import logging
from .plugin import SimStatePlugin
from .filesystem import SimMount, Stat
from ..storage.file import SimFile, SimPacketsStream, Flags, SimFileDescriptor, SimFileDescriptorDuplex
from .. import sim_options as options
l = logging.getLogger(name=__name__)
max_fds = 8192
[docs]class PosixDevFS(SimMount): # this'll be mounted at /dev
[docs] def get(self, path): # pylint: disable=arguments-differ
if path == ["stdin"]:
return self.state.posix.fd.get(0, None)
elif path == ["stdout"]:
return self.state.posix.fd.get(1, None)
elif path == ["stderr"]:
return self.state.posix.fd.get(2, None)
else:
return None
[docs] def insert(self, path, simfile): # pylint: disable=unused-argument, arguments-differ
return False
[docs] def delete(self, path): # pylint: disable=unused-argument, arguments-differ
return False
[docs] def lookup(self, _): # disable=unused-argument
return False
[docs] def merge(self, others, conditions, common_ancestor=None): # pylint: disable=unused-argument, arguments-differ
return False
[docs] def widen(self, others): # pylint: disable=unused-argument
return False
[docs] def copy(self, _):
return self # this holds no state!
[docs]class PosixProcFS(SimMount):
"""
The virtual file system mounted at /proc (as of now, on Linux).
"""
[docs] def get(self, path): # pylint: disable=arguments-differ
if path == [b"uptime"]:
return SimFile(b"uptime", content=b"0 0")
else:
return None
[docs] def insert(self, path, simfile): # pylint: disable=unused-argument, arguments-differ
return False
[docs] def delete(self, path): # pylint: disable=unused-argument, arguments-differ
return False
[docs] def lookup(self, _): # disable=unused-argument
return False
[docs] def merge(self, others, conditions, common_ancestor=None): # pylint: disable=unused-argument, arguments-differ
return False
[docs] def widen(self, others): # pylint: disable=unused-argument
return False
[docs] def copy(self, _):
return self # this holds no state!
[docs]class SimSystemPosix(SimStatePlugin):
"""
Data storage and interaction mechanisms for states with an environment conforming to posix.
Available as ``state.posix``.
"""
# __slots__ = [ 'maximum_symbolic_syscalls', 'files', 'max_length' ]
# some posix constants
SIG_BLOCK = 0
SIG_UNBLOCK = 1
SIG_SETMASK = 2
EPERM = 1 # /* Operation not permitted */
ENOENT = 2 # /* No such file or directory */
ESRCH = 3 # /* No such process */
EINTR = 4 # /* Interrupted system call */
EIO = 5 # /* I/O error */
ENXIO = 6 # /* No such device or address */
E2BIG = 7 # /* Argument list too long */
ENOEXEC = 8 # /* Exec format error */
EBADF = 9 # /* Bad file number */
ECHILD = 10 # /* No child processes */
EAGAIN = 11 # /* Try again */
ENOMEM = 12 # /* Out of memory */
EACCES = 13 # /* Permission denied */
EFAULT = 14 # /* Bad address */
ENOTBLK = 15 # /* Block device required */
EBUSY = 16 # /* Device or resource busy */
EEXIST = 17 # /* File exists */
EXDEV = 18 # /* Cross-device link */
ENODEV = 19 # /* No such device */
ENOTDIR = 20 # /* Not a directory */
EISDIR = 21 # /* Is a directory */
EINVAL = 22 # /* Invalid argument */
ENFILE = 23 # /* File table overflow */
EMFILE = 24 # /* Too many open files */
ENOTTY = 25 # /* Not a typewriter */
ETXTBSY = 26 # /* Text file busy */
EFBIG = 27 # /* File too large */
ENOSPC = 28 # /* No space left on device */
ESPIPE = 29 # /* Illegal seek */
EROFS = 30 # /* Read-only file system */
EMLINK = 31 # /* Too many links */
EPIPE = 32 # /* Broken pipe */
EDOM = 33 # /* Math argument out of domain of func */
ERANGE = 34 # /* Math result not representable */
[docs] def __init__(
self,
stdin=None,
stdout=None,
stderr=None,
fd=None,
sockets=None,
socket_queue=None,
argv=None,
argc=None,
environ=None,
auxv=None,
tls_modules=None,
sigmask=None,
pid=None,
ppid=None,
uid=None,
gid=None,
brk=None,
):
super().__init__()
# some limits and constants
self.sigmask_bits = 1024
self.maximum_symbolic_syscalls = 255
self.max_length = 2**16
self.argc = argc
self.argv = argv
self.environ = environ
self.auxv = auxv
self.tls_modules = tls_modules if tls_modules is not None else {}
self.brk = brk if brk is not None else 0x1B00000
self._sigmask = sigmask
self.pid = 1337 if pid is None else pid
self.ppid = 1336 if ppid is None else ppid
self.uid = 1000 if uid is None else uid
self.gid = 1000 if gid is None else gid
self.dev_fs = None
self.proc_fs = None
self.autotmp_counter = 0
self._closed_fds = []
self.sockets = sockets if sockets is not None else {}
self.socket_queue = socket_queue if socket_queue is not None else []
if stdin is None:
stdin = SimPacketsStream("stdin", write_mode=False, writable=False, ident="stdin")
if stdout is None:
stdout = SimPacketsStream("stdout", write_mode=True, writable=True, ident="stdout")
if stderr is None:
stderr = SimPacketsStream("stderr", write_mode=True, writable=True, ident="stderr")
if fd is None:
fd = {}
tty = SimFileDescriptorDuplex(stdin, stdout)
# the initial fd layout just looks like this:
# lrwx------ 1 audrey audrey 64 Jan 17 14:21 0 -> /dev/pts/4
# lrwx------ 1 audrey audrey 64 Jan 17 14:21 1 -> /dev/pts/4
# lrwx------ 1 audrey audrey 64 Jan 17 14:21 2 -> /dev/pts/4
# but we want to distinguish the streams. we compromise by having 0 and 1 go to the "tty"
# and stderr goes to a special stderr file
fd[0] = tty
fd[1] = tty
fd[2] = SimFileDescriptor(stderr, 0)
self.fd = fd
# these are the storage mechanisms!
self.stdin = stdin
self.stdout = stdout
self.stderr = stderr
@SimStatePlugin.memo
def copy(self, memo):
o = super().copy(memo)
o.sigmask_bits = self.sigmask_bits
o.maximum_symbolic_syscalls = self.maximum_symbolic_syscalls
o.max_length = self.max_length
o.stdin = self.stdin.copy(memo)
o.stdout = self.stdout.copy(memo)
o.stderr = self.stderr.copy(memo)
o.fd = {k: self.fd[k].copy(memo) for k in self.fd}
o.sockets = {ident: tuple(x.copy(memo) for x in self.sockets[ident]) for ident in self.sockets}
o.socket_queue = self.socket_queue # shouldn't need to copy this - should be copied before use.
o.argv = self.argv
o.argc = self.argc
o.environ = self.environ
o.auxv = self.auxv
o.tls_modules = self.tls_modules
o._sigmask = self._sigmask
o.pid = self.pid
o.ppid = self.ppid
o.uid = self.uid
o.gid = self.gid
o.brk = self.brk
o.autotmp_counter = self.autotmp_counter
o.dev_fs = self.dev_fs.copy(memo)
o.proc_fs = self.proc_fs.copy(memo)
o._closed_fds = list(self._closed_fds)
return o
@property
def closed_fds(self):
for _, f in self._closed_fds:
f.set_state(self.state)
return self._closed_fds
[docs] def init_state(self):
if self.dev_fs is None:
self.dev_fs = PosixDevFS()
self.state.fs.mount(b"/dev", self.dev_fs)
if self.proc_fs is None:
self.proc_fs = PosixProcFS()
self.state.fs.mount(b"/proc", self.proc_fs)
[docs] def set_brk(self, new_brk):
# arch word size is not available at init for some reason, fix that here
if isinstance(self.brk, int):
self.brk = self.state.solver.BVV(self.brk, self.state.arch.bits)
if new_brk.symbolic:
l.warning("Program is requesting a symbolic brk! This cannot be emulated cleanly!")
self.brk = self.state.solver.If(new_brk < self.brk, self.brk, new_brk)
else:
conc_start = self.state.solver.eval(self.brk)
conc_end = self.state.solver.eval(new_brk)
# failure case: new brk is less than old brk
if conc_end < conc_start:
pass
else:
# set break! we might not actually need to allocate memory though... pages
self.brk = new_brk
# if the old and new are in different pages, map
# we check the byte before each of them since the "break" is the address of the first
# "unmapped" byte...
if ((conc_start - 1) ^ (conc_end - 1)) & ~0xFFF:
# align up
if conc_start & 0xFFF:
conc_start = (conc_start & ~0xFFF) + 0x1000
if conc_end & 0xFFF:
conc_end = (conc_end & ~0xFFF) + 0x1000
# TODO: figure out what permissions to use
try:
self.state.memory.map_region(conc_start, conc_end - conc_start, 7)
except SimMemoryError as e:
if len(e.args) >= 2 and type(e.args[1]) is int:
l.warning("The heap seems to have collided with another allocation. Be careful!")
self.brk = e.args[1]
else:
raise
return self.brk
[docs] def set_state(self, state):
super().set_state(state)
for fd in self.fd:
self.fd[fd].set_state(state)
self.stdin.set_state(state)
self.stdout.set_state(state)
self.stderr.set_state(state)
if self.socket_queue:
for sock_pair in self.socket_queue:
if not sock_pair:
continue
sock_pair[0].set_state(state)
sock_pair[1].set_state(state)
if self.sockets:
for sock_pair in self.sockets.values():
sock_pair[0].set_state(state)
sock_pair[1].set_state(state)
def _pick_fd(self):
for fd in range(0, max_fds):
if fd not in self.fd:
return fd
raise SimPosixError("exhausted file descriptors")
[docs] def open(self, name, flags, preferred_fd=None):
"""
Open a symbolic file. Basically open(2).
:param name: Path of the symbolic file, as a string or bytes.
:type name: string or bytes
:param flags: File operation flags, a bitfield of constants from open(2), as an AST
:param preferred_fd: Assign this fd if it's not already claimed.
:return: The file descriptor number allocated (maps through posix.get_fd to a SimFileDescriptor)
or -1 if the open fails.
``mode`` from open(2) is unsupported at present.
"""
if len(name) == 0:
return -1
if type(name) is str:
name = name.encode()
# FIXME: HACK
if self.uid != 0 and name.startswith(b"/var/run"):
return -1
# TODO: speed this up (editor's note: ...really? this is fine)
if preferred_fd is not None and preferred_fd not in self.fd:
fd = preferred_fd
else:
fd = self._pick_fd()
flags = self.state.solver.eval(flags)
create_file = (flags & Flags.O_ACCMODE) in (Flags.O_RDWR, Flags.O_WRONLY)
simfile = self.state.fs.get(name)
if simfile is None:
ident = SimFile.make_ident(name)
if not create_file:
if options.ALL_FILES_EXIST not in self.state.options:
if options.ANY_FILE_MIGHT_EXIST in self.state.options:
file_exists = self.state.solver.BoolS("file_exists_%s" % ident, explicit_name=True)
else:
return -1
else:
file_exists = True
l.warning(
"Trying to open unknown file %s - created a symbolic file since ALL_FILES_EXIST is set", name
)
simfile = SimFile(
name,
ident=ident,
size=self.state.solver.BVS(
"filesize_%s" % ident, self.state.arch.bits, key=("file", ident, "filesize"), eternal=True
),
file_exists=file_exists,
)
else:
simfile = SimFile(name, ident=ident)
if not self.state.fs.insert(name, simfile):
return -1
simfd = SimFileDescriptor(simfile, flags)
simfd.set_state(self.state)
self.fd[fd] = simfd
if self.state.solver.is_true(simfd.file_exists):
return fd
else:
m1 = self.state.solver.BVV(-1, self.state.arch.sizeof["int"])
return self.state.solver.If(simfd.file_exists, fd, m1)
[docs] def open_socket(self, ident):
fd = self._pick_fd()
# we need a sockpair, or a pair of storage mechanisms that will be duplexed to form the socket
# we can get them from either:
# a) the socket identifier store
# b) the socket queue
# c) making them ourselves
# in the latter two cases we need to attach them to the socket identifier store
# control flow sucks. we should be doing our analysis with nothing but mov instructions
sockpair = None
if ident not in self.sockets:
if self.socket_queue:
sockpair = self.socket_queue.pop(0)
if sockpair is not None:
memo = {}
# Since we are not copying sockpairs when the FS state plugin branches, their original SimState
# instances might have long gone. Update their states before making copies.
sockpair[0].set_state(self.state)
sockpair[1].set_state(self.state)
sockpair = sockpair[0].copy(memo), sockpair[1].copy(memo)
if sockpair is None:
read_file = SimPacketsStream("socket %s read" % str(ident))
write_file = SimPacketsStream("socket %s write" % str(ident))
sockpair = (read_file, write_file)
self.sockets[ident] = sockpair
else:
sockpair = self.sockets[ident]
simfd = SimFileDescriptorDuplex(sockpair[0], sockpair[1])
simfd.set_state(self.state)
self.fd[fd] = simfd
return fd
[docs] def get_fd(self, fd, create_file=True):
"""
Looks up the SimFileDescriptor associated with the given number (an AST).
If the number is concrete and does not map to anything, return None.
If the number is symbolic, constrain it to an open fd and create a new file for it.
Set create_file to False if no write-access is planned (i.e. fd is read-only).
"""
concr_fd = self._get_concrete_fd(fd, create_file)
if concr_fd < 0 or max_fds <= concr_fd:
return None
return self.fd.get(concr_fd)
[docs] def get_concrete_fd(self, fd, create_file=True):
"""
Same behavior as get_fd(fd), only the result is a concrete integer fd (or -1) instead of a SimFileDescriptor.
"""
concr_fd = self._get_concrete_fd(fd, create_file)
if concr_fd < 0 or max_fds <= concr_fd:
return -1
return concr_fd
def _get_concrete_fd(self, fd, create_file):
if isinstance(fd, int):
return fd
if not self.state.satisfiable(extra_constraints=(fd < max_fds,)):
return -1
try:
return self.state.solver.eval_one(fd, extra_constraints=(fd < max_fds,))
except SimSolverError:
pass
new_filename = b"/tmp/angr_implicit_%d" % self.autotmp_counter
self.autotmp_counter += 1
if create_file:
flags = Flags.O_RDWR
else:
flags = Flags.O_RDONLY
concr_fd = self._pick_fd()
if not self.state.satisfiable(extra_constraints=(concr_fd == fd,)):
l.error("Could not look up a partially constrained symbolic fd")
return -1
opened_fd = self.open(new_filename, flags, preferred_fd=concr_fd)
if not self.state.satisfiable(extra_constraints=(concr_fd == opened_fd,)):
l.error("Something went wrong trying to open implicit temp")
return -1
self.state.add_constraints(fd == opened_fd)
l.warning("Tried to look up a symbolic fd - constrained to %d and opened %s", concr_fd, new_filename)
return concr_fd
[docs] def close(self, fd):
"""
Closes the given file descriptor (an AST).
Returns whether the operation succeeded (a concrete boolean)
"""
if not isinstance(fd, int):
try:
fd = self.state.solver.eval_one(fd, extra_constraints=(fd < max_fds,))
except SimSolverError:
l.error("Trying to close a symbolic file descriptor")
return False
if fd not in self.fd:
l.info("Trying to close an unopened file descriptor")
return False
self.state.history.add_event("fs_close", fd=fd, close_idx=len(self.closed_fds))
self.closed_fds.append((fd, self.fd[fd]))
del self.fd[fd]
return True
[docs] def fstat(self, fd):
stat, _ = self.fstat_with_result(fd)
return stat
[docs] def fstat_with_result(self, sim_fd):
# sizes are AMD64-specific for symbolic files for now
fd = None
mount = None
mode = None
guest_path = None
# set fd to the value of sim_fd, if positive and unique
try:
fd = self.state.solver.eval_one(sim_fd)
if fd < 0 or max_fds <= fd:
fd = None
except SimSolverError:
pass
if fd is not None:
fd_desc = self.state.posix.get_fd(fd)
# a fd can be SimFileDescriptorDuplex which is not backed by a file
if isinstance(fd_desc, SimFileDescriptor):
sim_file = fd_desc.file
mount = self.state.fs.get_mountpoint(sim_file.name)[0] # TODO this is wrong. .name starts with file://
if mount:
guest_path = mount.lookup(sim_file)
result = 0
else:
if options.ALL_FILES_EXIST not in self.state.options:
if options.ANY_FILE_MIGHT_EXIST in self.state.options:
m1 = self.state.solver.BVV(-1, self.state.arch.bits)
result = self.state.solver.If(self.state.solver.BoolS("file_exists"), 0, m1)
else:
result = -1
else:
result = 0
# if it is mounted, let the filesystem figure out the stat
if guest_path is not None and mount is not None:
stat = mount._get_stat(guest_path, dereference=True)
if stat is None:
raise SimPosixError(f"file {guest_path} does not exist on mount {mount}")
size = stat.st_size
mode = stat.st_mode
ino = stat.st_ino
else:
# now we know it is not mounted, do the same as before
if not fd:
mode = self.state.solver.BVS("st_mode", 32, key=("api", "fstat", "st_mode"))
else:
mode = (
self.state.solver.BVS("st_mode", 32, key=("api", "fstat", "st_mode"))
if fd > 2
else self.state.solver.BVV(0, 32)
)
size = self.state.solver.BVS("st_size", 64, key=("api", "fstat", "st_size")) # st_size
ino = 0
# return this weird bogus zero value to keep code paths in libc simple :\
return (
Stat(
self.state.solver.BVV(0, 64), # st_dev
self.state.solver.BVV(ino, 64), # st_ino
self.state.solver.BVV(0, 64), # st_nlink
mode, # st_mode
self.state.solver.BVV(0, 32), # st_uid (lol root)
self.state.solver.BVV(0, 32), # st_gid
self.state.solver.BVV(0, 64), # st_rdev
size, # st_size
self.state.solver.BVV(0x400, 64), # st_blksize
self.state.solver.BVV(0, 64), # st_blocks
self.state.solver.BVV(0, 64), # st_atime
self.state.solver.BVV(0, 64), # st_atimensec
self.state.solver.BVV(0, 64), # st_mtime
self.state.solver.BVV(0, 64), # st_mtimensec
self.state.solver.BVV(0, 64), # st_ctime
self.state.solver.BVV(0, 64), # st_ctimensec
),
result,
)
[docs] def sigmask(self, sigsetsize=None):
"""
Gets the current sigmask. If it's blank, a new one is created (of sigsetsize).
:param sigsetsize: the size (in *bytes* of the sigmask set)
:return: the sigmask
"""
if self._sigmask is None:
if sigsetsize is not None:
sc = self.state.solver.eval(sigsetsize)
self.state.add_constraints(sc == sigsetsize)
self._sigmask = self.state.solver.BVS(
"initial_sigmask", sc * self.state.arch.byte_width, key=("initial_sigmask",), eternal=True
)
else:
self._sigmask = self.state.solver.BVS(
"initial_sigmask", self.sigmask_bits, key=("initial_sigmask",), eternal=True
)
return self._sigmask
[docs] def sigprocmask(self, how, new_mask, sigsetsize, valid_ptr=True):
"""
Updates the signal mask.
:param how: the "how" argument of sigprocmask (see manpage)
:param new_mask: the mask modification to apply
:param sigsetsize: the size (in *bytes* of the sigmask set)
:param valid_ptr: is set if the new_mask was not NULL
"""
oldmask = self.sigmask(sigsetsize)
self._sigmask = self.state.solver.If(
valid_ptr,
self.state.solver.If(
how == self.SIG_BLOCK,
oldmask | new_mask,
self.state.solver.If(
how == self.SIG_UNBLOCK,
oldmask & (~new_mask),
self.state.solver.If(how == self.SIG_SETMASK, new_mask, oldmask),
),
),
oldmask,
)
[docs] def merge(self, others, merge_conditions, common_ancestor=None):
for o in others:
if len(self.fd) != len(o.fd):
raise SimMergeError("Can't merge states with disparate open file descriptors")
for fd in self.fd:
if fd not in o.fd:
raise SimMergeError("Can't merge states with disparate open file descriptors")
if len(self.sockets) != len(o.sockets):
raise SimMergeError("Can't merge states with disparate sockets")
for ident in self.sockets:
if ident not in o.sockets:
raise SimMergeError("Can't merge states with disparate sockets")
if len(self.socket_queue) != len(o.socket_queue) or any(
x is not y for x, y in zip(self.socket_queue, o.socket_queue)
):
raise SimMergeError("Can't merge states with disparate socket queues")
merging_occurred = False
for fd in self.fd:
try:
common_fd = common_ancestor.fd[fd]
except (AttributeError, KeyError):
common_fd = None
merging_occurred |= self.fd[fd].merge(
[o.fd[fd] for o in others], merge_conditions, common_ancestor=common_fd
)
for ident in self.sockets:
try:
common_sock = common_ancestor.sockets[ident]
except (AttributeError, KeyError):
common_sock = None
merging_occurred |= self.sockets[ident][0].merge(
[o.sockets[ident][0] for o in others], merge_conditions, common_ancestor=common_sock[0]
)
merging_occurred |= self.sockets[ident][1].merge(
[o.sockets[ident][1] for o in others], merge_conditions, common_ancestor=common_sock[1]
)
# pylint: disable=no-member
# pylint seems to be seriously flipping out here for reasons I'm unsure of
# it thinks others is a list of bools somehow
merging_occurred |= self.stdin.merge(
[o.stdin for o in others],
merge_conditions,
common_ancestor=common_ancestor.stdin if common_ancestor is not None else None,
)
merging_occurred |= self.stdout.merge(
[o.stdout for o in others],
merge_conditions,
common_ancestor=common_ancestor.stdout if common_ancestor is not None else None,
)
merging_occurred |= self.stderr.merge(
[o.stderr for o in others],
merge_conditions,
common_ancestor=common_ancestor.stderr if common_ancestor is not None else None,
)
return merging_occurred
[docs] def widen(self, _):
raise SimMergeError("Widening the system state is unsupported")
[docs] def dump_file_by_path(self, path, **kwargs):
"""
Returns the concrete content for a file by path.
:param path: file path as string
:param kwargs: passed to state.solver.eval
:return: file contents as string
"""
file = self.state.fs.get(path)
if file is None:
return None
return file.concretize(**kwargs)
[docs] def dumps(self, fd, **kwargs):
"""
Returns the concrete content for a file descriptor.
BACKWARD COMPATIBILITY: if you ask for file descriptors 0 1 or 2, it will return the data from stdin, stdout,
or stderr as a flat string.
:param fd: A file descriptor.
:return: The concrete content.
:rtype: str
"""
if 0 <= fd <= 2:
data = [self.stdin, self.stdout, self.stderr][fd].concretize(**kwargs)
if type(data) is list:
data = b"".join(data)
return data
return self.get_fd(fd).concretize(**kwargs)
from angr.sim_state import SimState
SimState.register_default("posix", SimSystemPosix)
from ..errors import SimPosixError, SimSolverError, SimMergeError, SimMemoryError