• Cyrill Gorcunov's avatar
    c/r: prctl: add ability to set new mm_struct::exe_file · b32dfe37
    Cyrill Gorcunov authored
    When we do restore we would like to have a way to setup a former
    mm_struct::exe_file so that /proc/pid/exe would point to the original
    executable file a process had at checkpoint time.
    
    For this the PR_SET_MM_EXE_FILE code is introduced.  This option takes a
    file descriptor which will be set as a source for new /proc/$pid/exe
    symlink.
    
    Note it allows to change /proc/$pid/exe if there are no VM_EXECUTABLE
    vmas present for current process, simply because this feature is a special
    to C/R and mm::num_exe_file_vmas become meaningless after that.
    
    To minimize the amount of transition the /proc/pid/exe symlink might have,
    this feature is implemented in one-shot manner.  Thus once changed the
    symlink can't be changed again.  This should help sysadmins to monitor the
    symlinks over all process running in a system.
    
    In particular one could make a snapshot of processes and ring alarm if
    there unexpected changes of /proc/pid/exe's in a system.
    
    Note -- this feature is available iif CONFIG_CHECKPOINT_RESTORE is set and
    the caller must have CAP_SYS_RESOURCE capability granted, otherwise the
    request to change symlink will be rejected.
    Signed-off-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
    Reviewed-by: default avatarOleg Nesterov <oleg@redhat.com>
    Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Cc: Pavel Emelyanov <xemul@parallels.com>
    Cc: Kees Cook <keescook@chromium.org>
    Cc: Tejun Heo <tj@kernel.org>
    Cc: Matt Helsley <matthltc@us.ibm.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    b32dfe37
sys.c 51.9 KB