kernel/linux.git/tools/lib/bpf/netlink.c, branch v6.3.3

libbpf: Fix bpf_xdp_query() in old kernels

2023-05-11T14:17:11+00:00

[ Upstream commit c8ee37bde4021a275d2e4f33bd48d54912bb00c4 ] Commit 04d58f1b26a4("libbpf: add API to get XDP/XSK supported features") added feature_flags to struct bpf_xdp_query_opts. If a user uses bpf_xdp_query_opts with feature_flags member, the bpf_xdp_query() will check whether 'netdev' family exists or not in the kernel. If it does not exist, the bpf_xdp_query() will return -ENOENT. But 'netdev' family does not exist in old kernels as it is introduced in the same patch set as Commit 04d58f1b26a4. So old kernel with newer libbpf won't work properly with bpf_xdp_query() api call. To fix this issue, if the return value of libbpf_netlink_resolve_genl_family_id() is -ENOENT, bpf_xdp_query() will just return 0, skipping the rest of xdp feature query. This preserves backward compatibility. Fixes: 04d58f1b26a4 ("libbpf: add API to get XDP/XSK supported features") Signed-off-by: Yonghong Song Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20230227224943.1153459-1-yhs@fb.com Signed-off-by: Sasha Levin

libbpf: Use bpf_{btf,link,map,prog}_get_info_by_fd()

2023-02-16T23:32:45+00:00

Use the new type-safe wrappers around bpf_obj_get_info_by_fd(). Signed-off-by: Ilya Leoshkevich Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20230214231221.249277-3-iii@linux.ibm.com

libbpf: Always use libbpf_err to return an error in bpf_xdp_query()

2023-02-07T21:56:11+00:00

In order to properly set errno, rely on libbpf_err utility routine in bpf_xdp_query() to return an error to the caller. Fixes: 04d58f1b26a4 ("libbpf: add API to get XDP/XSK supported features") Signed-off-by: Lorenzo Bianconi Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/827d40181f9f90fb37702f44328e1614df7c0503.1675768112.git.lorenzo@kernel.org

libbpf: add API to get XDP/XSK supported features

2023-02-03T04:48:24+00:00

Extend bpf_xdp_query routine in order to get XDP/XSK supported features of netdev over route netlink interface. Extend libbpf netlink implementation in order to support netlink_generic protocol. Co-developed-by: Kumar Kartikeya Dwivedi Signed-off-by: Kumar Kartikeya Dwivedi Co-developed-by: Marek Majtyka Signed-off-by: Marek Majtyka Signed-off-by: Lorenzo Bianconi Link: https://lore.kernel.org/r/a72609ef4f0de7fee5376c40dbf54ad7f13bfb8d.1675245258.git.lorenzo@kernel.org Signed-off-by: Alexei Starovoitov

libbpf: add the capability to specify netlink proto in libbpf_netlink_send_recv

2023-02-03T04:48:23+00:00

This is a preliminary patch in order to introduce netlink_generic protocol support to libbpf. Signed-off-by: Lorenzo Bianconi Link: https://lore.kernel.org/r/7878a54667e74afeec3ee519999c044bd514b44c.1675245258.git.lorenzo@kernel.org Signed-off-by: Alexei Starovoitov

libbpf: Streamline bpf_attr and perf_event_attr initialization

2022-08-17T20:42:10+00:00

Make sure that entire libbpf code base is initializing bpf_attr and perf_event_attr with memset(0). Also for bpf_attr make sure we clear and pass to kernel only relevant parts of bpf_attr. bpf_attr is a huge union of independent sub-command attributes, so there is no need to clear and pass entire union bpf_attr, which over time grows quite a lot and for most commands this growth is completely irrelevant. Few cases where we were relying on compiler initialization of BPF UAPI structs (like bpf_prog_info, bpf_map_info, etc) with `= {};` were switched to memset(0) pattern for future-proofing. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Hao Luo Link: https://lore.kernel.org/bpf/20220816001929.369487-3-andrii@kernel.org

libbpf: remove deprecated XDP APIs

2022-06-28T20:13:32+00:00

Get rid of deprecated bpf_set_link*() and bpf_get_link*() APIs. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20220627211527.2245459-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov

libbpf: Fix memleak in libbpf_netlink_recv()

2022-02-17T15:09:07+00:00

Ensure that libbpf_netlink_recv() frees dynamically allocated buffer in all code paths. Fixes: 9c3de619e13e ("libbpf: Use dynamically allocated buffer when receiving netlink messages") Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/20220217073958.276959-1-andrii@kernel.org

libbpf: Use dynamically allocated buffer when receiving netlink messages

2022-02-12T15:57:44+00:00

When receiving netlink messages, libbpf was using a statically allocated stack buffer of 4k bytes. This happened to work fine on systems with a 4k page size, but on systems with larger page sizes it can lead to truncated messages. The user-visible impact of this was that libbpf would insist no XDP program was attached to some interfaces because that bit of the netlink message got chopped off. Fix this by switching to a dynamically allocated buffer; we borrow the approach from iproute2 of using recvmsg() with MSG_PEEK|MSG_TRUNC to get the actual size of the pending message before receiving it, adjusting the buffer as necessary. While we're at it, also add retries on interrupted system calls around the recvmsg() call. v2: - Move peek logic to libbpf_netlink_recv(), don't double free on ENOMEM. Fixes: 8bbb77b7c7a2 ("libbpf: Add various netlink helpers") Reported-by: Zhiqian Guan Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: Andrii Nakryiko Acked-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/bpf/20220211234819.612288-1-toke@redhat.com

libbpf: streamline low-level XDP APIs

2022-01-21T05:22:02+00:00

Introduce 4 new netlink-based XDP APIs for attaching, detaching, and querying XDP programs: - bpf_xdp_attach; - bpf_xdp_detach; - bpf_xdp_query; - bpf_xdp_query_id. These APIs replace bpf_set_link_xdp_fd, bpf_set_link_xdp_fd_opts, bpf_get_link_xdp_id, and bpf_get_link_xdp_info APIs ([0]). The latter don't follow a consistent naming pattern and some of them use non-extensible approaches (e.g., struct xdp_link_info which can't be modified without breaking libbpf ABI). The approach I took with these low-level XDP APIs is similar to what we did with low-level TC APIs. There is a nice duality of bpf_tc_attach vs bpf_xdp_attach, and so on. I left bpf_xdp_attach() to support detaching when -1 is specified for prog_fd for generality and convenience, but bpf_xdp_detach() is preferred due to clearer naming and associated semantics. Both bpf_xdp_attach() and bpf_xdp_detach() accept the same opts struct allowing to specify expected old_prog_fd. While doing the refactoring, I noticed that old APIs require users to specify opts with old_fd == -1 to declare "don't care about already attached XDP prog fd" condition. Otherwise, FD 0 is assumed, which is essentially never an intended behavior. So I made this behavior consistent with other kernel and libbpf APIs, in which zero FD means "no FD". This seems to be more in line with the latest thinking in BPF land and should cause less user confusion, hopefully. For querying, I left two APIs, both more generic bpf_xdp_query() allowing to query multiple IDs and attach mode, but also a specialization of it, bpf_xdp_query_id(), which returns only requested prog_id. Uses of prog_id returning bpf_get_link_xdp_id() were so prevalent across selftests and samples, that it seemed a very common use case and using bpf_xdp_query() for doing it felt very cumbersome with a highly branches if/else chain based on flags and attach mode. Old APIs are scheduled for deprecation in libbpf 0.8 release. [0] Closes: https://github.com/libbpf/libbpf/issues/309 Signed-off-by: Andrii Nakryiko Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/20220120061422.2710637-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov