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* devices cgroup: allow mkfifoSerge E. Hallyn2009-01-081-0/+3
| | | | | | | | | | | | | | | | | | | | | | | The devcgroup_inode_permission() hook in the devices whitelist cgroup has always bypassed access checks on fifos. But the mknod hook did not. The devices whitelist is only about block and char devices, and fifos can't even be added to the whitelist, so fifos can't be created at all except by tasks which have 'a' in their whitelist (meaning they have access to all devices). Fix the behavior by bypassing access checks to mkfifo. Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Paul Menage <menage@google.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: James Morris <jmorris@namei.org> Reported-by: Daniel Lezcano <dlezcano@fr.ibm.com> Cc: <stable@kernel.org> [2.6.27.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devcgroup: use list_for_each_entry_rcu()Lai Jiangshan2009-01-081-1/+1
| | | | | | | | | | | | We should use list_for_each_entry_rcu in RCU read site. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Balbir Singh <balbir@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devcgroup: remove spin_lock()Lai Jiangshan2008-10-201-29/+5
| | | | | | | | | | | | | | | | Since we introduced rcu for read side, spin_lock is used only for update. But we always hold cgroup_lock() when update, so spin_lock() is not need. Additional cleanup: 1) include linux/rcupdate.h explicitly 2) remove unused variable cur_devcgroup in devcgroup_update_access() Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by: "Serge E. Hallyn" <serue@us.ibm.com> Cc: Paul Menage <menage@google.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>
* devcgroup: remove unused variableLi Zefan2008-10-201-2/+1
| | | | | | | | Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Paul Menage <menage@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devcgroup: use kmemdup()Li Zefan2008-10-201-7/+2
| | | | | | | | | | This saves 40 bytes on my x86_32 box. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Paul Menage <menage@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devcgroup: fix race against rmdir()Li Zefan2008-09-021-9/+9
| | | | | | | | | | | | | | | | During the use of a dev_cgroup, we should guarantee the corresponding cgroup won't be deleted (i.e. via rmdir). This can be done through css_get(&dev_cgroup->css), but here we can just get and use the dev_cgroup under rcu_read_lock. And also remove checking NULL dev_cgroup, it won't be NULL since a task always belongs to a cgroup. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Paul Menage <menage@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devcgroup: code cleanupLi Zefan2008-07-251-14/+8
| | | | | | | | | | | | | | | | - clean up set_majmin() - use simple_strtoul() to parse major/minor [akpm@linux-foundation.org: fix simple_strtoul() usage] [kosaki.motohiro@jp.fujitsu.com: fix warnings] Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Serge Hallyn <serue@us.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devcgroup: relax white-list protection down to RCUPavel Emelyanov2008-07-251-13/+22
| | | | | | | | | | | | | | | | | | | | | | | | Currently this list is protected with a simple spinlock, even for reading from one. This is OK, but can be better. Actually I want it to be better very much, since after replacing the OpenVZ device permissions engine with the cgroup-based one I noticed, that we set 12 default device permissions for each newly created container (for /dev/null, full, terminals, ect devices), and people sometimes have up to 20 perms more, so traversing the ~30-40 elements list under a spinlock doesn't seem very good. Here's the RCU protection for white-list - dev_whitelist_item-s are added and removed under the devcg->lock, but are looked up in permissions checking under the rcu_read_lock. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Menage <menage@google.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* cgroup files: convert devcgroup_access_write() into a cgroup write_string() ↵Paul Menage2008-07-251-63/+38
| | | | | | | | | | | | | | | | | | | handler This patch converts devcgroup_access_write() from a raw file handler into a handler for the cgroup write_string() method. This allows some boilerplate copying/locking/checking to be removed and simplifies the cleanup path, since these functions are performed by the cgroups framework before calling the handler. Signed-off-by: Paul Menage <menage@google.com> Cc: Paul Jackson <pj@sgi.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Balbir Singh <balbir@in.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devcgroup: fix permission check when adding entry to child cgroupLi Zefan2008-07-131-1/+1
| | | | | | | | | | | | | | | | | | | # cat devices.list c 1:3 r # echo 'c 1:3 w' > sub/devices.allow # cat sub/devices.list c 1:3 w As illustrated, the parent group has no write permission to /dev/null, so it's child should not be allowed to add this write permission. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Serge Hallyn <serue@us.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devcgroup: always show positive major/minor numLi Zefan2008-07-131-2/+2
| | | | | | | | | | | | | | | | | # echo "b $((0x7fffffff)):$((0x80000000)) rwm" > devices.allow # cat devices.list b 214748364:-21474836 rwm though a major/minor number of 0x800000000 is meaningless, we should not cast it to a negative value. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Serge Hallyn <serue@us.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devcgroup: fix odd behaviour when writing 'a' to devices.allowLi Zefan2008-07-041-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | # cat /devcg/devices.list a *:* rwm # echo a > devices.allow # cat /devcg/devices.list a *:* rwm a 0:0 rwm This is odd and maybe confusing. With this patch, writing 'a' to devices.allow will add 'a *:* rwm' to the whitelist. Also a few fixes and updates to the document. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: James Morris <jmorris@namei.org> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devscgroup: make white list more compact in some casesPavel Emelyanov2008-06-061-2/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | Consider you added a 'c foo:bar r' permission to some cgroup and then (a bit later) 'c'foo:bar w' for it. After this you'll see the c foo:bar r c foo:bar w lines in a devices.list file. Another example - consider you added 10 'c foo:bar r' permissions to some cgroup (e.g. by mistake). After this you'll see 10 c foo:bar r lines in a list file. This is weird. This situation also has one more annoying consequence. Having many items in a white list makes permissions checking slower, sine it has to walk a longer list. The proposal is to merge permissions for items, that correspond to the same device. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devscgroup: relax task to dev_cgroup conversionPavel Emelyanov2008-06-061-6/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Two functions, that need to get a device_cgroup from a task (they are devcgroup_inode_permission and devcgroup_inode_mknod) make it in a strange way: They get a css_set from task, then a subsys_state from css_set, then a cgroup from the state and then a subsys_state again from the cgroup. Besides, the devices_subsys_id is read from memory, whilst there's a enum-ed constant for it. Optimize this part a bit: 1. Get the subsys_stats form the task and be done - no 2 extra dereferences, 2. Use the device_subsys_id constant, not the value from memory (i.e. one less dereference). Found while preparing 2.6.26 OpenVZ port. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Acked-by: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: James Morris <jmorris@namei.org> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devcgroup: make a helper to convert cgroup_subsys_state to devs_cgroupPavel Emelyanov2008-06-061-2/+6
| | | | | | | | | | | | | | | | | This is just picking the container_of out of cgroup_to_devcgroup into a separate function. This new css_to_devcgroup will be used in the 2nd patch. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: James Morris <jmorris@namei.org> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* cgroups: introduce cft->read_seq()Serge E. Hallyn2008-04-291-51/+23
| | | | | | | | | | | | | | Introduce a read_seq() helper in cftype, which uses seq_file to print out lists. Use it in the devices cgroup. Also split devices.allow into two files, so now devices.deny and devices.allow are the ones to use to manipulate the whitelist, while devices.list outputs the cgroup's current whitelist. Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Acked-by: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* cgroups: implement device whitelistSerge E. Hallyn2008-04-291-0/+603
Implement a cgroup to track and enforce open and mknod restrictions on device files. A device cgroup associates a device access whitelist with each cgroup. A whitelist entry has 4 fields. 'type' is a (all), c (char), or b (block). 'all' means it applies to all types and all major and minor numbers. Major and minor are either an integer or * for all. Access is a composition of r (read), w (write), and m (mknod). The root device cgroup starts with rwm to 'all'. A child devcg gets a copy of the parent. Admins can then remove devices from the whitelist or add new entries. A child cgroup can never receive a device access which is denied its parent. However when a device access is removed from a parent it will not also be removed from the child(ren). An entry is added using devices.allow, and removed using devices.deny. For instance echo 'c 1:3 mr' > /cgroups/1/devices.allow allows cgroup 1 to read and mknod the device usually known as /dev/null. Doing echo a > /cgroups/1/devices.deny will remove the default 'a *:* mrw' entry. CAP_SYS_ADMIN is needed to change permissions or move another task to a new cgroup. A cgroup may not be granted more permissions than the cgroup's parent has. Any task can move itself between cgroups. This won't be sufficient, but we can decide the best way to adequately restrict movement later. [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix may-be-used-uninitialized warning] Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Acked-by: James Morris <jmorris@namei.org> Looks-good-to: Pavel Emelyanov <xemul@openvz.org> Cc: Daniel Hokka Zakrisson <daniel@hozac.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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