Messages in this thread |  | | Subject | Re: problems with changing UID/GID | From | Trond Myklebust <> | Date | 26 Aug 2002 20:47:02 +0200 |
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>>>>> " " == Alan Cox <alan@lxorguk.ukuu.org.uk> writes:
> On Mon, 2002-08-26 at 15:58, Thunder from the hill wrote: >> I personally like the task->cred->cr_uid, etc. approach. Helps >> a lot.
> It changes the whole semantics of every security test in Linux, > and breaks most of them totally. Our syscalls know the uid is > constant during the call
Right. Most people appear to prefer to make a lunge straight for CLONE_CRED.
One of the first steps should rather be to build up support for a copy-on-write BSD-style 'ucred' struct that can be passed around the VFS. Without the latter there is no way to ensure that the compound VFS operations such as, say, lookup(), followed by a call to permission() followed by a call to dentry_open(), ->readpage(), etc. all use the same creds. This they *have* to do irrespective of whether or not the process is using CLONE_CRED, or you might end up using one set of privileges for the security checks and a different set for the actual file/device ops...
Once those VFS changes have been done and audited, then one can start to add support for 'pcreds' a.k.a. process credentials and then finally CLONE_CRED...
Cheers, Trond - 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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