6.6-stable review patch. If anyone has any objections, please let me know.
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From: Toke Høiland-Jørgensen toke@redhat.com
[ Upstream commit 3595599fa8360bb3c7afa7ee50c810b4a64106ea ]
Device-bound programs are used to support RX metadata kfuncs. These kfuncs are driver-specific and rely on the driver context to read the metadata. This means they can't work in generic XDP mode. However, there is no check to disallow such programs from being attached in generic mode, in which case the metadata kfuncs will be called in an invalid context, leading to crashes.
Fix this by adding a check to disallow attaching device-bound programs in generic mode.
Fixes: 2b3486bc2d23 ("bpf: Introduce device-bound XDP programs") Reported-by: Marcus Wichelmann marcus.wichelmann@hetzner-cloud.de Closes: https://lore.kernel.org/r/dae862ec-43b5-41a0-8edf-46c59071cdda@hetzner-cloud... Tested-by: Marcus Wichelmann marcus.wichelmann@hetzner-cloud.de Acked-by: Stanislav Fomichev sdf@fomichev.me Signed-off-by: Toke Høiland-Jørgensen toke@redhat.com Acked-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Martin KaFai Lau martin.lau@kernel.org Link: https://patch.msgid.link/20250127131344.238147-1-toke@redhat.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/dev.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/net/core/dev.c b/net/core/dev.c index 69da7b009f8b9..479a3892f98c3 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -9346,6 +9346,10 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack NL_SET_ERR_MSG(extack, "Program bound to different device"); return -EINVAL; } + if (bpf_prog_is_dev_bound(new_prog->aux) && mode == XDP_MODE_SKB) { + NL_SET_ERR_MSG(extack, "Can't attach device-bound programs in generic mode"); + return -EINVAL; + } if (new_prog->expected_attach_type == BPF_XDP_DEVMAP) { NL_SET_ERR_MSG(extack, "BPF_XDP_DEVMAP programs can not be attached to a device"); return -EINVAL;