mirror of https://github.com/jetkvm/kvm.git
36 lines
1.1 KiB
Go
36 lines
1.1 KiB
Go
package openat
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import (
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"golang.org/x/sys/unix"
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)
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// OpenSymlinkAware is a symlink-aware syscall.Open replacement.
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//
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// What it does:
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//
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// 1. Open baseDir (usually an absolute path), following symlinks.
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//
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// The user may have set up the directory tree with symlinks,
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// that's not neccessarily malicous, but a normal use case.
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//
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// 2. Open path (must be a relative path) within baseDir, rejecting symlinks with ELOOP.
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//
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// On Linux, it calls openat2(2) with RESOLVE_NO_SYMLINKS. This prevents following
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// symlinks in any component of the path.
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//
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// On other platforms, it calls openat(2) with O_NOFOLLOW.
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// TODO: This is insecure as O_NOFOLLOW only affects the final path component.
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func OpenSymlinkAware(baseDir string, path string, flags int, mode uint32) (fd int, err error) {
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// Passing an absolute path is a bug in the caller
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if len(path) > 0 && path[0] == '/' {
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return -1, unix.EINVAL
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}
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baseFd, err := unix.Open(baseDir, unix.O_RDONLY|unix.O_DIRECTORY|unix.O_CLOEXEC, 0)
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if err != nil {
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return -1, err
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}
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defer unix.Close(baseFd)
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return openatNoSymlinks(baseFd, path, flags, mode)
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}
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