From 050d8e6e331e01d732471e4641dc51346e7a7d3b Mon Sep 17 00:00:00 2001
From: Dean Deng <deandeng@google.com>
Date: Mon, 1 Jun 2020 18:30:09 -0700
Subject: Add inotify events for extended attributes and splice.

Splice, setxattr and removexattr should generate events. Note that VFS2 already
generates events for extended attributes.

Updates #1479.

PiperOrigin-RevId: 314244261
---
 pkg/sentry/syscalls/linux/sys_splice.go  |  6 ++++++
 pkg/sentry/syscalls/linux/sys_xattr.go   | 12 ++++++++++--
 pkg/sentry/syscalls/linux/vfs2/splice.go |  5 +++++
 3 files changed, 21 insertions(+), 2 deletions(-)

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

diff --git a/pkg/sentry/syscalls/linux/sys_splice.go b/pkg/sentry/syscalls/linux/sys_splice.go
index 39f2b79ec..77c78889d 100644
--- a/pkg/sentry/syscalls/linux/sys_splice.go
+++ b/pkg/sentry/syscalls/linux/sys_splice.go
@@ -80,6 +80,12 @@ func doSplice(t *kernel.Task, outFile, inFile *fs.File, opts fs.SpliceOpts, nonB
 		}
 	}
 
+	if total > 0 {
+		// On Linux, inotify behavior is not very consistent with splice(2). We try
+		// our best to emulate Linux for very basic calls to splice, where for some
+		// reason, events are generated for output files, but not input files.
+		outFile.Dirent.InotifyEvent(linux.IN_MODIFY, 0)
+	}
 	return total, err
 }
 
diff --git a/pkg/sentry/syscalls/linux/sys_xattr.go b/pkg/sentry/syscalls/linux/sys_xattr.go
index 2de5e3422..c24946160 100644
--- a/pkg/sentry/syscalls/linux/sys_xattr.go
+++ b/pkg/sentry/syscalls/linux/sys_xattr.go
@@ -207,7 +207,11 @@ func setXattr(t *kernel.Task, d *fs.Dirent, nameAddr, valueAddr usermem.Addr, si
 		return syserror.EOPNOTSUPP
 	}
 
-	return d.Inode.SetXattr(t, d, name, value, flags)
+	if err := d.Inode.SetXattr(t, d, name, value, flags); err != nil {
+		return err
+	}
+	d.InotifyEvent(linux.IN_ATTRIB, 0)
+	return nil
 }
 
 func copyInXattrName(t *kernel.Task, nameAddr usermem.Addr) (string, error) {
@@ -418,7 +422,11 @@ func removeXattr(t *kernel.Task, d *fs.Dirent, nameAddr usermem.Addr) error {
 		return syserror.EOPNOTSUPP
 	}
 
-	return d.Inode.RemoveXattr(t, d, name)
+	if err := d.Inode.RemoveXattr(t, d, name); err != nil {
+		return err
+	}
+	d.InotifyEvent(linux.IN_ATTRIB, 0)
+	return nil
 }
 
 // LINT.ThenChange(vfs2/xattr.go)
diff --git a/pkg/sentry/syscalls/linux/vfs2/splice.go b/pkg/sentry/syscalls/linux/vfs2/splice.go
index 8f3c22a02..945a364a7 100644
--- a/pkg/sentry/syscalls/linux/vfs2/splice.go
+++ b/pkg/sentry/syscalls/linux/vfs2/splice.go
@@ -187,6 +187,11 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
 	if n == 0 {
 		return 0, nil, err
 	}
+
+	// On Linux, inotify behavior is not very consistent with splice(2). We try
+	// our best to emulate Linux for very basic calls to splice, where for some
+	// reason, events are generated for output files, but not input files.
+	outFile.Dentry().InotifyWithParent(linux.IN_MODIFY, 0, vfs.PathEvent)
 	return uintptr(n), nil, nil
 }
 
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