2009-04-07 05:46:58

by Li Zefan

Subject: [PATCH] devcgroup: skip superfluous checks when found the DEV_ALL elem

While walking through the whitelist, if the DEV_ALL item is found,
no more check is needed.

Signed-off-by: Li Zefan <[email protected]>
---
security/device_cgroup.c | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 5fda7df..b8186ba 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -490,7 +490,7 @@ int devcgroup_inode_permission(struct inode *inode, int mask)

list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) {
if (wh->type & DEV_ALL)
- goto acc_check;
+ goto found;
if ((wh->type & DEV_BLOCK) && !S_ISBLK(inode->i_mode))
continue;
if ((wh->type & DEV_CHAR) && !S_ISCHR(inode->i_mode))
@@ -499,11 +499,12 @@ int devcgroup_inode_permission(struct inode *inode, int mask)
continue;
if (wh->minor != ~0 && wh->minor != iminor(inode))
continue;
-acc_check:
+
if ((mask & MAY_WRITE) && !(wh->access & ACC_WRITE))
continue;
if ((mask & MAY_READ) && !(wh->access & ACC_READ))
continue;
+found:
rcu_read_unlock();
return 0;
}
@@ -527,7 +528,7 @@ int devcgroup_inode_mknod(int mode, dev_t dev)

list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) {
if (wh->type & DEV_ALL)
- goto acc_check;
+ goto found;
if ((wh->type & DEV_BLOCK) && !S_ISBLK(mode))
continue;
if ((wh->type & DEV_CHAR) && !S_ISCHR(mode))
@@ -536,9 +537,10 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
continue;
if (wh->minor != ~0 && wh->minor != MINOR(dev))
continue;
-acc_check:
+
if (!(wh->access & ACC_MKNOD))
continue;
+found:
rcu_read_unlock();
return 0;
}
--
1.5.4.rc3

2009-04-08 02:55:24

by Serge E. Hallyn

Subject: Re: [PATCH] devcgroup: skip superfluous checks when found the DEV_ALL elem

Quoting Li Zefan ([email protected]):
> While walking through the whitelist, if the DEV_ALL item is found,
> no more check is needed.

Right, because the DEV_ALL item always has all permissions.


> Signed-off-by: Li Zefan <[email protected]>

Acked-by: Serge Hallyn <[email protected]>

thanks,
-serge

> ---
> security/device_cgroup.c | 10 ++++++----
> 1 files changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> index 5fda7df..b8186ba 100644
> --- a/security/device_cgroup.c
> +++ b/security/device_cgroup.c
> @@ -490,7 +490,7 @@ int devcgroup_inode_permission(struct inode *inode, int mask)
>
> list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) {
> if (wh->type & DEV_ALL)
> - goto acc_check;
> + goto found;
> if ((wh->type & DEV_BLOCK) && !S_ISBLK(inode->i_mode))
> continue;
> if ((wh->type & DEV_CHAR) && !S_ISCHR(inode->i_mode))
> @@ -499,11 +499,12 @@ int devcgroup_inode_permission(struct inode *inode, int mask)
> continue;
> if (wh->minor != ~0 && wh->minor != iminor(inode))
> continue;
> -acc_check:
> +
> if ((mask & MAY_WRITE) && !(wh->access & ACC_WRITE))
> continue;
> if ((mask & MAY_READ) && !(wh->access & ACC_READ))
> continue;
> +found:
> rcu_read_unlock();
> return 0;
> }
> @@ -527,7 +528,7 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
>
> list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) {
> if (wh->type & DEV_ALL)
> - goto acc_check;
> + goto found;
> if ((wh->type & DEV_BLOCK) && !S_ISBLK(mode))
> continue;
> if ((wh->type & DEV_CHAR) && !S_ISCHR(mode))
> @@ -536,9 +537,10 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
> continue;
> if (wh->minor != ~0 && wh->minor != MINOR(dev))
> continue;
> -acc_check:
> +
> if (!(wh->access & ACC_MKNOD))
> continue;
> +found:
> rcu_read_unlock();
> return 0;
> }
> --
> 1.5.4.rc3

2009-04-10 00:08:31

by Andrew Morton

Subject: Re: [PATCH] devcgroup: skip superfluous checks when found the DEV_ALL elem

On Tue, 07 Apr 2009 13:47:16 +0800
Li Zefan <[email protected]> wrote:

> While walking through the whitelist, if the DEV_ALL item is found,
> no more check is needed.
>

It's unobvious whether this is a behavioural change, a bugfix or just a
speedup?

>
> diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> index 5fda7df..b8186ba 100644
> --- a/security/device_cgroup.c
> +++ b/security/device_cgroup.c
> @@ -490,7 +490,7 @@ int devcgroup_inode_permission(struct inode *inode, int mask)
>
> list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) {
> if (wh->type & DEV_ALL)
> - goto acc_check;
> + goto found;
> if ((wh->type & DEV_BLOCK) && !S_ISBLK(inode->i_mode))
> continue;
> if ((wh->type & DEV_CHAR) && !S_ISCHR(inode->i_mode))
> @@ -499,11 +499,12 @@ int devcgroup_inode_permission(struct inode *inode, int mask)
> continue;
> if (wh->minor != ~0 && wh->minor != iminor(inode))
> continue;
> -acc_check:
> +
> if ((mask & MAY_WRITE) && !(wh->access & ACC_WRITE))
> continue;
> if ((mask & MAY_READ) && !(wh->access & ACC_READ))
> continue;
> +found:
> rcu_read_unlock();
> return 0;
> }
> @@ -527,7 +528,7 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
>
> list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) {
> if (wh->type & DEV_ALL)
> - goto acc_check;
> + goto found;
> if ((wh->type & DEV_BLOCK) && !S_ISBLK(mode))
> continue;
> if ((wh->type & DEV_CHAR) && !S_ISCHR(mode))
> @@ -536,9 +537,10 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
> continue;
> if (wh->minor != ~0 && wh->minor != MINOR(dev))
> continue;
> -acc_check:
> +
> if (!(wh->access & ACC_MKNOD))
> continue;
> +found:
> rcu_read_unlock();
> return 0;
> }

2009-04-10 00:19:46

by Li Zefan

Subject: Re: [PATCH] devcgroup: skip superfluous checks when found the DEV_ALL elem

Andrew Morton wrote:
> On Tue, 07 Apr 2009 13:47:16 +0800
> Li Zefan <[email protected]> wrote:
>
>> While walking through the whitelist, if the DEV_ALL item is found,
>> no more check is needed.
>>
>
> It's unobvious whether this is a behavioural change, a bugfix or just a
> speedup?
>

It's a speedup. I thought it's obvious by saying "skip superfluous checks"..