Searched hist:dec827d174d7f76c457238800183ca864a639365 (Results 1 – 3 of 3) sorted by relevance
| /openbmc/linux/include/net/netns/ |
| H A D | generic.h | dec827d174d7f76c457238800183ca864a639365 Tue Apr 15 02:36:08 CDT 2008 Pavel Emelyanov <xemul@openvz.org> [NETNS]: The generic per-net pointers.
Add the elastic array of void * pointer to the struct net.
The access rules are simple:
1. register the ops with register_pernet_gen_device to get
the id of your private pointer
2. call net_assign_generic() to put the private data on the
struct net (most preferably this should be done in the
->init callback of the ops registered)
3. do not store any private reference on the net_generic array;
4. do not change this pointer while the net is alive;
5. use the net_generic() to get the pointer.
When adding a new pointer, I copy the old array, replace it
with a new one and schedule the old for kfree after an RCU
grace period.
Since the net_generic explores the net->gen array inside rcu
read section and once set the net->gen->ptr[x] pointer never
changes, this grants us a safe access to generic pointers.
Quoting Paul: "... RCU is protecting -only- the net_generic
structure that net_generic() is traversing, and the [pointer]
returned by net_generic() is protected by a reference counter
in the upper-level struct net."
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
|
| /openbmc/linux/net/core/ |
| H A D | net_namespace.c | diff 1a9a059203299ed42b984e91b87086bafeea36c6 Thu Dec 01 19:11:34 CST 2016 Alexey Dobriyan <adobriyan@gmail.com> netns: publish net_generic correctly
Publishing net_generic pointer is done with silly mistake: new array is
published BEFORE setting freshly acquired pernet subsystem pointer.
memcpy
rcu_assign_pointer
kfree_rcu
ng->ptr[id - 1] = data;
This bug was introduced with commit dec827d174d7f76c457238800183ca864a639365
("[NETNS]: The generic per-net pointers.") in the glorious days of
chopping networking stack into containers proper 8.5 years ago (whee...)
How it didn't trigger for so long?
Well, you need quite specific set of conditions:
*) race window opens once per pernet subsystem addition
(read: modprobe or boot)
*) not every pernet subsystem is eligible (need ->id and ->size)
*) not every pernet subsystem is vulnerable (need incorrect or absense
of ordering of register_pernet_sybsys() and actually using net_generic())
*) to hide the bug even more, default is to preallocate 13 pointers which
is actually quite a lot. You need IPv6, netfilter, bridging etc together
loaded to trigger reallocation in the first place. Trimmed down
config are OK.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff dec827d174d7f76c457238800183ca864a639365 Tue Apr 15 02:36:08 CDT 2008 Pavel Emelyanov <xemul@openvz.org> [NETNS]: The generic per-net pointers.
Add the elastic array of void * pointer to the struct net.
The access rules are simple:
1. register the ops with register_pernet_gen_device to get
the id of your private pointer
2. call net_assign_generic() to put the private data on the
struct net (most preferably this should be done in the
->init callback of the ops registered)
3. do not store any private reference on the net_generic array;
4. do not change this pointer while the net is alive;
5. use the net_generic() to get the pointer.
When adding a new pointer, I copy the old array, replace it
with a new one and schedule the old for kfree after an RCU
grace period.
Since the net_generic explores the net->gen array inside rcu
read section and once set the net->gen->ptr[x] pointer never
changes, this grants us a safe access to generic pointers.
Quoting Paul: "... RCU is protecting -only- the net_generic
structure that net_generic() is traversing, and the [pointer]
returned by net_generic() is protected by a reference counter
in the upper-level struct net."
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
|
| /openbmc/linux/include/net/ |
| H A D | net_namespace.h | diff dec827d174d7f76c457238800183ca864a639365 Tue Apr 15 02:36:08 CDT 2008 Pavel Emelyanov <xemul@openvz.org> [NETNS]: The generic per-net pointers.
Add the elastic array of void * pointer to the struct net.
The access rules are simple:
1. register the ops with register_pernet_gen_device to get
the id of your private pointer
2. call net_assign_generic() to put the private data on the
struct net (most preferably this should be done in the
->init callback of the ops registered)
3. do not store any private reference on the net_generic array;
4. do not change this pointer while the net is alive;
5. use the net_generic() to get the pointer.
When adding a new pointer, I copy the old array, replace it
with a new one and schedule the old for kfree after an RCU
grace period.
Since the net_generic explores the net->gen array inside rcu
read section and once set the net->gen->ptr[x] pointer never
changes, this grants us a safe access to generic pointers.
Quoting Paul: "... RCU is protecting -only- the net_generic
structure that net_generic() is traversing, and the [pointer]
returned by net_generic() is protected by a reference counter
in the upper-level struct net."
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
|