tests: Add 50-sim-hash_collision test

libseccomp utilizes a hash table to manage BPF blocks.  It
currently employs MurmurHash3 where the key is the hashed values
of the BPF instruction blocks, the accumulator start, and the
accumulator end.  This test was added because of a mishandled
hash collision reported by Tor in GitHub issue #148.
* https://github.com/seccomp/libseccomp/issues/148

Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/tests/50-sim-hash_collision.py b/tests/50-sim-hash_collision.py
new file mode 100755
index 0000000..d3c5f2f
--- /dev/null
+++ b/tests/50-sim-hash_collision.py
@@ -0,0 +1,61 @@
+#!/usr/bin/env python
+
+#
+# Seccomp Library test program
+#
+# Copyright (c) 2019 Oracle and/or its affiliates.  All rights reserved.
+# Author: Tom Hromatka <tom.hromatka@oracle.com>
+#
+
+#
+# This library is free software; you can redistribute it and/or modify it
+# under the terms of version 2.1 of the GNU Lesser General Public License as
+# published by the Free Software Foundation.
+#
+# This library is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
+# for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this library; if not, see <http://www.gnu.org/licenses>.
+#
+
+import argparse
+import sys
+
+import util
+
+from seccomp import *
+
+def test(args):
+    set_api(1)
+    f = SyscallFilter(ERRNO(100))
+    f.remove_arch(Arch())
+    f.add_arch(Arch("x86_64"))
+
+    # libseccomp utilizes a hash table to manage BPF blocks.  It currently
+    # employs MurmurHash3 where the key is the hashed values of the BPF
+    # instruction blocks, the accumulator start, and the accumulator end.
+    # Changes to the hash algorithm will likely affect this test.
+
+    # The following rules were derived from an issue reported by Tor:
+    # https://github.com/seccomp/libseccomp/issues/148
+    #
+    # In the steps below, syscall 1001 is configured similarly to how
+    # Tor configured socket.  The fairly complex rules below led to
+    # a hash collision with rt_sigaction (syscall 1000) in this test.
+
+    f.add_rule_exactly(ALLOW, 1001, Arg(0, EQ, 1), Arg(1, MASKED_EQ, 0xf, 2),
+                       Arg(2, EQ, 3))
+    f.add_rule_exactly(ALLOW, 1001, Arg(0, EQ, 1), Arg(1, MASKED_EQ, 0xf, 1))
+    f.add_rule_exactly(ALLOW, 1000, Arg(0, EQ, 2))
+    f.add_rule_exactly(ALLOW, 1000, Arg(0, EQ, 1))
+    return f
+
+args = util.get_opt()
+ctx = test(args)
+util.filter_output(args, ctx)
+
+# kate: syntax python;
+# kate: indent-mode python; space-indent on; indent-width 4; mixedindent off;