On Fri, Jan 03, 2020 at 08:29:27AM -0800, Sargun Dhillon wrote: > This syscall allows for the retrieval of file descriptors from other > processes, based on their pidfd. This is possible using ptrace, and > injection of parasitic code to inject code which leverages SCM_RIGHTS > to move file descriptors between a tracee and a tracer. Unfortunately, > ptrace comes with a high cost of requiring the process to be stopped, > and breaks debuggers. This does not require stopping the process under > manipulation. > > One reason to use this is to allow sandboxers to take actions on file > descriptors on the behalf of another process. For example, this can be > combined with seccomp-bpf's user notification to do on-demand fd > extraction and take privileged actions. One such privileged action > is binding a socket to a privileged port. > > This also adds the syscall to all architectures at the same time. > > /* prototype */ > /* flags is currently reserved and should be set to 0 */ > int sys_pidfd_getfd(int pidfd, int fd, unsigned int flags); > > /* testing */ > Ran self-test suite on x86_64 > > Signed-off-by: Sargun Dhillon <sargun@xxxxxxxxx> > Cc: Christian Brauner <christian.brauner@xxxxxxxxxx> The prefered way of adding a syscall is to keep the implementation separate from the wiring up into the syscall tables. So please split the patch into two: - [2/4] pidfd_getfd() implementation - [3/4] pidfd_getfd() wiring up otherwise Acked-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
