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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/kernel/bpf/preload/bpf_preload_kern.c
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// SPDX-License-Identifier: GPL-2.0

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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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#include <linux/init.h>

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#include <linux/module.h>

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#include "bpf_preload.h"

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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__

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#include "iterators/iterators.lskel-little-endian.h"

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#else

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#include "iterators/iterators.lskel-big-endian.h"

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#endif

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static struct bpf_link *maps_link, *progs_link;

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static struct iterators_bpf *skel;

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static void free_links_and_skel(void)

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{

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	if (!IS_ERR_OR_NULL(maps_link))

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		bpf_link_put(maps_link);

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	if (!IS_ERR_OR_NULL(progs_link))

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		bpf_link_put(progs_link);

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	iterators_bpf__destroy(skel);

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}

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static int preload(struct bpf_preload_info *obj)

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{

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	strscpy(obj[0].link_name, "maps.debug", sizeof(obj[0].link_name));

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	obj[0].link = maps_link;

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	strscpy(obj[1].link_name, "progs.debug", sizeof(obj[1].link_name));

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	obj[1].link = progs_link;

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	return 0;

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}

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static struct bpf_preload_ops ops = {

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	.preload = preload,

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	.owner = THIS_MODULE,

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};

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static int load_skel(void)

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{

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	int err;

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	skel = iterators_bpf__open();

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	if (!skel)

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		return -ENOMEM;

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	err = iterators_bpf__load(skel);

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	if (err)

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		goto out;

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	err = iterators_bpf__attach(skel);

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	if (err)

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		goto out;

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	maps_link = bpf_link_get_from_fd(skel->links.dump_bpf_map_fd);

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	if (IS_ERR(maps_link)) {

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		err = PTR_ERR(maps_link);

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		goto out;

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	}

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	progs_link = bpf_link_get_from_fd(skel->links.dump_bpf_prog_fd);

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	if (IS_ERR(progs_link)) {

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		err = PTR_ERR(progs_link);

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		goto out;

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	}

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	/* Avoid taking over stdin/stdout/stderr of init process. Zeroing out

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	 * makes skel_closenz() a no-op later in iterators_bpf__destroy().

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	 */

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	close_fd(skel->links.dump_bpf_map_fd);

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	skel->links.dump_bpf_map_fd = 0;

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	close_fd(skel->links.dump_bpf_prog_fd);

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	skel->links.dump_bpf_prog_fd = 0;

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	return 0;

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out:

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	free_links_and_skel();

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	return err;

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}

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static int __init load(void)

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{

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	int err;

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	err = load_skel();

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	if (err)

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		return err;

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	bpf_preload_ops = &ops;

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	return err;

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}

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static void __exit fini(void)

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{

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	bpf_preload_ops = NULL;

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	free_links_and_skel();

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}

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late_initcall(load);

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module_exit(fini);

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MODULE_IMPORT_NS("BPF_INTERNAL");

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MODULE_LICENSE("GPL");

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MODULE_DESCRIPTION("Embedded BPF programs for introspection in bpffs");

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