[PATCH 1/3] netprio_cgroup: fix an off-by-one bug

[PATCH 1/3] netprio_cgroup: fix an off-by-one bug

[Neil Horman]

  # mount -t cgroup xxx /mnt
  # mkdir /mnt/tmp
  # cat /mnt/tmp/net_prio.ifpriomap
  lo 0
  eth0 0
  virbr0 0
  # echo 'lo 999' > /mnt/tmp/net_prio.ifpriomap
  # cat /mnt/tmp/net_prio.ifpriomap
  lo 999
  eth0 0
  virbr0 4101267344

We got weired output, because we exceeded the boundary of the array.
We may even crash the kernel..

Origionally-authored-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: "David S. Miller" <davem@davemloft.net>
---
 net/core/netprio_cgroup.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index 9ae183a..72c6387 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -108,7 +108,7 @@ static void extend_netdev_table(struct net_device *dev, u32 new_len)
 static void update_netdev_tables(void)
 {
 	struct net_device *dev;
-	u32 max_len = atomic_read(&max_prioidx);
+	u32 max_len = atomic_read(&max_prioidx) + 1;
 	struct netprio_map *map;
 
 	rtnl_lock();
-- 
1.7.7.6

[PATCH 2/3] netprio_cgroup: don't allocate prio table when a device is registered

[Neil Horman]

So we delay the allocation till the priority is set through cgroup,
and this makes skb_update_priority() faster when it's not set.

This also eliminates an off-by-one bug similar with the one fixed
in the previous patch.

Origionally-authored-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: "David S. Miller" <davem@davemloft.net>
---
 net/core/netprio_cgroup.c |    6 ------
 1 files changed, 0 insertions(+), 6 deletions(-)

diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index 72c6387..4dacc44 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -271,7 +271,6 @@ static int netprio_device_event(struct notifier_block *unused,
 {
 	struct net_device *dev = ptr;
 	struct netprio_map *old;
-	u32 max_len = atomic_read(&max_prioidx);
 
 	/*
 	 * Note this is called with rtnl_lock held so we have update side
@@ -279,11 +278,6 @@ static int netprio_device_event(struct notifier_block *unused,
 	 */
 
 	switch (event) {
-
-	case NETDEV_REGISTER:
-		if (max_len)
-			extend_netdev_table(dev, max_len);
-		break;
 	case NETDEV_UNREGISTER:
 		old = rtnl_dereference(dev->priomap);
 		RCU_INIT_POINTER(dev->priomap, NULL);
-- 
1.7.7.6

[PATCH 3/3] netprio_cgroup: fix wrong memory access when NETPRIO_CGROUP=m

[Neil Horman]

When the netprio_cgroup module is not loaded, net_prio_subsys_id
is -1, and so sock_update_prioidx() accesses cgroup_subsys array
with negative index subsys[-1].

Make the code resembles cls_cgroup code, which is bug free.

Origionally-authored-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: "David S. Miller" <davem@davemloft.net>
---
 include/net/netprio_cgroup.h |   48 +++++++++++++++++++++++++++++++++++-------
 net/core/sock.c              |    7 +----
 2 files changed, 42 insertions(+), 13 deletions(-)

diff --git a/include/net/netprio_cgroup.h b/include/net/netprio_cgroup.h
index 7b2d431..d58fdec 100644
--- a/include/net/netprio_cgroup.h
+++ b/include/net/netprio_cgroup.h
@@ -37,19 +37,51 @@ extern int net_prio_subsys_id;
 
 extern void sock_update_netprioidx(struct sock *sk);
 
-static inline struct cgroup_netprio_state
-		*task_netprio_state(struct task_struct *p)
+#if IS_BUILTIN(CONFIG_NETPRIO_CGROUP)
+
+static inline u32 task_netprioidx(struct task_struct *p)
 {
-#if IS_ENABLED(CONFIG_NETPRIO_CGROUP)
-	return container_of(task_subsys_state(p, net_prio_subsys_id),
-			    struct cgroup_netprio_state, css);
-#else
-	return NULL;
-#endif
+	struct cgroup_netprio_state *state;
+	u32 idx;
+
+	rcu_read_lock();
+	state = container_of(task_subsys_state(p, net_prio_subsys_id),
+			     struct cgroup_netprio_state, css);
+	idx = state->prioidx;
+	rcu_read_unlock();
+	return idx;
+}
+
+#elif IS_MODULE(CONFIG_NETPRIO_CGROUP)
+
+static inline u32 task_netprioidx(struct task_struct *p)
+{
+	struct cgroup_netprio_state *state;
+	int subsys_id;
+	u32 idx = 0;
+
+	rcu_read_lock();
+	subsys_id = rcu_dereference_index_check(net_prio_subsys_id,
+						rcu_read_lock_held());
+	if (subsys_id >= 0) {
+		state = container_of(task_subsys_state(p, subsys_id),
+				     struct cgroup_netprio_state, css);
+		idx = state->prioidx;
+	}
+	rcu_read_unlock();
+	return idx;
 }
 
 #else
 
+static inline u32 task_netprioidx(struct task_struct *p)
+{
+	return 0;
+}
+
+#endif /* CONFIG_NETPRIO_CGROUP */
+
+#else
 #define sock_update_netprioidx(sk)
 #endif
 
diff --git a/net/core/sock.c b/net/core/sock.c
index 3e81fd2..02f8dfe 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1171,13 +1171,10 @@ EXPORT_SYMBOL(sock_update_classid);
 
 void sock_update_netprioidx(struct sock *sk)
 {
-	struct cgroup_netprio_state *state;
 	if (in_interrupt())
 		return;
-	rcu_read_lock();
-	state = task_netprio_state(current);
-	sk->sk_cgrp_prioidx = state ? state->prioidx : 0;
-	rcu_read_unlock();
+
+	sk->sk_cgrp_prioidx = task_netprioidx(current);
 }
 EXPORT_SYMBOL_GPL(sock_update_netprioidx);
 #endif
-- 
1.7.7.6

Re: [PATCH 0/3] netprio_cgroup: some miscelaneous off by one fixes

[David Miller]

From: Neil Horman <nhorman@tuxdriver.com>
Date: Fri, 10 Feb 2012 10:43:35 -0500

> About 2 weeks ago, Li Zefan posted a series of cleanups and fixes for cls_cgroup
> and netprio_cgroup.  It was requested that the cleanups and fixes be separated
> into two different series and reposted.  Its been about 2 weeks, and after
> pinging the author a few times and getting no response, I've decided to repost
> the fixes for netprio myself, as they're important and I don't want them to be
> forgotten or otherwise fall through the cracks.
> 
> Origionally-authored-by: Li Zefan <lizf@cn.fujitsu.com>
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com
> CC: Li Zefan <lizf@cn.fujitsu.com>
> CC: "David S. Miller" <davem@davemloft.net>

All applied, thanks Neil.

Re: [PATCH 0/3] netprio_cgroup: some miscelaneous off by one fixes

[Neil Horman]

On Fri, Feb 10, 2012 at 03:09:07PM -0500, David Miller wrote:
> From: Neil Horman <nhorman@tuxdriver.com>
> Date: Fri, 10 Feb 2012 10:43:35 -0500
> 
> > About 2 weeks ago, Li Zefan posted a series of cleanups and fixes for cls_cgroup
> > and netprio_cgroup.  It was requested that the cleanups and fixes be separated
> > into two different series and reposted.  Its been about 2 weeks, and after
> > pinging the author a few times and getting no response, I've decided to repost
> > the fixes for netprio myself, as they're important and I don't want them to be
> > forgotten or otherwise fall through the cracks.
> > 
> > Origionally-authored-by: Li Zefan <lizf@cn.fujitsu.com>
> > Signed-off-by: Neil Horman <nhorman@tuxdriver.com
> > CC: Li Zefan <lizf@cn.fujitsu.com>
> > CC: "David S. Miller" <davem@davemloft.net>
> 
> All applied, thanks Neil.
Thanks!
Neil

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Re: [PATCH 0/3] netprio_cgroup: some miscelaneous off by one fixes

[Li Zefan]

Neil Horman wrote:
> About 2 weeks ago, Li Zefan posted a series of cleanups and fixes for cls_cgroup
> and netprio_cgroup.  It was requested that the cleanups and fixes be separated
> into two different series and reposted.  Its been about 2 weeks, and after
> pinging the author a few times and getting no response, I've decided to repost
> the fixes for netprio myself, as they're important and I don't want them to be
> forgotten or otherwise fall through the cracks.
> 

Thanks for the reposting.

I was off office for a few days for some reason, and just came back to work.

Re: [PATCH 0/3] netprio_cgroup: some miscelaneous off by one fixes

[Neil Horman]

On Wed, Feb 15, 2012 at 10:22:28AM +0800, Li Zefan wrote:
> Neil Horman wrote:
> > About 2 weeks ago, Li Zefan posted a series of cleanups and fixes for cls_cgroup
> > and netprio_cgroup.  It was requested that the cleanups and fixes be separated
> > into two different series and reposted.  Its been about 2 weeks, and after
> > pinging the author a few times and getting no response, I've decided to repost
> > the fixes for netprio myself, as they're important and I don't want them to be
> > forgotten or otherwise fall through the cracks.
> > 
> 
> Thanks for the reposting.
> 
> I was off office for a few days for some reason, and just came back to work.
> 
No worries, thank you for checking back.
Neil