user/sven/linux.git/kernel/user_namespace.c, branch v5.18.3

ucounts: Fix systemd LimitNPROC with private users regression

2022-02-25T16:40:14Z

Long story short recursively enforcing RLIMIT_NPROC when it is not enforced on the process that creates a new user namespace, causes currently working code to fail. There is no reason to enforce RLIMIT_NPROC recursively when we don't enforce it normally so update the code to detect this case. I would like to simply use capable(CAP_SYS_RESOURCE) to detect when RLIMIT_NPROC is not enforced upon the caller. Unfortunately because RLIMIT_NPROC is charged and checked for enforcement based upon the real uid, using capable() which is euid based is inconsistent with reality. Come as close as possible to testing for capable(CAP_SYS_RESOURCE) by testing for when the real uid would match the conditions when CAP_SYS_RESOURCE would be present if the real uid was the effective uid. Reported-by: Etienne Dechamps Link: https://bugzilla.kernel.org/show_bug.cgi?id=215596 Link: https://lkml.kernel.org/r/e9589141-cfeb-90cd-2d0e-83a62787239a@edechamps.fr Link: https://lkml.kernel.org/r/87sfs8jmpz.fsf_-_@email.froward.int.ebiederm.org Cc: stable@vger.kernel.org Fixes: 21d1c5e386bc ("Reimplement RLIMIT_NPROC on top of ucounts") Reviewed-by: Kees Cook Signed-off-by: "Eric W. Biederman"

memcg: enable accounting for new namesapces and struct nsproxy

2021-09-03T16:58:12Z

Container admin can create new namespaces and force kernel to allocate up to several pages of memory for the namespaces and its associated structures. Net and uts namespaces have enabled accounting for such allocations. It makes sense to account for rest ones to restrict the host's memory consumption from inside the memcg-limited container. Link: https://lkml.kernel.org/r/5525bcbf-533e-da27-79b7-158686c64e13@virtuozzo.com Signed-off-by: Vasily Averin Acked-by: Serge Hallyn Acked-by: Christian Brauner Acked-by: Kirill Tkhai Reviewed-by: Shakeel Butt Cc: Alexander Viro Cc: Alexey Dobriyan Cc: Andrei Vagin Cc: Borislav Petkov Cc: Borislav Petkov Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: "Eric W. Biederman" Cc: Greg Kroah-Hartman Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: "J. Bruce Fields" Cc: Jeff Layton Cc: Jens Axboe Cc: Jiri Slaby Cc: Johannes Weiner Cc: Michal Hocko Cc: Oleg Nesterov Cc: Roman Gushchin Cc: Tejun Heo Cc: Thomas Gleixner Cc: Vladimir Davydov Cc: Yutian Yang Cc: Zefan Li Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2021-06-29T03:39:26Z

Pull user namespace rlimit handling update from Eric Biederman: "This is the work mainly by Alexey Gladkov to limit rlimits to the rlimits of the user that created a user namespace, and to allow users to have stricter limits on the resources created within a user namespace." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: cred: add missing return error code when set_cred_ucounts() failed ucounts: Silence warning in dec_rlimit_ucounts ucounts: Set ucount_max to the largest positive value the type can hold kselftests: Add test to check for rlimit changes in different user namespaces Reimplement RLIMIT_MEMLOCK on top of ucounts Reimplement RLIMIT_SIGPENDING on top of ucounts Reimplement RLIMIT_MSGQUEUE on top of ucounts Reimplement RLIMIT_NPROC on top of ucounts Use atomic_t for ucounts reference counting Add a reference to ucounts for each cred Increase size of ucounts to atomic_long_t

kernel/user_namespace.c: fix typos

2021-05-07T07:26:34Z

change 'verifing' to 'verifying' change 'certaint' to 'certain' change 'approprpiate' to 'appropriate' Link: https://lkml.kernel.org/r/20210317100129.12440-1-caoxiaofeng@yulong.com Signed-off-by: Xiaofeng Cao Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ucounts: Set ucount_max to the largest positive value the type can hold

2021-04-30T19:14:03Z

The ns->ucount_max[] is signed long which is less than the rlimit size. We have to protect ucount_max[] from overflow and only use the largest value that we can hold. On 32bit using "long" instead of "unsigned long" to hold the counts has the downside that RLIMIT_MSGQUEUE and RLIMIT_MEMLOCK are limited to 2GiB instead of 4GiB. I don't think anyone cares but it should be mentioned in case someone does. The RLIMIT_NPROC and RLIMIT_SIGPENDING used atomic_t so their maximum hasn't changed. Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/1825a5dfa18bc5a570e79feb05e2bd07fd57e7e3.1619094428.git.legion@kernel.org Signed-off-by: Eric W. Biederman

Reimplement RLIMIT_MEMLOCK on top of ucounts

2021-04-30T19:14:02Z

The rlimit counter is tied to uid in the user_namespace. This allows rlimit values to be specified in userns even if they are already globally exceeded by the user. However, the value of the previous user_namespaces cannot be exceeded. Changelog v11: * Fix issue found by lkp robot. v8: * Fix issues found by lkp-tests project. v7: * Keep only ucounts for RLIMIT_MEMLOCK checks instead of struct cred. v6: * Fix bug in hugetlb_file_setup() detected by trinity. Reported-by: kernel test robot Reported-by: kernel test robot Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/970d50c70c71bfd4496e0e8d2a0a32feebebb350.1619094428.git.legion@kernel.org Signed-off-by: Eric W. Biederman

Reimplement RLIMIT_SIGPENDING on top of ucounts

2021-04-30T19:14:02Z

The rlimit counter is tied to uid in the user_namespace. This allows rlimit values to be specified in userns even if they are already globally exceeded by the user. However, the value of the previous user_namespaces cannot be exceeded. Changelog v11: * Revert most of changes to fix performance issues. v10: * Fix memory leak on get_ucounts failure. Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/df9d7764dddd50f28616b7840de74ec0f81711a8.1619094428.git.legion@kernel.org Signed-off-by: Eric W. Biederman

Reimplement RLIMIT_MSGQUEUE on top of ucounts

2021-04-30T19:14:01Z

The rlimit counter is tied to uid in the user_namespace. This allows rlimit values to be specified in userns even if they are already globally exceeded by the user. However, the value of the previous user_namespaces cannot be exceeded. Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/2531f42f7884bbfee56a978040b3e0d25cdf6cde.1619094428.git.legion@kernel.org Signed-off-by: Eric W. Biederman

Reimplement RLIMIT_NPROC on top of ucounts

2021-04-30T19:14:01Z

The rlimit counter is tied to uid in the user_namespace. This allows rlimit values to be specified in userns even if they are already globally exceeded by the user. However, the value of the previous user_namespaces cannot be exceeded. To illustrate the impact of rlimits, let's say there is a program that does not fork. Some service-A wants to run this program as user X in multiple containers. Since the program never fork the service wants to set RLIMIT_NPROC=1. service-A \- program (uid=1000, container1, rlimit_nproc=1) \- program (uid=1000, container2, rlimit_nproc=1) The service-A sets RLIMIT_NPROC=1 and runs the program in container1. When the service-A tries to run a program with RLIMIT_NPROC=1 in container2 it fails since user X already has one running process. We cannot use existing inc_ucounts / dec_ucounts because they do not allow us to exceed the maximum for the counter. Some rlimits can be overlimited by root or if the user has the appropriate capability. Changelog v11: * Change inc_rlimit_ucounts() which now returns top value of ucounts. * Drop inc_rlimit_ucounts_and_test() because the return code of inc_rlimit_ucounts() can be checked. Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/c5286a8aa16d2d698c222f7532f3d735c82bc6bc.1619094428.git.legion@kernel.org Signed-off-by: Eric W. Biederman

Add a reference to ucounts for each cred

2021-04-30T19:14:00Z

For RLIMIT_NPROC and some other rlimits the user_struct that holds the global limit is kept alive for the lifetime of a process by keeping it in struct cred. Adding a pointer to ucounts in the struct cred will allow to track RLIMIT_NPROC not only for user in the system, but for user in the user_namespace. Updating ucounts may require memory allocation which may fail. So, we cannot change cred.ucounts in the commit_creds() because this function cannot fail and it should always return 0. For this reason, we modify cred.ucounts before calling the commit_creds(). Changelog v6: * Fix null-ptr-deref in is_ucounts_overlimit() detected by trinity. This error was caused by the fact that cred_alloc_blank() left the ucounts pointer empty. Reported-by: kernel test robot Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/b37aaef28d8b9b0d757e07ba6dd27281bbe39259.1619094428.git.legion@kernel.org Signed-off-by: Eric W. Biederman