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>
This patchset is a cleanup and a preparation to unshare the pid namespace.
These prerequisites prepare for Eric's patchset to give a file descriptor
to a namespace and join an existing namespace.
This patch:
It turns out that the existing assignment in copy_process of the
child_reaper can handle the initial assignment of child_reaper we just
need to generalize the test in kernel/fork.c
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Systems with unmaskable interrupts such as SMIs may massively
underestimate loops_per_jiffy, and fail to converge anywhere near the real
value. A case seen on x86_64 was an initial estimate of 256<<12, which
converged to 511<<12 where the real value should have been over 630<<12.
This admitedly requires bypassing the TSC calibration (lpj_fine), and a
failure to settle in the direct calibration too, but is physically
possible. This failure does not depend on my previous calibration
optimisation, but by luck is easy to fix with the optimisation in place
with a trivial retry loop.
In the context of the optimised converging method, as we can no longer
trust the starting estimate, enlarge the search bounds exponentially so
that the number of retries is logarithmically bounded.
[akpm@linux-foundation.org: mention x86_64 SMIs in comment]
Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Binary chop with a jiffy-resync on each step to find an upper bound is
slow, so just race in a tight-ish loop to find an underestimate.
If done with lots of individual steps, sometimes several hundreds of
iterations would be required, which would impose a significant overhead,
and make the initial estimate very low. By taking slowly increasing steps
there will be less overhead.
E.g. an x86_64 2.67GHz could have fitted in 613 individual small delays,
but in reality should have been able to fit in a single delay 644 times
longer, so underestimated by 31 steps. To reach the equivalent of 644
small delays with the accelerating scheme now requires about 130
iterations, so has <1/4th of the overhead, and can therefore be expected
to underestimate by only 7 steps.
As now we have a better initial estimate we can binary chop over a smaller
range. With the loop overhead in the initial estimate kept low, and the
step sizes moderate, we won't have under-estimated by much, so chose as
tight a range as we can.
Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The motivation for this patch series is that currently our OMAP calibrates
itself using the trial-and-error binary chop fallback that some other
architectures no longer need to perform. This is a lengthy process,
taking 0.2s in an environment where boot time is of great interest.
Patch 2/4 has two optimisations. Firstly, it replaces the initial
repeated- doubling to find the relevant power of 2 with a tight loop that
just does as much as it can in a jiffy. Secondly, it doesn't binary chop
over an entire power of 2 range, it choses a much smaller range based on
how much it squeezed in, and failed to squeeze in, during the first stage.
Both are significant optimisations, and bring our calibration down from
23 jiffies to 5, and, in the process, often arrive at a more accurate lpj
value.
The 'bands' and 'sub-logarithmic' growth may look over-engineered, but
they only cost a small level of inaccuracy in the initial guess (for all
architectures) in order to avoid the very large inaccuracies that appeared
during testing (on x86_64 architectures, and presumably others with less
metronomic operation). Note that due to the existence of the TSC and
other timers, the x86_64 will not typically use this fallback routine, but
I wanted to code defensively, able to cope with all kinds of processor
behaviours and kernel command line options.
Patch 3/4 is an additional trap for the nightmare scenario where the
initial estimate is very inaccurate, possibly due to things like SMIs.
It simply retries with a larger bound.
Stephen said:
I tried this patch set out on an MSM7630.
:
: Before:
:
: Calibrating delay loop... 681.57 BogoMIPS (lpj=3407872)
:
: After:
:
: Calibrating delay loop... 680.75 BogoMIPS (lpj=3403776)
:
: But the really good news is calibration time dropped from ~247ms to ~56ms.
: Sadly we won't be able to benefit from this should my udelay patches make
: it into ARM because we would be using calibrate_delay_direct() instead (at
: least on machines who choose to). Can we somehow reapply the logic behind
: this to calibrate_delay_direct()? That would be even better, but this is
: definitely a boot time improvement.
:
: Or maybe we could just replace calibrate_delay_direct() with this fallback
: calculation? If __delay() is a thin wrapper around read_current_timer()
: it should work just as well (plus patch 3 makes it handle SMIs). I'll try
: that out.
This patch:
... so that it can be modified more clinically.
This is almost entirely cosmetic. The only change to the operation
is that the global variable is only set once after the estimation is
completed, rather than taking on all the intermediate values. However,
there are no readers of that variable, so this change is unimportant.
Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
printk()s without a priority level default to KERN_WARNING. To reduce
noise at KERN_WARNING, this patch set the priority level appriopriately
for unleveled printks()s. This should be useful to folks that look at
dmesg warnings closely.
Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (47 commits)
doc: CONFIG_UNEVICTABLE_LRU doesn't exist anymore
Update cpuset info & webiste for cgroups
dcdbas: force SMI to happen when expected
arch/arm/Kconfig: remove one to many l's in the word.
asm-generic/user.h: Fix spelling in comment
drm: fix printk typo 'sracth'
Remove one to many n's in a word
Documentation/filesystems/romfs.txt: fixing link to genromfs
drivers:scsi Change printk typo initate -> initiate
serial, pch uart: Remove duplicate inclusion of linux/pci.h header
fs/eventpoll.c: fix spelling
mm: Fix out-of-date comments which refers non-existent functions
drm: Fix printk typo 'failled'
coh901318.c: Change initate to initiate.
mbox-db5500.c Change initate to initiate.
edac: correct i82975x error-info reported
edac: correct i82975x mci initialisation
edac: correct commented info
fs: update comments to point correct document
target: remove duplicate include of target/target_core_device.h from drivers/target/target_core_hba.c
...
Trivial conflict in fs/eventpoll.c (spelling vs addition)
* 'config' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl:
BKL: That's all, folks
fs/locks.c: Remove stale FIXME left over from BKL conversion
ipx: remove the BKL
appletalk: remove the BKL
x25: remove the BKL
ufs: remove the BKL
hpfs: remove the BKL
drivers: remove extraneous includes of smp_lock.h
tracing: don't trace the BKL
adfs: remove the big kernel lock
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (184 commits)
perf probe: Clean up probe_point_lazy_walker() return value
tracing: Fix irqoff selftest expanding max buffer
tracing: Align 4 byte ints together in struct tracer
tracing: Export trace_set_clr_event()
tracing: Explain about unstable clock on resume with ring buffer warning
ftrace/graph: Trace function entry before updating index
ftrace: Add .ref.text as one of the safe areas to trace
tracing: Adjust conditional expression latency formatting.
tracing: Fix event alignment: skb:kfree_skb
tracing: Fix event alignment: mce:mce_record
tracing: Fix event alignment: kvm:kvm_hv_hypercall
tracing: Fix event alignment: module:module_request
tracing: Fix event alignment: ftrace:context_switch and ftrace:wakeup
tracing: Remove lock_depth from event entry
perf header: Stop using 'self'
perf session: Use evlist/evsel for managing perf.data attributes
perf top: Don't let events to eat up whole header line
perf top: Fix events overflow in top command
ring-buffer: Remove unused #include <linux/trace_irq.h>
tracing: Add an 'overwrite' trace_option.
...
The syscall also return mount id which can be used
to lookup file system specific information such as uuid
in /proc/<pid>/mountinfo
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This kernel patch adds the ability to filter monitoring based on
container groups (cgroups). This is for use in per-cpu mode only.
The cgroup to monitor is passed as a file descriptor in the pid
argument to the syscall. The file descriptor must be opened to
the cgroup name in the cgroup filesystem. For instance, if the
cgroup name is foo and cgroupfs is mounted in /cgroup, then the
file descriptor is opened to /cgroup/foo. Cgroup mode is
activated by passing PERF_FLAG_PID_CGROUP in the flags argument
to the syscall.
For instance to measure in cgroup foo on CPU1 assuming
cgroupfs is mounted under /cgroup:
struct perf_event_attr attr;
int cgroup_fd, fd;
cgroup_fd = open("/cgroup/foo", O_RDONLY);
fd = perf_event_open(&attr, cgroup_fd, 1, -1, PERF_FLAG_PID_CGROUP);
close(cgroup_fd);
Signed-off-by: Stephane Eranian <eranian@google.com>
[ added perf_cgroup_{exit,attach} ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4d590250.114ddf0a.689e.4482@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Fixes a hang when booting as dom0 under Xen, when jiffies can be
quite large by the time the kernel init gets this far.
Signed-off-by: Tim Deegan <Tim.Deegan@citrix.com>
[jbeulich@novell.com: !time_after() -> time_before_eq() as suggested by Jiri Slaby]
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
smp: Allow on_each_cpu() to be called while early_boot_irqs_disabled status to init/main.c
lockdep: Move early boot local IRQ enable/disable status to init/main.c
The meaning of CONFIG_EMBEDDED has long since been obsoleted; the option
is used to configure any non-standard kernel with a much larger scope than
only small devices.
This patch renames the option to CONFIG_EXPERT in init/Kconfig and fixes
references to the option throughout the kernel. A new CONFIG_EMBEDDED
option is added that automatically selects CONFIG_EXPERT when enabled and
can be used in the future to isolate options that should only be
considered for embedded systems (RISC architectures, SLOB, etc).
Calling the option "EXPERT" more accurately represents its intention: only
expert users who understand the impact of the configuration changes they
are making should enable it.
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Acked-by: David Woodhouse <david.woodhouse@intel.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Greg KH <gregkh@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Robin Holt <holt@sgi.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During early boot, local IRQ is disabled until IRQ subsystem is
properly initialized. During this time, no one should enable
local IRQ and some operations which usually are not allowed with
IRQ disabled, e.g. operations which might sleep or require
communications with other processors, are allowed.
lockdep tracked this with early_boot_irqs_off/on() callbacks.
As other subsystems need this information too, move it to
init/main.c and make it generally available. While at it,
toggle the boolean to early_boot_irqs_disabled instead of
enabled so that it can be initialized with %false and %true
indicates the exceptional condition.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20110120110635.GB6036@htj.dyndns.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
It would seem that `CONFIG_BLK_THROTTLE' doesn't exist,
as it is only referenced in the documentation for
`CONFIG_BLK_CGROUP'. The only other choice is
`CONFIG_BLK_DEV_THROTTLING':
$ git grep --cached THROTTL -- \*Kconfig
block/Kconfig:config BLK_DEV_THROTTLING
init/Kconfig: CONFIG_BLK_THROTTLE=y.
Signed-off-by: Michael Witten <mfwitten@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Also, I introduced some punctuation to facilitate reading.
Signed-off-by: Michael Witten <mfwitten@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
rcu: avoid pointless blocked-task warnings
rcu: demote SRCU_SYNCHRONIZE_DELAY from kernel-parameter status
rtmutex: Fix comment about why new_owner can be NULL in wake_futex_pi()
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, olpc: Add missing Kconfig dependencies
x86, mrst: Set correct APB timer IRQ affinity for secondary cpu
x86: tsc: Fix calibration refinement conditionals to avoid divide by zero
x86, ia64, acpi: Clean up x86-ism in drivers/acpi/numa.c
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
timekeeping: Make local variables static
time: Rename misnamed minsec argument of clocks_calc_mult_shift()
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
tracing: Remove syscall_exit_fields
tracing: Only process module tracepoints once
perf record: Add "nodelay" mode, disabled by default
perf sched: Fix list of events, dropping unsupported ':r' modifier
Revert "perf tools: Emit clearer message for sys_perf_event_open ENOENT return"
perf top: Fix annotate segv
perf evsel: Fix order of event list deletion
