bpf: Explicitly check accesses to bpf_sock_addr

net/core/filter.c

@@ -9284,13 +9284,19 @@ static bool sock_addr_is_valid_access(int off, int size,
 			return false;
 		info->reg_type = PTR_TO_SOCKET;
 		break;
-	default:
+	case bpf_ctx_range(struct bpf_sock_addr, user_family):
+	case bpf_ctx_range(struct bpf_sock_addr, family):
+	case bpf_ctx_range(struct bpf_sock_addr, type):
+	case bpf_ctx_range(struct bpf_sock_addr, protocol):
 		if (type == BPF_READ) {
 			if (size != size_default)
 				return false;
 		} else {
 			return false;
 		}
+		break;
+	default:
+		return false;
 	}
 
 	return true;

tools/testing/selftests/bpf/progs/bpf_misc.h

@@ -156,6 +156,10 @@
 #define __imm_ptr(name) [name]"r"(&name)
 #define __imm_insn(name, expr) [name]"i"(*(long *)&(expr))
 
+#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
+#define offsetofend(TYPE, MEMBER) \
+	(offsetof(TYPE, MEMBER)	+ sizeof_field(TYPE, MEMBER))
+
 /* Magic constants used with __retval() */
 #define POINTER_VALUE	0xbadcafe
 #define TEST_DATA_LEN	64

tools/testing/selftests/bpf/progs/test_cls_redirect.c

@@ -22,6 +22,7 @@
 
 #include "bpf_compiler.h"
 #include "test_cls_redirect.h"
+#include "bpf_misc.h"
 
 #pragma GCC diagnostic ignored "-Waddress-of-packed-member"
 
@@ -31,9 +32,6 @@
 #define INLINING __always_inline
 #endif
 
-#define offsetofend(TYPE, MEMBER) \
-	(offsetof(TYPE, MEMBER) + sizeof((((TYPE *)0)->MEMBER)))
-
 #define IP_OFFSET_MASK (0x1FFF)
 #define IP_MF (0x2000)
 

tools/testing/selftests/bpf/progs/test_tcp_hdr_options.c

@@ -14,10 +14,7 @@
 #include <bpf/bpf_endian.h>
 #define BPF_PROG_TEST_TCP_HDR_OPTIONS
 #include "test_tcp_hdr_options.h"
-
-#ifndef sizeof_field
-#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
-#endif
+#include "bpf_misc.h"
 
 __u8 test_kind = TCPOPT_EXP;
 __u16 test_magic = 0xeB9F;

tools/testing/selftests/bpf/progs/verifier_ctx.c

@@ -5,8 +5,6 @@
 #include <bpf/bpf_helpers.h>
 #include "bpf_misc.h"
 
-#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
-
 SEC("tc")
 __description("context stores via BPF_ATOMIC")
 __failure __msg("BPF_ATOMIC stores into R1 ctx is not allowed")
@@ -264,4 +262,28 @@ narrow_load("sockops", bpf_sock_ops, skb_hwtstamp);
 unaligned_access("flow_dissector", __sk_buff, data);
 unaligned_access("netfilter", bpf_nf_ctx, skb);
 
+#define padding_access(type, ctx, prev_field, sz)			\
+	SEC(type)							\
+	__description("access on " #ctx " padding after " #prev_field)	\
+	__naked void padding_ctx_access_##ctx(void)			\
+	{								\
+		asm volatile ("						\
+		r1 = *(u%[size] *)(r1 + %[off]);			\
+		r0 = 0;							\
+		exit;"							\
+		:							\
+		: __imm_const(size, sz * 8),				\
+		  __imm_const(off, offsetofend(struct ctx, prev_field))	\
+		: __clobber_all);					\
+	}
+
+__failure __msg("invalid bpf_context access")
+padding_access("cgroup/bind4", bpf_sock_addr, msg_src_ip6[3], 4);
+
+__success
+padding_access("sk_lookup", bpf_sk_lookup, remote_port, 2);
+
+__failure __msg("invalid bpf_context access")
+padding_access("tc", __sk_buff, tstamp_type, 2);
+
 char _license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/progs/verifier_sock.c

@@ -5,10 +5,6 @@
 #include <bpf/bpf_helpers.h>
 #include "bpf_misc.h"
 
-#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
-#define offsetofend(TYPE, MEMBER) \
-	(offsetof(TYPE, MEMBER)	+ sizeof_field(TYPE, MEMBER))
-
 struct {
 	__uint(type, BPF_MAP_TYPE_REUSEPORT_SOCKARRAY);
 	__uint(max_entries, 1);