path: root/tools/lib/bpf/bpf.c

// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)

/*
 * common eBPF ELF operations.
 *
 * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
 * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
 * Copyright (C) 2015 Huawei Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License (not later!)
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not,  see <http://www.gnu.org/licenses>
 */

#include <stdlib.h>
#include <string.h>
#include <memory.h>
#include <unistd.h>
#include <asm/unistd.h>
#include <errno.h>
#include <linux/bpf.h>
#include <linux/filter.h>
#include <limits.h>
#include <sys/resource.h>
#include "bpf.h"
#include "libbpf.h"
#include "libbpf_internal.h"

/*
 * When building perf, unistd.h is overridden. __NR_bpf is
 * required to be defined explicitly.
 */
#ifndef __NR_bpf
# if defined(__i386__)
#  define __NR_bpf 357
# elif defined(__x86_64__)
#  define __NR_bpf 321
# elif defined(__aarch64__)
#  define __NR_bpf 280
# elif defined(__sparc__)
#  define __NR_bpf 349
# elif defined(__s390__)
#  define __NR_bpf 351
# elif defined(__arc__)
#  define __NR_bpf 280
# elif defined(__mips__) && defined(_ABIO32)
#  define __NR_bpf 4355
# elif defined(__mips__) && defined(_ABIN32)
#  define __NR_bpf 6319
# elif defined(__mips__) && defined(_ABI64)
#  define __NR_bpf 5315
# else
#  error __NR_bpf not defined. libbpf does not support your arch.
# endif
#endif

static inline __u64 ptr_to_u64(const void *ptr)
{
	return (__u64) (unsigned long) ptr;
}

static inline int sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr,
			  unsigned int size)
{
	return syscall(__NR_bpf, cmd, attr, size);
}

static inline int sys_bpf_fd(enum bpf_cmd cmd, union bpf_attr *attr,
			     unsigned int size)
{
	int fd;

	fd = sys_bpf(cmd, attr, size);
	return ensure_good_fd(fd);
}

#define PROG_LOAD_ATTEMPTS 5

static inline int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts)
{
	int fd;

	do {
		fd = sys_bpf_fd(BPF_PROG_LOAD, attr, size);
	} while (fd < 0 && errno == EAGAIN && --attempts > 0);

	return fd;
}

/* Probe whether kernel switched from memlock-based (RLIMIT_MEMLOCK) to
 * memcg-based memory accounting for BPF maps and progs. This was done in [0].
 * We use the support for bpf_ktime_get_coarse_ns() helper, which was added in
 * the same 5.11 Linux release ([1]), to detect memcg-based accounting for BPF.
 *
 *   [0] https://lore.kernel.org/bpf/20201201215900.3569844-1-guro@fb.com/
 *   [1] d05512618056 ("bpf: Add bpf_ktime_get_coarse_ns helper")
 */
int probe_memcg_account(void)
{
	const size_t prog_load_attr_sz = offsetofend(union bpf_attr, attach_btf_obj_fd);
	struct bpf_insn insns[] = {
		BPF_EMIT_CALL(BPF_FUNC_ktime_get_coarse_ns),
		BPF_EXIT_INSN(),
	};
	size_t insn_cnt = sizeof(insns) / sizeof(insns[0]);
	union bpf_attr attr;
	int prog_fd;

	/* attempt loading freplace trying to use custom BTF */
	memset(&attr, 0, prog_load_attr_sz);
	attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
	attr.insns = ptr_to_u64(insns);
	attr.insn_cnt = insn_cnt;
	attr.license = ptr_to_u64("GPL");

	prog_fd = sys_bpf_fd(BPF_PROG_LOAD, &attr, prog_load_attr_sz);
	if (prog_fd >= 0) {
		close(prog_fd);
		return 1;
	}
	return 0;
}

static bool memlock_bumped;
static rlim_t memlock_rlim = RLIM_INFINITY;

int libbpf_set_memlock_rlim(size_t memlock_bytes)
{
	if (memlock_bumped)
		return libbpf_err(-EBUSY);

	memlock_rlim = memlock_bytes;
	return 0;
}

int bump_rlimit_memlock(void)
{
	struct rlimit rlim