1.29

• linux: use the new mount API for more mount operations.
• linux: use OPEN_TREE_NAMESPACE when possible. It improves container startup performance.
• linux: use a trusted /proc file descriptor for more operations to harden accesses under /proc.
• linux: reject invalid capabilities in config.json.
• utils: detect the initial user namespace by the inode of /proc/self/ns/user instead of the uid_map layout, so an identity uid_map created by systemd 260 is no longer mistaken for the initial user namespace.
• utils: honor O_NOFOLLOW in the safe_openat fallback used on kernels without openat2(2), so a "dest-nofollow" bind mount whose destination is a symlink is created on the symlink itself.
• cgroup: reject a sub-cgroup that escapes the container cgroup.
• status: check the unlinkat result when removing the state directory.
• status: fix double-close.
• hooks: restore the JSON configuration passed to OCI hooks to the formatting used with YAJL (slashes not escaped, not prettified),
  avoiding breakages introduced by the switch to json-c.
• krun: require the virgl render server only when GPU support is requested.
• krun: passt, do not map the gateway address.