Le 19/11/2018 à 20:54, David Ahern a écrit : > On 11/19/18 12:47 PM, Joe Stringer wrote: >> On Mon, 19 Nov 2018 at 10:39, David Ahern <dsah...@gmail.com> wrote: >>> >>> On 11/19/18 11:36 AM, Joe Stringer wrote: >>>> Hi David, thanks for pointing this out. >>>> >>>> This is more of an oversight through iterations, the runtime lookup >>>> will fail to find a socket if the netns value is greater than the >>>> range of a uint32 so I think it would actually make more sense to drop >>>> the parameter size to u32 rather than u64 so that this would be >>>> validated at load time rather than silently returning NULL because of >>>> a bad parameter. >>> >>> ok. I was wondering if it was a u64 to handle nsid of 0 which as I >>> understand it is a legal nsid. If you drop to u32, how do you know when >>> nsid has been set? >> >> I was operating under the assumption that 0 represents the root netns >> id, and cannot be assigned to another non-root netns. >> >> Looking at __peernet2id_alloc(), it seems to me like it attempts to >> find a netns and if it cannot find one, returns 0, which then leads to >> a scroll over the idr starting from 0 to INT_MAX to find a legitimate >> id for the netns, so I think this is a fair assumption? The NET_ID_ZERO trick is used to manage nsid 0 in net_eq_idr() (idr_for_each() stops when the callback returns != 0).
>> > > Maybe Nicolas can give a definitive answer; as I recall he added the > NSID option. I have not had time to walk the code. But I do recall > seeing an id of 0. e.g, on my dev box: > $ ip netns > vms (id: 0) > > And include/uapi/linux/net_namespace.h shows -1 as not assigned. Yes, 0 is a valid value and can be assigned to any netns. nsid are signed 32 bit values. Note that -1 (NETNSA_NSID_NOT_ASSIGNED) is used by the kernel to express that the nsid is not assigned. It can also be used by the user to let the kernel chooses a nsid. $ ip netns add foo $ ip netns add bar $ ip netns bar foo $ ip netns set foo 0 $ ip netns set bar auto $ ip netns bar (id: 1) foo (id: 0) Regards, Nicolas
