From dd3bc499970c22ebbd270030b4564e6b8e4e929e Mon Sep 17 00:00:00 2001
From: Fabricio Voznika <fvoznika@google.com>
Date: Thu, 2 Apr 2020 19:37:41 -0700
Subject: Add NAME_MAX checks and update file times

NAME_MAX should be enforced per filesystem implementation
because other file systems may not have the same restriction.

Gofer filesystem now keeps a reference to the kernel clock to
avoid lookup in the Context on file access to update atime.

Update access, modification, and status change times in tmpfs.

Updates #1197, #1198.

PiperOrigin-RevId: 304527148
---
 pkg/sentry/fsimpl/tmpfs/filesystem.go | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

(limited to 'pkg/sentry/fsimpl/tmpfs/filesystem.go')

diff --git a/pkg/sentry/fsimpl/tmpfs/filesystem.go b/pkg/sentry/fsimpl/tmpfs/filesystem.go
index 4cf27bf13..1978af69c 100644
--- a/pkg/sentry/fsimpl/tmpfs/filesystem.go
+++ b/pkg/sentry/fsimpl/tmpfs/filesystem.go
@@ -46,6 +46,9 @@ func stepLocked(rp *vfs.ResolvingPath, d *dentry) (*dentry, error) {
 		return nil, err
 	}
 afterSymlink:
+	if len(rp.Component()) > linux.NAME_MAX {
+		return nil, syserror.ENAMETOOLONG
+	}
 	nextVFSD, err := rp.ResolveComponent(&d.vfsd)
 	if err != nil {
 		return nil, err
@@ -133,6 +136,9 @@ func (fs *filesystem) doCreateAt(rp *vfs.ResolvingPath, dir bool, create func(pa
 	if name == "." || name == ".." {
 		return syserror.EEXIST
 	}
+	if len(name) > linux.NAME_MAX {
+		return syserror.ENAMETOOLONG
+	}
 	// Call parent.vfsd.Child() instead of stepLocked() or rp.ResolveChild(),
 	// because if the child exists we want to return EEXIST immediately instead
 	// of attempting symlink/mount traversal.
@@ -153,7 +159,11 @@ func (fs *filesystem) doCreateAt(rp *vfs.ResolvingPath, dir bool, create func(pa
 		return err
 	}
 	defer mnt.EndWrite()
-	return create(parent, name)
+	if err := create(parent, name); err != nil {
+		return err
+	}
+	parent.inode.touchCMtime()
+	return nil
 }
 
 // AccessAt implements vfs.Filesystem.Impl.AccessAt.
@@ -328,7 +338,12 @@ afterTrailingSymlink:
 		child := fs.newDentry(fs.newRegularFile(rp.Credentials(), opts.Mode))
 		parent.vfsd.InsertChild(&child.vfsd, name)
 		parent.inode.impl.(*directory).childList.PushBack(child)
-		return child.open(ctx, rp, &opts, true)
+		fd, err := child.open(ctx, rp, &opts, true)
+		if err != nil {
+			return nil, err
+		}
+		parent.inode.touchCMtime()
+		return fd, nil
 	}
 	if err != nil {
 		return nil, err
@@ -398,6 +413,7 @@ func (fs *filesystem) ReadlinkAt(ctx context.Context, rp *vfs.ResolvingPath) (st
 	if !ok {
 		return "", syserror.EINVAL
 	}
+	symlink.inode.touchAtime(rp.Mount())
 	return symlink.target, nil
 }
 
@@ -515,6 +531,9 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 		oldParent.inode.decLinksLocked()
 		newParent.inode.incLinksLocked()
 	}
+	oldParent.inode.touchCMtime()
+	newParent.inode.touchCMtime()
+	renamed.inode.touchCtime()
 	// TODO(gvisor.dev/issue/1197): Update timestamps and parent directory
 	// sizes.
 	vfsObj.CommitRenameReplaceDentry(renamedVFSD, &newParent.vfsd, newName, replacedVFSD)
@@ -565,6 +584,7 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error
 	parent.inode.decLinksLocked() // from child's ".."
 	child.inode.decLinksLocked()
 	vfsObj.CommitDeleteDentry(childVFSD)
+	parent.inode.touchCMtime()
 	return nil
 }
 
@@ -654,6 +674,7 @@ func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error
 	parent.inode.impl.(*directory).childList.Remove(child)
 	child.inode.decLinksLocked()
 	vfsObj.CommitDeleteDentry(childVFSD)
+	parent.inode.touchCMtime()
 	return nil
 }
 
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