From 4e2cc2bef3220bb77a60b4a33fb02f491d5acf98 Mon Sep 17 00:00:00 2001 From: Bhasker Hariharan Date: Wed, 13 Oct 2021 15:17:23 -0700 Subject: Minor fixes to sharedmem. Use route/protocol from packetbuffer. Sharedmem implementation should use the EgressRoute/NetworkProtocolNumber embedded in the packetbuffer rather than what is passed as parameters to Write(Raw)Packet(s). PiperOrigin-RevId: 402934171 --- pkg/tcpip/link/sharedmem/sharedmem_unsafe.go | 33 ++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) (limited to 'pkg/tcpip/link/sharedmem/sharedmem_unsafe.go') diff --git a/pkg/tcpip/link/sharedmem/sharedmem_unsafe.go b/pkg/tcpip/link/sharedmem/sharedmem_unsafe.go index f7e816a41..d974c266e 100644 --- a/pkg/tcpip/link/sharedmem/sharedmem_unsafe.go +++ b/pkg/tcpip/link/sharedmem/sharedmem_unsafe.go @@ -15,7 +15,12 @@ package sharedmem import ( + "fmt" + "reflect" "unsafe" + + "golang.org/x/sys/unix" + "gvisor.dev/gvisor/pkg/memutil" ) // sharedDataPointer converts the shared data slice into a pointer so that it @@ -23,3 +28,31 @@ import ( func sharedDataPointer(sharedData []byte) *uint32 { return (*uint32)(unsafe.Pointer(&sharedData[0:4][0])) } + +// getBuffer returns a memory region mapped to the full contents of the given +// file descriptor. +func getBuffer(fd int) ([]byte, error) { + var s unix.Stat_t + if err := unix.Fstat(fd, &s); err != nil { + return nil, err + } + + // Check that size doesn't overflow an int. + if s.Size > int64(^uint(0)>>1) { + return nil, unix.EDOM + } + + addr, err := memutil.MapFile(0 /* addr */, uintptr(s.Size), unix.PROT_READ|unix.PROT_WRITE, unix.MAP_SHARED|unix.MAP_FILE, uintptr(fd), 0 /*offset*/) + if err != nil { + return nil, fmt.Errorf("failed to map memory for buffer fd: %d, error: %s", fd, err) + } + + // Use unsafe to conver addr into a []byte. + var b []byte + hdr := (*reflect.SliceHeader)(unsafe.Pointer(&b)) + hdr.Data = addr + hdr.Len = int(s.Size) + hdr.Cap = int(s.Size) + + return b, nil +} -- cgit v1.2.3