Overhaul Linux file emulation (#1673)

Overhaul Linux file emulation.

Previously, open file descriptors could be mapped to any of the `File`, `Directory`, `SocketDesc`, `Socket`, and `ProcSelfMaps` classes, which didn't share a common supertype, and which didn't have consistent interfaces.

Now, each of these classes implements the `FdLike` abstract base class, which specifies a number of methods.

This overhaul additionally fixes several issues with the Linux support code:

- A program that tried to ioctl on a socket would crash Manticore
- In several places, the error code returned by a failing syscall was incorrect
- Many file descriptor operations could crash Manticore when used on an already-closed descriptor
- Manticore state serialization / deserialization was incorrect for file descriptor types other than File or Socket
- In certain cases, `sys_open` / `sys_openat` could crash Manticore when trying to log a debug message
- In certain cases, `sys_readv` could crash Manticore, instead of correctly returning a negative int value
- `sys_sendfile` was broken due to a variable name typo
- In several places in Manticore’s Linux support code, incorrect type hints were present
- In some places, an exception would attempt to be raised, but that itself would crash due to a missing import.

This commit adds two more example / integration test programs.

Additionally, this adds a helper for working with Python abstract base classes.  This helper lets you declare on a class, via a decorator, that the class is expected to have no unimplemented abstract methods.  If this is not true at runtime, a `TypeError` is thrown.  Without this decorator, you will only discover that a class has unimplemented abstract methods when you try to _instantiate_ that class. This may be much, much later than at class creation time, or perhaps not at all, depending on your code coverage.

Thanks to Eric Kilmer <eric.d.kilmer@gmail.com> for review!

Author: Brad Larsen

examples/linux/Makefile

@@ -3,20 +3,22 @@ CFLAGS=-O3 -static
 NOSTDLIBFLAGS=-fno-builtin -static -nostdlib -fomit-frame-pointer -fno-stack-protector
 PYTHON=python3
 
-EXAMPLES=      \
-  arguments    \
-  basic        \
-  crackme      \
-  fclose       \
-  fileio       \
-  helloworld   \
-  ibranch      \
-  indexhell    \
-  sendmail     \
-  simpleassert \
-  simple_copy  \
-  sindex       \
-  strncmp      \
+EXAMPLES=        \
+  arguments      \
+  basic          \
+  crackme        \
+  fclose         \
+  fileio         \
+  helloworld     \
+  ibranch        \
+  indexhell      \
+  ioctl_bogus    \
+  ioctl_socket   \
+  sendmail       \
+  simpleassert   \
+  simple_copy    \
+  sindex         \
+  strncmp        \
 
 OTHER_EXAMPLES=nostdlib
 

examples/linux/fileio.c

@@ -25,7 +25,7 @@ int main(int argc, const char **argv) {
         return 3;
     }
 
-    if (strcmp("my voice is my passport verify me", line) == 0) {
+    if (strcmp("open sesame", line) == 0) {
         fprintf(stdout, "Welcome!\n");
         return 0;
     } else {

examples/linux/ioctl_bogus.c

@@ -0,0 +1,20 @@
+// This example demonstrates a particular syscall that fails at runtime.
+// Used primarily as a test of Manticore's file-related syscall implementation.
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <stropts.h>
+#include <sys/socket.h>
+
+int main() {
+    // try bogus ioctl on a non-open file descriptor
+    int rc = ioctl(42, I_FLUSH, FLUSHRW);
+    if (rc == -1) {
+        fprintf(stderr, "got expected error: %s\n", strerror(errno));
+        return 0;
+    } else {
+        fprintf(stdout, "unexpectedly succeeded!\n");
+        return 1;
+    }
+}

examples/linux/ioctl_socket.c

@@ -0,0 +1,26 @@
+// This example demonstrates a particular syscall that fails at runtime.
+// Used primarily as a test of Manticore's file-related syscall implementation.
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <stropts.h>
+#include <sys/socket.h>
+
+int main() {
+    // try bogus ioctl on a socket
+    int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+    if (sockfd < 0) {
+        fprintf(stderr, "error opening socket: %s\n", strerror(errno));
+        return 1;
+    }
+
+    int rc = ioctl(sockfd, I_FLUSH, FLUSHRW);
+    if (rc == -1) {
+        fprintf(stderr, "got expected error calling ioctl: %s\n", strerror(errno));
+        return 0;
+    } else {
+        fprintf(stdout, "unexpectedly succeeded!\n");
+        return 2;
+    }
+}

manticore/__main__.py

@@ -25,7 +25,7 @@
     from manticore.native.cli import native_main
 
 
-def main():
+def main() -> None:
     """
     Dispatches execution into one of Manticore's engines: evm or native.
     """
@@ -50,7 +50,7 @@ def main():
         native_main(args, logger)
 
 
-def parse_arguments():
+def parse_arguments() -> argparse.Namespace:
     def positive(value):
         ivalue = int(value)
         if ivalue <= 0:

manticore/native/manticore.py

@@ -13,6 +13,7 @@
 from ..core.manticore import ManticoreBase
 from ..core.smtlib import ConstraintSet
 from ..core.smtlib.solver import Z3Solver, issymbolic
+from ..exceptions import ManticoreError
 from ..utils import log, config
 
 logger = logging.getLogger(__name__)
@@ -383,7 +384,7 @@ def _make_linux(
     concrete_start="",
     pure_symbolic=False,
     stdin_size=None,
-):
+) -> State:
     from ..platforms import linux
 
     env = {} if env is None else env