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/438183726
TEST=presubmit
RELEASE_NOTE=None
cos-patch: security-high
Change-Id: I0b763c1424809f899311f39dd72d41865ba96254
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/+/109207
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Main-Branch-Verified: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Miri Amarilio <mirilio@google.com>
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 17de12a..0a09708 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -300,6 +300,7 @@ 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)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index b66349f..1d6bd01 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>
#include <net/netfilter/nf_bpf_link.h>
#include <net/tcx.h>
@@ -50,6 +51,7 @@
#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);
@@ -1253,6 +1255,10 @@ 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);
