74d5f2397f
When Go runs a program with os.exec, it uses the LookPath function to look up the path name if the path does not contain a path separator. On Unix, this provides the standard Unix semantics by looking in PATH. However, on Windows, it also looks in the current directory as well to emulate the behavior of CMD. Unfortunately, this is a well-known security flaw on Windows and similar behavior there is the source for several whole classes of security vulnerabilities. This leads to an untrusted repository being able to create a git.bat file that gets executed in preference to our trusted path for the git binary. Since we don't want to rely on Go fixing this behavior, let's import some code from Go to provide the Unix semantics for LookPath, which are secure if the user hasn't put the current directory in PATH. That should provide secure behavior in this case. Fortunately, our code goes through one particular place to run all commands, so this is a relatively simple fix. Update the various copyright and license files to reflect our imported code.
92 lines
2.5 KiB
Go
92 lines
2.5 KiB
Go
// Copyright 2010 The Go Authors. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// +build windows
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package subprocess
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import (
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"os"
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"strings"
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)
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func chkStat(file string) error {
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d, err := os.Stat(file)
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if err != nil {
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return err
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}
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if d.IsDir() {
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return os.ErrPermission
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}
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return nil
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}
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func hasExt(file string) bool {
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i := strings.LastIndex(file, ".")
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if i < 0 {
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return false
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}
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return strings.LastIndexAny(file, `:\/`) < i
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}
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func findExecutable(file string, exts []string) (string, error) {
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if len(exts) == 0 {
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return file, chkStat(file)
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}
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if hasExt(file) {
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if chkStat(file) == nil {
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return file, nil
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}
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}
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for _, e := range exts {
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if f := file + e; chkStat(f) == nil {
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return f, nil
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}
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}
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return "", os.ErrNotExist
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}
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func findPathExtensions() []string {
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var exts []string
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x := os.Getenv(`PATHEXT`)
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if x != "" {
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for _, e := range strings.Split(strings.ToLower(x), `;`) {
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if e == "" {
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continue
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}
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if e[0] != '.' {
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e = "." + e
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}
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exts = append(exts, e)
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}
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} else {
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exts = []string{".com", ".exe", ".bat", ".cmd"}
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}
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return exts
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}
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