On Mon, 18 Dec 2017 23:37:09 +0200 Serhey Popovich <serhe.popov...@gmail.com> wrote:
> Stephen Hemminger wrote:
> > On Mon, 18 Dec 2017 23:02:07 +0200
> > Serhey Popovich <serhe.popov...@gmail.com> wrote:
> >
> >> Stephen Hemminger wrote:
> >>> On Mon, 18 Dec 2017 20:54:06 +0200
> >>> Serhey Popovych <serhe.popov...@gmail.com> wrote:
> >>>
> >>>> diff --git a/ip/iplink.c b/ip/iplink.c
> >>>> index 1e685cc..4f9c169 100644
> >>>> --- a/ip/iplink.c
> >>>> +++ b/ip/iplink.c
> >>>> @@ -586,8 +586,10 @@ int iplink_parse(int argc, char **argv, struct
> >>>> iplink_req *req,
> >>>> *name = *argv;
> >>>> } else if (strcmp(*argv, "index") == 0) {
> >>>> NEXT_ARG();
> >>>> + if (*index)
> >>>> + duparg("index", *argv);
> >>>> *index = atoi(*argv);
> >>>> - if (*index < 0)
> >>>> + if (*index <= 0)
> >>>
> >>> Why not use strtoul instead of atoi?
> >> Do not see reason for strtoul() instead atoi():
> >>
> >> 1) main arg: indexes in kernel represented as "int", which is
> >> signed. <= 0 values are reserved for various special purposes
> >> (see net/core/fib_rules.c on how device matching implemented).
> >>
> >> Configuring network device manually with index <= 0 is not correct
> >> (however possible). Kernel itself never chooses ifindex <= 0.
> >>
> >> Having unsigned int > 0x7fffffff actually means index <= 0.
> >>
> >> 2) this is not single place in iproute2 where it is used: not
> >> going to remove last user.
> >>
> >> 3) make changes clear and transparent for review.
> >
> > I would rather all of iproute2 correctly handles unsigned values.
> > Too much code is old K&R style C "the world is an int" and "who needs
> > to check for negative".
>
> You are right :(. I'm just trying to improve things a bit.
>
> >
> > There already is get_unsigned() in iproute2 util functions.
> This is good one based on strtoul(). But do we want to submit say
> index = (unsigned int)2147483648(0x7fffffff) to the kernel that is
> illegal from it's perspective?
>
> Or do you mean I can prepare treewide change to replace atoi() with
> get_unsigned()/get_integer() where appropriate?
>
> We already check if (*index < 0) since commit 3c682146aeff
> (iplink: forbid negative ifindex and modifying ifindex), and I just
> put index == 0 in the same range of invalid indexes.
>
The legacy BSD ABI for interfaces uses int, so that sets the upper
bound for kernel.
The netlink ABI limit is u32 for ifindex so technically 1..UINT32_MAX are
possible values but kernel is bound by BSD mistake.
I will take the original patch.
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