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bpf-helpers.7: Resync against kernel 5.7 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2020-06-09 09:47:48 +02:00
parent 599e0cef94
commit 7dc03d8607
1 changed files with 303 additions and 48 deletions
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man7/bpf-helpers.7
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@ -59,7 +59,6 @@ level margin: \\n[rst2man-indent\\n[rst2man-indent-level]]
.\" located in file include/uapi/linux/bpf.h of the Linux kernel sources
.\" (helpers description), and from scripts/bpf_helpers_doc.py in the same
.\" repository (header and footer).
.
.SH DESCRIPTION
.sp
The extended Berkeley Packet Filter (eBPF) subsystem consists in programs
@ -143,8 +142,8 @@ Delete entry with \fIkey\fP from \fImap\fP\&.
For tracing programs, safely attempt to read \fIsize\fP bytes from
kernel space address \fIunsafe_ptr\fP and store the data in \fIdst\fP\&.
.sp
Generally, use bpf_probe_read_user() or bpf_probe_read_kernel()
instead.
Generally, use \fBbpf_probe_read_user\fP() or
\fBbpf_probe_read_kernel\fP() instead.
.TP
.B Return
0 on success, or a negative error in case of failure.
@ -155,6 +154,8 @@ instead.
.TP
.B Description
Return the time elapsed since system boot, in nanoseconds.
Does not include time the system was suspended.
See: \fBclock_gettime\fP(\fBCLOCK_MONOTONIC\fP)
.TP
.B Return
Current \fIktime\fP\&.
@ -1229,11 +1230,11 @@ direct packet access.
.TP
.B Description
Copy a NUL terminated string from an unsafe kernel address
\fIunsafe_ptr\fP to \fIdst\fP\&. See bpf_probe_read_kernel_str() for
\fIunsafe_ptr\fP to \fIdst\fP\&. See \fBbpf_probe_read_kernel_str\fP() for
more details.
.sp
Generally, use bpf_probe_read_user_str() or bpf_probe_read_kernel_str()
instead.
Generally, use \fBbpf_probe_read_user_str\fP() or
\fBbpf_probe_read_kernel_str\fP() instead.
.TP
.B Return
On success, the strictly positive length of the string,
@ -1273,7 +1274,7 @@ A 8\-byte long non\-decreasing number.
.INDENT 7.0
.TP
.B Description
Equivalent to bpf_get_socket_cookie() helper that accepts
Equivalent to \fBbpf_get_socket_cookie\fP() helper that accepts
\fIskb\fP, but gets socket from \fBstruct bpf_sock_ops\fP context.
.TP
.B Return
@ -1302,7 +1303,7 @@ to value \fIhash\fP\&.
0
.UNINDENT
.TP
.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
.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
.INDENT 7.0
.TP
.B Description
@ -1312,6 +1313,15 @@ which the option resides and the name \fIoptname\fP of the option
must be specified, see \fBsetsockopt(2)\fP for more information.
The option value of length \fIoptlen\fP is pointed by \fIoptval\fP\&.
.sp
\fIbpf_socket\fP should be one of the following:
.INDENT 7.0
.IP \(bu 2
\fBstruct bpf_sock_ops\fP for \fBBPF_PROG_TYPE_SOCK_OPS\fP\&.
.IP \(bu 2
\fBstruct bpf_sock_addr\fP for \fBBPF_CGROUP_INET4_CONNECT\fP
and \fBBPF_CGROUP_INET6_CONNECT\fP\&.
.UNINDENT
.sp
This helper actually implements a subset of \fBsetsockopt()\fP\&.
It supports the following \fIlevel\fPs:
.INDENT 7.0
@ -1340,6 +1350,15 @@ It supports the following \fIlevel\fPs:
Grow or shrink the room for data in the packet associated to
\fIskb\fP by \fIlen_diff\fP, and according to the selected \fImode\fP\&.
.sp
By default, the helper will reset any offloaded checksum
indicator of the skb to CHECKSUM_NONE. This can be avoided
by the following flag:
.INDENT 7.0
.IP \(bu 2
\fBBPF_F_ADJ_ROOM_NO_CSUM_RESET\fP: Do not reset offloaded
checksum data of the skb to CHECKSUM_NONE.
.UNINDENT
.sp
There are two supported modes at this time:
.INDENT 7.0
.IP \(bu 2
@ -1393,22 +1412,16 @@ support) as of this writing).
.sp
The lower two bits of \fIflags\fP are used as the return code if
the map lookup fails. This is so that the return value can be
one of the XDP program return codes up to XDP_TX, as chosen by
the caller. Any higher bits in the \fIflags\fP argument must be
one of the XDP program return codes up to \fBXDP_TX\fP, as chosen
by the caller. Any higher bits in the \fIflags\fP argument must be
unset.
.sp
See also bpf_redirect(), which only supports redirecting to an
ifindex, but doesn\(aqt require a map to do so.
See also \fBbpf_redirect\fP(), which only supports redirecting
to an ifindex, but doesn\(aqt require a map to do so.
.TP
.B Return
\fBXDP_REDIRECT\fP on success, or the value of the two lower bits
of the
.nf
**
.fi
flags* argument on error.
.IP "System Message: WARNING/2 (/tmp/bpf-helpers.rst:, line 1105)"
Inline strong start\-string without end\-string.
of the \fIflags\fP argument on error.
.UNINDENT
.TP
.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
@ -1537,7 +1550,7 @@ Where t_enabled is the time enabled for event and t_running is
the time running for event since last normalization. The
enabled and running times are accumulated since the perf event
open. To achieve scaling factor between two invocations of an
eBPF program, users can can use CPU id as the key (which is
eBPF program, users can use CPU id as the key (which is
typical for perf array usage model) to remember the previous
value and do the calculation inside the eBPF program.
.TP
@ -1560,7 +1573,7 @@ more details).
0 on success, or a negative error in case of failure.
.UNINDENT
.TP
.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
.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
.INDENT 7.0
.TP
.B Description
@ -1571,6 +1584,15 @@ must be specified, see \fBgetsockopt(2)\fP for more information.
The retrieved value is stored in the structure pointed by
\fIopval\fP and of length \fIoptlen\fP\&.
.sp
\fIbpf_socket\fP should be one of the following:
.INDENT 7.0
.IP \(bu 2
\fBstruct bpf_sock_ops\fP for \fBBPF_PROG_TYPE_SOCK_OPS\fP\&.
.IP \(bu 2
\fBstruct bpf_sock_addr\fP for \fBBPF_CGROUP_INET4_CONNECT\fP
and \fBBPF_CGROUP_INET6_CONNECT\fP\&.
.UNINDENT
.sp
This helper actually implements a subset of \fBgetsockopt()\fP\&.
It supports the following \fIlevel\fPs:
.INDENT 7.0
@ -1596,7 +1618,7 @@ the return value of the probed function, and to set it to \fIrc\fP\&.
The first argument is the context \fIregs\fP on which the kprobe
works.
.sp
This helper works by setting setting the PC (program counter)
This helper works by setting the PC (program counter)
to an override function which is run in place of the original
probed function. This means the probed function is not run at
all. The replacement function just returns with the required
@ -1804,10 +1826,11 @@ single IP address on a host that has multiple IP configured.
.sp
This helper works for IPv4 and IPv6, TCP and UDP sockets. The
domain (\fIaddr\fP\fB\->sa_family\fP) must be \fBAF_INET\fP (or
\fBAF_INET6\fP). Looking for a free port to bind to can be
expensive, therefore binding to port is not permitted by the
helper: \fIaddr\fP\fB\->sin_port\fP (or \fBsin6_port\fP, respectively)
must be set to zero.
\fBAF_INET6\fP). It\(aqs advised to pass zero port (\fBsin_port\fP
or \fBsin6_port\fP) which triggers IP_BIND_ADDRESS_NO_PORT\-like
behavior and lets the kernel efficiently pick up an unused
port as long as 4\-tuple is unique. Passing non\-zero port might
lead to degraded performance.
.TP
.B Return
0 on success, or a negative error in case of failure.
@ -1818,8 +1841,8 @@ must be set to zero.
.TP
.B Description
Adjust (move) \fIxdp_md\fP\fB\->data_end\fP by \fIdelta\fP bytes. It is
only possible to shrink the packet as of this writing,
therefore \fIdelta\fP must be a negative integer.
possible to both shrink and grow the packet tail.
Shrink done via \fIdelta\fP being a negative integer.
.sp
A call to this helper is susceptible to change the underlying
packet buffer. Therefore, at load time, all checks on pointers
@ -2974,7 +2997,7 @@ void bpf_sys_open(struct pt_regs *ctx)
.UNINDENT
.UNINDENT
.sp
In comparison, using \fBbpf_probe_read_user()\fP helper here
In comparison, using \fBbpf_probe_read_user\fP() helper here
instead to read the string would require to estimate the length
at compile time, and would often result in copying more memory
than necessary.
@ -2995,7 +3018,7 @@ value.
.TP
.B Description
Copy a NUL terminated string from an unsafe kernel address \fIunsafe_ptr\fP
to \fIdst\fP\&. Same semantics as with bpf_probe_read_user_str() apply.
to \fIdst\fP\&. Same semantics as with \fBbpf_probe_read_user_str\fP() apply.
.TP
.B Return
On success, the strictly positive length of the string, including
@ -3006,7 +3029,7 @@ the trailing NUL character. On error, a negative value.
.INDENT 7.0
.TP
.B Description
Send out a tcp\-ack. \fItp\fP is the in\-kernel struct tcp_sock.
Send out a tcp\-ack. \fItp\fP is the in\-kernel struct \fBtcp_sock\fP\&.
\fIrcv_nxt\fP is the ack_seq to be sent out.
.TP
.B Return
@ -3046,7 +3069,7 @@ The 64 bit jiffies
.TP
.B Description
For an eBPF program attached to a perf event, retrieve the
branch records (struct perf_branch_entry) associated to \fIctx\fP
branch records (\fBstruct perf_branch_entry\fP) associated to \fIctx\fP
and store it in the buffer pointed by \fIbuf\fP up to size
\fIsize\fP bytes.
.TP
@ -3059,7 +3082,7 @@ instead return the number of bytes required to store all the
branch entries. If this flag is set, \fIbuf\fP may be NULL.
.sp
\fB\-EINVAL\fP if arguments invalid or \fBsize\fP not a multiple
of sizeof(struct perf_branch_entry).
of \fBsizeof\fP(\fBstruct perf_branch_entry\fP).
.sp
\fB\-ENOENT\fP if architecture does not support branch records.
.UNINDENT
@ -3070,8 +3093,9 @@ of sizeof(struct perf_branch_entry).
.B Description
Returns 0 on success, values for \fIpid\fP and \fItgid\fP as seen from the current
\fInamespace\fP will be returned in \fInsdata\fP\&.
.sp
On failure, the returned value is one of the following:
.TP
.B Return
0 on success, or one of the following in case of failure:
.sp
\fB\-EINVAL\fP if dev and inum supplied don\(aqt match dev_t and inode number
with nsfs of current task, or if dev conversion to dev_t lost high bits.
@ -3117,8 +3141,8 @@ 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 bpf_get_socket_cookie() helper, but for network namespaces
instead of sockets.
of \fBbpf_get_socket_cookie\fP() helper, but for network
namespaces instead of sockets.
.TP
.B Return
A 8\-byte long opaque number.
@ -3162,23 +3186,247 @@ This operation is only valid from TC ingress path.
The \fIflags\fP argument must be zero.
.TP
.B Return
0 on success, or a negative errno in case of failure.
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
\fB\-EINVAL\fP Unsupported flags specified.
\fBBPF_CSUM_LEVEL_INC\fP: Increases skb\->csum_level for skbs
with CHECKSUM_UNNECESSARY.
.IP \(bu 2
\fB\-ENOENT\fP Socket is unavailable for assignment.
\fBBPF_CSUM_LEVEL_DEC\fP: Decreases skb\->csum_level for skbs
with CHECKSUM_UNNECESSARY.
.IP \(bu 2
\fB\-ENETUNREACH\fP Socket is unreachable (wrong netns).
\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
.INDENT 2.0
\fBBPF_CSUM_LEVEL_QUERY\fP: No\-op, returns the current
skb\->csum_level.
.UNINDENT
.TP
.B \fB\-EOPNOTSUPP\fP Unsupported operation, for example a
call from outside of TC ingress.
.UNINDENT
.IP \(bu 2
\fB\-ESOCKTNOSUPPORT\fP Socket type not supported (reuseport).
.UNINDENT
.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
@ -3240,6 +3488,12 @@ 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
@ -3259,6 +3513,7 @@ 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),