From: Andrii Nakryiko Date: Wed, 12 Aug 2020 02:29:23 +0000 (-0700) Subject: bpf: Fix XDP FD-based attach/detach logic around XDP_FLAGS_UPDATE_IF_NOEXIST X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=068d9d1eba72423e99162aad3586727180715c2a;p=linux.git bpf: Fix XDP FD-based attach/detach logic around XDP_FLAGS_UPDATE_IF_NOEXIST Enforce XDP_FLAGS_UPDATE_IF_NOEXIST only if new BPF program to be attached is non-NULL (i.e., we are not detaching a BPF program). Fixes: d4baa9368a5e ("bpf, xdp: Extract common XDP program attachment logic") Reported-by: Stanislav Fomichev Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Tested-by: Stanislav Fomichev Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/20200812022923.1217922-1-andriin@fb.com --- diff --git a/net/core/dev.c b/net/core/dev.c index 7df6c9617321a..b5d1129d83103 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -8913,10 +8913,6 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack NL_SET_ERR_MSG(extack, "Active program does not match expected"); return -EEXIST; } - if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && cur_prog) { - NL_SET_ERR_MSG(extack, "XDP program already attached"); - return -EBUSY; - } /* put effective new program into new_prog */ if (link) @@ -8927,6 +8923,10 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack enum bpf_xdp_mode other_mode = mode == XDP_MODE_SKB ? XDP_MODE_DRV : XDP_MODE_SKB; + if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && cur_prog) { + NL_SET_ERR_MSG(extack, "XDP program already attached"); + return -EBUSY; + } if (!offload && dev_xdp_prog(dev, other_mode)) { NL_SET_ERR_MSG(extack, "Native and generic XDP can't be active at the same time"); return -EEXIST;