netdev - [PATCH bpf-next 07/17] bpf: Document BPF_PROG

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Date:   Tue, 16 Feb 2021 17:08:11 -0800
From:   Joe Stringer <joe@...d.net.nz>
To:     bpf@...r.kernel.org
Cc:     Joe Stringer <joe@...ium.io>, netdev@...r.kernel.org,
        daniel@...earbox.net, ast@...nel.org, mtk.manpages@...il.com,
        Quentin Monnet <quentin@...valent.com>
Subject: [PATCH bpf-next 07/17] bpf: Document BPF_PROG_QUERY syscall command

From: Joe Stringer <joe@...ium.io>

Commit 468e2f64d220 ("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.

Reviewed-by: Quentin Monnet <quentin@...valent.com>
Signed-off-by: Joe Stringer <joe@...ium.io>
---
CC: Alexei Starovoitov <ast@...nel.org>
---
 include/uapi/linux/bpf.h | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 86fe0445c395..a07cecfd2148 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -386,6 +386,43 @@ 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.
-- 
2.27.0