Messages in this thread | | | From | Kay Sievers <> | Date | Fri, 5 Mar 2010 10:51:47 -0800 | Subject | Re: [PATCH] exit: PR_SET_ANCHOR for marking processes as reapers for child processes |
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On Thu, Mar 4, 2010 at 14:14, Roland McGrath <roland@redhat.com> wrote: >> Security. This is beyond my understanding, hopefully the cc'ed >> experts can help. > > There are a few different aspects of behavior change to think about. > > 1. Who can get a SIGCHLD and wait result they weren't expecting. > 2. Who sees some PID for getppid() when they are expecting 1. > 3. What ps shows. > > When I start thinking through what might be security issues, they are > almost all #1 questions. There is a hairy nest of many variations of #1 > questions. The #2 question is pretty simple, but it also could be an issue > for security when setuid is involved (or just correctness for any > application). > > My impression is that #3 is the only actual motivation for this feature. > So perhaps we should consider an approach that leaves the rest of the > semantics alone and only affects that.
Oh, no. Actually getting the SIGCHILD is the needed feature here. A process who sets the ANCHOR flag is surely expected to handle these signals. It's all about a user "init-like" process" that can do similar things for a logged-in user what /sbin/init can to for the system. So, it's all about 1.), and 3.) is a nice side-effect, but not the motivation to do this.
And 2.) is just very broken behavior that should be fixed in the application, and it can be worked around in the sub-init process if needed.
Thanks, Kay -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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