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Commit f367540c authored by Joe Stringer's avatar Joe Stringer Committed by Arnaldo Carvalho de Melo
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tools lib bpf: Add BPF program pinning APIs 



Add new APIs to pin a BPF program (or specific instances) to the
filesystem.  The user can specify the path full path within a BPF
filesystem to pin the program.

bpf_program__pin_instance(prog, path, n) will pin the nth instance of
'prog' to the specified path.

bpf_program__pin(prog, path) will create the directory 'path' (if it
does not exist) and pin each instance within that directory. For
instance, path/0, path/1, path/2.

Committer notes:

- Add missing headers for mkdir()

- Check strdup() for failure

- Check snprintf >= size, not >, as == also means truncated, see 'man
  snprintf', return value.

- Conditionally define BPF_FS_MAGIC, as it isn't in magic.h in older
  systems and we're not yet having a tools/include/uapi/linux/magic.h
  copy.

- Do not include linux/magic.h, not present in older distros.

Signed-off-by: default avatarJoe Stringer <joe@ovn.org>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/20170126212001.14103-2-joe@ovn.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 9c68ae98

tools/lib/bpf/libbpf.c

+120 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
 * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>

 * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>

 * Copyright (C) 2015 Huawei Inc.

 * Copyright (C) 2017 Nicira, Inc.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public
@@ -22,6 +23,7 @@ 
#include <stdlib.h>

#include <stdio.h>

#include <stdarg.h>

#include <libgen.h>

#include <inttypes.h>

#include <string.h>

#include <unistd.h>
@@ -32,6 +34,10 @@ 
#include <linux/kernel.h>

#include <linux/bpf.h>

#include <linux/list.h>

#include <linux/limits.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <sys/vfs.h>

#include <libelf.h>

#include <gelf.h>
@@ -42,6 +48,10 @@ 
#define EM_BPF 247

#endif



#ifndef BPF_FS_MAGIC

#define BPF_FS_MAGIC		0xcafe4a11

#endif



#define __printf(a, b)	__attribute__((format(printf, a, b)))



__printf(1, 2)
@@ -1237,6 +1247,116 @@ int bpf_object__load(struct bpf_object *obj) 
	return err;

}



static int check_path(const char *path)

{

	struct statfs st_fs;

	char *dname, *dir;

	int err = 0;



	if (path == NULL)

		return -EINVAL;



	dname = strdup(path);

	if (dname == NULL)

		return -ENOMEM;



	dir = dirname(dname);

	if (statfs(dir, &st_fs)) {

		pr_warning("failed to statfs %s: %s\n", dir, strerror(errno));

		err = -errno;

	}

	free(dname);



	if (!err && st_fs.f_type != BPF_FS_MAGIC) {

		pr_warning("specified path %s is not on BPF FS\n", path);

		err = -EINVAL;

	}



	return err;

}



int bpf_program__pin_instance(struct bpf_program *prog, const char *path,

			      int instance)

{

	int err;



	err = check_path(path);

	if (err)

		return err;



	if (prog == NULL) {

		pr_warning("invalid program pointer\n");

		return -EINVAL;

	}



	if (instance < 0 || instance >= prog->instances.nr) {

		pr_warning("invalid prog instance %d of prog %s (max %d)\n",

			   instance, prog->section_name, prog->instances.nr);

		return -EINVAL;

	}



	if (bpf_obj_pin(prog->instances.fds[instance], path)) {

		pr_warning("failed to pin program: %s\n", strerror(errno));

		return -errno;

	}

	pr_debug("pinned program '%s'\n", path);



	return 0;

}



static int make_dir(const char *path)

{

	int err = 0;



	if (mkdir(path, 0700) && errno != EEXIST)

		err = -errno;



	if (err)

		pr_warning("failed to mkdir %s: %s\n", path, strerror(-err));

	return err;

}



int bpf_program__pin(struct bpf_program *prog, const char *path)

{

	int i, err;



	err = check_path(path);

	if (err)

		return err;



	if (prog == NULL) {

		pr_warning("invalid program pointer\n");

		return -EINVAL;

	}



	if (prog->instances.nr <= 0) {

		pr_warning("no instances of prog %s to pin\n",

			   prog->section_name);

		return -EINVAL;

	}



	err = make_dir(path);

	if (err)

		return err;



	for (i = 0; i < prog->instances.nr; i++) {

		char buf[PATH_MAX];

		int len;



		len = snprintf(buf, PATH_MAX, "%s/%d", path, i);

		if (len < 0)

			return -EINVAL;

		else if (len >= PATH_MAX)

			return -ENAMETOOLONG;



		err = bpf_program__pin_instance(prog, buf, i);

		if (err)

			return err;

	}



	return 0;

}



void bpf_object__close(struct bpf_object *obj)

{

	size_t i;

tools/lib/bpf/libbpf.h

+3 −0
Original line number Diff line number Diff line
@@ -106,6 +106,9 @@ void *bpf_program__priv(struct bpf_program *prog); 
const char *bpf_program__title(struct bpf_program *prog, bool needs_copy);



int bpf_program__fd(struct bpf_program *prog);

int bpf_program__pin_instance(struct bpf_program *prog, const char *path,

			      int instance);

int bpf_program__pin(struct bpf_program *prog, const char *path);



struct bpf_insn;