bpf: Document BPF_PROG_QUERY syscall command

Commit 468e2f64d2 ("bpf: introduce BPF_PROG_QUERY command") originally
introduced this, but there have been several additions since then.
Unlike BPF_PROG_ATTACH, it appears that the sockmap progs are not able
to be queried so far.

Signed-off-by: Joe Stringer <joe@cilium.io>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210302171947.2268128-8-joe@cilium.io
This commit is contained in:
Joe Stringer 2021-03-02 09:19:39 -08:00 committed by Alexei Starovoitov
parent 2a3fdca4e3
commit 5d999994e0

View File

@ -389,6 +389,43 @@ union bpf_iter_link_info {
* Obtain information about eBPF programs associated with the
* specified *attach_type* hook.
*
* The *target_fd* must be a valid file descriptor for a kernel
* object which depends on the attach type of *attach_bpf_fd*:
*
* **BPF_PROG_TYPE_CGROUP_DEVICE**,
* **BPF_PROG_TYPE_CGROUP_SKB**,
* **BPF_PROG_TYPE_CGROUP_SOCK**,
* **BPF_PROG_TYPE_CGROUP_SOCK_ADDR**,
* **BPF_PROG_TYPE_CGROUP_SOCKOPT**,
* **BPF_PROG_TYPE_CGROUP_SYSCTL**,
* **BPF_PROG_TYPE_SOCK_OPS**
*
* Control Group v2 hierarchy with the eBPF controller
* enabled. Requires the kernel to be compiled with
* **CONFIG_CGROUP_BPF**.
*
* **BPF_PROG_TYPE_FLOW_DISSECTOR**
*
* Network namespace (eg /proc/self/ns/net).
*
* **BPF_PROG_TYPE_LIRC_MODE2**
*
* LIRC device path (eg /dev/lircN). Requires the kernel
* to be compiled with **CONFIG_BPF_LIRC_MODE2**.
*
* **BPF_PROG_QUERY** always fetches the number of programs
* attached and the *attach_flags* which were used to attach those
* programs. Additionally, if *prog_ids* is nonzero and the number
* of attached programs is less than *prog_cnt*, populates
* *prog_ids* with the eBPF program ids of the programs attached
* at *target_fd*.
*
* The following flags may alter the result:
*
* **BPF_F_QUERY_EFFECTIVE**
* Only return information regarding programs which are
* currently effective at the specified *target_fd*.
*
* Return
* Returns zero on success. On error, -1 is returned and *errno*
* is set appropriately.