Re: [Patch][RFC] fcntl: add ability to stop monitored processes

[Neil Horman <nhorman@redhat.com>]

How about this?  Its the same feature, with an added check in fcntl_dirnotify to
ensure that only processes with CAP_SYS_ADMIN set can tell processes preforming
the monitored actions to stop.

Signed-off-by: Neil Horman <nhorman@redhat.com>


 fs/dnotify.c          |    4 ++++
 fs/fcntl.c            |    1 +
 include/linux/fcntl.h |    1 +
 3 files changed, 6 insertions(+)


--- linux-2.6/include/linux/fcntl.h.orig	2005-06-10 16:04:48.000000000 -0400
+++ linux-2.6/include/linux/fcntl.h	2005-06-10 16:02:16.000000000 -0400
@@ -21,6 +21,7 @@
 #define DN_DELETE	0x00000008	/* File removed */
 #define DN_RENAME	0x00000010	/* File renamed */
 #define DN_ATTRIB	0x00000020	/* File changed attibutes */
+#define DN_STOPSND	0x40000000	/* Send a SIGSTOP to the sender */
 #define DN_MULTISHOT	0x80000000	/* Don't remove notifier */
 
 #ifdef __KERNEL__
--- linux-2.6/fs/dnotify.c.orig	2005-05-04 21:47:58.000000000 -0400
+++ linux-2.6/fs/dnotify.c	2005-06-11 21:27:37.000000000 -0400
@@ -74,6 +74,8 @@ int fcntl_dirnotify(int fd, struct file 
 	}
 	if (!dir_notify_enable)
 		return -EINVAL;
+	if(!capable(CAP_SYS_ADMIN) && (arg & DN_STOPSND))
+		return -EPERM;
 	inode = filp->f_dentry->d_inode;
 	if (!S_ISDIR(inode->i_mode))
 		return -ENOTDIR;
@@ -138,6 +140,8 @@ void __inode_dir_notify(struct inode *in
 			changed = 1;
 			kmem_cache_free(dn_cache, dn);
 		}
+		if (dn->dn_mask & DN_STOPSND)
+			send_sig(SIGSTOP,current,1);
 	}
 	if (changed)
 		redo_inode_mask(inode);
--- linux-2.6/fs/fcntl.c.orig	2005-05-04 21:47:58.000000000 -0400
+++ linux-2.6/fs/fcntl.c	2005-06-10 16:05:17.000000000 -0400
@@ -438,6 +438,7 @@ static void send_sigio_to_task(struct ta
 			else
 				si.si_band = band_table[reason - POLL_IN];
 			si.si_fd    = fd;
+			si.si_pid   = current->pid;
 			if (!send_group_sig_info(fown->signum, &si, p))
 				break;
 		/* fall-through: fall back on the old plain SIGIO signal */
-- 
/***************************************************
 *Neil Horman
 *Software Engineer
 *Red Hat, Inc.
 *nhorman@redhat.com
 *gpg keyid: 1024D / 0x92A74FA1
 *http://pgp.mit.edu
 ***************************************************/