From 56c69fb0e7f96e5bd5da9e0d29a78e05dd3e2bba Mon Sep 17 00:00:00 2001 From: Mithun Iyer Date: Mon, 5 Apr 2021 21:51:31 -0700 Subject: Fix listen backlog handling to be in parity with Linux - Change the accept queue full condition for a listening endpoint to only honor completed (and delivered) connections. - Use syncookies if the number of incomplete connections is beyond listen backlog. This also cleans up the SynThreshold option code as that is no longer used with this change. - Added a new stack option to unconditionally generate syncookies. Similar to sysctl -w net.ipv4.tcp_syncookies=2 on Linux. - Enable keeping of incomplete connections beyond listen backlog. - Drop incoming SYNs only if the accept queue is filled up. - Drop incoming ACKs that complete handshakes when accept queue is full - Enable the stack to accept one more connection than programmed by listen backlog. - Handle backlog argument being zero, negative for listen, as Linux. - Add syscall and packetimpact tests to reflect the changes above. - Remove TCPConnectBacklog test which is polling for completed connections on the client side which is not reflective of whether the accept queue is filled up by the test. The modified syscall test in this CL addresses testing of connecting sockets. Fixes #3153 PiperOrigin-RevId: 366935921 --- pkg/sentry/syscalls/linux/sys_socket.go | 14 -------------- pkg/sentry/syscalls/linux/vfs2/socket.go | 14 -------------- 2 files changed, 28 deletions(-) (limited to 'pkg/sentry/syscalls') diff --git a/pkg/sentry/syscalls/linux/sys_socket.go b/pkg/sentry/syscalls/linux/sys_socket.go index 9bdf6d3d8..0141e8a96 100644 --- a/pkg/sentry/syscalls/linux/sys_socket.go +++ b/pkg/sentry/syscalls/linux/sys_socket.go @@ -35,12 +35,6 @@ import ( // LINT.IfChange -// minListenBacklog is the minimum reasonable backlog for listening sockets. -const minListenBacklog = 8 - -// maxListenBacklog is the maximum allowed backlog for listening sockets. -const maxListenBacklog = 1024 - // maxAddrLen is the maximum socket address length we're willing to accept. const maxAddrLen = 200 @@ -382,14 +376,6 @@ func Listen(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal return 0, nil, syserror.ENOTSOCK } - // Per Linux, the backlog is silently capped to reasonable values. - if backlog <= 0 { - backlog = minListenBacklog - } - if backlog > maxListenBacklog { - backlog = maxListenBacklog - } - return 0, nil, s.Listen(t, int(backlog)).ToError() } diff --git a/pkg/sentry/syscalls/linux/vfs2/socket.go b/pkg/sentry/syscalls/linux/vfs2/socket.go index a87a66146..7cc0be892 100644 --- a/pkg/sentry/syscalls/linux/vfs2/socket.go +++ b/pkg/sentry/syscalls/linux/vfs2/socket.go @@ -35,12 +35,6 @@ import ( "gvisor.dev/gvisor/pkg/hostarch" ) -// minListenBacklog is the minimum reasonable backlog for listening sockets. -const minListenBacklog = 8 - -// maxListenBacklog is the maximum allowed backlog for listening sockets. -const maxListenBacklog = 1024 - // maxAddrLen is the maximum socket address length we're willing to accept. const maxAddrLen = 200 @@ -386,14 +380,6 @@ func Listen(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal return 0, nil, syserror.ENOTSOCK } - // Per Linux, the backlog is silently capped to reasonable values. - if backlog <= 0 { - backlog = minListenBacklog - } - if backlog > maxListenBacklog { - backlog = maxListenBacklog - } - return 0, nil, s.Listen(t, int(backlog)).ToError() } -- cgit v1.2.3