mirror of
https://gitlab.postmarketos.org/postmarketOS/pmbootstrap.git
synced 2025-07-13 11:29:46 +03:00
cb1bdcb6d0
After we pivot into the new mount namespace we need to reset our CWD for some commands to work. Signed-off-by: Casey Connolly <kcxt@postmarketos.org>
67 lines
2.3 KiB
Python
Executable file
67 lines
2.3 KiB
Python
Executable file
#!/usr/bin/env python3
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# -*- encoding: UTF-8 -*-
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# Copyright 2023 Oliver Smith
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# SPDX-License-Identifier: GPL-3.0-or-later
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# PYTHON_ARGCOMPLETE_OK
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import sys
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import pmb
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import os
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from pmb.init import sandbox
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# Sanitise environment a bit
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os.environ["SHELL"] = "/bin/sh" if os.path.exists("/bin/sh") else "/bin/bash"
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original_uid = os.geteuid()
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sandbox.acquire_privileges(become_root=False)
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# Unshare mount and PID namespaces. We create a new PID namespace so
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# that any log-running daemons (e.g. adbd, sccache) will be killed when
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# pmbootstrap exits
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sandbox.unshare(sandbox.CLONE_NEWNS | sandbox.CLONE_NEWPID)
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# We are now PID 1 in a new PID namespace. We don't want to run all our
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# logic as PID 1 since subprocess.Popen() seemingly causes our PID to
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# change. So we fork now, the child process continues and we just wait
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# around and propagate the exit code.
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# This is all kinda hacky, we should integrate this with the acquire_privileges()
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# implementation since it's already doing similar fork shenanigans, we could
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# save a call to fork() this way. But for now it's fine.
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pid = os.fork()
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if pid > 0:
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# We are PID 1! let's hang out
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pid, wstatus = os.waitpid(pid, 0)
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exitcode = os.waitstatus_to_exitcode(wstatus)
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os._exit(exitcode)
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# print("Caps: ")
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# with open("/proc/self/status", "rb") as f:
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# for line in f.readlines():
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# if line.startswith(b"CapEff:"):
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# print(line)
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# print(f"cap_sys_admin: {sandbox.have_effective_cap(sandbox.CAP_SYS_ADMIN)}")
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# print(f"single user: {sandbox.userns_has_single_user()}")
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# We set up a very basic mount environment, where we just bind mount the host
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# rootfs in. We can extend this in the future to isolate the pmb workdir but
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# for now this is enough.
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fsops = [
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sandbox.BindOperation(
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"/",
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"/",
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readonly=False,
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required=True,
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relative=False,
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),
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# Mount binfmt_misc at /tmp/pmb_binfmt_misc
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sandbox.BinfmtOperation(pmb.config.binfmt_misc),
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]
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sandbox.setup_mounts(fsops)
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# Reset our CWD now that we're inside the mount namespace
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os.chdir(os.environ["PWD"])
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# A convenience wrapper for running pmbootstrap from the git repository. This
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# script is not part of the python packaging, so don't add more logic here!
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if __name__ == "__main__":
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sys.exit(pmb.main(original_uid=original_uid))
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