From f2a8d52e0a4db968c346c4332630a71cba377567 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Tue, 5 May 2020 16:04:30 +0200 Subject: nsproxy: add struct nsset Add a simple struct nsset. It holds all necessary pieces to switch to a new set of namespaces without leaving a task in a half-switched state which we will make use of in the next patch. This patch switches the existing setns logic over without causing a change in setns() behavior. This brings setns() closer to how unshare() works(). The prepare_ns() function is responsible to prepare all necessary information. This has two reasons. First it minimizes dependencies between individual namespaces, i.e. all install handler can expect that all fields are properly initialized independent in what order they are called in. Second, this makes the code easier to maintain and easier to follow if it needs to be changed. The prepare_ns() helper will only be switched over to use a flags argument in the next patch. Here it will still use nstype as a simple integer argument which was argued would be clearer. I'm not particularly opinionated about this if it really helps or not. The struct nsset itself already contains the flags field since its name already indicates that it can contain information required by different namespaces. None of this should have functional consequences. Signed-off-by: Christian Brauner Reviewed-by: Serge Hallyn Cc: Eric W. Biederman Cc: Serge Hallyn Cc: Jann Horn Cc: Michael Kerrisk Cc: Aleksa Sarai Link: https://lore.kernel.org/r/20200505140432.181565-2-christian.brauner@ubuntu.com --- include/linux/nsproxy.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'include/linux/nsproxy.h') diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h index 074f395b9ad2..cdb171efc7cb 100644 --- a/include/linux/nsproxy.h +++ b/include/linux/nsproxy.h @@ -41,6 +41,30 @@ struct nsproxy { }; extern struct nsproxy init_nsproxy; +/* + * A structure to encompass all bits needed to install + * a partial or complete new set of namespaces. + * + * If a new user namespace is requested cred will + * point to a modifiable set of credentials. If a pointer + * to a modifiable set is needed nsset_cred() must be + * used and tested. + */ +struct nsset { + unsigned flags; + struct nsproxy *nsproxy; + struct fs_struct *fs; + const struct cred *cred; +}; + +static inline struct cred *nsset_cred(struct nsset *set) +{ + if (set->flags & CLONE_NEWUSER) + return (struct cred *)set->cred; + + return NULL; +} + /* * the namespaces access rules are: * -- cgit v1.2.3