| Message ID | 0e9e30490b44b447bb2bebc69c7135e7fe7e4e40.1586236080.git.rdna@fb.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | libbpf: Fix bpf_get_link_xdp_id flags handling | expand |
Andrey Ignatov <rdna@fb.com> writes: > Currently if one of XDP_FLAGS_{DRV,HW,SKB}_MODE flags is passed to > bpf_get_link_xdp_id() and there is a single XDP program attached to > ifindex, that program's id will be returned by bpf_get_link_xdp_id() in > prog_id argument no matter what mode the program is attached in, i.e. > flags argument is not taken into account. > > For example, if there is a single program attached with > XDP_FLAGS_SKB_MODE but user calls bpf_get_link_xdp_id() with flags = > XDP_FLAGS_DRV_MODE, that skb program will be returned. > > Fix it by returning info->prog_id only if user didn't specify flags. If > flags is specified then return corresponding mode-specific-field from > struct xdp_link_info. > > The initial error was introduced in commit 50db9f073188 ("libbpf: Add a > support for getting xdp prog id on ifindex") and then refactored in > 473f4e133a12 so 473f4e133a12 is used in the Fixes tag. > > Fixes: 473f4e133a12 ("libbpf: Add bpf_get_link_xdp_info() function to get more XDP information") > Signed-off-by: Andrey Ignatov <rdna@fb.com> Makes sense Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
diff --git a/tools/lib/bpf/netlink.c b/tools/lib/bpf/netlink.c index 18b5319025e1..f5732d35930d 100644 --- a/tools/lib/bpf/netlink.c +++ b/tools/lib/bpf/netlink.c @@ -321,7 +321,7 @@ int bpf_get_link_xdp_info(int ifindex, struct xdp_link_info *info, static __u32 get_xdp_id(struct xdp_link_info *info, __u32 flags) { - if (info->attach_mode != XDP_ATTACHED_MULTI) + if (info->attach_mode != XDP_ATTACHED_MULTI && !flags) return info->prog_id; if (flags & XDP_FLAGS_DRV_MODE) return info->drv_prog_id;
Currently if one of XDP_FLAGS_{DRV,HW,SKB}_MODE flags is passed to bpf_get_link_xdp_id() and there is a single XDP program attached to ifindex, that program's id will be returned by bpf_get_link_xdp_id() in prog_id argument no matter what mode the program is attached in, i.e. flags argument is not taken into account. For example, if there is a single program attached with XDP_FLAGS_SKB_MODE but user calls bpf_get_link_xdp_id() with flags = XDP_FLAGS_DRV_MODE, that skb program will be returned. Fix it by returning info->prog_id only if user didn't specify flags. If flags is specified then return corresponding mode-specific-field from struct xdp_link_info. The initial error was introduced in commit 50db9f073188 ("libbpf: Add a support for getting xdp prog id on ifindex") and then refactored in 473f4e133a12 so 473f4e133a12 is used in the Fixes tag. Fixes: 473f4e133a12 ("libbpf: Add bpf_get_link_xdp_info() function to get more XDP information") Signed-off-by: Andrey Ignatov <rdna@fb.com> --- tools/lib/bpf/netlink.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)