linux/kernel/bpf/preload/bpf_preload_kern.c
Azeem Shaikh ffadc37252 bpf: Replace all non-returning strlcpy with strscpy
strlcpy() reads the entire source buffer first. This read may exceed the
destination size limit. This is both inefficient and can lead to linear
read overflows if a source string is not NUL-terminated [1]. This is not
the case here, however, in an effort to remove strlcpy() completely [2],
lets replace strlcpy() here with strscpy(). No return values were used,
so a direct replacement is safe.

  [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
  [2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/bpf/20230530155659.309657-1-azeemshaikh38@gmail.com
2023-05-31 13:04:20 +02:00

93 lines
2.0 KiB
C

// SPDX-License-Identifier: GPL-2.0
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/module.h>
#include "bpf_preload.h"
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#include "iterators/iterators.lskel-little-endian.h"
#else
#include "iterators/iterators.lskel-big-endian.h"
#endif
static struct bpf_link *maps_link, *progs_link;
static struct iterators_bpf *skel;
static void free_links_and_skel(void)
{
if (!IS_ERR_OR_NULL(maps_link))
bpf_link_put(maps_link);
if (!IS_ERR_OR_NULL(progs_link))
bpf_link_put(progs_link);
iterators_bpf__destroy(skel);
}
static int preload(struct bpf_preload_info *obj)
{
strscpy(obj[0].link_name, "maps.debug", sizeof(obj[0].link_name));
obj[0].link = maps_link;
strscpy(obj[1].link_name, "progs.debug", sizeof(obj[1].link_name));
obj[1].link = progs_link;
return 0;
}
static struct bpf_preload_ops ops = {
.preload = preload,
.owner = THIS_MODULE,
};
static int load_skel(void)
{
int err;
skel = iterators_bpf__open();
if (!skel)
return -ENOMEM;
err = iterators_bpf__load(skel);
if (err)
goto out;
err = iterators_bpf__attach(skel);
if (err)
goto out;
maps_link = bpf_link_get_from_fd(skel->links.dump_bpf_map_fd);
if (IS_ERR(maps_link)) {
err = PTR_ERR(maps_link);
goto out;
}
progs_link = bpf_link_get_from_fd(skel->links.dump_bpf_prog_fd);
if (IS_ERR(progs_link)) {
err = PTR_ERR(progs_link);
goto out;
}
/* Avoid taking over stdin/stdout/stderr of init process. Zeroing out
* makes skel_closenz() a no-op later in iterators_bpf__destroy().
*/
close_fd(skel->links.dump_bpf_map_fd);
skel->links.dump_bpf_map_fd = 0;
close_fd(skel->links.dump_bpf_prog_fd);
skel->links.dump_bpf_prog_fd = 0;
return 0;
out:
free_links_and_skel();
return err;
}
static int __init load(void)
{
int err;
err = load_skel();
if (err)
return err;
bpf_preload_ops = &ops;
return err;
}
static void __exit fini(void)
{
bpf_preload_ops = NULL;
free_links_and_skel();
}
late_initcall(load);
module_exit(fini);
MODULE_LICENSE("GPL");