Linux Zero-Copy: Transfer memory pages between two processes with vmsplice
As R.. mentioned, you only need to pass the fd to the receiving process somehow and on the other side use it as a normal fd.
edit:Actually, you have to use vmsplice() on the sending side to map the buffer to the pipe and splice() on the receiving side on the other end of the pipe. See an example here.
Another choice would be to use a shared mmap-ing.