Commit 5d999994 authored by Joe Stringer's avatar Joe Stringer Committed by Alexei Starovoitov
Browse files

bpf: Document BPF_PROG_QUERY syscall command 



Commit 468e2f64 ("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: default avatarJoe Stringer <joe@cilium.io>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Reviewed-by: default avatarQuentin Monnet <quentin@isovalent.com>
Acked-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210302171947.2268128-8-joe@cilium.io
parent 2a3fdca4

include/uapi/linux/bpf.h

+37 −0
Original line number Diff line number Diff line
@@ -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.