• Eric W. Biederman's avatar
    ptrace: Capture the ptracer's creds not PT_PTRACE_CAP · 64b875f7
    Eric W. Biederman authored
    When the flag PT_PTRACE_CAP was added the PTRACE_TRACEME path was
    overlooked.  This can result in incorrect behavior when an application
    like strace traces an exec of a setuid executable.
    
    Further PT_PTRACE_CAP does not have enough information for making good
    security decisions as it does not report which user namespace the
    capability is in.  This has already allowed one mistake through
    insufficient granulariy.
    
    I found this issue when I was testing another corner case of exec and
    discovered that I could not get strace to set PT_PTRACE_CAP even when
    running strace as root with a full set of caps.
    
    This change fixes the above issue with strace allowing stracing as
    root a setuid executable without disabling setuid.  More fundamentaly
    this change allows what is allowable at all times, by using the correct
    information in it's decision.
    
    Cc: stable@vger.kernel.org
    Fixes: 4214e42f96d4 ("v2.4.9.11 -> v2.4.9.12")
    Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
    64b875f7
ptrace.c 31.7 KB