bpf: Add cookie object to bpf maps Upstream commit: 12df58ad294253ac1d8df0c9bb9cf726397a671d 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. BUG=b/438183971 TEST=presubmit RELEASE_NOTE=None cos-patch: security-high Change-Id: I25f627edf7b25ca38218a4132882569d8ff5cd7c Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/109196 Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com> Reviewed-by: Kevin Berry <kpberry@google.com> Reviewed-by: Miri Amarilio <mirilio@google.com> Main-Branch-Verified: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com> Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/109249 Tested-by: He Gao <hegao@google.com> Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index e281c20..0c2f95a 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h

@@ -277,6 +277,7 @@ struct bpf_map {
 	bool frozen; /* write-once; write-protected by freeze_mutex */
 	bool free_after_mult_rcu_gp;
 	s64 __percpu *elem_count;
+	u64 cookie; /* write-once */
 };
 
 static inline bool map_value_has_spin_lock(const struct bpf_map *map)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 7dfe231..c15d243 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c

@@ -35,6 +35,7 @@
 #include <linux/rcupdate_trace.h>
 #include <linux/memcontrol.h>
 #include <linux/trace_events.h>
+#include <linux/cookie.h>
 
 #define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \
 			  (map)->map_type == BPF_MAP_TYPE_CGROUP_ARRAY || \
@@ -47,6 +48,7 @@
 #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);
@@ -1153,6 +1155,10 @@ static int map_create(union bpf_attr *attr)
 	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);