From 744401297a8c93ce5992ba99aa84f3dcdc19ae9e Mon Sep 17 00:00:00 2001
From: Jamie Liu <jamieliu@google.com>
Date: Wed, 18 Dec 2019 15:47:24 -0800
Subject: Add VFS2 plumbing for extended attributes.

PiperOrigin-RevId: 286281274
---
 pkg/sentry/vfs/file_description.go | 49 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 48 insertions(+), 1 deletion(-)

(limited to 'pkg/sentry/vfs/file_description.go')

diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go
index 6575afd16..c5a9adca3 100644
--- a/pkg/sentry/vfs/file_description.go
+++ b/pkg/sentry/vfs/file_description.go
@@ -22,6 +22,7 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
@@ -212,7 +213,21 @@ type FileDescriptionImpl interface {
 	// Ioctl implements the ioctl(2) syscall.
 	Ioctl(ctx context.Context, uio usermem.IO, args arch.SyscallArguments) (uintptr, error)
 
-	// TODO: extended attributes; file locking
+	// Listxattr returns all extended attribute names for the file.
+	Listxattr(ctx context.Context) ([]string, error)
+
+	// Getxattr returns the value associated with the given extended attribute
+	// for the file.
+	Getxattr(ctx context.Context, name string) (string, error)
+
+	// Setxattr changes the value associated with the given extended attribute
+	// for the file.
+	Setxattr(ctx context.Context, opts SetxattrOptions) error
+
+	// Removexattr removes the given extended attribute from the file.
+	Removexattr(ctx context.Context, name string) error
+
+	// TODO: file locking
 }
 
 // Dirent holds the information contained in struct linux_dirent64.
@@ -329,6 +344,38 @@ func (fd *FileDescription) Ioctl(ctx context.Context, uio usermem.IO, args arch.
 	return fd.impl.Ioctl(ctx, uio, args)
 }
 
+// Listxattr returns all extended attribute names for the file represented by
+// fd.
+func (fd *FileDescription) Listxattr(ctx context.Context) ([]string, error) {
+	names, err := fd.impl.Listxattr(ctx)
+	if err == syserror.ENOTSUP {
+		// Linux doesn't actually return ENOTSUP in this case; instead,
+		// fs/xattr.c:vfs_listxattr() falls back to allowing the security
+		// subsystem to return security extended attributes, which by default
+		// don't exist.
+		return nil, nil
+	}
+	return names, err
+}
+
+// Getxattr returns the value associated with the given extended attribute for
+// the file represented by fd.
+func (fd *FileDescription) Getxattr(ctx context.Context, name string) (string, error) {
+	return fd.impl.Getxattr(ctx, name)
+}
+
+// Setxattr changes the value associated with the given extended attribute for
+// the file represented by fd.
+func (fd *FileDescription) Setxattr(ctx context.Context, opts SetxattrOptions) error {
+	return fd.impl.Setxattr(ctx, opts)
+}
+
+// Removexattr removes the given extended attribute from the file represented
+// by fd.
+func (fd *FileDescription) Removexattr(ctx context.Context, name string) error {
+	return fd.impl.Removexattr(ctx, name)
+}
+
 // SyncFS instructs the filesystem containing fd to execute the semantics of
 // syncfs(2).
 func (fd *FileDescription) SyncFS(ctx context.Context) error {
-- 
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