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authorMartin KaFai Lau <kafai@fb.com>2018-08-08 01:01:22 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2018-08-11 01:58:45 +0200
commit736b46027eb4a4c602d3b8b93d2f48c9facbd915 (patch)
tree3ca5ea85e32ffc3df549f6dc1e26d04871f0c911 /include/net
parent40a1227ea845a37ab197dd1caffb60b047fa36b1 (diff)
net: Add ID (if needed) to sock_reuseport and expose reuseport_lock
A later patch will introduce a BPF_MAP_TYPE_REUSEPORT_ARRAY which allows a SO_REUSEPORT sk to be added to a bpf map. When a sk is removed from reuse->socks[], it also needs to be removed from the bpf map. Also, when adding a sk to a bpf map, the bpf map needs to ensure it is indeed in a reuse->socks[]. Hence, reuseport_lock is needed by the bpf map to ensure its map_update_elem() and map_delete_elem() operations are in-sync with the reuse->socks[]. The BPF_MAP_TYPE_REUSEPORT_ARRAY map will only acquire the reuseport_lock after ensuring the adding sk is already in a reuseport group (i.e. reuse->socks[]). The map_lookup_elem() will be lockless. This patch also adds an ID to sock_reuseport. A later patch will introduce BPF_PROG_TYPE_SK_REUSEPORT which allows a bpf prog to select a sk from a bpf map. It is inflexible to statically enforce a bpf map can only contain the sk belonging to a particular reuse->socks[] (i.e. same IP:PORT) during the bpf verification time. For example, think about the the map-in-map situation where the inner map can be dynamically changed in runtime and the outer map may have inner maps belonging to different reuseport groups. Hence, when the bpf prog (in the new BPF_PROG_TYPE_SK_REUSEPORT type) selects a sk, this selected sk has to be checked to ensure it belongs to the requesting reuseport group (i.e. the group serving that IP:PORT). The "sk->sk_reuseport_cb" pointer cannot be used for this checking purpose because the pointer value will change after reuseport_grow(). Instead of saving all checking conditions like the ones preced calling "reuseport_add_sock()" and compare them everytime a bpf_prog is run, a 32bits ID is introduced to survive the reuseport_grow(). The ID is only acquired if any of the reuse->socks[] is added to the newly introduced "BPF_MAP_TYPE_REUSEPORT_ARRAY" map. If "BPF_MAP_TYPE_REUSEPORT_ARRAY" is not used, the changes in this patch is a no-op. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'include/net')
-rw-r--r--include/net/sock_reuseport.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/net/sock_reuseport.h b/include/net/sock_reuseport.h
index 6bef7a0052f2..e1a7681856f7 100644
--- a/include/net/sock_reuseport.h
+++ b/include/net/sock_reuseport.h
@@ -5,8 +5,11 @@
#include <linux/filter.h>
#include <linux/skbuff.h>
#include <linux/types.h>
+#include <linux/spinlock.h>
#include <net/sock.h>
+extern spinlock_t reuseport_lock;
+
struct sock_reuseport {
struct rcu_head rcu;
@@ -16,6 +19,8 @@ struct sock_reuseport {
* reuse->socks[] group.
*/
unsigned int synq_overflow_ts;
+ /* ID stays the same even after the size of socks[] grows. */
+ unsigned int reuseport_id;
struct bpf_prog __rcu *prog; /* optional BPF sock selector */
struct sock *socks[0]; /* array of sock pointers */
};
@@ -29,5 +34,6 @@ extern struct sock *reuseport_select_sock(struct sock *sk,
int hdr_len);
extern struct bpf_prog *reuseport_attach_prog(struct sock *sk,
struct bpf_prog *prog);
+int reuseport_get_id(struct sock_reuseport *reuse);
#endif /* _SOCK_REUSEPORT_H */