Commit 12df58ad authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Alexei Starovoitov
Browse files

bpf: Add cookie object to bpf maps 



Add a cookie to BPF maps to uniquely identify BPF maps for the timespan
when the node is up. This is different to comparing a pointer or BPF map
id which could get rolled over and reused.

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20250730234733.530041-1-daniel@iogearbox.net


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent d6084bb8

include/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -310,6 +310,7 @@ struct bpf_map { 
	bool free_after_rcu_gp;

	atomic64_t sleepable_refcnt;

	s64 __percpu *elem_count;

	u64 cookie; /* write-once */

};



static inline const char *btf_field_type_name(enum btf_field_type type)

kernel/bpf/syscall.c

+6 −0
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ 
#include <linux/trace_events.h>

#include <linux/tracepoint.h>

#include <linux/overflow.h>

#include <linux/cookie.h>



#include <net/netfilter/nf_bpf_link.h>

#include <net/netkit.h>
@@ -53,6 +54,7 @@ 
#define BPF_OBJ_FLAG_MASK   (BPF_F_RDONLY | BPF_F_WRONLY)



DEFINE_PER_CPU(int, bpf_prog_active);

DEFINE_COOKIE(bpf_map_cookie);

static DEFINE_IDR(prog_idr);

static DEFINE_SPINLOCK(prog_idr_lock);

static DEFINE_IDR(map_idr);
@@ -1487,6 +1489,10 @@ static int map_create(union bpf_attr *attr, bool kernel) 
	if (err < 0)

		goto free_map;



	preempt_disable();

	map->cookie = gen_cookie_next(&bpf_map_cookie);

	preempt_enable();



	atomic64_set(&map->refcnt, 1);

	atomic64_set(&map->usercnt, 1);

	mutex_init(&map->freeze_mutex);