kadm5: Add a fuzzer input for test_marshall

TODO:

 - Add more inputs.

lib/kadm5/fuzz-inputs-txt/test_marshall-ent0.txt

@@ -0,0 +1,101 @@
+# The body of this file contains a representation of a very small and contrived
+# kadm5_principal_ent_rec meant for fuzzing.  For fuzzing purposes, the smaller
+# the input, the better.
+#
+# To compile this input into a binary input file suitable for fuzzing:
+#
+#   cd build
+#   make -j4
+#   cd lib/kadm5
+#   make test_marshall
+#   ./test_marshall --in-text --byte-order-in=packed     \
+#                   --byte-order-out=packed              \
+#                   --out-hex                            \
+#                   kadm5_principal_ent_rec              \
+#                   ../../../lib/kadm5/fuzz-inputs-txt/test_marshall-ent0.txt
+#
+# then decode the hex (e.g., with xxd -r -p) and save it in a file.
+#
+# Currently we have that saved in lib/kadm5/fuzz-inputs-packed/.
+#
+# To build and fuzz with this input:
+#
+# cd build
+# AFL_HARDEN=1 make -j4 CC=afl-clang all
+# cd lib/kadm5
+# AFL_HARDEN=1 make -j4 CC=afl-clang test_marshall
+# rm -rf f; mkdir f
+# ../../libtool --mode=execute afl-fuzz \
+#               -i ../../../lib/kadm5/fuzz-inputs-packed \
+#               -o $PWD/f                                \
+#               ./test_marshall --byte-order-in=packed   \
+#                               --byte-order-out=packed  \
+#                               --out-hex                \
+#                               kadm5_principal_ent_rec '@@'
+#
+# A kadm5_principal_ent_rec follows:
+#
+# principal name
+int32 0
+int32 1
+string TEST.H5L.SE
+string foo
+# expiration
+int32 2
+# pw expiration
+int32 3
+# last pw change
+int32 4
+# max life
+int32 5
+# mod name optional (boolean, principal name)
+int32 1
+int32 0
+int32 1
+string TEST.H5L.SE
+string bar
+# mod time
+int32 6
+# attrs
+int32 7
+# kvno
+int32 8
+# master kvno
+int32 9
+# policy (boolean, string)
+int32 1
+string default
+# aux attrs
+int32 10
+# max renew life
+int32 11
+# last success
+int32 12
+# last fail
+int32 13
+# fail count
+int32 14
+# nkeydata
+int32 2
+# keydata[0] (ver, kvno, type, data, type, data)
+int32 15
+int32 16
+int32 17
+data 1122
+int32 18
+data 2233
+# keydata[1]
+int32 19
+int32 21
+int32 22
+data 3344
+int32 23
+data 4455
+# ntldata
+int32 2
+# ntldata[0] (type, data)
+int32 24
+data 5566
+# ntldata[1]
+int32 25
+data 6677

lib/kadm5/marshall.c

@@ -486,7 +486,6 @@ static int in_binary_flag = 0;
 static int out_hex_flag = 0;
 static int out_binary_flag = 0;
 static int must_round_trip_flag = 0;
-static int byteorder_packed_flag = 0;
 static char *byteorder_string_in_string;
 static char *byteorder_string_out_string;
 static struct getargs args[] = {
@@ -508,8 +507,7 @@ static struct getargs args[] = {
     { "byte-order-out", '\0', arg_string, &byteorder_string_out_string,
         "Output byte order", "host, network, be, or le" },
     { "byte-order-in", '\0', arg_string, &byteorder_string_in_string,
-        "Input byte order", "host, network, be, or le" },
+        "Input byte order", "host, network, packed, be, or le" },
-    { "byte-order-packed", '\0', arg_flag, &byteorder_packed_flag, NULL, NULL },
 };
 
 #define DO_TYPE1(t, r, s)               \
@@ -765,7 +763,9 @@ static krb5_flags
 byteorder_flags(const char *s)
 {
     if (s == NULL)
-        return KRB5_STORAGE_BYTEORDER_HOST;
+        return KRB5_STORAGE_BYTEORDER_BE;
+    if (strcasecmp(s, "packed") == 0)
+        return KRB5_STORAGE_BYTEORDER_PACKED;
     if (strcasecmp(s, "host") == 0)
         return KRB5_STORAGE_BYTEORDER_HOST;
     if (strcasecmp(s, "network") == 0)
@@ -839,10 +839,6 @@ main(int argc, char **argv)
         }
     }
 
-    if (byteorder_packed_flag) {
-        spflags_in  |= KRB5_STORAGE_BYTEORDER_PACKED;
-        spflags_out |= KRB5_STORAGE_BYTEORDER_PACKED;
-    }
     spflags_in  |= byteorder_flags(byteorder_string_in_string);
     spflags_out |= byteorder_flags(byteorder_string_out_string);
 
@@ -878,22 +874,53 @@ main(int argc, char **argv)
     if (ret)
         krb5_err(NULL, 1, ret, "Could not check round-tripping");
     if (i.length != o.length || memcmp(i.data, o.data, i.length) != 0) {
-        if (must_round_trip_flag) {
+        krb5_storage *insp2;
-            char *hexstr = NULL;
+        krb5_data i2;
+        char *hexin = NULL;
+        char *hexout = NULL;
 
-            if (hex_encode(inbin, insz, &hexstr) == -1)
+        /*
-                err(1, "Encoding does not round-trip");
+         * kadm5_ret_principal_ent() reverses the TL data list.  So try to
-            if (fprintf(stderr, "%s\n", hexstr) < 0)
+         * re-encode once more.
-                err(1, "Could not output encoding");
+         */
-            free(hexstr);
+
-            errx(1, "Encoding does not round-trip");
+        if (strcmp(argv[0], "kadm5_principal_ent_rec") == 0) {
-        } else {
+            insp2 = krb5_storage_emem();
-            warnx("Encoding does not round-trip");
+            if (insp2 == NULL)
+                errx(1, "Out of memory");
+
+            krb5_storage_set_flags(insp2, spflags_in);
+            ret = reencode(argv[0], outsp, insp2);
+            if (ret == 0)
+                ret = krb5_storage_to_data(insp2, &i2);
+            if (ret)
+                krb5_err(NULL, 1, ret, "Could not decode and re-encode");
+            if (i.length == i2.length && memcmp(i.data, i2.data, i.length) == 0) {
+                krb5_storage_free(insp2);
+                krb5_data_free(&i2);
+                goto good;
+            }
         }
+        if (hex_encode(i.data, i.length, &hexin) < 0)
+            errx(1, "Out of memory");
+        if (hex_encode(o.data, o.length, &hexout) < 0)
+            errx(1, "Out of memory");
+        if (must_round_trip_flag) {
+            errx(1, "Encoding does not round-trip\n(in:  %s)\n(out: %s)", hexin,
+                 hexout);
+        } else {
+            warnx("Encoding does not round-trip\n(in:  %s)\n(out: %s)", hexin,
+                  hexout);
+        }
+        krb5_storage_free(insp2);
+        krb5_data_free(&i2);
+        free(hexin);
+        free(hexout);
     } else if (verbose_flag) {
         fprintf(stderr, "Encoding round-trips!\n");
     }
 
+good:
     if (out_hex_flag) {
         char *hexstr = NULL;