18 Dec, 2014
1 commit
-
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> Tested on Fedora20 with libvirt 1.2.11, works fine.
> Tested-by: Chen Hanxiao> 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> I tested this with Sandstorm. It breaks as is and it works if I add
> the setgroups thing.
> Tested-by: Andy Lutomirski # 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
12 Dec, 2014
1 commit
-
- Expose the knob to user space through a proc file /proc//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"
05 Dec, 2014
2 commits
-
Signed-off-by: Al Viro
-
for now - just move corresponding ->proc_inum instances over there
Acked-by: "Eric W. Biederman"
Signed-off-by: Al Viro
05 Jun, 2014
1 commit
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Nobody seems uses it for a long time. Let's drop it.
Signed-off-by: Kirill A. Shutemov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
04 Apr, 2014
1 commit
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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_NSNote 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
Cc: Ingo Molnar
Cc: Peter Zijlstra
Cc: Eric Biederman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Dec, 2013
1 commit
-
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 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 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
Signed-off-by: David Howells
24 Sep, 2013
1 commit
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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 blobOr 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_keyWhat 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." 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
Tested-by: Simo Sorce
cc: Serge E. Hallyn
cc: Eric W. Biederman
27 Aug, 2013
1 commit
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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"
02 May, 2013
2 commits
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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
... -
Split the proc namespace stuff out into linux/proc_ns.h.
Signed-off-by: David Howells
cc: netdev@vger.kernel.org
cc: Serge E. Hallyn
cc: Eric W. Biederman
Signed-off-by: Al Viro
27 Mar, 2013
1 commit
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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
Signed-off-by: "Eric W. Biederman"
28 Feb, 2013
1 commit
-
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;
[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
Acked-by: Paul E. McKenney
Signed-off-by: Sasha Levin
Cc: Wu Fengguang
Cc: Marcelo Tosatti
Cc: Gleb Natapov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
27 Jan, 2013
1 commit
-
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
Pointed-out-by: Vasily Kulikov
Signed-off-by: "Eric W. Biederman"
20 Nov, 2012
1 commit
-
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
18 Sep, 2012
1 commit
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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//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
Cc: Jan Kara
Signed-off-by: "Eric W. Biederman"
20 May, 2012
1 commit
-
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
26 Apr, 2012
2 commits
-
- 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
Signed-off-by: Eric W. Biederman -
- 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
Signed-off-by: Eric W. Biederman
08 Apr, 2012
2 commits
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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
Signed-off-by: Eric W. Biederman -
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
Signed-off-by: Eric W. Biederman
31 Oct, 2011
1 commit
-
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
+#includeThis commit is only changing the kernel dir; next targets
will probably be mm, fs, the arch dirs, etc.Signed-off-by: Paul Gortmaker
24 Mar, 2011
1 commit
-
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
Acked-by: "Eric W. Biederman"
Acked-by: Daniel Lezcano
Acked-by: David Howells
Cc: James Morris
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
30 Dec, 2010
1 commit
-
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
Acked-by: Serge Hallyn
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds
27 Oct, 2010
1 commit
-
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 exitSigned-off-by: Namhyung Kim
Cc: Ingo Molnar
Cc: Dhaval Giani
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
10 May, 2010
1 commit
-
This comment should have been removed together with uids_mutex
when removing user sched.Signed-off-by: Li Zefan
Cc: Peter Zijlstra
Cc: Dhaval Giani
LKML-Reference:
Signed-off-by: Ingo Molnar
03 Apr, 2010
1 commit
-
This is left over from commit 7c9414385e ("sched: Remove USER_SCHED"")
Signed-off-by: Li Zefan
Acked-by: Dhaval Giani
Signed-off-by: Peter Zijlstra
Cc: David Howells
LKML-Reference:
Signed-off-by: Ingo Molnar
16 Mar, 2010
1 commit
-
This was left over from "7c9414385e sched: Remove USER_SCHED"
Signed-off-by: Dan Carpenter
Acked-by: Dhaval Giani
Cc: Kay Sievers
Cc: Greg Kroah-Hartman
LKML-Reference:
Signed-off-by: Ingo Molnar
21 Jan, 2010
1 commit
-
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=2Signed-off-by: Dhaval Giani
Signed-off-by: Peter Zijlstra
LKML-Reference:
Signed-off-by: Ingo Molnar
02 Nov, 2009
1 commit
-
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:
[] warn_slowpath_common+0x6a/0x81
[] ? debug_print_object+0x42/0x50
[] warn_slowpath_fmt+0x29/0x2c
[] debug_print_object+0x42/0x50
[] __debug_object_init+0x279/0x2d7
[] debug_object_init+0x13/0x18
[] init_timer_key+0x17/0x6f
[] free_uid+0x50/0x6c
[] put_cred_rcu+0x61/0x72
[] rcu_do_batch+0x70/0x121debugobjects 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
Acked-by: Dhaval Giani
Cc: Paul E. McKenney
Cc: Kay Sievers
Cc: stable@kernel.org
16 Jun, 2009
1 commit
-
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))
178With 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))
1Acked-by: Dhaval Giani
Signed-off-by: Kay Sievers
Signed-off-by: Greg Kroah-Hartman
24 Mar, 2009
1 commit
11 Mar, 2009
1 commit
-
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
Signed-off-by: Dhaval Giani
Acked-by: Serge Hallyn
Tested-by: Serge Hallyn
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
27 Feb, 2009
2 commits
-
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
Signed-off-by: Dhaval Giani
Acked-by: Peter Zijlstra
Signed-off-by: Ingo Molnar -
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
Acked-by: David Howells
Signed-off-by: James Morris
14 Feb, 2009
1 commit
-
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
Signed-off-by: Serge E. Hallyn
Acked-by: David Howells
Tested-by: Ingo Molnar
Signed-off-by: Linus Torvalds
29 Dec, 2008
1 commit
-
…/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
...
09 Dec, 2008
1 commit
-
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
Acked-by: Dhaval GianiSigned-off-by: Serge E. Hallyn
Signed-off-by: James Morris
08 Dec, 2008
1 commit
-
(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
Signed-off-by: James Morris
02 Dec, 2008
1 commit
-
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
Acked-by: Peter Zijlstra
Signed-off-by: Ingo Molnar
