forked from hardcoresushi/DroidFS
45 lines
1.2 KiB
Go
45 lines
1.2 KiB
Go
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package syscallcompat
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import (
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"path/filepath"
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"strings"
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"syscall"
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)
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// OpenDirNofollow opens the dir at "relPath" in a way that is secure against
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// symlink attacks. Symlinks that are part of "relPath" are never followed.
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// This function is implemented by walking the directory tree, starting at
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// "baseDir", using the Openat syscall with the O_NOFOLLOW flag.
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// Symlinks that are part of the "baseDir" path are followed.
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func OpenDirNofollow(baseDir string, relPath string) (fd int, err error) {
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if !filepath.IsAbs(baseDir) {
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return -1, syscall.EINVAL
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}
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if filepath.IsAbs(relPath) {
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return -1, syscall.EINVAL
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}
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// Open the base dir (following symlinks)
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dirfd, err := syscall.Open(baseDir, syscall.O_DIRECTORY|O_PATH, 0)
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if err != nil {
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return -1, err
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}
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// Caller wanted to open baseDir itself?
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if relPath == "" {
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return dirfd, nil
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}
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// Split the path into components
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parts := strings.Split(relPath, "/")
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// Walk the directory tree
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var dirfd2 int
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for _, name := range parts {
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dirfd2, err = Openat(dirfd, name, syscall.O_NOFOLLOW|syscall.O_DIRECTORY|O_PATH, 0)
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syscall.Close(dirfd)
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if err != nil {
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return -1, err
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}
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dirfd = dirfd2
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}
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// Return fd to final directory
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return dirfd, nil
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}
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