bpf: Add PTR_TO_SOCKET verifier type

Teach the verifier a little bit about a new type of pointer, a
PTR_TO_SOCKET. This pointer type is accessed from BPF through the
'struct bpf_sock' structure.

Signed-off-by: Joe Stringer <joe@wand.net.nz>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

2 files changed, 36 insertions, 0 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 018299a595c8..027697b6a22f 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -154,6 +154,7 @@ enum bpf_arg_type {
 
 	ARG_PTR_TO_CTX,		/* pointer to context */
 	ARG_ANYTHING,		/* any (initialized) argument is ok */
+	ARG_PTR_TO_SOCKET,	/* pointer to bpf_sock */
 };
 
 /* type of values returned from helper functions */
@@ -162,6 +163,7 @@ enum bpf_return_type {
 	RET_VOID,			/* function doesn't return anything */
 	RET_PTR_TO_MAP_VALUE,		/* returns a pointer to map elem value */
 	RET_PTR_TO_MAP_VALUE_OR_NULL,	/* returns a pointer to map elem value or NULL */
+	RET_PTR_TO_SOCKET_OR_NULL,	/* returns a pointer to a socket or NULL */
 };
 
 /* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
@@ -213,6 +215,8 @@ enum bpf_reg_type {
 	PTR_TO_PACKET,		 /* reg points to skb->data */
 	PTR_TO_PACKET_END,	 /* skb->data + headlen */
 	PTR_TO_FLOW_KEYS,	 /* reg points to bpf_flow_keys */
+	PTR_TO_SOCKET,		 /* reg points to struct bpf_sock */
+	PTR_TO_SOCKET_OR_NULL,	 /* reg points to struct bpf_sock or NULL */
 };
 
 /* The information passed from prog-specific *_is_valid_access
@@ -343,6 +347,11 @@ const struct bpf_func_proto *bpf_get_trace_printk_proto(void);
 
 typedef unsigned long (*bpf_ctx_copy_t)(void *dst, const void *src,
 					unsigned long off, unsigned long len);
+typedef u32 (*bpf_convert_ctx_access_t)(enum bpf_access_type type,
+					const struct bpf_insn *src,
+					struct bpf_insn *dst,
+					struct bpf_prog *prog,
+					u32 *target_size);
 
 u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
 		     void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy);
@@ -836,4 +845,29 @@ extern const struct bpf_func_proto bpf_get_local_storage_proto;
 void bpf_user_rnd_init_once(void);
 u64 bpf_user_rnd_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 
+#if defined(CONFIG_NET)
+bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type,
+			      struct bpf_insn_access_aux *info);
+u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
+				const struct bpf_insn *si,
+				struct bpf_insn *insn_buf,
+				struct bpf_prog *prog,
+				u32 *target_size);
+#else
+static inline bool bpf_sock_is_valid_access(int off, int size,
+					    enum bpf_access_type type,
+					    struct bpf_insn_access_aux *info)
+{
+	return false;
+}
+static inline u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
+					      const struct bpf_insn *si,
+					      struct bpf_insn *insn_buf,
+					      struct bpf_prog *prog,
+					      u32 *target_size)
+{
+	return 0;
+}
+#endif
+
 #endif /* _LINUX_BPF_H */
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index d0e7f97e8b60..a411363098a5 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -58,6 +58,8 @@ struct bpf_reg_state {
 	 * offset, so they can share range knowledge.
 	 * For PTR_TO_MAP_VALUE_OR_NULL this is used to share which map value we
 	 * came from, when one is tested for != NULL.
+	 * For PTR_TO_SOCKET this is used to share which pointers retain the
+	 * same reference to the socket, to determine proper reference freeing.
 	 */
 	u32 id;
 	/* For scalar types (SCALAR_VALUE), this represents our knowledge of