Return a well-defined socket address type from socket funtions.

Previously we were representing socket addresses as an interface{},
which allowed any type which could be binary.Marshal()ed to be used as
a socket address. This is fine when the address is passed to userspace
via the linux ABI, but is problematic when used from within the sentry
such as by networking procfs files.

PiperOrigin-RevId: 262460640

1 files changed, 14 insertions, 0 deletions

diff --git a/pkg/abi/linux/socket.go b/pkg/abi/linux/socket.go
index 6d22002c4..e53165622 100644
--- a/pkg/abi/linux/socket.go
+++ b/pkg/abi/linux/socket.go
@@ -267,6 +267,20 @@ type SockAddrUnix struct {
 	Path   [UnixPathMax]int8
 }
 
+// SockAddr represents a union of valid socket address types. This is logically
+// equivalent to struct sockaddr. SockAddr ensures that a well-defined set of
+// types can be used as socket addresses.
+type SockAddr interface {
+	// implementsSockAddr exists purely to allow a type to indicate that they
+	// implement this interface. This method is a no-op and shouldn't be called.
+	implementsSockAddr()
+}
+
+func (s *SockAddrInet) implementsSockAddr()    {}
+func (s *SockAddrInet6) implementsSockAddr()   {}
+func (s *SockAddrUnix) implementsSockAddr()    {}
+func (s *SockAddrNetlink) implementsSockAddr() {}
+
 // Linger is struct linger, from include/linux/socket.h.
 type Linger struct {
 	OnOff  int32