Mercurial > hg
view mercurial/pathutil.py @ 40626:87a872555e90
revlog: detect incomplete revlog reads
_readsegment() is supposed to return N bytes of revlog revision
data starting at a file offset. Surprisingly, its behavior before
this patch never verified that it actually read and returned N
bytes! Instead, it would perform the read(), then return whatever
data was available. And even more surprisingly, nothing in the
call chain appears to have been validating that it received all
the data it was expecting.
This behavior could lead to partial or incomplete revision chunks
being operated on. This could result in e.g. cached deltas being
applied against incomplete base revisions. The delta application
process would happily perform this operation. Only hash
verification would detect the corruption and save us.
This commit changes the behavior of raw revlog reading to validate
that we actually read() the number of bytes that were requested.
We will raise a more specific error faster, rather than possibly
have it go undetected or manifest later in the call stack, at
delta application or hash verification.
Differential Revision: https://phab.mercurial-scm.org/D5266
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Tue, 13 Nov 2018 12:30:59 -0800 |
parents | 21be76e07148 |
children | 2372284d9457 |
line wrap: on
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from __future__ import absolute_import import errno import os import posixpath import stat from .i18n import _ from . import ( encoding, error, pycompat, util, ) def _lowerclean(s): return encoding.hfsignoreclean(s.lower()) class pathauditor(object): '''ensure that a filesystem path contains no banned components. the following properties of a path are checked: - ends with a directory separator - under top-level .hg - starts at the root of a windows drive - contains ".." More check are also done about the file system states: - traverses a symlink (e.g. a/symlink_here/b) - inside a nested repository (a callback can be used to approve some nested repositories, e.g., subrepositories) The file system checks are only done when 'realfs' is set to True (the default). They should be disable then we are auditing path for operation on stored history. If 'cached' is set to True, audited paths and sub-directories are cached. Be careful to not keep the cache of unmanaged directories for long because audited paths may be replaced with symlinks. ''' def __init__(self, root, callback=None, realfs=True, cached=False): self.audited = set() self.auditeddir = set() self.root = root self._realfs = realfs self._cached = cached self.callback = callback if os.path.lexists(root) and not util.fscasesensitive(root): self.normcase = util.normcase else: self.normcase = lambda x: x def __call__(self, path, mode=None): '''Check the relative path. path may contain a pattern (e.g. foodir/**.txt)''' path = util.localpath(path) normpath = self.normcase(path) if normpath in self.audited: return # AIX ignores "/" at end of path, others raise EISDIR. if util.endswithsep(path): raise error.Abort(_("path ends in directory separator: %s") % path) parts = util.splitpath(path) if (os.path.splitdrive(path)[0] or _lowerclean(parts[0]) in ('.hg', '.hg.', '') or pycompat.ospardir in parts): raise error.Abort(_("path contains illegal component: %s") % path) # Windows shortname aliases for p in parts: if "~" in p: first, last = p.split("~", 1) if last.isdigit() and first.upper() in ["HG", "HG8B6C"]: raise error.Abort(_("path contains illegal component: %s") % path) if '.hg' in _lowerclean(path): lparts = [_lowerclean(p.lower()) for p in parts] for p in '.hg', '.hg.': if p in lparts[1:]: pos = lparts.index(p) base = os.path.join(*parts[:pos]) raise error.Abort(_("path '%s' is inside nested repo %r") % (path, pycompat.bytestr(base))) normparts = util.splitpath(normpath) assert len(parts) == len(normparts) parts.pop() normparts.pop() prefixes = [] # It's important that we check the path parts starting from the root. # This means we won't accidentally traverse a symlink into some other # filesystem (which is potentially expensive to access). for i in range(len(parts)): prefix = pycompat.ossep.join(parts[:i + 1]) normprefix = pycompat.ossep.join(normparts[:i + 1]) if normprefix in self.auditeddir: continue if self._realfs: self._checkfs(prefix, path) prefixes.append(normprefix) if self._cached: self.audited.add(normpath) # only add prefixes to the cache after checking everything: we don't # want to add "foo/bar/baz" before checking if there's a "foo/.hg" self.auditeddir.update(prefixes) def _checkfs(self, prefix, path): """raise exception if a file system backed check fails""" curpath = os.path.join(self.root, prefix) try: st = os.lstat(curpath) except OSError as err: # EINVAL can be raised as invalid path syntax under win32. # They must be ignored for patterns can be checked too. if err.errno not in (errno.ENOENT, errno.ENOTDIR, errno.EINVAL): raise else: if stat.S_ISLNK(st.st_mode): msg = (_('path %r traverses symbolic link %r') % (pycompat.bytestr(path), pycompat.bytestr(prefix))) raise error.Abort(msg) elif (stat.S_ISDIR(st.st_mode) and os.path.isdir(os.path.join(curpath, '.hg'))): if not self.callback or not self.callback(curpath): msg = _("path '%s' is inside nested repo %r") raise error.Abort(msg % (path, pycompat.bytestr(prefix))) def check(self, path): try: self(path) return True except (OSError, error.Abort): return False def canonpath(root, cwd, myname, auditor=None): '''return the canonical path of myname, given cwd and root >>> def check(root, cwd, myname): ... a = pathauditor(root, realfs=False) ... try: ... return canonpath(root, cwd, myname, a) ... except error.Abort: ... return 'aborted' >>> def unixonly(root, cwd, myname, expected='aborted'): ... if pycompat.iswindows: ... return expected ... return check(root, cwd, myname) >>> def winonly(root, cwd, myname, expected='aborted'): ... if not pycompat.iswindows: ... return expected ... return check(root, cwd, myname) >>> winonly(b'd:\\\\repo', b'c:\\\\dir', b'filename') 'aborted' >>> winonly(b'c:\\\\repo', b'c:\\\\dir', b'filename') 'aborted' >>> winonly(b'c:\\\\repo', b'c:\\\\', b'filename') 'aborted' >>> winonly(b'c:\\\\repo', b'c:\\\\', b'repo\\\\filename', ... b'filename') 'filename' >>> winonly(b'c:\\\\repo', b'c:\\\\repo', b'filename', b'filename') 'filename' >>> winonly(b'c:\\\\repo', b'c:\\\\repo\\\\subdir', b'filename', ... b'subdir/filename') 'subdir/filename' >>> unixonly(b'/repo', b'/dir', b'filename') 'aborted' >>> unixonly(b'/repo', b'/', b'filename') 'aborted' >>> unixonly(b'/repo', b'/', b'repo/filename', b'filename') 'filename' >>> unixonly(b'/repo', b'/repo', b'filename', b'filename') 'filename' >>> unixonly(b'/repo', b'/repo/subdir', b'filename', b'subdir/filename') 'subdir/filename' ''' if util.endswithsep(root): rootsep = root else: rootsep = root + pycompat.ossep name = myname if not os.path.isabs(name): name = os.path.join(root, cwd, name) name = os.path.normpath(name) if auditor is None: auditor = pathauditor(root) if name != rootsep and name.startswith(rootsep): name = name[len(rootsep):] auditor(name) return util.pconvert(name) elif name == root: return '' else: # Determine whether `name' is in the hierarchy at or beneath `root', # by iterating name=dirname(name) until that causes no change (can't # check name == '/', because that doesn't work on windows). The list # `rel' holds the reversed list of components making up the relative # file name we want. rel = [] while True: try: s = util.samefile(name, root) except OSError: s = False if s: if not rel: # name was actually the same as root (maybe a symlink) return '' rel.reverse() name = os.path.join(*rel) auditor(name) return util.pconvert(name) dirname, basename = util.split(name) rel.append(basename) if dirname == name: break name = dirname # A common mistake is to use -R, but specify a file relative to the repo # instead of cwd. Detect that case, and provide a hint to the user. hint = None try: if cwd != root: canonpath(root, root, myname, auditor) relpath = util.pathto(root, cwd, '') if relpath.endswith(pycompat.ossep): relpath = relpath[:-1] hint = (_("consider using '--cwd %s'") % relpath) except error.Abort: pass raise error.Abort(_("%s not under root '%s'") % (myname, root), hint=hint) def normasprefix(path): '''normalize the specified path as path prefix Returned value can be used safely for "p.startswith(prefix)", "p[len(prefix):]", and so on. For efficiency, this expects "path" argument to be already normalized by "os.path.normpath", "os.path.realpath", and so on. See also issue3033 for detail about need of this function. >>> normasprefix(b'/foo/bar').replace(pycompat.ossep, b'/') '/foo/bar/' >>> normasprefix(b'/').replace(pycompat.ossep, b'/') '/' ''' d, p = os.path.splitdrive(path) if len(p) != len(pycompat.ossep): return path + pycompat.ossep else: return path # forward two methods from posixpath that do what we need, but we'd # rather not let our internals know that we're thinking in posix terms # - instead we'll let them be oblivious. join = posixpath.join dirname = posixpath.dirname