mirror of https://github.com/mkerrisk/man-pages
bpf-helpers.7: Resync with current kernel source
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk
parent
e00e18a247
commit
7b203a3d6d
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@ -31,34 +31,63 @@ level margin: \\n[rst2man-indent\\n[rst2man-indent-level]]
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.in \\n[rst2man-indent\\n[rst2man-indent-level]]u
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..
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.\" Copyright (C) All BPF authors and contributors from 2014 to present.
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.
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.\" See git log include/uapi/linux/bpf.h in kernel tree for details.
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.\"
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.
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.\"
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.
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.\" %%%LICENSE_START(VERBATIM)
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.
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.\" Permission is granted to make and distribute verbatim copies of this
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.
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.\" manual provided the copyright notice and this permission notice are
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.
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.\" preserved on all copies.
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.\"
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.
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.\"
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.
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.\" Permission is granted to copy and distribute modified versions of this
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.
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.\" manual under the conditions for verbatim copying, provided that the
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.
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.\" entire resulting derived work is distributed under the terms of a
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.
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.\" permission notice identical to this one.
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.\"
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.
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.\"
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.
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.\" Since the Linux kernel and libraries are constantly changing, this
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.
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.
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.\" responsibility for errors or omissions, or for damages resulting from
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.
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.\" the use of the information contained herein. The author(s) may not
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.
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.\" have taken the same level of care in the production of this manual,
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.
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.\" which is licensed free of charge, as they might when working
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.
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.\" professionally.
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.\"
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.
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.\"
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.
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.
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.\" the source, must acknowledge the copyright and authors of this work.
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.
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.\" %%%LICENSE_END
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.\"
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.
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.\"
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.
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.\" Please do not edit this file. It was generated from the documentation
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.
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.\" located in file include/uapi/linux/bpf.h of the Linux kernel sources
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.
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.\" (helpers description), and from scripts/bpf_helpers_doc.py in the same
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.
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.\" repository (header and footer).
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.
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.SH DESCRIPTION
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.sp
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The extended Berkeley Packet Filter (eBPF) subsystem consists in programs
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@ -142,8 +171,8 @@ Delete entry with \fIkey\fP from \fImap\fP\&.
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For tracing programs, safely attempt to read \fIsize\fP bytes from
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kernel space address \fIunsafe_ptr\fP and store the data in \fIdst\fP\&.
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.sp
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Generally, use \fBbpf_probe_read_user\fP() or
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\fBbpf_probe_read_kernel\fP() instead.
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Generally, use bpf_probe_read_user() or bpf_probe_read_kernel()
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instead.
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.TP
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.B Return
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0 on success, or a negative error in case of failure.
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@ -154,8 +183,6 @@ Generally, use \fBbpf_probe_read_user\fP() or
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.TP
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.B Description
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Return the time elapsed since system boot, in nanoseconds.
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Does not include time the system was suspended.
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See: \fBclock_gettime\fP(\fBCLOCK_MONOTONIC\fP)
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.TP
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.B Return
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Current \fIktime\fP\&.
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@ -1230,11 +1257,11 @@ direct packet access.
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.TP
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.B Description
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Copy a NUL terminated string from an unsafe kernel address
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\fIunsafe_ptr\fP to \fIdst\fP\&. See \fBbpf_probe_read_kernel_str\fP() for
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\fIunsafe_ptr\fP to \fIdst\fP\&. See bpf_probe_read_kernel_str() for
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more details.
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.sp
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Generally, use \fBbpf_probe_read_user_str\fP() or
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\fBbpf_probe_read_kernel_str\fP() instead.
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Generally, use bpf_probe_read_user_str() or bpf_probe_read_kernel_str()
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instead.
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.TP
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.B Return
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On success, the strictly positive length of the string,
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@ -1274,7 +1301,7 @@ A 8\-byte long non\-decreasing number.
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.INDENT 7.0
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.TP
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.B Description
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Equivalent to \fBbpf_get_socket_cookie\fP() helper that accepts
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Equivalent to bpf_get_socket_cookie() helper that accepts
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\fIskb\fP, but gets socket from \fBstruct bpf_sock_ops\fP context.
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.TP
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.B Return
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@ -1303,7 +1330,7 @@ to value \fIhash\fP\&.
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0
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.UNINDENT
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.TP
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.B \fBint bpf_setsockopt(void *\fP\fIbpf_socket\fP\fB, int\fP \fIlevel\fP\fB, int\fP \fIoptname\fP\fB, void *\fP\fIoptval\fP\fB, int\fP \fIoptlen\fP\fB)\fP
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.B \fBint bpf_setsockopt(struct bpf_sock_ops *\fP\fIbpf_socket\fP\fB, int\fP \fIlevel\fP\fB, int\fP \fIoptname\fP\fB, void *\fP\fIoptval\fP\fB, int\fP \fIoptlen\fP\fB)\fP
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.INDENT 7.0
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.TP
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.B Description
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@ -1313,15 +1340,6 @@ which the option resides and the name \fIoptname\fP of the option
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must be specified, see \fBsetsockopt(2)\fP for more information.
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The option value of length \fIoptlen\fP is pointed by \fIoptval\fP\&.
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.sp
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\fIbpf_socket\fP should be one of the following:
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.INDENT 7.0
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.IP \(bu 2
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\fBstruct bpf_sock_ops\fP for \fBBPF_PROG_TYPE_SOCK_OPS\fP\&.
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.IP \(bu 2
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\fBstruct bpf_sock_addr\fP for \fBBPF_CGROUP_INET4_CONNECT\fP
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and \fBBPF_CGROUP_INET6_CONNECT\fP\&.
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.UNINDENT
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.sp
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This helper actually implements a subset of \fBsetsockopt()\fP\&.
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It supports the following \fIlevel\fPs:
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.INDENT 7.0
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@ -1350,15 +1368,6 @@ It supports the following \fIlevel\fPs:
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Grow or shrink the room for data in the packet associated to
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\fIskb\fP by \fIlen_diff\fP, and according to the selected \fImode\fP\&.
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.sp
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By default, the helper will reset any offloaded checksum
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indicator of the skb to CHECKSUM_NONE. This can be avoided
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by the following flag:
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.INDENT 7.0
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.IP \(bu 2
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\fBBPF_F_ADJ_ROOM_NO_CSUM_RESET\fP: Do not reset offloaded
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checksum data of the skb to CHECKSUM_NONE.
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.UNINDENT
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.sp
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There are two supported modes at this time:
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.INDENT 7.0
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.IP \(bu 2
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@ -1412,16 +1421,22 @@ support) as of this writing).
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.sp
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The lower two bits of \fIflags\fP are used as the return code if
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the map lookup fails. This is so that the return value can be
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one of the XDP program return codes up to \fBXDP_TX\fP, as chosen
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by the caller. Any higher bits in the \fIflags\fP argument must be
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one of the XDP program return codes up to XDP_TX, as chosen by
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the caller. Any higher bits in the \fIflags\fP argument must be
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unset.
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.sp
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See also \fBbpf_redirect\fP(), which only supports redirecting
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to an ifindex, but doesn\(aqt require a map to do so.
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See also bpf_redirect(), which only supports redirecting to an
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ifindex, but doesn\(aqt require a map to do so.
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.TP
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.B Return
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\fBXDP_REDIRECT\fP on success, or the value of the two lower bits
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of the \fIflags\fP argument on error.
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of the
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.nf
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**
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.fi
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flags* argument on error.
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.IP "System Message: WARNING/2 (/tmp/bpf-helpers.rst:, line 1105)"
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Inline strong start\-string without end\-string.
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.UNINDENT
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.TP
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.B \fBint bpf_sk_redirect_map(struct sk_buff *\fP\fIskb\fP\fB, struct bpf_map *\fP\fImap\fP\fB, u32\fP \fIkey\fP\fB, u64\fP \fIflags\fP\fB)\fP
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@ -1550,7 +1565,7 @@ Where t_enabled is the time enabled for event and t_running is
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the time running for event since last normalization. The
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enabled and running times are accumulated since the perf event
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open. To achieve scaling factor between two invocations of an
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eBPF program, users can use CPU id as the key (which is
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eBPF program, users can can use CPU id as the key (which is
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typical for perf array usage model) to remember the previous
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value and do the calculation inside the eBPF program.
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.TP
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@ -1573,7 +1588,7 @@ more details).
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0 on success, or a negative error in case of failure.
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.UNINDENT
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.TP
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.B \fBint bpf_getsockopt(void *\fP\fIbpf_socket\fP\fB, int\fP \fIlevel\fP\fB, int\fP \fIoptname\fP\fB, void *\fP\fIoptval\fP\fB, int\fP \fIoptlen\fP\fB)\fP
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.B \fBint bpf_getsockopt(struct bpf_sock_ops *\fP\fIbpf_socket\fP\fB, int\fP \fIlevel\fP\fB, int\fP \fIoptname\fP\fB, void *\fP\fIoptval\fP\fB, int\fP \fIoptlen\fP\fB)\fP
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.INDENT 7.0
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.TP
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.B Description
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@ -1584,15 +1599,6 @@ must be specified, see \fBgetsockopt(2)\fP for more information.
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The retrieved value is stored in the structure pointed by
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\fIopval\fP and of length \fIoptlen\fP\&.
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.sp
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\fIbpf_socket\fP should be one of the following:
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.INDENT 7.0
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.IP \(bu 2
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\fBstruct bpf_sock_ops\fP for \fBBPF_PROG_TYPE_SOCK_OPS\fP\&.
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.IP \(bu 2
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\fBstruct bpf_sock_addr\fP for \fBBPF_CGROUP_INET4_CONNECT\fP
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and \fBBPF_CGROUP_INET6_CONNECT\fP\&.
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.UNINDENT
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.sp
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This helper actually implements a subset of \fBgetsockopt()\fP\&.
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It supports the following \fIlevel\fPs:
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.INDENT 7.0
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@ -1618,7 +1624,7 @@ the return value of the probed function, and to set it to \fIrc\fP\&.
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The first argument is the context \fIregs\fP on which the kprobe
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works.
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.sp
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This helper works by setting the PC (program counter)
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This helper works by setting setting the PC (program counter)
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to an override function which is run in place of the original
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probed function. This means the probed function is not run at
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all. The replacement function just returns with the required
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@ -1674,7 +1680,7 @@ callback:
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.INDENT 7.0
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.TP
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.B \fBbpf_sock_ops_cb_flags_set(bpf_sock,\fP
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\fBbpf_sock\->bpf_sock_ops_cb_flags & \(tiBPF_SOCK_OPS_RTO_CB_FLAG)\fP
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\fBbpf_sock\->bpf_sock_ops_cb_flags & ~BPF_SOCK_OPS_RTO_CB_FLAG)\fP
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.UNINDENT
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.sp
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Here are some examples of where one could call such eBPF
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@ -1826,11 +1832,10 @@ single IP address on a host that has multiple IP configured.
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.sp
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This helper works for IPv4 and IPv6, TCP and UDP sockets. The
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domain (\fIaddr\fP\fB\->sa_family\fP) must be \fBAF_INET\fP (or
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\fBAF_INET6\fP). It\(aqs advised to pass zero port (\fBsin_port\fP
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or \fBsin6_port\fP) which triggers IP_BIND_ADDRESS_NO_PORT\-like
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behavior and lets the kernel efficiently pick up an unused
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port as long as 4\-tuple is unique. Passing non\-zero port might
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lead to degraded performance.
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\fBAF_INET6\fP). Looking for a free port to bind to can be
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expensive, therefore binding to port is not permitted by the
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helper: \fIaddr\fP\fB\->sin_port\fP (or \fBsin6_port\fP, respectively)
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must be set to zero.
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.TP
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.B Return
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0 on success, or a negative error in case of failure.
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@ -1841,8 +1846,8 @@ lead to degraded performance.
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.TP
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.B Description
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Adjust (move) \fIxdp_md\fP\fB\->data_end\fP by \fIdelta\fP bytes. It is
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possible to both shrink and grow the packet tail.
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Shrink done via \fIdelta\fP being a negative integer.
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only possible to shrink the packet as of this writing,
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therefore \fIdelta\fP must be a negative integer.
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.sp
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A call to this helper is susceptible to change the underlying
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packet buffer. Therefore, at load time, all checks on pointers
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@ -2997,7 +3002,7 @@ void bpf_sys_open(struct pt_regs *ctx)
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.UNINDENT
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.UNINDENT
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.sp
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In comparison, using \fBbpf_probe_read_user\fP() helper here
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In comparison, using \fBbpf_probe_read_user()\fP helper here
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instead to read the string would require to estimate the length
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at compile time, and would often result in copying more memory
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than necessary.
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@ -3018,7 +3023,7 @@ value.
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.TP
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.B Description
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Copy a NUL terminated string from an unsafe kernel address \fIunsafe_ptr\fP
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to \fIdst\fP\&. Same semantics as with \fBbpf_probe_read_user_str\fP() apply.
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to \fIdst\fP\&. Same semantics as with bpf_probe_read_user_str() apply.
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.TP
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.B Return
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On success, the strictly positive length of the string, including
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@ -3029,7 +3034,7 @@ the trailing NUL character. On error, a negative value.
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.INDENT 7.0
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.TP
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.B Description
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Send out a tcp\-ack. \fItp\fP is the in\-kernel struct \fBtcp_sock\fP\&.
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Send out a tcp\-ack. \fItp\fP is the in\-kernel struct tcp_sock.
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\fIrcv_nxt\fP is the ack_seq to be sent out.
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.TP
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.B Return
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@ -3063,371 +3068,6 @@ Obtain the 64bit jiffies
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.B Return
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The 64 bit jiffies
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.UNINDENT
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.TP
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.B \fBint bpf_read_branch_records(struct bpf_perf_event_data *\fP\fIctx\fP\fB, void *\fP\fIbuf\fP\fB, u32\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB)\fP
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.INDENT 7.0
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.TP
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.B Description
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For an eBPF program attached to a perf event, retrieve the
|
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branch records (\fBstruct perf_branch_entry\fP) associated to \fIctx\fP
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and store it in the buffer pointed by \fIbuf\fP up to size
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\fIsize\fP bytes.
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.TP
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.B Return
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On success, number of bytes written to \fIbuf\fP\&. On error, a
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negative value.
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.sp
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The \fIflags\fP can be set to \fBBPF_F_GET_BRANCH_RECORDS_SIZE\fP to
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instead return the number of bytes required to store all the
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branch entries. If this flag is set, \fIbuf\fP may be NULL.
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.sp
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\fB\-EINVAL\fP if arguments invalid or \fBsize\fP not a multiple
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of \fBsizeof\fP(\fBstruct perf_branch_entry\fP).
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.sp
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\fB\-ENOENT\fP if architecture does not support branch records.
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.UNINDENT
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.TP
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.B \fBint bpf_get_ns_current_pid_tgid(u64\fP \fIdev\fP\fB, u64\fP \fIino\fP\fB, struct bpf_pidns_info *\fP\fInsdata\fP\fB, u32\fP \fIsize\fP\fB)\fP
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.INDENT 7.0
|
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.TP
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.B Description
|
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Returns 0 on success, values for \fIpid\fP and \fItgid\fP as seen from the current
|
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\fInamespace\fP will be returned in \fInsdata\fP\&.
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.TP
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.B Return
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0 on success, or one of the following in case of failure:
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.sp
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\fB\-EINVAL\fP if dev and inum supplied don\(aqt match dev_t and inode number
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with nsfs of current task, or if dev conversion to dev_t lost high bits.
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.sp
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\fB\-ENOENT\fP if pidns does not exists for the current task.
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.UNINDENT
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.TP
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.B \fBint bpf_xdp_output(void *\fP\fIctx\fP\fB, struct bpf_map *\fP\fImap\fP\fB, u64\fP \fIflags\fP\fB, void *\fP\fIdata\fP\fB, u64\fP \fIsize\fP\fB)\fP
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.INDENT 7.0
|
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.TP
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.B Description
|
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Write raw \fIdata\fP blob into a special BPF perf event held by
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\fImap\fP of type \fBBPF_MAP_TYPE_PERF_EVENT_ARRAY\fP\&. This perf
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event must have the following attributes: \fBPERF_SAMPLE_RAW\fP
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as \fBsample_type\fP, \fBPERF_TYPE_SOFTWARE\fP as \fBtype\fP, and
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\fBPERF_COUNT_SW_BPF_OUTPUT\fP as \fBconfig\fP\&.
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.sp
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The \fIflags\fP are used to indicate the index in \fImap\fP for which
|
||||
the value must be put, masked with \fBBPF_F_INDEX_MASK\fP\&.
|
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Alternatively, \fIflags\fP can be set to \fBBPF_F_CURRENT_CPU\fP
|
||||
to indicate that the index of the current CPU core should be
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used.
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.sp
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||||
The value to write, of \fIsize\fP, is passed through eBPF stack and
|
||||
pointed by \fIdata\fP\&.
|
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.sp
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\fIctx\fP is a pointer to in\-kernel struct xdp_buff.
|
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.sp
|
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This helper is similar to \fBbpf_perf_eventoutput\fP() but
|
||||
restricted to raw_tracepoint bpf programs.
|
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.TP
|
||||
.B Return
|
||||
0 on success, or a negative error in case of failure.
|
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.UNINDENT
|
||||
.TP
|
||||
.B \fBu64 bpf_get_netns_cookie(void *\fP\fIctx\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
Retrieve the cookie (generated by the kernel) of the network
|
||||
namespace the input \fIctx\fP is associated with. The network
|
||||
namespace cookie remains stable for its lifetime and provides
|
||||
a global identifier that can be assumed unique. If \fIctx\fP is
|
||||
NULL, then the helper returns the cookie for the initial
|
||||
network namespace. The cookie itself is very similar to that
|
||||
of \fBbpf_get_socket_cookie\fP() helper, but for network
|
||||
namespaces instead of sockets.
|
||||
.TP
|
||||
.B Return
|
||||
A 8\-byte long opaque number.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBu64 bpf_get_current_ancestor_cgroup_id(int\fP \fIancestor_level\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
Return id of cgroup v2 that is ancestor of the cgroup associated
|
||||
with the current task at the \fIancestor_level\fP\&. The root cgroup
|
||||
is at \fIancestor_level\fP zero and each step down the hierarchy
|
||||
increments the level. If \fIancestor_level\fP == level of cgroup
|
||||
associated with the current task, then return value will be the
|
||||
same as that of \fBbpf_get_current_cgroup_id\fP().
|
||||
.sp
|
||||
The helper is useful to implement policies based on cgroups
|
||||
that are upper in hierarchy than immediate cgroup associated
|
||||
with the current task.
|
||||
.sp
|
||||
The format of returned id and helper limitations are same as in
|
||||
\fBbpf_get_current_cgroup_id\fP().
|
||||
.TP
|
||||
.B Return
|
||||
The id is returned or 0 in case the id could not be retrieved.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBint bpf_sk_assign(struct sk_buff *\fP\fIskb\fP\fB, struct bpf_sock *\fP\fIsk\fP\fB, u64\fP \fIflags\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
Assign the \fIsk\fP to the \fIskb\fP\&. When combined with appropriate
|
||||
routing configuration to receive the packet towards the socket,
|
||||
will cause \fIskb\fP to be delivered to the specified socket.
|
||||
Subsequent redirection of \fIskb\fP via \fBbpf_redirect\fP(),
|
||||
\fBbpf_clone_redirect\fP() or other methods outside of BPF may
|
||||
interfere with successful delivery to the socket.
|
||||
.sp
|
||||
This operation is only valid from TC ingress path.
|
||||
.sp
|
||||
The \fIflags\fP argument must be zero.
|
||||
.TP
|
||||
.B Return
|
||||
0 on success, or a negative error in case of failure:
|
||||
.sp
|
||||
\fB\-EINVAL\fP if specified \fIflags\fP are not supported.
|
||||
.sp
|
||||
\fB\-ENOENT\fP if the socket is unavailable for assignment.
|
||||
.sp
|
||||
\fB\-ENETUNREACH\fP if the socket is unreachable (wrong netns).
|
||||
.sp
|
||||
\fB\-EOPNOTSUPP\fP if the operation is not supported, for example
|
||||
a call from outside of TC ingress.
|
||||
.sp
|
||||
\fB\-ESOCKTNOSUPPORT\fP if the socket type is not supported
|
||||
(reuseport).
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBu64 bpf_ktime_get_boot_ns(void)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
Return the time elapsed since system boot, in nanoseconds.
|
||||
Does include the time the system was suspended.
|
||||
See: \fBclock_gettime\fP(\fBCLOCK_BOOTTIME\fP)
|
||||
.TP
|
||||
.B Return
|
||||
Current \fIktime\fP\&.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBint bpf_seq_printf(struct seq_file *\fP\fIm\fP\fB, const char *\fP\fIfmt\fP\fB, u32\fP \fIfmt_size\fP\fB, const void *\fP\fIdata\fP\fB, u32\fP \fIdata_len\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
\fBbpf_seq_printf\fP() uses seq_file \fBseq_printf\fP() to print
|
||||
out the format string.
|
||||
The \fIm\fP represents the seq_file. The \fIfmt\fP and \fIfmt_size\fP are for
|
||||
the format string itself. The \fIdata\fP and \fIdata_len\fP are format string
|
||||
arguments. The \fIdata\fP are a \fBu64\fP array and corresponding format string
|
||||
values are stored in the array. For strings and pointers where pointees
|
||||
are accessed, only the pointer values are stored in the \fIdata\fP array.
|
||||
The \fIdata_len\fP is the size of \fIdata\fP in bytes.
|
||||
.sp
|
||||
Formats \fB%s\fP, \fB%p{i,I}{4,6}\fP requires to read kernel memory.
|
||||
Reading kernel memory may fail due to either invalid address or
|
||||
valid address but requiring a major memory fault. If reading kernel memory
|
||||
fails, the string for \fB%s\fP will be an empty string, and the ip
|
||||
address for \fB%p{i,I}{4,6}\fP will be 0. Not returning error to
|
||||
bpf program is consistent with what \fBbpf_trace_printk\fP() does for now.
|
||||
.TP
|
||||
.B Return
|
||||
0 on success, or a negative error in case of failure:
|
||||
.sp
|
||||
\fB\-EBUSY\fP if per\-CPU memory copy buffer is busy, can try again
|
||||
by returning 1 from bpf program.
|
||||
.sp
|
||||
\fB\-EINVAL\fP if arguments are invalid, or if \fIfmt\fP is invalid/unsupported.
|
||||
.sp
|
||||
\fB\-E2BIG\fP if \fIfmt\fP contains too many format specifiers.
|
||||
.sp
|
||||
\fB\-EOVERFLOW\fP if an overflow happened: The same object will be tried again.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBint bpf_seq_write(struct seq_file *\fP\fIm\fP\fB, const void *\fP\fIdata\fP\fB, u32\fP \fIlen\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
\fBbpf_seq_write\fP() uses seq_file \fBseq_write\fP() to write the data.
|
||||
The \fIm\fP represents the seq_file. The \fIdata\fP and \fIlen\fP represent the
|
||||
data to write in bytes.
|
||||
.TP
|
||||
.B Return
|
||||
0 on success, or a negative error in case of failure:
|
||||
.sp
|
||||
\fB\-EOVERFLOW\fP if an overflow happened: The same object will be tried again.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBu64 bpf_sk_cgroup_id(struct bpf_sock *\fP\fIsk\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
Return the cgroup v2 id of the socket \fIsk\fP\&.
|
||||
.sp
|
||||
\fIsk\fP must be a non\-\fBNULL\fP pointer to a full socket, e.g. one
|
||||
returned from \fBbpf_sk_lookup_xxx\fP(),
|
||||
\fBbpf_sk_fullsock\fP(), etc. The format of returned id is
|
||||
same as in \fBbpf_skb_cgroup_id\fP().
|
||||
.sp
|
||||
This helper is available only if the kernel was compiled with
|
||||
the \fBCONFIG_SOCK_CGROUP_DATA\fP configuration option.
|
||||
.TP
|
||||
.B Return
|
||||
The id is returned or 0 in case the id could not be retrieved.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBu64 bpf_sk_ancestor_cgroup_id(struct bpf_sock *\fP\fIsk\fP\fB, int\fP \fIancestor_level\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
Return id of cgroup v2 that is ancestor of cgroup associated
|
||||
with the \fIsk\fP at the \fIancestor_level\fP\&. The root cgroup is at
|
||||
\fIancestor_level\fP zero and each step down the hierarchy
|
||||
increments the level. If \fIancestor_level\fP == level of cgroup
|
||||
associated with \fIsk\fP, then return value will be same as that
|
||||
of \fBbpf_sk_cgroup_id\fP().
|
||||
.sp
|
||||
The helper is useful to implement policies based on cgroups
|
||||
that are upper in hierarchy than immediate cgroup associated
|
||||
with \fIsk\fP\&.
|
||||
.sp
|
||||
The format of returned id and helper limitations are same as in
|
||||
\fBbpf_sk_cgroup_id\fP().
|
||||
.TP
|
||||
.B Return
|
||||
The id is returned or 0 in case the id could not be retrieved.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBvoid *bpf_ringbuf_output(void *\fP\fIringbuf\fP\fB, void *\fP\fIdata\fP\fB, u64\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
Copy \fIsize\fP bytes from \fIdata\fP into a ring buffer \fIringbuf\fP\&.
|
||||
If BPF_RB_NO_WAKEUP is specified in \fIflags\fP, no notification of
|
||||
new data availability is sent.
|
||||
IF BPF_RB_FORCE_WAKEUP is specified in \fIflags\fP, notification of
|
||||
new data availability is sent unconditionally.
|
||||
.TP
|
||||
.B Return
|
||||
0, on success;
|
||||
< 0, on error.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBvoid *bpf_ringbuf_reserve(void *\fP\fIringbuf\fP\fB, u64\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
Reserve \fIsize\fP bytes of payload in a ring buffer \fIringbuf\fP\&.
|
||||
.TP
|
||||
.B Return
|
||||
Valid pointer with \fIsize\fP bytes of memory available; NULL,
|
||||
otherwise.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBvoid bpf_ringbuf_submit(void *\fP\fIdata\fP\fB, u64\fP \fIflags\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
Submit reserved ring buffer sample, pointed to by \fIdata\fP\&.
|
||||
If BPF_RB_NO_WAKEUP is specified in \fIflags\fP, no notification of
|
||||
new data availability is sent.
|
||||
IF BPF_RB_FORCE_WAKEUP is specified in \fIflags\fP, notification of
|
||||
new data availability is sent unconditionally.
|
||||
.TP
|
||||
.B Return
|
||||
Nothing. Always succeeds.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBvoid bpf_ringbuf_discard(void *\fP\fIdata\fP\fB, u64\fP \fIflags\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
Discard reserved ring buffer sample, pointed to by \fIdata\fP\&.
|
||||
If BPF_RB_NO_WAKEUP is specified in \fIflags\fP, no notification of
|
||||
new data availability is sent.
|
||||
IF BPF_RB_FORCE_WAKEUP is specified in \fIflags\fP, notification of
|
||||
new data availability is sent unconditionally.
|
||||
.TP
|
||||
.B Return
|
||||
Nothing. Always succeeds.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBu64 bpf_ringbuf_query(void *\fP\fIringbuf\fP\fB, u64\fP \fIflags\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
Query various characteristics of provided ring buffer. What
|
||||
exactly is queries is determined by \fIflags\fP:
|
||||
.IP "System Message: ERROR/3 (/tmp/bpf-helpers.rst:, line 2636)"
|
||||
Unexpected indentation.
|
||||
.INDENT 7.0
|
||||
.INDENT 3.5
|
||||
.INDENT 0.0
|
||||
.IP \(bu 2
|
||||
BPF_RB_AVAIL_DATA \- amount of data not yet consumed;
|
||||
.IP \(bu 2
|
||||
BPF_RB_RING_SIZE \- the size of ring buffer;
|
||||
.IP \(bu 2
|
||||
BPF_RB_CONS_POS \- consumer position (can wrap around);
|
||||
.IP \(bu 2
|
||||
BPF_RB_PROD_POS \- producer(s) position (can wrap around);
|
||||
.UNINDENT
|
||||
.UNINDENT
|
||||
.UNINDENT
|
||||
.IP "System Message: WARNING/2 (/tmp/bpf-helpers.rst:, line 2640)"
|
||||
Block quote ends without a blank line; unexpected unindent.
|
||||
.sp
|
||||
Data returned is just a momentary snapshots of actual values
|
||||
and could be inaccurate, so this facility should be used to
|
||||
power heuristics and for reporting, not to make 100% correct
|
||||
calculation.
|
||||
.TP
|
||||
.B Return
|
||||
Requested value, or 0, if flags are not recognized.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B \fBint bpf_csum_level(struct sk_buff *\fP\fIskb\fP\fB, u64\fP \fIlevel\fP\fB)\fP
|
||||
.INDENT 7.0
|
||||
.TP
|
||||
.B Description
|
||||
Change the skbs checksum level by one layer up or down, or
|
||||
reset it entirely to none in order to have the stack perform
|
||||
checksum validation. The level is applicable to the following
|
||||
protocols: TCP, UDP, GRE, SCTP, FCOE. For example, a decap of
|
||||
| ETH | IP | UDP | GUE | IP | TCP | into | ETH | IP | TCP |
|
||||
through \fBbpf_skb_adjust_room\fP() helper with passing in
|
||||
\fBBPF_F_ADJ_ROOM_NO_CSUM_RESET\fP flag would require one call
|
||||
to \fBbpf_csum_level\fP() with \fBBPF_CSUM_LEVEL_DEC\fP since
|
||||
the UDP header is removed. Similarly, an encap of the latter
|
||||
into the former could be accompanied by a helper call to
|
||||
\fBbpf_csum_level\fP() with \fBBPF_CSUM_LEVEL_INC\fP if the
|
||||
skb is still intended to be processed in higher layers of the
|
||||
stack instead of just egressing at tc.
|
||||
.sp
|
||||
There are three supported level settings at this time:
|
||||
.INDENT 7.0
|
||||
.IP \(bu 2
|
||||
\fBBPF_CSUM_LEVEL_INC\fP: Increases skb\->csum_level for skbs
|
||||
with CHECKSUM_UNNECESSARY.
|
||||
.IP \(bu 2
|
||||
\fBBPF_CSUM_LEVEL_DEC\fP: Decreases skb\->csum_level for skbs
|
||||
with CHECKSUM_UNNECESSARY.
|
||||
.IP \(bu 2
|
||||
\fBBPF_CSUM_LEVEL_RESET\fP: Resets skb\->csum_level to 0 and
|
||||
sets CHECKSUM_NONE to force checksum validation by the stack.
|
||||
.IP \(bu 2
|
||||
\fBBPF_CSUM_LEVEL_QUERY\fP: No\-op, returns the current
|
||||
skb\->csum_level.
|
||||
.UNINDENT
|
||||
.TP
|
||||
.B Return
|
||||
0 on success, or a negative error in case of failure. In the
|
||||
case of \fBBPF_CSUM_LEVEL_QUERY\fP, the current skb\->csum_level
|
||||
is returned or the error code \-EACCES in case the skb is not
|
||||
subject to CHECKSUM_UNNECESSARY.
|
||||
.UNINDENT
|
||||
.UNINDENT
|
||||
.SH EXAMPLES
|
||||
.sp
|
||||
|
|
@ -3488,12 +3128,6 @@ of eBPF maps are used with a given helper function.
|
|||
.IP \(bu 2
|
||||
\fIkernel/bpf/\fP directory contains other files in which additional helpers are
|
||||
defined (for cgroups, sockmaps, etc.).
|
||||
.IP \(bu 2
|
||||
The bpftool utility can be used to probe the availability of helper functions
|
||||
on the system (as well as supported program and map types, and a number of
|
||||
other parameters). To do so, run \fBbpftool feature probe\fP (see
|
||||
\fBbpftool\-feature\fP(8) for details). Add the \fBunprivileged\fP keyword to
|
||||
list features available to unprivileged users.
|
||||
.UNINDENT
|
||||
.sp
|
||||
Compatibility between helper functions and program types can generally be found
|
||||
|
|
@ -3513,7 +3147,6 @@ pointers for network processing are listed in function
|
|||
.SH SEE ALSO
|
||||
.sp
|
||||
\fBbpf\fP(2),
|
||||
\fBbpftool\fP(8),
|
||||
\fBcgroups\fP(7),
|
||||
\fBip\fP(8),
|
||||
\fBperf_event_open\fP(2),
|
||||
|
|
|
|||
Loading…
Reference in New Issue