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authorZach Koopmans <zkoopmans@google.com>2018-11-26 09:49:53 -0800
committerShentubot <shentubot@google.com>2018-11-26 09:50:47 -0800
commitb3b60ea29adf9415c9c7b98ba331dacd92f231b7 (patch)
treeba5ede8546c86e3e0ea1efb5b2f473d219a1ccab /pkg/sentry/syscalls
parent1918563525662d6645ec921e61aa7e6da92af0dd (diff)
Implementation of preadv2 for Linux 4.4 support
Implement RWF_HIPRI (4.6) silently passes the read call. Implement -1 offset calls readv. PiperOrigin-RevId: 222840324 Change-Id: If9ddc1e8d086e1a632bdf5e00bae08205f95b6b0
Diffstat (limited to 'pkg/sentry/syscalls')
-rw-r--r--pkg/sentry/syscalls/linux/linux64.go3
-rw-r--r--pkg/sentry/syscalls/linux/sys_read.go62
2 files changed, 65 insertions, 0 deletions
diff --git a/pkg/sentry/syscalls/linux/linux64.go b/pkg/sentry/syscalls/linux/linux64.go
index 9912ab2b5..2aab948da 100644
--- a/pkg/sentry/syscalls/linux/linux64.go
+++ b/pkg/sentry/syscalls/linux/linux64.go
@@ -373,7 +373,10 @@ var AMD64 = &kernel.SyscallTable{
// 322: Execveat, TODO
// 323: Userfaultfd, TODO
// 324: Membarrier, TODO
+ // Syscalls after 325 are backports from 4.6.
325: syscalls.Error(nil), // Mlock2, TODO
+ 327: Preadv2,
+ // 328: Pwritev2, // Pwritev2, TODO
},
Emulate: map[usermem.Addr]uintptr{
diff --git a/pkg/sentry/syscalls/linux/sys_read.go b/pkg/sentry/syscalls/linux/sys_read.go
index b2e5a5449..cbb9eb9f8 100644
--- a/pkg/sentry/syscalls/linux/sys_read.go
+++ b/pkg/sentry/syscalls/linux/sys_read.go
@@ -187,6 +187,68 @@ func Preadv(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "preadv", file)
}
+// Preadv2 implements linux syscall preadv2(2).
+func Preadv2(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+ fd := kdefs.FD(args[0].Int())
+ addr := args[1].Pointer()
+ iovcnt := int(args[2].Int())
+ offset := args[3].Int64()
+ flags := int(args[4].Int())
+
+ validFlags := linux.RWF_HIPRI
+
+ file := t.FDMap().GetFile(fd)
+ if file == nil {
+ return 0, nil, syserror.EBADF
+ }
+ defer file.DecRef()
+
+ // Check that the offset is legitimate.
+ if offset < -1 {
+ return 0, nil, syserror.EINVAL
+ }
+
+ // Is reading at an offset supported?
+ if offset > -1 && !file.Flags().Pread {
+ return 0, nil, syserror.ESPIPE
+ }
+
+ // Check that the file is readable.
+ if !file.Flags().Read {
+ return 0, nil, syserror.EBADF
+ }
+
+ // Check flags field.
+ if flags != 0 {
+ if flags&^validFlags != 0 {
+ return 0, nil, syserror.EINVAL
+ }
+ // RWF_HIPRI must be called on a file with O_DIRECT flag set.
+ if flags&linux.RWF_HIPRI != 0 && !file.Flags().Direct {
+ return 0, nil, syserror.EINVAL
+ }
+ }
+
+ // Read the iovecs that specify the destination of the read.
+ dst, err := t.IovecsIOSequence(addr, iovcnt, usermem.IOOpts{
+ AddressSpaceActive: true,
+ })
+ if err != nil {
+ return 0, nil, err
+ }
+
+ // If preadv2 is called with an offset of -1, readv is called.
+ if offset == -1 {
+ n, err := readv(t, file, dst)
+ t.IOUsage().AccountReadSyscall(n)
+ return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "preadv2", file)
+ }
+
+ n, err := preadv(t, file, dst, offset)
+ t.IOUsage().AccountReadSyscall(n)
+ return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "preadv2", file)
+}
+
func readv(t *kernel.Task, f *fs.File, dst usermem.IOSequence) (int64, error) {
n, err := f.Readv(t, dst)
if err != syserror.ErrWouldBlock || f.Flags().NonBlocking {