* [PATCH] devcgroup: fix race against rmdir()
@ 2008-08-25 2:22 Li Zefan
[not found] ` <48B2174E.9060608-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
0 siblings, 1 reply; 4+ messages in thread
From: Li Zefan @ 2008-08-25 2:22 UTC (permalink / raw)
To: Andrew Morton; +Cc: Serge E. Hallyn, Paul Menage, LKML, Linux Containers
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>
---
security/device_cgroup.c | 18 +++++++++---------
1 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 7bd296c..46f2397 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -508,12 +508,11 @@ int devcgroup_inode_permission(struct inode *inode, int mask)
return 0;
if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode))
return 0;
- dev_cgroup = css_to_devcgroup(task_subsys_state(current,
- devices_subsys_id));
- if (!dev_cgroup)
- return 0;
rcu_read_lock();
+
+ dev_cgroup = task_devcgroup(current);
+
list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) {
if (wh->type & DEV_ALL)
goto acc_check;
@@ -533,6 +532,7 @@ acc_check:
rcu_read_unlock();
return 0;
}
+
rcu_read_unlock();
return -EPERM;
@@ -543,12 +543,10 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
struct dev_cgroup *dev_cgroup;
struct dev_whitelist_item *wh;
- dev_cgroup = css_to_devcgroup(task_subsys_state(current,
- devices_subsys_id));
- if (!dev_cgroup)
- return 0;
-
rcu_read_lock();
+
+ dev_cgroup = task_devcgroup(current);
+
list_for_each_entry(wh, &dev_cgroup->whitelist, list) {
if (wh->type & DEV_ALL)
goto acc_check;
@@ -566,6 +564,8 @@ acc_check:
rcu_read_unlock();
return 0;
}
+
rcu_read_unlock();
+
return -EPERM;
}
--
1.5.4.rc3
^ permalink raw reply related [flat|nested] 4+ messages in thread[parent not found: <48B2174E.9060608-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>]
* Re: [PATCH] devcgroup: fix race against rmdir() 2008-08-25 2:22 [PATCH] devcgroup: fix race against rmdir() Li Zefan @ 2008-08-25 16:43 ` Serge E. Hallyn 0 siblings, 0 replies; 4+ messages in thread From: Serge E. Hallyn @ 2008-08-25 16:43 UTC (permalink / raw) To: Li Zefan; +Cc: Linux Containers, Andrew Morton, Paul Menage, LKML Quoting Li Zefan (lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org): > 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-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org> Looks good. Thanks, Li. Acked-by: Serge Hallyn <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> > --- > security/device_cgroup.c | 18 +++++++++--------- > 1 files changed, 9 insertions(+), 9 deletions(-) > > diff --git a/security/device_cgroup.c b/security/device_cgroup.c > index 7bd296c..46f2397 100644 > --- a/security/device_cgroup.c > +++ b/security/device_cgroup.c > @@ -508,12 +508,11 @@ int devcgroup_inode_permission(struct inode *inode, int mask) > return 0; > if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode)) > return 0; > - dev_cgroup = css_to_devcgroup(task_subsys_state(current, > - devices_subsys_id)); > - if (!dev_cgroup) > - return 0; > > rcu_read_lock(); > + > + dev_cgroup = task_devcgroup(current); > + > list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) { > if (wh->type & DEV_ALL) > goto acc_check; > @@ -533,6 +532,7 @@ acc_check: > rcu_read_unlock(); > return 0; > } > + > rcu_read_unlock(); > > return -EPERM; > @@ -543,12 +543,10 @@ int devcgroup_inode_mknod(int mode, dev_t dev) > struct dev_cgroup *dev_cgroup; > struct dev_whitelist_item *wh; > > - dev_cgroup = css_to_devcgroup(task_subsys_state(current, > - devices_subsys_id)); > - if (!dev_cgroup) > - return 0; > - > rcu_read_lock(); > + > + dev_cgroup = task_devcgroup(current); > + > list_for_each_entry(wh, &dev_cgroup->whitelist, list) { > if (wh->type & DEV_ALL) > goto acc_check; > @@ -566,6 +564,8 @@ acc_check: > rcu_read_unlock(); > return 0; > } > + > rcu_read_unlock(); > + > return -EPERM; > } > -- > 1.5.4.rc3 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] devcgroup: fix race against rmdir() @ 2008-08-25 16:43 ` Serge E. Hallyn 0 siblings, 0 replies; 4+ messages in thread From: Serge E. Hallyn @ 2008-08-25 16:43 UTC (permalink / raw) To: Li Zefan; +Cc: Andrew Morton, Paul Menage, LKML, Linux Containers Quoting Li Zefan (lizf@cn.fujitsu.com): > 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> Looks good. Thanks, Li. Acked-by: Serge Hallyn <serue@us.ibm.com> > --- > security/device_cgroup.c | 18 +++++++++--------- > 1 files changed, 9 insertions(+), 9 deletions(-) > > diff --git a/security/device_cgroup.c b/security/device_cgroup.c > index 7bd296c..46f2397 100644 > --- a/security/device_cgroup.c > +++ b/security/device_cgroup.c > @@ -508,12 +508,11 @@ int devcgroup_inode_permission(struct inode *inode, int mask) > return 0; > if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode)) > return 0; > - dev_cgroup = css_to_devcgroup(task_subsys_state(current, > - devices_subsys_id)); > - if (!dev_cgroup) > - return 0; > > rcu_read_lock(); > + > + dev_cgroup = task_devcgroup(current); > + > list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) { > if (wh->type & DEV_ALL) > goto acc_check; > @@ -533,6 +532,7 @@ acc_check: > rcu_read_unlock(); > return 0; > } > + > rcu_read_unlock(); > > return -EPERM; > @@ -543,12 +543,10 @@ int devcgroup_inode_mknod(int mode, dev_t dev) > struct dev_cgroup *dev_cgroup; > struct dev_whitelist_item *wh; > > - dev_cgroup = css_to_devcgroup(task_subsys_state(current, > - devices_subsys_id)); > - if (!dev_cgroup) > - return 0; > - > rcu_read_lock(); > + > + dev_cgroup = task_devcgroup(current); > + > list_for_each_entry(wh, &dev_cgroup->whitelist, list) { > if (wh->type & DEV_ALL) > goto acc_check; > @@ -566,6 +564,8 @@ acc_check: > rcu_read_unlock(); > return 0; > } > + > rcu_read_unlock(); > + > return -EPERM; > } > -- > 1.5.4.rc3 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] devcgroup: fix race against rmdir() @ 2008-08-25 2:22 Li Zefan 0 siblings, 0 replies; 4+ messages in thread From: Li Zefan @ 2008-08-25 2:22 UTC (permalink / raw) To: Andrew Morton; +Cc: Paul Menage, Linux Containers, LKML 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-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org> --- security/device_cgroup.c | 18 +++++++++--------- 1 files changed, 9 insertions(+), 9 deletions(-) diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 7bd296c..46f2397 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -508,12 +508,11 @@ int devcgroup_inode_permission(struct inode *inode, int mask) return 0; if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode)) return 0; - dev_cgroup = css_to_devcgroup(task_subsys_state(current, - devices_subsys_id)); - if (!dev_cgroup) - return 0; rcu_read_lock(); + + dev_cgroup = task_devcgroup(current); + list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) { if (wh->type & DEV_ALL) goto acc_check; @@ -533,6 +532,7 @@ acc_check: rcu_read_unlock(); return 0; } + rcu_read_unlock(); return -EPERM; @@ -543,12 +543,10 @@ int devcgroup_inode_mknod(int mode, dev_t dev) struct dev_cgroup *dev_cgroup; struct dev_whitelist_item *wh; - dev_cgroup = css_to_devcgroup(task_subsys_state(current, - devices_subsys_id)); - if (!dev_cgroup) - return 0; - rcu_read_lock(); + + dev_cgroup = task_devcgroup(current); + list_for_each_entry(wh, &dev_cgroup->whitelist, list) { if (wh->type & DEV_ALL) goto acc_check; @@ -566,6 +564,8 @@ acc_check: rcu_read_unlock(); return 0; } + rcu_read_unlock(); + return -EPERM; } -- 1.5.4.rc3 ^ permalink raw reply related [flat|nested] 4+ messages in thread
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2008-08-25 2:22 [PATCH] devcgroup: fix race against rmdir() Li Zefan
[not found] ` <48B2174E.9060608-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2008-08-25 16:43 ` Serge E. Hallyn
2008-08-25 16:43 ` Serge E. Hallyn
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2008-08-25 2:22 Li Zefan
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