The patch titled userns: add a user_namespace as creator/owner of uts_namespace has been removed from the -mm tree. Its filename was userns-add-a-user_namespace-as-creator-owner-of-uts_namespace.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: userns: add a user_namespace as creator/owner of uts_namespace From: "Serge E. Hallyn" <serge@xxxxxxxxxx> The expected course of development for user namespaces targeted capabilities is laid out at https://wiki.ubuntu.com/UserNamespace. Goals: - Make it safe for an unprivileged user to unshare namespaces. They will be privileged with respect to the new namespace, but this should only include resources which the unprivileged user already owns. - Provide separate limits and accounting for userids in different namespaces. Status: Currently (as of 2.6.38) you can clone with the CLONE_NEWUSER flag to get a new user namespace if you have the CAP_SYS_ADMIN, CAP_SETUID, and CAP_SETGID capabilities. What this gets you is a whole new set of userids, meaning that user 500 will have a different 'struct user' in your namespace than in other namespaces. So any accounting information stored in struct user will be unique to your namespace. However, throughout the kernel there are checks which - simply check for a capability. Since root in a child namespace has all capabilities, this means that a child namespace is not constrained. - simply compare uid1 == uid2. Since these are the integer uids, uid 500 in namespace 1 will be said to be equal to uid 500 in namespace 2. As a result, the lxc implementation at lxc.sf.net does not use user namespaces. This is actually helpful because it leaves us free to develop user namespaces in such a way that, for some time, user namespaces may be unuseful. Bugs aside, this patchset is supposed to not at all affect systems which are not actively using user namespaces, and only restrict what tasks in child user namespace can do. They begin to limit privilege to a user namespace, so that root in a container cannot kill or ptrace tasks in the parent user namespace, and can only get world access rights to files. Since all files currently belong to the initila user namespace, that means that child user namespaces can only get world access rights to *all* files. While this temporarily makes user namespaces bad for system containers, it starts to get useful for some sandboxing. I've run the 'runltplite.sh' with and without this patchset and found no difference. This patch: copy_process() handles CLONE_NEWUSER before the rest of the namespaces. So in the case of clone(CLONE_NEWUSER|CLONE_NEWUTS) the new uts namespace will have the new user namespace as its owner. That is what we want, since we want root in that new userns to be able to have privilege over it. Changelog: Feb 15: don't set uts_ns->user_ns if we didn't create a new uts_ns. Feb 23: Move extern init_user_ns declaration from init/version.c to utsname.h. Signed-off-by: Serge E. Hallyn <serge.hallyn@xxxxxxxxxxxxx> Acked-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxx> Acked-by: David Howells <dhowells@xxxxxxxxxx> Cc: James Morris <jmorris@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/utsname.h | 4 ++++ init/version.c | 1 + kernel/nsproxy.c | 5 +++++ kernel/user.c | 8 ++++++-- kernel/utsname.c | 4 ++++ 5 files changed, 20 insertions(+), 2 deletions(-) diff -puN include/linux/utsname.h~userns-add-a-user_namespace-as-creator-owner-of-uts_namespace include/linux/utsname.h --- a/include/linux/utsname.h~userns-add-a-user_namespace-as-creator-owner-of-uts_namespace +++ a/include/linux/utsname.h @@ -37,9 +37,13 @@ struct new_utsname { #include <linux/nsproxy.h> #include <linux/err.h> +struct user_namespace; +extern struct user_namespace init_user_ns; + struct uts_namespace { struct kref kref; struct new_utsname name; + struct user_namespace *user_ns; }; extern struct uts_namespace init_uts_ns; diff -puN init/version.c~userns-add-a-user_namespace-as-creator-owner-of-uts_namespace init/version.c --- a/init/version.c~userns-add-a-user_namespace-as-creator-owner-of-uts_namespace +++ a/init/version.c @@ -33,6 +33,7 @@ struct uts_namespace init_uts_ns = { .machine = UTS_MACHINE, .domainname = UTS_DOMAINNAME, }, + .user_ns = &init_user_ns, }; EXPORT_SYMBOL_GPL(init_uts_ns); diff -puN kernel/nsproxy.c~userns-add-a-user_namespace-as-creator-owner-of-uts_namespace kernel/nsproxy.c --- a/kernel/nsproxy.c~userns-add-a-user_namespace-as-creator-owner-of-uts_namespace +++ a/kernel/nsproxy.c @@ -74,6 +74,11 @@ static struct nsproxy *create_new_namesp err = PTR_ERR(new_nsp->uts_ns); goto out_uts; } + if (new_nsp->uts_ns != tsk->nsproxy->uts_ns) { + put_user_ns(new_nsp->uts_ns->user_ns); + new_nsp->uts_ns->user_ns = task_cred_xxx(tsk, user)->user_ns; + get_user_ns(new_nsp->uts_ns->user_ns); + } new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns); if (IS_ERR(new_nsp->ipc_ns)) { diff -puN kernel/user.c~userns-add-a-user_namespace-as-creator-owner-of-uts_namespace kernel/user.c --- a/kernel/user.c~userns-add-a-user_namespace-as-creator-owner-of-uts_namespace +++ a/kernel/user.c @@ -17,9 +17,13 @@ #include <linux/module.h> #include <linux/user_namespace.h> +/* + * userns count is 1 for root user, 1 for init_uts_ns, + * and 1 for... ? + */ struct user_namespace init_user_ns = { .kref = { - .refcount = ATOMIC_INIT(2), + .refcount = ATOMIC_INIT(3), }, .creator = &root_user, }; @@ -47,7 +51,7 @@ static struct kmem_cache *uid_cachep; */ static DEFINE_SPINLOCK(uidhash_lock); -/* root_user.__count is 2, 1 for init task cred, 1 for init_user_ns->creator */ +/* root_user.__count is 2, 1 for init task cred, 1 for init_user_ns->user_ns */ struct user_struct root_user = { .__count = ATOMIC_INIT(2), .processes = ATOMIC_INIT(1), diff -puN kernel/utsname.c~userns-add-a-user_namespace-as-creator-owner-of-uts_namespace kernel/utsname.c --- a/kernel/utsname.c~userns-add-a-user_namespace-as-creator-owner-of-uts_namespace +++ a/kernel/utsname.c @@ -14,6 +14,7 @@ #include <linux/utsname.h> #include <linux/err.h> #include <linux/slab.h> +#include <linux/user_namespace.h> static struct uts_namespace *create_uts_ns(void) { @@ -40,6 +41,8 @@ static struct uts_namespace *clone_uts_n down_read(&uts_sem); memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); + ns->user_ns = old_ns->user_ns; + get_user_ns(ns->user_ns); up_read(&uts_sem); return ns; } @@ -71,5 +74,6 @@ void free_uts_ns(struct kref *kref) struct uts_namespace *ns; ns = container_of(kref, struct uts_namespace, kref); + put_user_ns(ns->user_ns); kfree(ns); } _ Patches currently in -mm which might be from serge@xxxxxxxxxx are origin.patch lib-hexdumpc-make-hex2bin-return-the-updated-src-address.patch fs-binfmt_miscc-use-kernels-hex_to_bin-method.patch fs-binfmt_miscc-use-kernels-hex_to_bin-method-fix.patch fs-binfmt_miscc-use-kernels-hex_to_bin-method-fix-fix.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html