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Diffstat (limited to 'vendor/github.com/cyphar/filepath-securejoin')
5 files changed, 269 insertions, 0 deletions
diff --git a/vendor/github.com/cyphar/filepath-securejoin/LICENSE b/vendor/github.com/cyphar/filepath-securejoin/LICENSE new file mode 100644 index 000000000..bec842f29 --- /dev/null +++ b/vendor/github.com/cyphar/filepath-securejoin/LICENSE @@ -0,0 +1,28 @@ +Copyright (C) 2014-2015 Docker Inc & Go Authors. All rights reserved. +Copyright (C) 2017 SUSE LLC. All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are +met: + + * Redistributions of source code must retain the above copyright +notice, this list of conditions and the following disclaimer. + * Redistributions in binary form must reproduce the above +copyright notice, this list of conditions and the following disclaimer +in the documentation and/or other materials provided with the +distribution. + * Neither the name of Google Inc. nor the names of its +contributors may be used to endorse or promote products derived from +this software without specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. diff --git a/vendor/github.com/cyphar/filepath-securejoin/README.md b/vendor/github.com/cyphar/filepath-securejoin/README.md new file mode 100644 index 000000000..49b2baa9f --- /dev/null +++ b/vendor/github.com/cyphar/filepath-securejoin/README.md @@ -0,0 +1,65 @@ +## `filepath-securejoin` ## + +[](https://travis-ci.org/cyphar/filepath-securejoin) + +An implementation of `SecureJoin`, a [candidate for inclusion in the Go +standard library][go#20126]. The purpose of this function is to be a "secure" +alternative to `filepath.Join`, and in particular it provides certain +guarantees that are not provided by `filepath.Join`. + +This is the function prototype: + +```go +func SecureJoin(root, unsafePath string) (string, error) +``` + +This library **guarantees** the following: + +* If no error is set, the resulting string **must** be a child path of + `SecureJoin` and will not contain any symlink path components (they will all + be expanded). + +* When expanding symlinks, all symlink path components **must** be resolved + relative to the provided root. In particular, this can be considered a + userspace implementation of how `chroot(2)` operates on file paths. Note that + these symlinks will **not** be expanded lexically (`filepath.Clean` is not + called on the input before processing). + +* Non-existant path components are unaffected by `SecureJoin` (similar to + `filepath.EvalSymlinks`'s semantics). + +* The returned path will always be `filepath.Clean`ed and thus not contain any + `..` components. + +A (trivial) implementation of this function on GNU/Linux systems could be done +with the following (note that this requires root privileges and is far more +opaque than the implementation in this library, and also requires that +`readlink` is inside the `root` path): + +```go +package securejoin + +import ( + "os/exec" + "path/filepath" +) + +func SecureJoin(root, unsafePath string) (string, error) { + unsafePath = string(filepath.Separator) + unsafePath + cmd := exec.Command("chroot", root, + "readlink", "--canonicalize-missing", "--no-newline", unsafePath) + output, err := cmd.CombinedOutput() + if err != nil { + return "", err + } + expanded := string(output) + return filepath.Join(root, expanded), nil +} +``` + +[go#20126]: https://github.com/golang/go/issues/20126 + +### License ### + +The license of this project is the same as Go, which is a BSD 3-clause license +available in the `LICENSE` file. diff --git a/vendor/github.com/cyphar/filepath-securejoin/join.go b/vendor/github.com/cyphar/filepath-securejoin/join.go new file mode 100644 index 000000000..c4ca3d713 --- /dev/null +++ b/vendor/github.com/cyphar/filepath-securejoin/join.go @@ -0,0 +1,134 @@ +// Copyright (C) 2014-2015 Docker Inc & Go Authors. All rights reserved. +// Copyright (C) 2017 SUSE LLC. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Package securejoin is an implementation of the hopefully-soon-to-be-included +// SecureJoin helper that is meant to be part of the "path/filepath" package. +// The purpose of this project is to provide a PoC implementation to make the +// SecureJoin proposal (https://github.com/golang/go/issues/20126) more +// tangible. +package securejoin + +import ( + "bytes" + "os" + "path/filepath" + "strings" + "syscall" + + "github.com/pkg/errors" +) + +// ErrSymlinkLoop is returned by SecureJoinVFS when too many symlinks have been +// evaluated in attempting to securely join the two given paths. +var ErrSymlinkLoop = errors.Wrap(syscall.ELOOP, "secure join") + +// IsNotExist tells you if err is an error that implies that either the path +// accessed does not exist (or path components don't exist). This is +// effectively a more broad version of os.IsNotExist. +func IsNotExist(err error) bool { + // If it's a bone-fide ENOENT just bail. + if os.IsNotExist(errors.Cause(err)) { + return true + } + + // Check that it's not actually an ENOTDIR, which in some cases is a more + // convoluted case of ENOENT (usually involving weird paths). + var errno error + switch err := errors.Cause(err).(type) { + case *os.PathError: + errno = err.Err + case *os.LinkError: + errno = err.Err + case *os.SyscallError: + errno = err.Err + } + return errno == syscall.ENOTDIR || errno == syscall.ENOENT +} + +// SecureJoinVFS joins the two given path components (similar to Join) except +// that the returned path is guaranteed to be scoped inside the provided root +// path (when evaluated). Any symbolic links in the path are evaluated with the +// given root treated as the root of the filesystem, similar to a chroot. The +// filesystem state is evaluated through the given VFS interface (if nil, the +// standard os.* family of functions are used). +// +// Note that the guarantees provided by this function only apply if the path +// components in the returned string are not modified (in other words are not +// replaced with symlinks on the filesystem) after this function has returned. +// Such a symlink race is necessarily out-of-scope of SecureJoin. +func SecureJoinVFS(root, unsafePath string, vfs VFS) (string, error) { + // Use the os.* VFS implementation if none was specified. + if vfs == nil { + vfs = osVFS{} + } + + var path bytes.Buffer + n := 0 + for unsafePath != "" { + if n > 255 { + return "", ErrSymlinkLoop + } + + // Next path component, p. + i := strings.IndexRune(unsafePath, filepath.Separator) + var p string + if i == -1 { + p, unsafePath = unsafePath, "" + } else { + p, unsafePath = unsafePath[:i], unsafePath[i+1:] + } + + // Create a cleaned path, using the lexical semantics of /../a, to + // create a "scoped" path component which can safely be joined to fullP + // for evaluation. At this point, path.String() doesn't contain any + // symlink components. + cleanP := filepath.Clean(string(filepath.Separator) + path.String() + p) + if cleanP == string(filepath.Separator) { + path.Reset() + continue + } + fullP := filepath.Clean(root + cleanP) + + // Figure out whether the path is a symlink. + fi, err := vfs.Lstat(fullP) + if err != nil && !IsNotExist(err) { + return "", err + } + // Treat non-existent path components the same as non-symlinks (we + // can't do any better here). + if IsNotExist(err) || fi.Mode()&os.ModeSymlink == 0 { + path.WriteString(p) + path.WriteRune(filepath.Separator) + continue + } + + // Only increment when we actually dereference a link. + n++ + + // It's a symlink, expand it by prepending it to the yet-unparsed path. + dest, err := vfs.Readlink(fullP) + if err != nil { + return "", err + } + // Absolute symlinks reset any work we've already done. + if filepath.IsAbs(dest) { + path.Reset() + } + unsafePath = dest + string(filepath.Separator) + unsafePath + } + + // We have to clean path.String() here because it may contain '..' + // components that are entirely lexical, but would be misleading otherwise. + // And finally do a final clean to ensure that root is also lexically + // clean. + fullP := filepath.Clean(string(filepath.Separator) + path.String()) + return filepath.Clean(root + fullP), nil +} + +// SecureJoin is a wrapper around SecureJoinVFS that just uses the os.* library +// of functions as the VFS. If in doubt, use this function over SecureJoinVFS. +func SecureJoin(root, unsafePath string) (string, error) { + return SecureJoinVFS(root, unsafePath, nil) +} diff --git a/vendor/github.com/cyphar/filepath-securejoin/vendor.conf b/vendor/github.com/cyphar/filepath-securejoin/vendor.conf new file mode 100644 index 000000000..66bb574b9 --- /dev/null +++ b/vendor/github.com/cyphar/filepath-securejoin/vendor.conf @@ -0,0 +1 @@ +github.com/pkg/errors v0.8.0 diff --git a/vendor/github.com/cyphar/filepath-securejoin/vfs.go b/vendor/github.com/cyphar/filepath-securejoin/vfs.go new file mode 100644 index 000000000..a82a5eae1 --- /dev/null +++ b/vendor/github.com/cyphar/filepath-securejoin/vfs.go @@ -0,0 +1,41 @@ +// Copyright (C) 2017 SUSE LLC. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package securejoin + +import "os" + +// In future this should be moved into a separate package, because now there +// are several projects (umoci and go-mtree) that are using this sort of +// interface. + +// VFS is the minimal interface necessary to use SecureJoinVFS. A nil VFS is +// equivalent to using the standard os.* family of functions. This is mainly +// used for the purposes of mock testing, but also can be used to otherwise use +// SecureJoin with VFS-like system. +type VFS interface { + // Lstat returns a FileInfo describing the named file. If the file is a + // symbolic link, the returned FileInfo describes the symbolic link. Lstat + // makes no attempt to follow the link. These semantics are identical to + // os.Lstat. + Lstat(name string) (os.FileInfo, error) + + // Readlink returns the destination of the named symbolic link. These + // semantics are identical to os.Readlink. + Readlink(name string) (string, error) +} + +// osVFS is the "nil" VFS, in that it just passes everything through to the os +// module. +type osVFS struct{} + +// Lstat returns a FileInfo describing the named file. If the file is a +// symbolic link, the returned FileInfo describes the symbolic link. Lstat +// makes no attempt to follow the link. These semantics are identical to +// os.Lstat. +func (o osVFS) Lstat(name string) (os.FileInfo, error) { return os.Lstat(name) } + +// Readlink returns the destination of the named symbolic link. These +// semantics are identical to os.Readlink. +func (o osVFS) Readlink(name string) (string, error) { return os.Readlink(name) } |