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50 lines
1001 B
Go
50 lines
1001 B
Go
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// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build linux
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package ipnserver
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import (
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"net"
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"golang.org/x/sys/unix"
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"tailscale.com/types/logger"
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)
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func isReadonlyConn(c net.Conn, logf logger.Logf) (ro bool) {
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ro = true // conservative default for naked returns below
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uc, ok := c.(*net.UnixConn)
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if !ok {
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logf("unexpected connection type %T", c)
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return
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}
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raw, err := uc.SyscallConn()
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if err != nil {
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logf("SyscallConn: %v", err)
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return
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}
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var cred *unix.Ucred
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cerr := raw.Control(func(fd uintptr) {
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cred, err = unix.GetsockoptUcred(int(fd),
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unix.SOL_SOCKET,
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unix.SO_PEERCRED)
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})
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if cerr != nil {
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logf("raw.Control: %v", err)
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return
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}
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if err != nil {
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logf("raw.Control: %v", err)
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return
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}
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if cred.Uid == 0 {
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// root is not read-only.
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return false
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}
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logf("non-root connection from %v (read-only)", cred.Uid)
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return true
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}
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