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* Merge branch 'for-linus' of ↵Linus Torvalds2014-12-171-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull user namespace related fixes from Eric Biederman: "As these are bug fixes almost all of thes changes are marked for backporting to stable. The first change (implicitly adding MNT_NODEV on remount) addresses a regression that was created when security issues with unprivileged remount were closed. I go on to update the remount test to make it easy to detect if this issue reoccurs. Then there are a handful of mount and umount related fixes. Then half of the changes deal with the a recently discovered design bug in the permission checks of gid_map. Unix since the beginning has allowed setting group permissions on files to less than the user and other permissions (aka ---rwx---rwx). As the unix permission checks stop as soon as a group matches, and setgroups allows setting groups that can not later be dropped, results in a situtation where it is possible to legitimately use a group to assign fewer privileges to a process. Which means dropping a group can increase a processes privileges. The fix I have adopted is that gid_map is now no longer writable without privilege unless the new file /proc/self/setgroups has been set to permanently disable setgroups. The bulk of user namespace using applications even the applications using applications using user namespaces without privilege remain unaffected by this change. Unfortunately this ix breaks a couple user space applications, that were relying on the problematic behavior (one of which was tools/selftests/mount/unprivileged-remount-test.c). To hopefully prevent needing a regression fix on top of my security fix I rounded folks who work with the container implementations mostly like to be affected and encouraged them to test the changes. > So far nothing broke on my libvirt-lxc test bed. :-) > Tested with openSUSE 13.2 and libvirt 1.2.9. > Tested-by: Richard Weinberger <richard@nod.at> > Tested on Fedora20 with libvirt 1.2.11, works fine. > Tested-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com> > Ok, thanks - yes, unprivileged lxc is working fine with your kernels. > Just to be sure I was testing the right thing I also tested using > my unprivileged nsexec testcases, and they failed on setgroup/setgid > as now expected, and succeeded there without your patches. > Tested-by: Serge Hallyn <serge.hallyn@ubuntu.com> > I tested this with Sandstorm. It breaks as is and it works if I add > the setgroups thing. > Tested-by: Andy Lutomirski <luto@amacapital.net> # breaks things as designed :(" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: userns: Unbreak the unprivileged remount tests userns; Correct the comment in map_write userns: Allow setting gid_maps without privilege when setgroups is disabled userns: Add a knob to disable setgroups on a per user namespace basis userns: Rename id_map_mutex to userns_state_mutex userns: Only allow the creator of the userns unprivileged mappings userns: Check euid no fsuid when establishing an unprivileged uid mapping userns: Don't allow unprivileged creation of gid mappings userns: Don't allow setgroups until a gid mapping has been setablished userns: Document what the invariant required for safe unprivileged mappings. groups: Consolidate the setgroups permission checks mnt: Clear mnt_expire during pivot_root mnt: Carefully set CL_UNPRIVILEGED in clone_mnt mnt: Move the clear of MNT_LOCKED from copy_tree to it's callers. umount: Do not allow unmounting rootfs. umount: Disallow unprivileged mount force mnt: Update unprivileged remount test mnt: Implicitly add MNT_NODEV on remount when it was implicitly added by mount
| * userns: Add a knob to disable setgroups on a per user namespace basisEric W. Biederman2014-12-121-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Expose the knob to user space through a proc file /proc/<pid>/setgroups A value of "deny" means the setgroups system call is disabled in the current processes user namespace and can not be enabled in the future in this user namespace. A value of "allow" means the segtoups system call is enabled. - Descendant user namespaces inherit the value of setgroups from their parents. - A proc file is used (instead of a sysctl) as sysctls currently do not allow checking the permissions at open time. - Writing to the proc file is restricted to before the gid_map for the user namespace is set. This ensures that disabling setgroups at a user namespace level will never remove the ability to call setgroups from a process that already has that ability. A process may opt in to the setgroups disable for itself by creating, entering and configuring a user namespace or by calling setns on an existing user namespace with setgroups disabled. Processes without privileges already can not call setgroups so this is a noop. Prodcess with privilege become processes without privilege when entering a user namespace and as with any other path to dropping privilege they would not have the ability to call setgroups. So this remains within the bounds of what is possible without a knob to disable setgroups permanently in a user namespace. Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* | copy address of proc_ns_ops into ns_commonAl Viro2014-12-041-0/+3
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | common object embedded into various struct ....nsAl Viro2014-12-041-1/+1
|/ | | | | | | for now - just move corresponding ->proc_inum instances over there Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* kernel/user.c: drop unused field 'files' from user_structKirill A. Shutemov2014-06-051-1/+0
| | | | | | | | Nobody seems uses it for a long time. Let's drop it. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel: audit/fix non-modular users of module_init in core codePaul Gortmaker2014-04-041-2/+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>
* KEYS: fix uninitialized persistent_keyring_register_semXiao Guangrong2013-12-131-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We run into this bug: [ 2736.063245] Unable to handle kernel paging request for data at address 0x00000000 [ 2736.063293] Faulting instruction address: 0xc00000000037efb0 [ 2736.063300] Oops: Kernel access of bad area, sig: 11 [#1] [ 2736.063303] SMP NR_CPUS=2048 NUMA pSeries [ 2736.063310] Modules linked in: sg nfsv3 rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache nf_conntrack_netbios_ns nf_conntrack_broadcast ipt_MASQUERADE ip6table_mangle ip6table_security ip6table_raw ip6t_REJECT iptable_nat nf_nat_ipv4 iptable_mangle iptable_security iptable_raw ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack ebtable_filter ebtables ip6table_filter iptable_filter ip_tables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 nf_nat nf_conntrack ip6_tables ibmveth pseries_rng nx_crypto nfsd auth_rpcgss nfs_acl lockd sunrpc binfmt_misc xfs libcrc32c dm_service_time sd_mod crc_t10dif crct10dif_common ibmvfc scsi_transport_fc scsi_tgt dm_mirror dm_region_hash dm_log dm_multipath dm_mod [ 2736.063383] CPU: 1 PID: 7128 Comm: ssh Not tainted 3.10.0-48.el7.ppc64 #1 [ 2736.063389] task: c000000131930120 ti: c0000001319a0000 task.ti: c0000001319a0000 [ 2736.063394] NIP: c00000000037efb0 LR: c0000000006c40f8 CTR: 0000000000000000 [ 2736.063399] REGS: c0000001319a3870 TRAP: 0300 Not tainted (3.10.0-48.el7.ppc64) [ 2736.063403] MSR: 8000000000009032 <SF,EE,ME,IR,DR,RI> CR: 28824242 XER: 20000000 [ 2736.063415] SOFTE: 0 [ 2736.063418] CFAR: c00000000000908c [ 2736.063421] DAR: 0000000000000000, DSISR: 40000000 [ 2736.063425] GPR00: c0000000006c40f8 c0000001319a3af0 c000000001074788 c0000001319a3bf0 GPR04: 0000000000000000 0000000000000000 0000000000000020 000000000000000a GPR08: fffffffe00000002 00000000ffff0000 0000000080000001 c000000000924888 GPR12: 0000000028824248 c000000007e00400 00001fffffa0f998 0000000000000000 GPR16: 0000000000000022 00001fffffa0f998 0000010022e92470 0000000000000000 GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR24: 0000000000000000 c000000000f4a828 00003ffffe527108 0000000000000000 GPR28: c000000000f4a730 c000000000f4a828 0000000000000000 c0000001319a3bf0 [ 2736.063498] NIP [c00000000037efb0] .__list_add+0x30/0x110 [ 2736.063504] LR [c0000000006c40f8] .rwsem_down_write_failed+0x78/0x264 [ 2736.063508] PACATMSCRATCH [800000000280f032] [ 2736.063511] Call Trace: [ 2736.063516] [c0000001319a3af0] [c0000001319a3b80] 0xc0000001319a3b80 (unreliable) [ 2736.063523] [c0000001319a3b80] [c0000000006c40f8] .rwsem_down_write_failed+0x78/0x264 [ 2736.063530] [c0000001319a3c50] [c0000000006c1bb0] .down_write+0x70/0x78 [ 2736.063536] [c0000001319a3cd0] [c0000000002e5ffc] .keyctl_get_persistent+0x20c/0x320 [ 2736.063542] [c0000001319a3dc0] [c0000000002e2388] .SyS_keyctl+0x238/0x260 [ 2736.063548] [c0000001319a3e30] [c000000000009e7c] syscall_exit+0x0/0x7c [ 2736.063553] Instruction dump: [ 2736.063556] 7c0802a6 fba1ffe8 fbc1fff0 fbe1fff8 7cbd2b78 7c9e2378 7c7f1b78 f8010010 [ 2736.063566] f821ff71 e8a50008 7fa52040 40de00c0 <e8be0000> 7fbd2840 40de0094 7fbff040 [ 2736.063579] ---[ end trace 2708241785538296 ]--- It's caused by uninitialized persistent_keyring_register_sem. The bug was introduced by commit f36f8c75, two typos are in that commit: CONFIG_KEYS_KERBEROS_CACHE should be CONFIG_PERSISTENT_KEYRINGS and krb_cache_register_sem should be persistent_keyring_register_sem. Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: David Howells <dhowells@redhat.com>
* KEYS: Add per-user_namespace registers for persistent per-UID kerberos cachesDavid Howells2013-09-241-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* 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>
* 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: 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>
* hlist: drop the node parameter from iteratorsSasha Levin2013-02-281-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I'm not sure why, but the hlist for each entry iterators were conceived list_for_each_entry(pos, head, member) The hlist ones were greedy and wanted an extra parameter: hlist_for_each_entry(tpos, pos, head, member) Why did they need an extra pos parameter? I'm not quite sure. Not only they don't really need it, it also prevents the iterator from looking exactly like the list iterator, which is unfortunate. Besides the semantic patch, there was some manual work required: - Fix up the actual hlist iterators in linux/list.h - Fix up the declaration of other iterators based on the hlist ones. - A very small amount of places were using the 'node' parameter, this was modified to use 'obj->member' instead. - Coccinelle didn't handle the hlist_for_each_entry_safe iterator properly, so those had to be fixed up manually. The semantic patch which is mostly the work of Peter Senna Tschudin is here: @@ iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host; type T; expression a,c,d,e; identifier b; statement S; @@ -T b; <+... when != b ( hlist_for_each_entry(a, - b, c, d) S | hlist_for_each_entry_continue(a, - b, c) S | hlist_for_each_entry_from(a, - b, c) S | hlist_for_each_entry_rcu(a, - b, c, d) S | hlist_for_each_entry_rcu_bh(a, - b, c, d) S | hlist_for_each_entry_continue_rcu_bh(a, - b, c) S | for_each_busy_worker(a, c, - b, d) S | ax25_uid_for_each(a, - b, c) S | ax25_for_each(a, - b, c) S | inet_bind_bucket_for_each(a, - b, c) S | sctp_for_each_hentry(a, - b, c) S | sk_for_each(a, - b, c) S | sk_for_each_rcu(a, - b, c) S | sk_for_each_from -(a, b) +(a) S + sk_for_each_from(a) S | sk_for_each_safe(a, - b, c, d) S | sk_for_each_bound(a, - b, c) S | hlist_for_each_entry_safe(a, - b, c, d, e) S | hlist_for_each_entry_continue_rcu(a, - b, c) S | nr_neigh_for_each(a, - b, c) S | nr_neigh_for_each_safe(a, - b, c, d) S | nr_node_for_each(a, - b, c) S | nr_node_for_each_safe(a, - b, c, d) S | - for_each_gfn_sp(a, c, d, b) S + for_each_gfn_sp(a, c, d) S | - for_each_gfn_indirect_valid_sp(a, c, d, b) S + for_each_gfn_indirect_valid_sp(a, c, d) S | for_each_host(a, - b, c) S | for_each_host_safe(a, - b, c, d) S | for_each_mesh_entry(a, - b, c, d) S ) ...+> [akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c] [akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c] [akpm@linux-foundation.org: checkpatch fixes] [akpm@linux-foundation.org: fix warnings] [akpm@linux-foudnation.org: redo intrusive kvm changes] Tested-by: Peter Senna Tschudin <peter.senna@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* userns: Avoid recursion in put_user_nsEric W. Biederman2013-01-271-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | | 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>
* proc: Usable inode numbers for the namespace file descriptors.Eric W. Biederman2012-11-201-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | 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: Add kprojid_t and associated infrastructure in projid.hEric W. Biederman2012-09-181-0/+8
| | | | | | | | | | | | | | | | | | | | | | | 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: Silence silly gcc warning.Eric W. Biederman2012-05-191-2/+2
| | | | | | | | | | On 32bit builds gcc says: kernel/user.c:30:4: warning: this decimal constant is unsigned only in ISO C90 [enabled by default] kernel/user.c:38:4: warning: this decimal constant is unsigned only in ISO C90 [enabled by default] Silence gcc by changing the constant 4294967295 to 4294967295U. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* userns: Rework the user_namespace adding uid/gid mapping supportEric W. Biederman2012-04-261-0/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - 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. Biederman2012-04-261-3/+4
| | | | | | | | | | | | | | | | | | | | | - 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. Biederman2012-04-081-15/+13
| | | | | | | | | | | 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: Deprecate and rename the user_namespace reference in the user_structEric W. Biederman2012-04-081-3/+3
| | | | | | | | | | | | | With a user_ns reference in struct cred the only user of the user namespace reference in struct user_struct is to keep the uid hash table alive. The user_namespace reference in struct user_struct will be going away soon, and I have removed all of the references. Rename the field from user_ns to _user_ns so that the compiler can verify nothing follows the user struct to the user namespace anymore. 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>
* userns: add a user_namespace as creator/owner of uts_namespaceSerge E. Hallyn2011-03-241-2/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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@canonical.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: Daniel Lezcano <daniel.lezcano@free.fr> Acked-by: David Howells <dhowells@redhat.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fix freeing user_struct in user cacheHillf Danton2010-12-291-0/+1
| | | | | | | | | | | | | When racing on adding into user cache, the new allocated from mm slab is freed without putting user namespace. Since the user namespace is already operated by getting, putting has to be issued. Signed-off-by: Hillf Danton <dhillf@gmail.com> Acked-by: Serge Hallyn <serge@hallyn.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel/user.c: add lock release annotation on free_user()Namhyung Kim2010-10-271-0/+1
| | | | | | | | | | | | | | free_user() releases uidhash_lock but was missing annotation. Add it. This removes following sparse warnings: include/linux/spinlock.h:339:9: warning: context imbalance in 'free_user' - unexpected unlock kernel/user.c:120:6: warning: context imbalance in 'free_uid' - wrong count at exit Signed-off-by: Namhyung Kim <namhyung@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Dhaval Giani <dhaval.giani@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched: Remove a stale commentLi Zefan2010-05-101-1/+0
| | | | | | | | | | | This comment should have been removed together with uids_mutex when removing user sched. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Dhaval Giani <dhaval.giani@gmail.com> LKML-Reference: <4BE77C6B.5010402@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Remove remaining USER_SCHED codeLi Zefan2010-04-021-9/+1
| | | | | | | | | | | This is left over from commit 7c9414385e ("sched: Remove USER_SCHED"") Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Dhaval Giani <dhaval.giani@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: David Howells <dhowells@redhat.com> LKML-Reference: <4BA9A05F.7010407@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Remove some dead codeDan Carpenter2010-03-161-2/+0
| | | | | | | | | | | This was left over from "7c9414385e sched: Remove USER_SCHED" Signed-off-by: Dan Carpenter <error27@gmail.com> Acked-by: Dhaval Giani <dhaval.giani@gmail.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Greg Kroah-Hartman <gregkh@suse.de> LKML-Reference: <20100315082148.GD18181@bicker> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Remove USER_SCHEDDhaval Giani2010-01-211-305/+0
| | | | | | | | | | Remove the USER_SCHED feature. It has been scheduled to be removed in 2.6.34 as per http://marc.info/?l=linux-kernel&m=125728479022976&w=2 Signed-off-by: Dhaval Giani <dhaval.giani@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1263990378.24844.3.camel@localhost> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* uids: Prevent tear down raceThomas Gleixner2009-11-021-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Ingo triggered the following warning: WARNING: at lib/debugobjects.c:255 debug_print_object+0x42/0x50() Hardware name: System Product Name ODEBUG: init active object type: timer_list Modules linked in: Pid: 2619, comm: dmesg Tainted: G W 2.6.32-rc5-tip+ #5298 Call Trace: [<81035443>] warn_slowpath_common+0x6a/0x81 [<8120e483>] ? debug_print_object+0x42/0x50 [<81035498>] warn_slowpath_fmt+0x29/0x2c [<8120e483>] debug_print_object+0x42/0x50 [<8120ec2a>] __debug_object_init+0x279/0x2d7 [<8120ecb3>] debug_object_init+0x13/0x18 [<810409d2>] init_timer_key+0x17/0x6f [<81041526>] free_uid+0x50/0x6c [<8104ed2d>] put_cred_rcu+0x61/0x72 [<81067fac>] rcu_do_batch+0x70/0x121 debugobjects warns about an enqueued timer being initialized. If CONFIG_USER_SCHED=y the user management code uses delayed work to remove the user from the hash table and tear down the sysfs objects. free_uid is called from RCU and initializes/schedules delayed work if the usage count of the user_struct is 0. The init/schedule happens outside of the uidhash_lock protected region which allows a concurrent caller of find_user() to reference the about to be destroyed user_struct w/o preventing the work from being scheduled. If the next free_uid call happens before the work timer expired then the active timer is initialized and the work scheduled again. The race was introduced in commit 5cb350ba (sched: group scheduling, sysfs tunables) and made more prominent by commit 3959214f (sched: delayed cleanup of user_struct) Move the init/schedule_delayed_work inside of the uidhash_lock protected region to prevent the race. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@us.ibm.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: stable@kernel.org
* sched: delayed cleanup of user_structKay Sievers2009-06-161-28/+39
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | During bootup performance tracing we see repeated occurrences of /sys/kernel/uid/* events for the same uid, leading to a, in this case, rather pointless userspace processing for the same uid over and over. This is usually caused by tools which change their uid to "nobody", to run without privileges to read data supplied by untrusted users. This change delays the execution of the (already existing) scheduled work, to cleanup the uid after one second, so the allocated and announced uid can possibly be re-used by another process. This is the current behavior, where almost every invocation of a binary, which changes the uid, creates two events: $ read START < /sys/kernel/uevent_seqnum; \ for i in `seq 100`; do su --shell=/bin/true bin; done; \ read END < /sys/kernel/uevent_seqnum; \ echo $(($END - $START)) 178 With the delayed cleanup, we get only two events, and userspace finishes a bit faster too: $ read START < /sys/kernel/uevent_seqnum; \ for i in `seq 100`; do su --shell=/bin/true bin; done; \ read END < /sys/kernel/uevent_seqnum; \ echo $(($END - $START)) 1 Acked-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* Merge branch 'master' into nextJames Morris2009-03-241-9/+26
|\
| * kernel/user.c: fix a memory leak when freeing up non-init usernamespaces usersDhaval Giani2009-03-101-7/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | We were returning early in the sysfs directory cleanup function if the user belonged to a non init usernamespace. Due to this a lot of the cleanup was not done and we were left with a leak. Fix the leak. Reported-by: Serge Hallyn <serue@linux.vnet.ibm.com> Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Tested-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>
| * sched: don't allow setuid to succeed if the user does not have rt bandwidthDhaval Giani2009-02-271-0/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: fix hung task with certain (non-default) rt-limit settings Corey Hickey reported that on using setuid to change the uid of a rt process, the process would be unkillable and not be running. This is because there was no rt runtime for that user group. Add in a check to see if a user can attach an rt task to its task group. On failure, return EINVAL, which is also returned in CONFIG_CGROUP_SCHED. Reported-by: Corey Hickey <bugfood-ml@fatooh.org> Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * User namespaces: Only put the userns when we unhash the uidSerge E. Hallyn2009-02-131-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | uids in namespaces other than init don't get a sysfs entry. For those in the init namespace, while we're waiting to remove the sysfs entry for the uid the uid is still hashed, and alloc_uid() may re-grab that uid without getting a new reference to the user_ns, which we've already put in free_user before scheduling remove_user_sysfs_dir(). Reported-and-tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Acked-by: David Howells <dhowells@redhat.com> Tested-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | keys: distinguish per-uid keys in different namespacesSerge E. Hallyn2009-02-271-1/+1
|/ | | | | | | | | | | | | per-uid keys were looked by uid only. Use the user namespace to distinguish the same uid in different namespaces. This does not address key_permission. So a task can for instance try to join a keyring owned by the same uid in another namespace. That will be handled by a separate patch. Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
* Merge branch 'sched-core-for-linus' of ↵Linus Torvalds2008-12-281-0/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (31 commits) sched: fix warning in fs/proc/base.c schedstat: consolidate per-task cpu runtime stats sched: use RCU variant of list traversal in for_each_leaf_rt_rq() sched, cpuacct: export percpu cpuacct cgroup stats sched, cpuacct: refactoring cpuusage_read / cpuusage_write sched: optimize update_curr() sched: fix wakeup preemption clock sched: add missing arch_update_cpu_topology() call sched: let arch_update_cpu_topology indicate if topology changed sched: idle_balance() does not call load_balance_newidle() sched: fix sd_parent_degenerate on non-numa smp machine sched: add uid information to sched_debug for CONFIG_USER_SCHED sched: move double_unlock_balance() higher sched: update comment for move_task_off_dead_cpu sched: fix inconsistency when redistribute per-cpu tg->cfs_rq shares sched/rt: removed unneeded defintion sched: add hierarchical accounting to cpu accounting controller sched: include group statistics in /proc/sched_debug sched: rename SCHED_NO_NO_OMIT_FRAME_POINTER => SCHED_OMIT_FRAME_POINTER sched: clean up SCHED_CPUMASK_ALLOC ...
| * sched: add uid information to sched_debug for CONFIG_USER_SCHEDArun R Bharadwaj2008-12-011-0/+2
| | | | | | | | | | | | | | | | | | | | Impact: extend information in /proc/sched_debug This patch adds uid information in sched_debug for CONFIG_USER_SCHED Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | user namespaces: document CFS behaviorSerge E. Hallyn2008-12-081-1/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | Documented the currently bogus state of support for CFS user groups with user namespaces. In particular, all users in a user namespace should be children of the user which created the user namespace. This is yet to be implemented. Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Acked-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
* | user namespaces: let user_ns be cloned with fairschedSerge E. Hallyn2008-12-071-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | (These two patches are in the next-unacked branch of git://git.kernel.org/pub/scm/linux/kernel/git/sergeh/userns-2.6. If they get some ACKs, then I hope to feed this into security-next. After these two, I think we're ready to tackle userns+capabilities) Fairsched creates a per-uid directory under /sys/kernel/uids/. So when you clone(CLONE_NEWUSER), it tries to create /sys/kernel/uids/0, which already exists, and you get back -ENOMEM. This was supposed to be fixed by sysfs tagging, but that was postponed (ok, rejected until sysfs locking is fixed). So, just as with network namespaces, we just don't create those directories for user namespaces other than the init. Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
* | User namespaces: use the current_user_ns() macroSerge Hallyn2008-11-251-1/+1
| | | | | | | | | | | | | | Fix up the last current_user()->user_ns instance to use current_user_ns(). Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
* | User namespaces: set of cleanups (v2)Serge Hallyn2008-11-251-34/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 Howells2008-11-141-36/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: Separate task security context from task_structDavid Howells2008-11-141-2/+2
|/ | | | | | | | | | | | | | | | Separate the task security context from task_struct. At this point, the security data is temporarily embedded in the task_struct with two pointers pointing to it. Note that the Alpha arch is altered as it refers to (E)UID and (E)GID in entry.S via asm-offsets. With comment fixes Signed-off-by: Marc Dionne <marc.c.dionne@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <jmorris@namei.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
* sched: rt-bandwidth for user grouping interfacePeter Zijlstra2008-08-191-2/+2
| | | | | | | rt_runtime is a signed value Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* alloc_uid: cleanupAndrew Morton2008-04-301-16/+2
| | | | | | | | | | | | | | Use kmem_cache_zalloc(), remove large amounts of initialisation code and ifdeffery. Note: this assumes that memset(*atomic_t, 0) correctly initialises the atomic_t. This is true for all present archtiectures and if it becomes false for a future architecture then we'll need to make large changes all over the place anyway. Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* keys: don't generate user and user session keyrings unless they're accessedDavid Howells2008-04-291-11/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | Don't generate the per-UID user and user session keyrings unless they're explicitly accessed. This solves a problem during a login process whereby set*uid() is called before the SELinux PAM module, resulting in the per-UID keyrings having the wrong security labels. This also cures the problem of multiple per-UID keyrings sometimes appearing due to PAM modules (including pam_keyinit) setuiding and causing user_structs to come into and go out of existence whilst the session keyring pins the user keyring. This is achieved by first searching for extant per-UID keyrings before inventing new ones. The serial bound argument is also dropped from find_keyring_by_name() as it's not currently made use of (setting it to 0 disables the feature). Signed-off-by: David Howells <dhowells@redhat.com> Cc: <kwc@citi.umich.edu> Cc: <arunsr@cse.iitk.ac.in> Cc: <dwalsh@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched: fix the task_group hierarchy for UID groupingPeter Zijlstra2008-04-191-1/+1
| | | | | | | | UID grouping doesn't actually have a task_group representing the root of the task_group tree. Add one. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: allow the group scheduler to have multiple levelsDhaval Giani2008-04-191-1/+1
| | | | | | | | | This patch makes the group scheduler multi hierarchy aware. [a.p.zijlstra@chello.nl: rt-parts and assorted fixes] Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: rt-group: synchonised bandwidth periodPeter Zijlstra2008-04-191-0/+28
| | | | | | | | | | | Various SMP balancing algorithms require that the bandwidth period run in sync. Possible improvements are moving the rt_bandwidth thing into root_domain and keeping a span per rt_bandwidth which marks throttled cpus. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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