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[bpf-next,07/17] bpf: Document BPF_PROG_QUERY syscall command

Message ID 20210217010821.1810741-8-joe@wand.net.nz (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series Improve BPF syscall command documentation | expand

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netdev/build_32bit success Errors and warnings before: 12137 this patch: 12137
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netdev/stable success Stable not CCed

Commit Message

Joe Stringer Feb. 17, 2021, 1:08 a.m. UTC 
From: Joe Stringer <joe@cilium.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@isovalent.com>
Signed-off-by: Joe Stringer <joe@cilium.io>
---
CC: Alexei Starovoitov <ast@kernel.org>
---
 include/uapi/linux/bpf.h | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
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Patch

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.