09 Jan, 2015
1 commit
-
commit 9cc46516ddf497ea16e8d7cb986ae03a0f6b92f8 upstream.
- 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.Signed-off-by: "Eric W. Biederman"
Signed-off-by: Greg Kroah-Hartman
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
-
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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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…/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
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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
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(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
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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
25 Nov, 2008
2 commits
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Fix up the last current_user()->user_ns instance to use
current_user_ns().Signed-off-by: Serge E. Hallyn
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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
Changelog:
Oct 20: integrate dhowells comments
1. leave thread_keyring alone
2. use current_user_ns() in set_user()Signed-off-by: Serge Hallyn
14 Nov, 2008
1 commit
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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
Acked-by: James Morris
Signed-off-by: James Morris