On Thu, Oct 10, 2024 at 5:18 PM Menglong Dong <menglong8.dong@xxxxxxxxx> wrote: > > On Thu, Oct 10, 2024 at 4:25 PM Paolo Abeni <pabeni@xxxxxxxxxx> wrote: > > > > > > > > On 10/7/24 09:46, Menglong Dong wrote: > > > In this commit, we make fib_validate_source/__fib_validate_source return > > > -reason instead of errno on error. As the return value of them can be > > > -errno, 0, and 1, we can't make it return enum skb_drop_reason directly. > > > > > > In the origin logic, if __fib_validate_source() return -EXDEV, > > > LINUX_MIB_IPRPFILTER will be counted. And now, we need to adjust it by > > > checking "reason == SKB_DROP_REASON_IP_RPFILTER". However, this will take > > > effect only after the patch "net: ip: make ip_route_input_noref() return > > > drop reasons", as we can't pass the drop reasons from > > > fib_validate_source() to ip_rcv_finish_core() in this patch. > > > > > > We set the errno to -EINVAL when fib_validate_source() is called and the > > > validation fails, as the errno can be checked in the caller and now its > > > value is -reason, which can lead misunderstand. > > > > > > Following new drop reasons are added in this patch: > > > > > > SKB_DROP_REASON_IP_LOCAL_SOURCE > > > SKB_DROP_REASON_IP_INVALID_SOURCE > > > > > > Signed-off-by: Menglong Dong <dongml2@xxxxxxxxxxxxxxx> > > > > Looking at the next patches, I'm under the impression that the overall > > code will be simpler if you let __fib_validate_source() return directly > > a drop reason, and fib_validate_source(), too. Hard to be sure without > > actually do the attempt... did you try such patch by any chance? > > > > I analysed the usages of fib_validate_source() before. The > return value of fib_validate_source() can be -errno, "0", and "1". > And the value "1" can be used by the caller, such as > __mkroute_input(). Making it return drop reasons can't cover this > case. > > It seems that __mkroute_input() is the only case that uses the > positive returning value of fib_validate_source(). Let me think > about it more in this case. Hello, After digging into the code of __fib_validate_source() and __mkroute_input(), I think it's hard to make __fib_validate_source() return drop reasons directly. The __fib_validate_source() will return 1 if the scope of the source(revert) route is HOST. And the __mkroute_input() will mark the skb with IPSKB_DOREDIRECT in this case (combine with some other conditions). And then, a REDIRECT ICMP will be sent in ip_forward() if this flag exists. I don't find a way to pass this information to __mkroute_input if we make __fib_validate_source() return drop reasons. Can we? An option is to add a wrapper for fib_validate_source(), such as fib_validate_source_reason(), which returns drop reasons. And in __mkroute_input(), we still call fib_validate_source(). What do you think? Thanks! Menglong Dong > > > Thanks! > > > > Paolo > >
