From 7db196c4dbb33562dbfaa28a9476c590f356b2b5 Mon Sep 17 00:00:00 2001
From: Dean Deng <deandeng@google.com>
Date: Fri, 19 Jun 2020 11:48:24 -0700
Subject: Port fadvise64 to vfs2.

Like vfs1, we have a trivial implementation that ignores all valid advice.

Updates #2923.

PiperOrigin-RevId: 317349505
---
 pkg/sentry/syscalls/linux/sys_file.go  | 25 ++++++----------------
 pkg/sentry/syscalls/linux/vfs2/fd.go   | 38 ++++++++++++++++++++++++++++++++++
 pkg/sentry/syscalls/linux/vfs2/vfs2.go |  2 +-
 3 files changed, 45 insertions(+), 20 deletions(-)

(limited to 'pkg/sentry/syscalls/linux')

diff --git a/pkg/sentry/syscalls/linux/sys_file.go b/pkg/sentry/syscalls/linux/sys_file.go
index 696e1c8d3..35eba20c5 100644
--- a/pkg/sentry/syscalls/linux/sys_file.go
+++ b/pkg/sentry/syscalls/linux/sys_file.go
@@ -1111,17 +1111,6 @@ func Fcntl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
 	}
 }
 
-// LINT.ThenChange(vfs2/fd.go)
-
-const (
-	_FADV_NORMAL     = 0
-	_FADV_RANDOM     = 1
-	_FADV_SEQUENTIAL = 2
-	_FADV_WILLNEED   = 3
-	_FADV_DONTNEED   = 4
-	_FADV_NOREUSE    = 5
-)
-
 // Fadvise64 implements linux syscall fadvise64(2).
 // This implementation currently ignores the provided advice.
 func Fadvise64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
@@ -1146,12 +1135,12 @@ func Fadvise64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sys
 	}
 
 	switch advice {
-	case _FADV_NORMAL:
-	case _FADV_RANDOM:
-	case _FADV_SEQUENTIAL:
-	case _FADV_WILLNEED:
-	case _FADV_DONTNEED:
-	case _FADV_NOREUSE:
+	case linux.POSIX_FADV_NORMAL:
+	case linux.POSIX_FADV_RANDOM:
+	case linux.POSIX_FADV_SEQUENTIAL:
+	case linux.POSIX_FADV_WILLNEED:
+	case linux.POSIX_FADV_DONTNEED:
+	case linux.POSIX_FADV_NOREUSE:
 	default:
 		return 0, nil, syserror.EINVAL
 	}
@@ -1160,8 +1149,6 @@ func Fadvise64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sys
 	return 0, nil, nil
 }
 
-// LINT.IfChange
-
 func mkdirAt(t *kernel.Task, dirFD int32, addr usermem.Addr, mode linux.FileMode) error {
 	path, _, err := copyInPath(t, addr, false /* allowEmpty */)
 	if err != nil {
diff --git a/pkg/sentry/syscalls/linux/vfs2/fd.go b/pkg/sentry/syscalls/linux/vfs2/fd.go
index f5eaa076b..e68b20bed 100644
--- a/pkg/sentry/syscalls/linux/vfs2/fd.go
+++ b/pkg/sentry/syscalls/linux/vfs2/fd.go
@@ -210,3 +210,41 @@ func posixLock(t *kernel.Task, args arch.SyscallArguments, file *vfs.FileDescrip
 		return syserror.EINVAL
 	}
 }
+
+// Fadvise64 implements fadvise64(2).
+// This implementation currently ignores the provided advice.
+func Fadvise64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	fd := args[0].Int()
+	length := args[2].Int64()
+	advice := args[3].Int()
+
+	// Note: offset is allowed to be negative.
+	if length < 0 {
+		return 0, nil, syserror.EINVAL
+	}
+
+	file := t.GetFileVFS2(fd)
+	if file == nil {
+		return 0, nil, syserror.EBADF
+	}
+	defer file.DecRef()
+
+	// If the FD refers to a pipe or FIFO, return error.
+	if _, isPipe := file.Impl().(*pipe.VFSPipeFD); isPipe {
+		return 0, nil, syserror.ESPIPE
+	}
+
+	switch advice {
+	case linux.POSIX_FADV_NORMAL:
+	case linux.POSIX_FADV_RANDOM:
+	case linux.POSIX_FADV_SEQUENTIAL:
+	case linux.POSIX_FADV_WILLNEED:
+	case linux.POSIX_FADV_DONTNEED:
+	case linux.POSIX_FADV_NOREUSE:
+	default:
+		return 0, nil, syserror.EINVAL
+	}
+
+	// Sure, whatever.
+	return 0, nil, nil
+}
diff --git a/pkg/sentry/syscalls/linux/vfs2/vfs2.go b/pkg/sentry/syscalls/linux/vfs2/vfs2.go
index caa6a98ff..b463edf2a 100644
--- a/pkg/sentry/syscalls/linux/vfs2/vfs2.go
+++ b/pkg/sentry/syscalls/linux/vfs2/vfs2.go
@@ -108,7 +108,7 @@ func Override() {
 	s.Table[209] = syscalls.PartiallySupported("io_submit", IoSubmit, "Generally supported with exceptions. User ring optimizations are not implemented.", []string{"gvisor.dev/issue/204"})
 	s.Table[213] = syscalls.Supported("epoll_create", EpollCreate)
 	s.Table[217] = syscalls.Supported("getdents64", Getdents64)
-	delete(s.Table, 221) // fdavise64
+	s.Table[221] = syscalls.PartiallySupported("fadvise64", Fadvise64, "The syscall is 'supported', but ignores all provided advice.", nil)
 	s.Table[232] = syscalls.Supported("epoll_wait", EpollWait)
 	s.Table[233] = syscalls.Supported("epoll_ctl", EpollCtl)
 	s.Table[235] = syscalls.Supported("utimes", Utimes)
-- 
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