_request crypto_kpp kpp_alg kpp_secret
+
+Key-agreement Protocol Primitives (KPP) Cipher API
+--------------------------------------------------
+
+.. kernel-doc:: include/crypto/kpp.h
+   :doc: Generic Key-agreement Protocol Primitives API
+
+.. kernel-doc:: include/crypto/kpp.h
+   :functions: crypto_alloc_kpp crypto_free_kpp crypto_kpp_set_secret crypto_kpp_generate_public_key crypto_kpp_compute_shared_secret crypto_kpp_maxsize
+
+Key-agreement Protocol Primitives (KPP) Cipher Request Handle
+-------------------------------------------------------------
+
+.. kernel-doc:: include/crypto/kpp.h
+   :functions: kpp_request_alloc kpp_request_free kpp_request_set_callback kpp_request_set_input kpp_request_set_output
+
+ECDH Helper Functions
+---------------------
+
+.. kernel-doc:: include/crypto/ecdh.h
+   :doc: ECDH Helper Functions
+
+.. kernel-doc:: include/crypto/ecdh.h
+   :functions: ecdh crypto_ecdh_key_len crypto_ecdh_encode_key crypto_ecdh_decode_key
+
+DH Helper Functions
+-------------------
+
+.. kernel-doc:: include/crypto/dh.h
+   :doc: DH Helper Functions
+
+.. kernel-doc:: include/crypto/dh.h
+   :functions: dh crypto_dh_key_len crypto_dh_encode_key crypto_dh_decode_key