From 2ba6198851dc1e293295d7cadf8c0ae456b68beb Mon Sep 17 00:00:00 2001
From: Dean Deng <deandeng@google.com>
Date: Tue, 21 Jan 2020 12:41:50 -0800
Subject: Add syscalls for lgetxattr, fgetxattr, lsetxattr, and fsetxattr.
Note that these simply will use the same logic as getxattr and setxattr, which
is not yet implemented for most filesystems.
PiperOrigin-RevId: 290800960
---
pkg/sentry/syscalls/linux/linux64_amd64.go | 8 +-
pkg/sentry/syscalls/linux/linux64_arm64.go | 8 +-
pkg/sentry/syscalls/linux/sys_xattr.go | 136 +++++++++++++++++++++--------
3 files changed, 109 insertions(+), 43 deletions(-)
(limited to 'pkg')
diff --git a/pkg/sentry/syscalls/linux/linux64_amd64.go b/pkg/sentry/syscalls/linux/linux64_amd64.go
index 6b2920900..c76771a54 100644
--- a/pkg/sentry/syscalls/linux/linux64_amd64.go
+++ b/pkg/sentry/syscalls/linux/linux64_amd64.go
@@ -229,11 +229,11 @@ var AMD64 = &kernel.SyscallTable{
186: syscalls.Supported("gettid", Gettid),
187: syscalls.Supported("readahead", Readahead),
188: syscalls.PartiallySupported("setxattr", SetXattr, "Only supported for tmpfs.", nil),
- 189: syscalls.Error("lsetxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
- 190: syscalls.Error("fsetxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
+ 189: syscalls.PartiallySupported("lsetxattr", LSetXattr, "Only supported for tmpfs.", nil),
+ 190: syscalls.PartiallySupported("fsetxattr", FSetXattr, "Only supported for tmpfs.", nil),
191: syscalls.PartiallySupported("getxattr", GetXattr, "Only supported for tmpfs.", nil),
- 192: syscalls.ErrorWithEvent("lgetxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
- 193: syscalls.ErrorWithEvent("fgetxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
+ 192: syscalls.PartiallySupported("lgetxattr", LGetXattr, "Only supported for tmpfs.", nil),
+ 193: syscalls.PartiallySupported("fgetxattr", FGetXattr, "Only supported for tmpfs.", nil),
194: syscalls.ErrorWithEvent("listxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
195: syscalls.ErrorWithEvent("llistxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
196: syscalls.ErrorWithEvent("flistxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
diff --git a/pkg/sentry/syscalls/linux/linux64_arm64.go b/pkg/sentry/syscalls/linux/linux64_arm64.go
index c9629f6f3..d3587fda6 100644
--- a/pkg/sentry/syscalls/linux/linux64_arm64.go
+++ b/pkg/sentry/syscalls/linux/linux64_arm64.go
@@ -42,11 +42,11 @@ var ARM64 = &kernel.SyscallTable{
3: syscalls.PartiallySupported("io_cancel", IoCancel, "Generally supported with exceptions. User ring optimizations are not implemented.", []string{"gvisor.dev/issue/204"}),
4: syscalls.PartiallySupported("io_getevents", IoGetevents, "Generally supported with exceptions. User ring optimizations are not implemented.", []string{"gvisor.dev/issue/204"}),
5: syscalls.PartiallySupported("setxattr", SetXattr, "Only supported for tmpfs.", nil),
- 6: syscalls.Error("lsetxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
- 7: syscalls.Error("fsetxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
+ 6: syscalls.PartiallySupported("lsetxattr", LSetXattr, "Only supported for tmpfs.", nil),
+ 7: syscalls.PartiallySupported("fsetxattr", FSetXattr, "Only supported for tmpfs.", nil),
8: syscalls.PartiallySupported("getxattr", GetXattr, "Only supported for tmpfs.", nil),
- 9: syscalls.ErrorWithEvent("lgetxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
- 10: syscalls.ErrorWithEvent("fgetxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
+ 9: syscalls.PartiallySupported("lgetxattr", LGetXattr, "Only supported for tmpfs.", nil),
+ 10: syscalls.PartiallySupported("fgetxattr", FGetXattr, "Only supported for tmpfs.", nil),
11: syscalls.ErrorWithEvent("listxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
12: syscalls.ErrorWithEvent("llistxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
13: syscalls.ErrorWithEvent("flistxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
diff --git a/pkg/sentry/syscalls/linux/sys_xattr.go b/pkg/sentry/syscalls/linux/sys_xattr.go
index 23d20da6f..e35c077d6 100644
--- a/pkg/sentry/syscalls/linux/sys_xattr.go
+++ b/pkg/sentry/syscalls/linux/sys_xattr.go
@@ -27,6 +27,40 @@ import (
// GetXattr implements linux syscall getxattr(2).
func GetXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+ return getXattrFromPath(t, args, true)
+}
+
+// LGetXattr implements linux syscall lgetxattr(2).
+func LGetXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+ return getXattrFromPath(t, args, false)
+}
+
+// FGetXattr implements linux syscall fgetxattr(2).
+func FGetXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+ fd := args[0].Int()
+ nameAddr := args[1].Pointer()
+ valueAddr := args[2].Pointer()
+ size := uint64(args[3].SizeT())
+
+ // TODO(b/113957122): Return EBADF if the fd was opened with O_PATH.
+ f := t.GetFile(fd)
+ if f == nil {
+ return 0, nil, syserror.EBADF
+ }
+ defer f.DecRef()
+
+ n, value, err := getXattr(t, f.Dirent, nameAddr, size)
+ if err != nil {
+ return 0, nil, err
+ }
+
+ if _, err := t.CopyOutBytes(valueAddr, []byte(value)); err != nil {
+ return 0, nil, err
+ }
+ return uintptr(n), nil, nil
+}
+
+func getXattrFromPath(t *kernel.Task, args arch.SyscallArguments, resolveSymlink bool) (uintptr, *kernel.SyscallControl, error) {
pathAddr := args[0].Pointer()
nameAddr := args[1].Pointer()
valueAddr := args[2].Pointer()
@@ -38,29 +72,17 @@ func GetXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
}
valueLen := 0
- err = fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
- // If getxattr(2) is called with size 0, the size of the value will be
- // returned successfully even if it is nonzero. In that case, we need to
- // retrieve the entire attribute value so we can return the correct size.
- requestedSize := size
- if size == 0 || size > linux.XATTR_SIZE_MAX {
- requestedSize = linux.XATTR_SIZE_MAX
+ err = fileOpOn(t, linux.AT_FDCWD, path, resolveSymlink, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
+ if dirPath && !fs.IsDir(d.Inode.StableAttr) {
+ return syserror.ENOTDIR
}
- value, err := getXattr(t, d, dirPath, nameAddr, uint64(requestedSize))
+ n, value, err := getXattr(t, d, nameAddr, size)
+ valueLen = n
if err != nil {
return err
}
- valueLen = len(value)
- if uint64(valueLen) > requestedSize {
- return syserror.ERANGE
- }
-
- // Skip copying out the attribute value if size is 0.
- if size == 0 {
- return nil
- }
_, err = t.CopyOutBytes(valueAddr, []byte(value))
return err
})
@@ -71,29 +93,73 @@ func GetXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
}
// getXattr implements getxattr(2) from the given *fs.Dirent.
-func getXattr(t *kernel.Task, d *fs.Dirent, dirPath bool, nameAddr usermem.Addr, size uint64) (string, error) {
- if dirPath && !fs.IsDir(d.Inode.StableAttr) {
- return "", syserror.ENOTDIR
- }
-
+func getXattr(t *kernel.Task, d *fs.Dirent, nameAddr usermem.Addr, size uint64) (int, string, error) {
if err := checkXattrPermissions(t, d.Inode, fs.PermMask{Read: true}); err != nil {
- return "", err
+ return 0, "", err
}
name, err := copyInXattrName(t, nameAddr)
if err != nil {
- return "", err
+ return 0, "", err
}
if !strings.HasPrefix(name, linux.XATTR_USER_PREFIX) {
- return "", syserror.EOPNOTSUPP
+ return 0, "", syserror.EOPNOTSUPP
}
- return d.Inode.GetXattr(t, name, size)
+ // If getxattr(2) is called with size 0, the size of the value will be
+ // returned successfully even if it is nonzero. In that case, we need to
+ // retrieve the entire attribute value so we can return the correct size.
+ requestedSize := size
+ if size == 0 || size > linux.XATTR_SIZE_MAX {
+ requestedSize = linux.XATTR_SIZE_MAX
+ }
+
+ value, err := d.Inode.GetXattr(t, name, requestedSize)
+ if err != nil {
+ return 0, "", err
+ }
+ n := len(value)
+ if uint64(n) > requestedSize {
+ return 0, "", syserror.ERANGE
+ }
+
+ // Don't copy out the attribute value if size is 0.
+ if size == 0 {
+ return n, "", nil
+ }
+ return n, value, nil
}
// SetXattr implements linux syscall setxattr(2).
func SetXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+ return setXattrFromPath(t, args, true)
+}
+
+// LSetXattr implements linux syscall lsetxattr(2).
+func LSetXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+ return setXattrFromPath(t, args, false)
+}
+
+// FSetXattr implements linux syscall fsetxattr(2).
+func FSetXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+ fd := args[0].Int()
+ nameAddr := args[1].Pointer()
+ valueAddr := args[2].Pointer()
+ size := uint64(args[3].SizeT())
+ flags := args[4].Uint()
+
+ // TODO(b/113957122): Return EBADF if the fd was opened with O_PATH.
+ f := t.GetFile(fd)
+ if f == nil {
+ return 0, nil, syserror.EBADF
+ }
+ defer f.DecRef()
+
+ return 0, nil, setXattr(t, f.Dirent, nameAddr, valueAddr, uint64(size), flags)
+}
+
+func setXattrFromPath(t *kernel.Task, args arch.SyscallArguments, resolveSymlink bool) (uintptr, *kernel.SyscallControl, error) {
pathAddr := args[0].Pointer()
nameAddr := args[1].Pointer()
valueAddr := args[2].Pointer()
@@ -105,19 +171,19 @@ func SetXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
return 0, nil, err
}
- if flags&^(linux.XATTR_CREATE|linux.XATTR_REPLACE) != 0 {
- return 0, nil, syserror.EINVAL
- }
+ return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, resolveSymlink, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
+ if dirPath && !fs.IsDir(d.Inode.StableAttr) {
+ return syserror.ENOTDIR
+ }
- return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
- return setXattr(t, d, dirPath, nameAddr, valueAddr, uint64(size), flags)
+ return setXattr(t, d, nameAddr, valueAddr, uint64(size), flags)
})
}
// setXattr implements setxattr(2) from the given *fs.Dirent.
-func setXattr(t *kernel.Task, d *fs.Dirent, dirPath bool, nameAddr, valueAddr usermem.Addr, size uint64, flags uint32) error {
- if dirPath && !fs.IsDir(d.Inode.StableAttr) {
- return syserror.ENOTDIR
+func setXattr(t *kernel.Task, d *fs.Dirent, nameAddr, valueAddr usermem.Addr, size uint64, flags uint32) error {
+ if flags&^(linux.XATTR_CREATE|linux.XATTR_REPLACE) != 0 {
+ return syserror.EINVAL
}
if err := checkXattrPermissions(t, d.Inode, fs.PermMask{Write: true}); err != nil {
@@ -133,7 +199,7 @@ func setXattr(t *kernel.Task, d *fs.Dirent, dirPath bool, nameAddr, valueAddr us
return syserror.E2BIG
}
buf := make([]byte, size)
- if _, err = t.CopyInBytes(valueAddr, buf); err != nil {
+ if _, err := t.CopyInBytes(valueAddr, buf); err != nil {
return err
}
value := string(buf)
--
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