Aleksa Sarai e34a0a0936 console: verify /dev/pts/ptmx before use ...

This is primarily done out of an abudance of caution against runc exec
being attacked by a container where /dev/pts/ptmx has been replaced with
some other bad inode (a disconnected NFS handle, a symlink that goes
through a leaked runc file descriptor to reference a host ptmx, etc).

Unfortunately, we cannot trivially verify that /dev/pts/ptmx is actually
the /dev/pts from the container without storing stuff like the fsid in
the runc state.json, which is probably not worth the extra effort. This
should at least avoid the most concerning cases.

Reported-by: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>

2025-10-16 11:29:32 +11:00

..

console

console: verify /dev/pts/ptmx before use

2025-10-16 11:29:32 +11:00