Squashed 'lib/mbedtls/external/mbedtls/' content from commit 2ca6c285a0dd

git-subtree-dir: lib/mbedtls/external/mbedtls
git-subtree-split: 2ca6c285a0dd3f33982dd57299012dacab1ff206

1 files changed, 183 insertions, 0 deletions

diff --git a/tests/scripts/generate_pkcs7_tests.py b/tests/scripts/generate_pkcs7_tests.py
new file mode 100755
index 00000000000..0e484b023d9
--- /dev/null
+++ b/tests/scripts/generate_pkcs7_tests.py
@@ -0,0 +1,183 @@
+#!/usr/bin/env python3
+#
+#  Copyright The Mbed TLS Contributors
+#  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+#
+
+"""
+Make fuzz like testing for pkcs7 tests
+Given a valid DER pkcs7 file add tests to the test_suite_pkcs7.data file
+ - It is expected that the pkcs7_asn1_fail( data_t *pkcs7_buf )
+    function is defined in test_suite_pkcs7.function
+ - This is not meant to be portable code, if anything it is meant to serve as
+   documentation for showing how those ugly tests in test_suite_pkcs7.data were created
+"""
+
+
+import sys
+from os.path import exists
+
+PKCS7_TEST_FILE = "../suites/test_suite_pkcs7.data"
+
+class Test: # pylint: disable=too-few-public-methods
+    """
+    A instance of a test in test_suite_pkcs7.data
+    """
+    def __init__(self, name, depends, func_call):
+        self.name = name
+        self.depends = depends
+        self.func_call = func_call
+
+    # pylint: disable=no-self-use
+    def to_string(self):
+        return "\n" + self.name + "\n" + self.depends + "\n" + self.func_call + "\n"
+
+class TestData:
+    """
+    Take in test_suite_pkcs7.data file.
+    Allow for new tests to be added.
+    """
+    mandatory_dep = "MBEDTLS_MD_CAN_SHA256"
+    test_name = "PKCS7 Parse Failure Invalid ASN1"
+    test_function = "pkcs7_asn1_fail:"
+    def __init__(self, file_name):
+        self.file_name = file_name
+        self.last_test_num, self.old_tests = self.read_test_file(file_name)
+        self.new_tests = []
+
+    # pylint: disable=no-self-use
+    def read_test_file(self, file):
+        """
+        Parse the test_suite_pkcs7.data file.
+        """
+        tests = []
+        if not exists(file):
+            print(file + " Does not exist")
+            sys.exit()
+        with open(file, "r", encoding='UTF-8') as fp:
+            data = fp.read()
+        lines = [line.strip() for line in data.split('\n') if len(line.strip()) > 1]
+        i = 0
+        while i < len(lines):
+            if "depends" in lines[i+1]:
+                tests.append(Test(lines[i], lines[i+1], lines[i+2]))
+                i += 3
+            else:
+                tests.append(Test(lines[i], None, lines[i+1]))
+                i += 2
+        latest_test_num = float(tests[-1].name.split('#')[1])
+        return latest_test_num, tests
+
+    def add(self, name, func_call):
+        self.last_test_num += 1
+        self.new_tests.append(Test(self.test_name + ": " + name +  " #" + \
+                str(self.last_test_num), "depends_on:" + self.mandatory_dep, \
+                self.test_function + '"' + func_call + '"'))
+
+    def write_changes(self):
+        with open(self.file_name, 'a', encoding='UTF-8') as fw:
+            fw.write("\n")
+            for t in self.new_tests:
+                fw.write(t.to_string())
+
+
+def asn1_mutate(data):
+    """
+    We have been given an asn1 structure representing a pkcs7.
+    We want to return an array of slightly modified versions of this data
+    they should be modified in a way which makes the structure invalid
+
+    We know that asn1 structures are:
+    |---1 byte showing data type---|----byte(s) for length of data---|---data content--|
+    We know that some data types can contain other data types.
+    Return a dictionary of reasons and mutated data types.
+    """
+
+    # off the bat just add bytes to start and end of the buffer
+    mutations = []
+    reasons = []
+    mutations.append(["00"] + data)
+    reasons.append("Add null byte to start")
+    mutations.append(data + ["00"])
+    reasons.append("Add null byte to end")
+    # for every asn1 entry we should attempt to:
+    #    - change the data type tag
+    #    - make the length longer than actual
+    #    - make the length shorter than actual
+    i = 0
+    while i < len(data):
+        tag_i = i
+        leng_i = tag_i + 1
+        data_i = leng_i + 1 + (int(data[leng_i][1], 16) if data[leng_i][0] == '8' else 0)
+        if data[leng_i][0] == '8':
+            length = int(''.join(data[leng_i + 1: data_i]), 16)
+        else:
+            length = int(data[leng_i], 16)
+
+        tag = data[tag_i]
+        print("Looking at ans1: offset " + str(i) + " tag = " + tag + \
+                ", length = " + str(length)+ ":")
+        print(''.join(data[data_i:data_i+length]))
+        # change tag to something else
+        if tag == "02":
+            # turn integers into octet strings
+            new_tag = "04"
+        else:
+            # turn everything else into an integer
+            new_tag = "02"
+        mutations.append(data[:tag_i] + [new_tag] + data[leng_i:])
+        reasons.append("Change tag " + tag + " to " + new_tag)
+
+        # change lengths to too big
+        # skip any edge cases which would cause carry over
+        if int(data[data_i - 1], 16) < 255:
+            new_length = str(hex(int(data[data_i - 1], 16) + 1))[2:]
+            if len(new_length) == 1:
+                new_length = "0"+new_length
+            mutations.append(data[:data_i -1] + [new_length] + data[data_i:])
+            reasons.append("Change length from " + str(length) + " to " \
+                    + str(length + 1))
+            # we can add another test here for tags that contain other tags \
+            # where they have more data than there containing tags account for
+            if tag in ["30", "a0", "31"]:
+                mutations.append(data[:data_i -1] + [new_length] + \
+                        data[data_i:data_i + length] + ["00"] + \
+                        data[data_i + length:])
+                reasons.append("Change contents of tag " + tag + " to contain \
+                        one unaccounted extra byte")
+        # change lengths to too small
+        if int(data[data_i - 1], 16) > 0:
+            new_length = str(hex(int(data[data_i - 1], 16) - 1))[2:]
+            if len(new_length) == 1:
+                new_length = "0"+new_length
+            mutations.append(data[:data_i -1] + [new_length] + data[data_i:])
+            reasons.append("Change length from " + str(length) + " to " + str(length - 1))
+
+        # some tag types contain other tag types so we should iterate into the data
+        if tag in ["30", "a0", "31"]:
+            i = data_i
+        else:
+            i = data_i + length
+
+    return list(zip(reasons, mutations))
+
+if __name__ == "__main__":
+    if len(sys.argv) < 2:
+        print("USAGE: " + sys.argv[0] + " <pkcs7_der_file>")
+        sys.exit()
+
+    DATA_FILE = sys.argv[1]
+    TEST_DATA = TestData(PKCS7_TEST_FILE)
+    with open(DATA_FILE, 'rb') as f:
+        DATA_STR = f.read().hex()
+    # make data an array of byte strings eg ['de','ad','be','ef']
+    HEX_DATA = list(map(''.join, [[DATA_STR[i], DATA_STR[i+1]] for i in range(0, len(DATA_STR), \
+            2)]))
+    # returns tuples of test_names and modified data buffers
+    MUT_ARR = asn1_mutate(HEX_DATA)
+
+    print("made " + str(len(MUT_ARR)) + " new tests")
+    for new_test in MUT_ARR:
+        TEST_DATA.add(new_test[0], ''.join(new_test[1]))
+
+    TEST_DATA.write_changes()