On 5/22/2020 9:27 PM, Andrei Vagin wrote: > On Fri, May 22, 2020 at 09:40:37AM -0700, Casey Schaufler wrote: >> On 5/21/2020 10:53 PM, Adrian Reber wrote: >>> There are probably a few more things guarded by CAP_SYS_ADMIN required >>> to run checkpoint/restore as non-root, >> If you need CAP_SYS_ADMIN anyway you're not gaining anything by >> separating out CAP_RESTORE. >> >>> but by applying this patch I can >>> already checkpoint and restore processes as non-root. As there are >>> already multiple workarounds I would prefer to do it correctly in the >>> kernel to avoid that CRIU users are starting to invent more workarounds. >> You've presented a couple of really inappropriate implementations >> that would qualify as workarounds. But the other two are completely >> appropriate within the system security policy. They don't "get around" >> the problem, they use existing mechanisms as they are intended. >> > With CAP_CHECKPOINT_RESTORE, we will need to use the same mechanisms. Then why call them out as objectionable "workarounds"? > The problem is that CAP_SYS_ADMIN is too wide. This is well understood, and irrelevant. If we broke out CAP_SYS_ADMIN properly we'd have hundreds of capabilities, and no one would be able to manage the capability sets on anything. Just breaking out of CAP_SYS_ADMIN, especially if the process is going to need other capabilities anyway, gains you nothing. > If a process has > CAP_SYS_ADMIN, it can do a lot of things and the operation of forking a > process with a specified pid isn't the most dangerous one in this case. > Offten security policies don't allow to grant CAP_SYS_ADMIN to any > third-party tools even in non-root user namespaces. >
