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* kernel/user_namespace.c: kernel-doc/checkpatch fixesFabian Frederick2014-06-071-13/+20
| | | | | | | | | | | -uid->gid -split some function declarations -if/then/else warning Signed-off-by: Fabian Frederick <fabf@skynet.be> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* user namespace: fix incorrect memory barriersMikulas Patocka2014-04-151-6/+5
| | | | | | | | | | | | | | | | | | | | | | | | smp_read_barrier_depends() can be used if there is data dependency between the readers - i.e. if the read operation after the barrier uses address that was obtained from the read operation before the barrier. In this file, there is only control dependency, no data dependecy, so the use of smp_read_barrier_depends() is incorrect. The code could fail in the following way: * the cpu predicts that idx < entries is true and starts executing the body of the for loop * the cpu fetches map->extent[0].first and map->extent[0].count * the cpu fetches map->nr_extents * the cpu verifies that idx < extents is true, so it commits the instructions in the body of the for loop The problem is that in this scenario, the cpu read map->extent[0].first and map->nr_extents in the wrong order. We need a full read memory barrier to prevent it. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel: audit/fix non-modular users of module_init in core codePaul Gortmaker2014-04-041-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Code that is obj-y (always built-in) or dependent on a bool Kconfig (built-in or absent) can never be modular. So using module_init as an alias for __initcall can be somewhat misleading. Fix these up now, so that we can relocate module_init from init.h into module.h in the future. If we don't do this, we'd have to add module.h to obviously non-modular code, and that would be a worse thing. The audit targets the following module_init users for change: kernel/user.c obj-y kernel/kexec.c bool KEXEC (one instance per arch) kernel/profile.c bool PROFILING kernel/hung_task.c bool DETECT_HUNG_TASK kernel/sched/stats.c bool SCHEDSTATS kernel/user_namespace.c bool USER_NS Note that direct use of __initcall is discouraged, vs. one of the priority categorized subgroups. As __initcall gets mapped onto device_initcall, our use of subsys_initcall (which makes sense for these files) will thus change this registration from level 6-device to level 4-subsys (i.e. slightly earlier). However no observable impact of that difference has been observed during testing. Also, two instances of missing ";" at EOL are fixed in kexec. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Eric Biederman <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* user_namespace.c: Remove duplicated word in commentBrian Campbell2014-02-201-1/+1
| | | | | Signed-off-by: Brian Campbell <brian.campbell@editshare.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* KEYS: Add per-user_namespace registers for persistent per-UID kerberos cachesDavid Howells2013-09-241-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add support for per-user_namespace registers of persistent per-UID kerberos caches held within the kernel. This allows the kerberos cache to be retained beyond the life of all a user's processes so that the user's cron jobs can work. The kerberos cache is envisioned as a keyring/key tree looking something like: struct user_namespace \___ .krb_cache keyring - The register \___ _krb.0 keyring - Root's Kerberos cache \___ _krb.5000 keyring - User 5000's Kerberos cache \___ _krb.5001 keyring - User 5001's Kerberos cache \___ tkt785 big_key - A ccache blob \___ tkt12345 big_key - Another ccache blob Or possibly: struct user_namespace \___ .krb_cache keyring - The register \___ _krb.0 keyring - Root's Kerberos cache \___ _krb.5000 keyring - User 5000's Kerberos cache \___ _krb.5001 keyring - User 5001's Kerberos cache \___ tkt785 keyring - A ccache \___ krbtgt/REDHAT.COM@REDHAT.COM big_key \___ http/REDHAT.COM@REDHAT.COM user \___ afs/REDHAT.COM@REDHAT.COM user \___ nfs/REDHAT.COM@REDHAT.COM user \___ krbtgt/KERNEL.ORG@KERNEL.ORG big_key \___ http/KERNEL.ORG@KERNEL.ORG big_key What goes into a particular Kerberos cache is entirely up to userspace. Kernel support is limited to giving you the Kerberos cache keyring that you want. The user asks for their Kerberos cache by: krb_cache = keyctl_get_krbcache(uid, dest_keyring); The uid is -1 or the user's own UID for the user's own cache or the uid of some other user's cache (requires CAP_SETUID). This permits rpc.gssd or whatever to mess with the cache. The cache returned is a keyring named "_krb.<uid>" that the possessor can read, search, clear, invalidate, unlink from and add links to. Active LSMs get a chance to rule on whether the caller is permitted to make a link. Each uid's cache keyring is created when it first accessed and is given a timeout that is extended each time this function is called so that the keyring goes away after a while. The timeout is configurable by sysctl but defaults to three days. Each user_namespace struct gets a lazily-created keyring that serves as the register. The cache keyrings are added to it. This means that standard key search and garbage collection facilities are available. The user_namespace struct's register goes away when it does and anything left in it is then automatically gc'd. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Simo Sorce <simo@redhat.com> cc: Serge E. Hallyn <serge.hallyn@ubuntu.com> cc: Eric W. Biederman <ebiederm@xmission.com>
* Merge branch 'for-linus' of ↵Linus Torvalds2013-09-071-2/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull namespace changes from Eric Biederman: "This is an assorted mishmash of small cleanups, enhancements and bug fixes. The major theme is user namespace mount restrictions. nsown_capable is killed as it encourages not thinking about details that need to be considered. A very hard to hit pid namespace exiting bug was finally tracked and fixed. A couple of cleanups to the basic namespace infrastructure. Finally there is an enhancement that makes per user namespace capabilities usable as capabilities, and an enhancement that allows the per userns root to nice other processes in the user namespace" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: userns: Kill nsown_capable it makes the wrong thing easy capabilities: allow nice if we are privileged pidns: Don't have unshare(CLONE_NEWPID) imply CLONE_THREAD userns: Allow PR_CAPBSET_DROP in a user namespace. namespaces: Simplify copy_namespaces so it is clear what is going on. pidns: Fix hang in zap_pid_ns_processes by sending a potentially extra wakeup sysfs: Restrict mounting sysfs userns: Better restrictions on when proc and sysfs can be mounted vfs: Don't copy mount bind mounts of /proc/<pid>/ns/mnt between namespaces kernel/nsproxy.c: Improving a snippet of code. proc: Restrict mounting the proc filesystem vfs: Lock in place mounts from more privileged users
| * userns: Better restrictions on when proc and sysfs can be mountedEric W. Biederman2013-08-271-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rely on the fact that another flavor of the filesystem is already mounted and do not rely on state in the user namespace. Verify that the mounted filesystem is not covered in any significant way. I would love to verify that the previously mounted filesystem has no mounts on top but there are at least the directories /proc/sys/fs/binfmt_misc and /sys/fs/cgroup/ that exist explicitly for other filesystems to mount on top of. Refactor the test into a function named fs_fully_visible and call that function from the mount routines of proc and sysfs. This makes this test local to the filesystems involved and the results current of when the mounts take place, removing a weird threading of the user namespace, the mount namespace and the filesystems themselves. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* | userns: limit the maximum depth of user_namespace->parent chainOleg Nesterov2013-08-081-0/+4
| | | | | | | | | | | | | | | | | | Ensure that user_namespace->parent chain can't grow too much. Currently we use the hardroded 32 as limit. Reported-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | userns: unshare_userns(&cred) should not populate cred on failureOleg Nesterov2013-08-061-4/+9
|/ | | | | | | | | | | | | | | | unshare_userns(new_cred) does *new_cred = prepare_creds() before create_user_ns() which can fail. However, the caller expects that it doesn't need to take care of new_cred if unshare_userns() fails. We could change the single caller, sys_unshare(), but I think it would be more clean to avoid the side effects on failure, so with this patch unshare_userns() does put_cred() itself and initializes *new_cred only if create_user_ns() succeeeds. Cc: stable@vger.kernel.org Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-linus' of ↵Linus Torvalds2013-05-021-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull VFS updates from Al Viro, Misc cleanups all over the place, mainly wrt /proc interfaces (switch create_proc_entry to proc_create(), get rid of the deprecated create_proc_read_entry() in favor of using proc_create_data() and seq_file etc). 7kloc removed. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (204 commits) don't bother with deferred freeing of fdtables proc: Move non-public stuff from linux/proc_fs.h to fs/proc/internal.h proc: Make the PROC_I() and PDE() macros internal to procfs proc: Supply a function to remove a proc entry by PDE take cgroup_open() and cpuset_open() to fs/proc/base.c ppc: Clean up scanlog ppc: Clean up rtas_flash driver somewhat hostap: proc: Use remove_proc_subtree() drm: proc: Use remove_proc_subtree() drm: proc: Use minor->index to label things, not PDE->name drm: Constify drm_proc_list[] zoran: Don't print proc_dir_entry data in debug reiserfs: Don't access the proc_dir_entry in r_open(), r_start() r_show() proc: Supply an accessor for getting the data from a PDE's parent airo: Use remove_proc_subtree() rtl8192u: Don't need to save device proc dir PDE rtl8187se: Use a dir under /proc/net/r8180/ proc: Add proc_mkdir_data() proc: Move some bits from linux/proc_fs.h to linux/{of.h,signal.h,tty.h} proc: Move PDE_NET() to fs/proc/proc_net.c ...
| * proc: Split the namespace stuff out into linux/proc_ns.hDavid Howells2013-05-011-1/+1
| | | | | | | | | | | | | | | | | | | | Split the proc namespace stuff out into linux/proc_ns.h. Signed-off-by: David Howells <dhowells@redhat.com> cc: netdev@vger.kernel.org cc: Serge E. Hallyn <serge.hallyn@ubuntu.com> cc: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | userns: Changing any namespace id mappings should require privilegesAndy Lutomirski2013-04-151-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | Changing uid/gid/projid mappings doesn't change your id within the namespace; it reconfigures the namespace. Unprivileged programs should *not* be able to write these files. (We're also checking the privileges on the wrong task.) Given the write-once nature of these files and the other security checks, this is likely impossible to usefully exploit. Signed-off-by: Andy Lutomirski <luto@amacapital.net>
* | userns: Check uid_map's opener's fsuid, not the current fsuidAndy Lutomirski2013-04-151-2/+2
| | | | | | | | Signed-off-by: Andy Lutomirski <luto@amacapital.net>
* | userns: Don't let unprivileged users trick privileged users into setting the ↵Eric W. Biederman2013-04-151-4/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | id_map When we require privilege for setting /proc/<pid>/uid_map or /proc/<pid>/gid_map no longer allow an unprivileged user to open the file and pass it to a privileged program to write to the file. Instead when privilege is required require both the opener and the writer to have the necessary capabilities. I have tested this code and verified that setting /proc/<pid>/uid_map fails when an unprivileged user opens the file and a privielged user attempts to set the mapping, that unprivileged users can still map their own id, and that a privileged users can still setup an arbitrary mapping. Reported-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andy Lutomirski <luto@amacapital.net>
* | userns: Restrict when proc and sysfs can be mountedEric W. Biederman2013-03-271-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Only allow unprivileged mounts of proc and sysfs if they are already mounted when the user namespace is created. proc and sysfs are interesting because they have content that is per namespace, and so fresh mounts are needed when new namespaces are created while at the same time proc and sysfs have content that is shared between every instance. Respect the policy of who may see the shared content of proc and sysfs by only allowing new mounts if there was an existing mount at the time the user namespace was created. In practice there are only two interesting cases: proc and sysfs are mounted at their usual places, proc and sysfs are not mounted at all (some form of mount namespace jail). Cc: stable@vger.kernel.org Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* | userns: Don't allow creation if the user is chrootedEric W. Biederman2013-03-271-0/+9
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | Guarantee that the policy of which files may be access that is established by setting the root directory will not be violated by user namespaces by verifying that the root directory points to the root of the mount namespace at the time of user namespace creation. Changing the root is a privileged operation, and as a matter of policy it serves to limit unprivileged processes to files below the current root directory. For reasons of simplicity and comprehensibility the privilege to change the root directory is gated solely on the CAP_SYS_CHROOT capability in the user namespace. Therefore when creating a user namespace we must ensure that the policy of which files may be access can not be violated by changing the root directory. Anyone who runs a processes in a chroot and would like to use user namespace can setup the same view of filesystems with a mount namespace instead. With this result that this is not a practical limitation for using user namespaces. Cc: stable@vger.kernel.org Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Reported-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* userns: Don't allow CLONE_NEWUSER | CLONE_FSEric W. Biederman2013-03-131-0/+4
| | | | | | | | | | | | | | | | | | | | Don't allowing sharing the root directory with processes in a different user namespace. There doesn't seem to be any point, and to allow it would require the overhead of putting a user namespace reference in fs_struct (for permission checks) and incrementing that reference count on practically every call to fork. So just perform the inexpensive test of forbidding sharing fs_struct acrosss processes in different user namespaces. We already disallow other forms of threading when unsharing a user namespace so this should be no real burden in practice. This updates setns, clone, and unshare to disallow multiple user namespaces sharing an fs_struct. Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* userns: Allow any uid or gid mappings that don't overlap.Eric W. Biederman2013-01-271-6/+39
| | | | | | | | | | | | | | When I initially wrote the code for /proc/<pid>/uid_map. I was lazy and avoided duplicate mappings by the simple expedient of ensuring the first number in a new extent was greater than any number in the previous extent. Unfortunately that precludes a number of valid mappings, and someone noticed and complained. So use a simple check to ensure that ranges in the mapping extents don't overlap. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* userns: Avoid recursion in put_user_nsEric W. Biederman2013-01-271-8/+9
| | | | | | | | | | | | | | | | | | | | | | | | | When freeing a deeply nested user namespace free_user_ns calls put_user_ns on it's parent which may in turn call free_user_ns again. When -fno-optimize-sibling-calls is passed to gcc one stack frame per user namespace is left on the stack, potentially overflowing the kernel stack. CONFIG_FRAME_POINTER forces -fno-optimize-sibling-calls so we can't count on gcc to optimize this code. Remove struct kref and use a plain atomic_t. Making the code more flexible and easier to comprehend. Make the loop in free_user_ns explict to guarantee that the stack does not overflow with CONFIG_FRAME_POINTER enabled. I have tested this fix with a simple program that uses unshare to create a deeply nested user namespace structure and then calls exit. With 1000 nesteuser namespaces before this change running my test program causes the kernel to die a horrible death. With 10,000,000 nested user namespaces after this change my test program runs to completion and causes no harm. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Pointed-out-by: Vasily Kulikov <segoon@openwall.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* userns: Fix typo in description of the limitation of userns_installEric W. Biederman2012-12-151-1/+1
| | | | | Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* proc: Usable inode numbers for the namespace file descriptors.Eric W. Biederman2012-11-201-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | Assign a unique proc inode to each namespace, and use that inode number to ensure we only allocate at most one proc inode for every namespace in proc. A single proc inode per namespace allows userspace to test to see if two processes are in the same namespace. This has been a long requested feature and only blocked because a naive implementation would put the id in a global space and would ultimately require having a namespace for the names of namespaces, making migration and certain virtualization tricks impossible. We still don't have per superblock inode numbers for proc, which appears necessary for application unaware checkpoint/restart and migrations (if the application is using namespace file descriptors) but that is now allowd by the design if it becomes important. I have preallocated the ipc and uts initial proc inode numbers so their structures can be statically initialized. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* userns: For /proc/self/{uid,gid}_map derive the lower userns from the struct ↵Eric W. Biederman2012-11-201-2/+10
| | | | | | | | | | | | | | | | | file To keep things sane in the context of file descriptor passing derive the user namespace that uids are mapped into from the opener of the file instead of from current. When writing to the maps file the lower user namespace must always be the parent user namespace, or setting the mapping simply does not make sense. Enforce that the opener of the file was in the parent user namespace or the user namespace whose mapping is being set. Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* userns: Implement unshare of the user namespaceEric W. Biederman2012-11-201-0/+15
| | | | | | | | | | | | - Add CLONE_THREAD to the unshare flags if CLONE_NEWUSER is selected As changing user namespaces is only valid if all there is only a single thread. - Restore the code to add CLONE_VM if CLONE_THREAD is selected and the code to addCLONE_SIGHAND if CLONE_VM is selected. Making the constraints in the code clear. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* userns: Implent proc namespace operationsEric W. Biederman2012-11-201-17/+73
| | | | | | | | | | | | This allows entering a user namespace, and the ability to store a reference to a user namespace with a bind mount. Addition of missing userns_ns_put in userns_install from Gao feng <gaofeng@cn.fujitsu.com> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* userns: Allow setting a userns mapping to your current uid.Eric W. Biederman2012-11-201-0/+15
| | | | | Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* userns: Add kprojid_t and associated infrastructure in projid.hEric W. Biederman2012-09-181-1/+127
| | | | | | | | | | | | | | | | | | | | | | | Implement kprojid_t a cousin of the kuid_t and kgid_t. The per user namespace mapping of project id values can be set with /proc/<pid>/projid_map. A full compliment of helpers is provided: make_kprojid, from_kprojid, from_kprojid_munged, kporjid_has_mapping, projid_valid, projid_eq, projid_eq, projid_lt. Project identifiers are part of the generic disk quota interface, although it appears only xfs implements project identifiers currently. The xfs code allows anyone who has permission to set the project identifier on a file to use any project identifier so when setting up the user namespace project identifier mappings I do not require a capability. Cc: Dave Chinner <david@fromorbit.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* userns: Store uid and gid values in struct cred with kuid_t and kgid_t typesEric W. Biederman2012-05-031-2/+2
| | | | | | | | | | | cred.h and a few trivial users of struct cred are changed. The rest of the users of struct cred are left for other patches as there are too many changes to make in one go and leave the change reviewable. If the user namespace is disabled and CONFIG_UIDGID_STRICT_TYPE_CHECKS are disabled the code will contiue to compile and behave correctly. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* userns: Rework the user_namespace adding uid/gid mapping supportEric W. Biederman2012-04-261-41/+504
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Convert the old uid mapping functions into compatibility wrappers - Add a uid/gid mapping layer from user space uid and gids to kernel internal uids and gids that is extent based for simplicty and speed. * Working with number space after mapping uids/gids into their kernel internal version adds only mapping complexity over what we have today, leaving the kernel code easy to understand and test. - Add proc files /proc/self/uid_map /proc/self/gid_map These files display the mapping and allow a mapping to be added if a mapping does not exist. - Allow entering the user namespace without a uid or gid mapping. Since we are starting with an existing user our uids and gids still have global mappings so are still valid and useful they just don't have local mappings. The requirement for things to work are global uid and gid so it is odd but perfectly fine not to have a local uid and gid mapping. Not requiring global uid and gid mappings greatly simplifies the logic of setting up the uid and gid mappings by allowing the mappings to be set after the namespace is created which makes the slight weirdness worth it. - Make the mappings in the initial user namespace to the global uid/gid space explicit. Today it is an identity mapping but in the future we may want to twist this for debugging, similar to what we do with jiffies. - Document the memory ordering requirements of setting the uid and gid mappings. We only allow the mappings to be set once and there are no pointers involved so the requirments are trivial but a little atypical. Performance: In this scheme for the permission checks the performance is expected to stay the same as the actuall machine instructions should remain the same. The worst case I could think of is ls -l on a large directory where all of the stat results need to be translated with from kuids and kgids to uids and gids. So I benchmarked that case on my laptop with a dual core hyperthread Intel i5-2520M cpu with 3M of cpu cache. My benchmark consisted of going to single user mode where nothing else was running. On an ext4 filesystem opening 1,000,000 files and looping through all of the files 1000 times and calling fstat on the individuals files. This was to ensure I was benchmarking stat times where the inodes were in the kernels cache, but the inode values were not in the processors cache. My results: v3.4-rc1: ~= 156ns (unmodified v3.4-rc1 with user namespace support disabled) v3.4-rc1-userns-: ~= 155ns (v3.4-rc1 with my user namespace patches and user namespace support disabled) v3.4-rc1-userns+: ~= 164ns (v3.4-rc1 with my user namespace patches and user namespace support enabled) All of the configurations ran in roughly 120ns when I performed tests that ran in the cpu cache. So in summary the performance impact is: 1ns improvement in the worst case with user namespace support compiled out. 8ns aka 5% slowdown in the worst case with user namespace support compiled in. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* userns: Simplify the user_namespace by making userns->creator a kuid.Eric W. Biederman2012-04-261-22/+20
| | | | | | | | | | | | | | | | | | | | | - Transform userns->creator from a user_struct reference to a simple kuid_t, kgid_t pair. In cap_capable this allows the check to see if we are the creator of a namespace to become the classic suser style euid permission check. This allows us to remove the need for a struct cred in the mapping functions and still be able to dispaly the user namespace creators uid and gid as 0. - Remove the now unnecessary delayed_work in free_user_ns. All that is left for free_user_ns to do is to call kmem_cache_free and put_user_ns. Those functions can be called in any context so call them directly from free_user_ns removing the need for delayed work. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* userns: Disassociate user_struct from the user_namespace.Eric W. Biederman2012-04-081-5/+1
| | | | | | | | | | | Modify alloc_uid to take a kuid and make the user hash table global. Stop holding a reference to the user namespace in struct user_struct. This simplifies the code and makes the per user accounting not care about which user namespace a uid happens to appear in. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* userns: Start out with a full set of capabilities.Eric W. Biederman2012-04-081-0/+9
| | | | | Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* userns: Add an explicit reference to the parent user namespaceEric W. Biederman2012-04-081-7/+6
| | | | | | | | | | | I am about to remove the struct user_namespace reference from struct user_struct. So keep an explicit track of the parent user namespace. Take advantage of this new reference and replace instances of user_ns->creator->user_ns with user_ns->parent. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* cred: Refcount the user_ns pointed to by the cred.Eric W. Biederman2012-04-081-3/+5
| | | | | | | | | struct user_struct will shortly loose it's user_ns reference so make the cred user_ns reference a proper reference complete with reference counting. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* userns: Use cred->user_ns instead of cred->user->user_nsEric W. Biederman2012-04-081-2/+2
| | | | | | | | | Optimize performance and prepare for the removal of the user_ns reference from user_struct. Remove the slow long walk through cred->user->user_ns and instead go straight to cred->user_ns. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* kernel: Map most files to use export.h instead of module.hPaul Gortmaker2011-10-311-1/+1
| | | | | | | | | | | | | | | | The changed files were only including linux/module.h for the EXPORT_SYMBOL infrastructure, and nothing else. Revector them onto the isolated export header for faster compile times. Nothing to see here but a whole lot of instances of: -#include <linux/module.h> +#include <linux/export.h> This commit is only changing the kernel dir; next targets will probably be mm, fs, the arch dirs, etc. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
* user_ns: improve the user_ns on-the-slab packagingPavel Emelyanov2011-01-131-3/+12
| | | | | | | | | | | | | | | Currently on 64-bit arch the user_namespace is 2096 and when being kmalloc-ed it resides on a 4k slab wasting 2003 bytes. If we allocate a separate cache for it and reduce the hash size from 128 to 64 chains the packaging becomes *much* better - the struct is 1072 bytes and the hole between is 98 bytes. [akpm@linux-foundation.org: s/__initcall/module_init/] Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: Serge E. Hallyn <serge@hallyn.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* user_ns: Introduce user_nsmap_uid and user_ns_map_gid.Eric W. Biederman2010-06-161-0/+44
| | | | | | | | | | | | | | | | | | | | Define what happens when a we view a uid from one user_namespace in another user_namepece. - If the user namespaces are the same no mapping is necessary. - For most cases of difference use overflowuid and overflowgid, the uid and gid currently used for 16bit apis when we have a 32bit uid that does fit in 16bits. Effectively the situation is the same, we want to return a uid or gid that is not assigned to any user. - For the case when we happen to be mapping the uid or gid of the creator of the target user namespace use uid 0 and gid as confusing that user with root is not a problem. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Serge E. Hallyn <serue@us.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* kref: remove kref_setNeilBrown2010-05-211-2/+2
| | | | | | | | | | | | | | | | | | Of the three uses of kref_set in the kernel: One really should be kref_put as the code is letting go of a reference, Two really should be kref_init because the kref is being initialised. This suggests that making kref_set available encourages bad code. So fix the three uses and remove kref_set completely. Signed-off-by: NeilBrown <neilb@suse.de> Acked-by: Mimi Zohar <zohar@us.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* Fix recursive lock in free_uid()/free_user_ns()David Howells2009-02-281-4/+17
| | | | | | | | | | | | | | free_uid() and free_user_ns() are corecursive when CONFIG_USER_SCHED=n, but free_user_ns() is called from free_uid() by way of uid_hash_remove(), which requires uidhash_lock to be held. free_user_ns() then calls free_uid() to complete the destruction. Fix this by deferring the destruction of the user_namespace. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* User namespaces: set of cleanups (v2)Serge Hallyn2008-11-251-45/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The user_ns is moved from nsproxy to user_struct, so that a struct cred by itself is sufficient to determine access (which it otherwise would not be). Corresponding ecryptfs fixes (by David Howells) are here as well. Fix refcounting. The following rules now apply: 1. The task pins the user struct. 2. The user struct pins its user namespace. 3. The user namespace pins the struct user which created it. User namespaces are cloned during copy_creds(). Unsharing a new user_ns is no longer possible. (We could re-add that, but it'll cause code duplication and doesn't seem useful if PAM doesn't need to clone user namespaces). When a user namespace is created, its first user (uid 0) gets empty keyrings and a clean group_info. This incorporates a previous patch by David Howells. Here is his original patch description: >I suggest adding the attached incremental patch. It makes the following >changes: > > (1) Provides a current_user_ns() macro to wrap accesses to current's user > namespace. > > (2) Fixes eCryptFS. > > (3) Renames create_new_userns() to create_user_ns() to be more consistent > with the other associated functions and because the 'new' in the name is > superfluous. > > (4) Moves the argument and permission checks made for CLONE_NEWUSER to the > beginning of do_fork() so that they're done prior to making any attempts > at allocation. > > (5) Calls create_user_ns() after prepare_creds(), and gives it the new creds > to fill in rather than have it return the new root user. I don't imagine > the new root user being used for anything other than filling in a cred > struct. > > This also permits me to get rid of a get_uid() and a free_uid(), as the > reference the creds were holding on the old user_struct can just be > transferred to the new namespace's creator pointer. > > (6) Makes create_user_ns() reset the UIDs and GIDs of the creds under > preparation rather than doing it in copy_creds(). > >David >Signed-off-by: David Howells <dhowells@redhat.com> Changelog: Oct 20: integrate dhowells comments 1. leave thread_keyring alone 2. use current_user_ns() in set_user() Signed-off-by: Serge Hallyn <serue@us.ibm.com>
* CRED: Inaugurate COW credentialsDavid Howells2008-11-141-1/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Inaugurate copy-on-write credentials management. This uses RCU to manage the credentials pointer in the task_struct with respect to accesses by other tasks. A process may only modify its own credentials, and so does not need locking to access or modify its own credentials. A mutex (cred_replace_mutex) is added to the task_struct to control the effect of PTRACE_ATTACHED on credential calculations, particularly with respect to execve(). With this patch, the contents of an active credentials struct may not be changed directly; rather a new set of credentials must be prepared, modified and committed using something like the following sequence of events: struct cred *new = prepare_creds(); int ret = blah(new); if (ret < 0) { abort_creds(new); return ret; } return commit_creds(new); There are some exceptions to this rule: the keyrings pointed to by the active credentials may be instantiated - keyrings violate the COW rule as managing COW keyrings is tricky, given that it is possible for a task to directly alter the keys in a keyring in use by another task. To help enforce this, various pointers to sets of credentials, such as those in the task_struct, are declared const. The purpose of this is compile-time discouragement of altering credentials through those pointers. Once a set of credentials has been made public through one of these pointers, it may not be modified, except under special circumstances: (1) Its reference count may incremented and decremented. (2) The keyrings to which it points may be modified, but not replaced. The only safe way to modify anything else is to create a replacement and commit using the functions described in Documentation/credentials.txt (which will be added by a later patch). This patch and the preceding patches have been tested with the LTP SELinux testsuite. This patch makes several logical sets of alteration: (1) execve(). This now prepares and commits credentials in various places in the security code rather than altering the current creds directly. (2) Temporary credential overrides. do_coredump() and sys_faccessat() now prepare their own credentials and temporarily override the ones currently on the acting thread, whilst preventing interference from other threads by holding cred_replace_mutex on the thread being dumped. This will be replaced in a future patch by something that hands down the credentials directly to the functions being called, rather than altering the task's objective credentials. (3) LSM interface. A number of functions have been changed, added or removed: (*) security_capset_check(), ->capset_check() (*) security_capset_set(), ->capset_set() Removed in favour of security_capset(). (*) security_capset(), ->capset() New. This is passed a pointer to the new creds, a pointer to the old creds and the proposed capability sets. It should fill in the new creds or return an error. All pointers, barring the pointer to the new creds, are now const. (*) security_bprm_apply_creds(), ->bprm_apply_creds() Changed; now returns a value, which will cause the process to be killed if it's an error. (*) security_task_alloc(), ->task_alloc_security() Removed in favour of security_prepare_creds(). (*) security_cred_free(), ->cred_free() New. Free security data attached to cred->security. (*) security_prepare_creds(), ->cred_prepare() New. Duplicate any security data attached to cred->security. (*) security_commit_creds(), ->cred_commit() New. Apply any security effects for the upcoming installation of new security by commit_creds(). (*) security_task_post_setuid(), ->task_post_setuid() Removed in favour of security_task_fix_setuid(). (*) security_task_fix_setuid(), ->task_fix_setuid() Fix up the proposed new credentials for setuid(). This is used by cap_set_fix_setuid() to implicitly adjust capabilities in line with setuid() changes. Changes are made to the new credentials, rather than the task itself as in security_task_post_setuid(). (*) security_task_reparent_to_init(), ->task_reparent_to_init() Removed. Instead the task being reparented to init is referred directly to init's credentials. NOTE! This results in the loss of some state: SELinux's osid no longer records the sid of the thread that forked it. (*) security_key_alloc(), ->key_alloc() (*) security_key_permission(), ->key_permission() Changed. These now take cred pointers rather than task pointers to refer to the security context. (4) sys_capset(). This has been simplified and uses less locking. The LSM functions it calls have been merged. (5) reparent_to_kthreadd(). This gives the current thread the same credentials as init by simply using commit_thread() to point that way. (6) __sigqueue_alloc() and switch_uid() __sigqueue_alloc() can't stop the target task from changing its creds beneath it, so this function gets a reference to the currently applicable user_struct which it then passes into the sigqueue struct it returns if successful. switch_uid() is now called from commit_creds(), and possibly should be folded into that. commit_creds() should take care of protecting __sigqueue_alloc(). (7) [sg]et[ug]id() and co and [sg]et_current_groups. The set functions now all use prepare_creds(), commit_creds() and abort_creds() to build and check a new set of credentials before applying it. security_task_set[ug]id() is called inside the prepared section. This guarantees that nothing else will affect the creds until we've finished. The calling of set_dumpable() has been moved into commit_creds(). Much of the functionality of set_user() has been moved into commit_creds(). The get functions all simply access the data directly. (8) security_task_prctl() and cap_task_prctl(). security_task_prctl() has been modified to return -ENOSYS if it doesn't want to handle a function, or otherwise return the return value directly rather than through an argument. Additionally, cap_task_prctl() now prepares a new set of credentials, even if it doesn't end up using it. (9) Keyrings. A number of changes have been made to the keyrings code: (a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have all been dropped and built in to the credentials functions directly. They may want separating out again later. (b) key_alloc() and search_process_keyrings() now take a cred pointer rather than a task pointer to specify the security context. (c) copy_creds() gives a new thread within the same thread group a new thread keyring if its parent had one, otherwise it discards the thread keyring. (d) The authorisation key now points directly to the credentials to extend the search into rather pointing to the task that carries them. (e) Installing thread, process or session keyrings causes a new set of credentials to be created, even though it's not strictly necessary for process or session keyrings (they're shared). (10) Usermode helper. The usermode helper code now carries a cred struct pointer in its subprocess_info struct instead of a new session keyring pointer. This set of credentials is derived from init_cred and installed on the new process after it has been cloned. call_usermodehelper_setup() allocates the new credentials and call_usermodehelper_freeinfo() discards them if they haven't been used. A special cred function (prepare_usermodeinfo_creds()) is provided specifically for call_usermodehelper_setup() to call. call_usermodehelper_setkeys() adjusts the credentials to sport the supplied keyring as the new session keyring. (11) SELinux. SELinux has a number of changes, in addition to those to support the LSM interface changes mentioned above: (a) selinux_setprocattr() no longer does its check for whether the current ptracer can access processes with the new SID inside the lock that covers getting the ptracer's SID. Whilst this lock ensures that the check is done with the ptracer pinned, the result is only valid until the lock is released, so there's no point doing it inside the lock. (12) is_single_threaded(). This function has been extracted from selinux_setprocattr() and put into a file of its own in the lib/ directory as join_session_keyring() now wants to use it too. The code in SELinux just checked to see whether a task shared mm_structs with other tasks (CLONE_VM), but that isn't good enough. We really want to know if they're part of the same thread group (CLONE_THREAD). (13) nfsd. The NFS server daemon now has to use the COW credentials to set the credentials it is going to use. It really needs to pass the credentials down to the functions it calls, but it can't do that until other patches in this series have been applied. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <jmorris@namei.org> Signed-off-by: James Morris <jmorris@namei.org>
* CRED: Wrap task credential accesses in the core kernelDavid Howells2008-11-141-1/+1
| | | | | | | | | | | | | | | | | | | | Wrap access to task credentials so that they can be separated more easily from the task_struct during the introduction of COW creds. Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id(). Change some task->e?[ug]id to task_e?[ug]id(). In some places it makes more sense to use RCU directly rather than a convenient wrapper; these will be addressed by later patches. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: James Morris <jmorris@namei.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-audit@redhat.com Cc: containers@lists.linux-foundation.org Cc: linux-mm@kvack.org Signed-off-by: James Morris <jmorris@namei.org>
* removed unused #include <linux/version.h>'sAdrian Bunk2008-08-231-1/+0
| | | | | | | | This patch lets the files using linux/version.h match the files that #include it. Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* eCryptfs: make key module subsystem respect namespacesMichael Halcrow2008-04-291-0/+1
| | | | | | | | | | | | | | | Make eCryptfs key module subsystem respect namespaces. Since I will be removing the netlink interface in a future patch, I just made changes to the netlink.c code so that it will not break the build. With my recent patches, the kernel module currently defaults to the device handle interface rather than the netlink interface. [akpm@linux-foundation.org: export free_user_ns()] Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel: explicitly include required header files under kernel/Robert P. J. Day2008-04-291-0/+1
| | | | | | | | | | | | | | Following an experimental deletion of the unnecessary directive #include <linux/slab.h> from the header file <linux/percpu.h>, these files under kernel/ were exposed as needing to include one of <linux/slab.h> or <linux/gfp.h>, so explicit includes were added where necessary. Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* namespaces: cleanup the code managed with the USER_NS optionPavel Emelyanov2008-02-081-13/+0
| | | | | | | | | | | | | | | | | | | | Make the user_namespace.o compilation depend on this option and move the init_user_ns into user.c file to make the kernel compile and work without the namespaces support. This make the user namespace code be organized similar to other namespaces'. Also mask the USER_NS option as "depend on NAMESPACES". [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Kirill Korotaev <dev@sw.ru> Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Fix user namespace exiting OOPsPavel Emelyanov2007-09-191-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It turned out, that the user namespace is released during the do_exit() in exit_task_namespaces(), but the struct user_struct is released only during the put_task_struct(), i.e. MUCH later. On debug kernels with poisoned slabs this will cause the oops in uid_hash_remove() because the head of the chain, which resides inside the struct user_namespace, will be already freed and poisoned. Since the uid hash itself is required only when someone can search it, i.e. when the namespace is alive, we can safely unhash all the user_struct-s from it during the namespace exiting. The subsequent free_uid() will complete the user_struct destruction. For example simple program #include <sched.h> char stack[2 * 1024 * 1024]; int f(void *foo) { return 0; } int main(void) { clone(f, stack + 1 * 1024 * 1024, 0x10000000, 0); return 0; } run on kernel with CONFIG_USER_NS turned on will oops the kernel immediately. This was spotted during OpenVZ kernel testing. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org> Acked-by: "Serge E. Hallyn" <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Convert uid hash to hlistPavel Emelyanov2007-09-191-1/+1
| | | | | | | | | | | | Surprisingly, but (spotted by Alexey Dobriyan) the uid hash still uses list_heads, thus occupying twice as much place as it could. Convert it to hlist_heads. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* userns: don't leak root userAlexey Dobriyan2007-08-311-0/+1
| | | | | | | | Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> Acked-by: Cedric Le Goater <clg@fr.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fix create_new_namespaces() return valueCedric Le Goater2007-07-161-3/+3
| | | | | | | | | | | | | | | | | | | | | dup_mnt_ns() and clone_uts_ns() return NULL on failure. This is wrong, create_new_namespaces() uses ERR_PTR() to catch an error. This means that the subsequent create_new_namespaces() will hit BUG_ON() in copy_mnt_ns() or copy_utsname(). Modify create_new_namespaces() to also use the errors returned by the copy_*_ns routines and not to systematically return ENOMEM. [oleg@tv-sign.ru: better changelog] Signed-off-by: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Pavel Emelianov <xemul@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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