On Thu, Dec 4, 2008 at 2:04 PM, Serge E. Hallyn <serue@xxxxxxxxxx> wrote: > Quoting Michael Kerrisk (mtk.manpages@xxxxxxxxxxxxxx): >> Hi Serge, >> >> Thanks for CCing me on recent CLONE_NEWUSER patches. >> >> Would you be will to write some documentation for this flag? (It's >> the only remaining undocumented flag in clone(2).) Plain text would >> be fine -- I'll integrate it into the man page with suitable macros. > > Well here is a start. David, writing this actually reminded me that > the per-user keys still aren't per-namespace. Did you say you were > looking at that, or should I send a patch (starting at > security/keys/key.c:key_user_lookup())? > > Eric, if you get a second, could you please review? > > thanks, > -serge > > > CLONE_NEWUSER > Start the child in a new user namespace. > > User namespaces are very incomplete. When complete, they > will implement hierarchical userid namespaces designed to > be safely used without privilege. User namespaces are > unnamed, but for the sake of this explanation we will give > them a single-letter ID. Let us refer to userid 500 in user > namespace B as (B, 500). Assume a process owned by (B, 500) > passes CLONE_NEWUSER to clone(2). A new user namespace, C, > will be created. The new task will be owned by user > (C, 0). No userid in user namespace C will be able to > gain more access than (B, 500) could obtain. User (C, 500) > will be protected from (C, 501) as usual. Files created > by (C, 501) are owned by both (C, 501) and (B, 500), so > (B, 500) owns all files created in user namespace C. Likewise > (B, 500) can kill and ptrace any processes owned by (C, 501). This is something more of a general question than one about this manpage, but how will files owned by user namespaces be represented on the underlying filesystem? Since (C, 501) will be meaningless after a reboot at the latest, it makes little sense to persist them... -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
