On Wed, May 10, 2017 at 04:54:37PM +0200, Florian Westphal wrote: > Phil Sutter <phil@xxxxxx> wrote: > > Hi, > > > > On Wed, May 10, 2017 at 01:57:48PM +0200, Florian Westphal wrote: > > > Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote: > > > > On Wed, May 10, 2017 at 01:27:24PM +0200, Florian Westphal wrote: > > > > > While most programs set it to their process id there is no guarantee. > > > > > Its just a (unique) 32 bit identifier. > > > > > > > > It's actually the kernel that decides what portID the socket gets > > > > IIRC. For the first socket it uses the process ID, then for follow up > > > > sockets, it just looks for a spare ID in the negative range of the 32 > > > > bit, if my memory serves well. > > > > > > Argh, yes, of course... > > > > > > > > Afaics one has to use /proc/net/netlink to map the portid to the inode > > > > > and then walk /proc/*/fd/* to find the socket with that inode. > > > > > > > > > > Perhaps there is a simpler way, maybe you can check what ss is doing > > > > > and what info can be obtained via netlink diag. > > > > > > > > I wouldn't be surprise if we need more kernel infrastructure to deal > > > > with this. Parsing /proc for a netlink thing is definitely not ideal. > > > > > > Yes. From nft monitor point of view the most easy solution would be > > > if the process id (or even the name?) would be sent back to userspace in a netlink > > > attribute. Do you think we can extend nf_tables to include > > > get_task_comm() name and/or pid when/if we send update notifications? > > > > > > (The pid is actually not that useful as process might have exited > > > already). > > > > The question is where to put it. Looking at the netlink message > > structure, I see two options: > > > > A) Extend struct nfgenmsg to contain PID and process name (a buffer of > > length TASK_COMM_LEN). > > B) Add type-specific attributes for each type, like NFTA_RULE_PID and > > NFTA_RULE_PNAME. > > > > The problem with A) is that it will break older user space expecting > > sizeof(struct nfgenmsg) to be shorter. > > Right, A) is a non-starter. > > > Additional attributes should not > > be a problem here, but having to add them for each object type seems to > > be a really ugly solution. > > I don't find it ugly, but alternatively we could add a new type of info > sent at the beginning of the commit phase (before all the table/rule etc > updates) and include it there. You mean as a separate netlink message? Then we would have to map that message to the actual notification, no? Or do you think it's sufficient to cache the last PID/name received and use it for the monitor messages until an update to them comes in? Thanks, Phil -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
