Use raw unix.Mount for rootfs self-bind-mount#13240
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specutils.SafeMount intentionally fails if the target path contains symlinks to prevent TOCTOU attacks on attacker-controlled paths. However, spec.Root.Path is host-controlled (provisioned by the container manager) and frequently contains legitimate host-level symlinks (e.g., /var/run -> /run). Since the rootfs path is trusted and not susceptible to payload manipulation, using unix.Mount() directly prevents false-positive mount failures while remaining secure. This is what runc does as well in libcontainer/rootfs_linux.go:prepareRoot(). Fixes #13238 PiperOrigin-RevId: 919484028
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Use raw unix.Mount for rootfs self-bind-mount
specutils.SafeMount intentionally fails if the target path contains
symlinks to prevent TOCTOU attacks on attacker-controlled paths.
However, spec.Root.Path is host-controlled (provisioned by the container
manager) and frequently contains legitimate host-level symlinks
(e.g., /var/run -> /run).
Since the rootfs path is trusted and not susceptible to payload
manipulation, using unix.Mount() directly prevents false-positive
mount failures while remaining secure.
This is what runc does as well in libcontainer/rootfs_linux.go:prepareRoot().
Fixes #13238