pkg/host: add fuchsia support

1 files changed, 161 insertions, 0 deletions

diff --git a/pkg/host/host_linux.go b/pkg/host/host_linux.go
new file mode 100644
index 000000000..ef301e2dc
--- /dev/null
+++ b/pkg/host/host_linux.go
@@ -0,0 +1,161 @@
+// Copyright 2015 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package host
+
+import (
+	"bytes"
+	"io/ioutil"
+	"runtime"
+	"strconv"
+	"strings"
+	"syscall"
+
+	"github.com/google/syzkaller/pkg/osutil"
+	"github.com/google/syzkaller/prog"
+)
+
+// DetectSupportedSyscalls returns list on supported syscalls on host.
+func DetectSupportedSyscalls(target *prog.Target) (map[*prog.Syscall]bool, error) {
+	// There are 3 possible strategies:
+	// 1. Executes all syscalls with presumably invalid arguments and check for ENOprog.
+	//    But not all syscalls are safe to execute. For example, pause will hang,
+	//    while setpgrp will push the process into own process group.
+	// 2. Check presence of /sys/kernel/debug/tracing/events/syscalls/sys_enter_* files.
+	//    This requires root and CONFIG_FTRACE_SYSCALLS. Also it lies for some syscalls.
+	//    For example, on x86_64 it says that sendfile is not present (only sendfile64).
+	// 3. Check sys_syscallname in /proc/kallsyms.
+	//    Requires CONFIG_KALLSYMS. Seems to be the most reliable. That's what we use here.
+
+	kallsyms, _ := ioutil.ReadFile("/proc/kallsyms")
+	supported := make(map[*prog.Syscall]bool)
+	for _, c := range target.Syscalls {
+		if isSupported(kallsyms, c) {
+			supported[c] = true
+		}
+	}
+	return supported, nil
+}
+
+func isSupported(kallsyms []byte, c *prog.Syscall) bool {
+	if strings.HasPrefix(c.CallName, "syz_") {
+		return isSupportedSyzkall(c)
+	}
+	if strings.HasPrefix(c.Name, "socket$") {
+		return isSupportedSocket(c)
+	}
+	if strings.HasPrefix(c.Name, "open$") {
+		return isSupportedOpen(c)
+	}
+	if strings.HasPrefix(c.Name, "openat$") {
+		return isSupportedOpenAt(c)
+	}
+	if len(kallsyms) == 0 {
+		return true
+	}
+	return bytes.Index(kallsyms, []byte(" T sys_"+c.CallName+"\n")) != -1
+}
+
+func isSupportedSyzkall(c *prog.Syscall) bool {
+	switch c.CallName {
+	case "syz_test":
+		return false
+	case "syz_open_dev":
+		if _, ok := c.Args[0].(*prog.ConstType); ok {
+			// This is for syz_open_dev$char/block.
+			// They are currently commented out, but in case one enables them.
+			return true
+		}
+		fname, ok := extractStringConst(c.Args[0])
+		if !ok {
+			panic("first open arg is not a pointer to string const")
+		}
+		if syscall.Getuid() != 0 {
+			return false
+		}
+		var check func(dev string) bool
+		check = func(dev string) bool {
+			if !strings.Contains(dev, "#") {
+				return osutil.IsExist(dev)
+			}
+			for i := 0; i < 10; i++ {
+				if check(strings.Replace(dev, "#", strconv.Itoa(i), 1)) {
+					return true
+				}
+			}
+			return false
+		}
+		return check(fname)
+	case "syz_open_pts":
+		return true
+	case "syz_fuse_mount":
+		return osutil.IsExist("/dev/fuse")
+	case "syz_fuseblk_mount":
+		return osutil.IsExist("/dev/fuse") && syscall.Getuid() == 0
+	case "syz_emit_ethernet", "syz_extract_tcp_res":
+		fd, err := syscall.Open("/dev/net/tun", syscall.O_RDWR, 0)
+		if err == nil {
+			syscall.Close(fd)
+		}
+		return err == nil && syscall.Getuid() == 0
+	case "syz_kvm_setup_cpu":
+		switch c.Name {
+		case "syz_kvm_setup_cpu$x86":
+			return runtime.GOARCH == "amd64" || runtime.GOARCH == "386"
+		case "syz_kvm_setup_cpu$arm64":
+			return runtime.GOARCH == "arm64"
+		}
+	}
+	panic("unknown syzkall: " + c.Name)
+}
+
+func isSupportedSocket(c *prog.Syscall) bool {
+	af, ok := c.Args[0].(*prog.ConstType)
+	if !ok {
+		println(c.Name)
+		panic("socket family is not const")
+	}
+	fd, err := syscall.Socket(int(af.Val), 0, 0)
+	if fd != -1 {
+		syscall.Close(fd)
+	}
+	return err != syscall.ENOSYS && err != syscall.EAFNOSUPPORT
+}
+
+func isSupportedOpen(c *prog.Syscall) bool {
+	fname, ok := extractStringConst(c.Args[0])
+	if !ok {
+		return true
+	}
+	fd, err := syscall.Open(fname, syscall.O_RDONLY, 0)
+	if fd != -1 {
+		syscall.Close(fd)
+	}
+	return err == nil
+}
+
+func isSupportedOpenAt(c *prog.Syscall) bool {
+	fname, ok := extractStringConst(c.Args[1])
+	if !ok {
+		return true
+	}
+	fd, err := syscall.Open(fname, syscall.O_RDONLY, 0)
+	if fd != -1 {
+		syscall.Close(fd)
+	}
+	return err == nil
+}
+
+func extractStringConst(typ prog.Type) (string, bool) {
+	ptr, ok := typ.(*prog.PtrType)
+	if !ok {
+		panic("first open arg is not a pointer to string const")
+	}
+	str, ok := ptr.Type.(*prog.BufferType)
+	if !ok || str.Kind != prog.BufferString || len(str.Values) != 1 {
+		return "", false
+	}
+	v := str.Values[0]
+	v = v[:len(v)-1] // string terminating \x00
+	return v, true
+}