Re: [PATCH ghak90 V7 20/21] audit: add capcontid to set contid outside init_user_ns

On 2019-10-31 10:50, Steve Grubb wrote: > Hello, > > TLDR; I see a lot of benefit to switching away from procfs for setting > auid & sessionid. > > On Wednesday, October 30, 2019 6:03:20 PM EDT Richard Guy Briggs wrote: > > > Also, for the record, removing the audit loginuid from procfs is not > > > something to take lightly, if at all; like it or not, it's part of > > > the > > > kernel API. > > It can also be used by tools to iterate processes related to one user or > session. I use this in my Intrusion Prevention System which will land in > audit user space at some point in the future. > > > Oh, I'm quite aware of how important this change is and it was > > discussed > > with Steve Grubb who saw the concern and value of considering such a > > disruptive change. > > Actually, I advocated for syscall. I think the gist of Eric's idea was > that / proc is the intersection of many nasty problems. By relying on > it, you can't simplify the API to reduce the complexity. Almost no > program actually needs access to /proc. ps does. But almost everything > else is happy without it. For example, when you setup chroot jails, you > may have to add /dev/random or / dev/null, but almost never /proc. What > does force you to add /proc is any entry point daemon like sshd because > it needs to set the loginuid. If we switch away from /proc, then sshd or > crond will no longer /require/ procfs to be available which again > simplifies the system design. > > > Removing proc support for auid/ses would be a > > long-term deprecation if accepted. > > It might need to just be turned into readonly for a while. But then > again, > perhaps auid and session should be part of /proc/<pid>/status? Maybe this > can be done independently and ahead of the container work so there is a > migration path for things that read auid or session. TBH, maybe this > should have been done from the beginning. How about making loginuid/contid/capcontid writable only via netlink but still provide the /proc interface for reading? Deprecation of proc can be left as a decision for later. This way sshd/crond/getty don't need /proc, but the info is still there for tools that want to read it.