linux-kernel - [PATCH v2] kernfs: attach uuid for every kernfs and report it in fsid

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230731184731.64568-1-ivan@cloudflare.com>
Date:   Mon, 31 Jul 2023 11:47:31 -0700
From:   Ivan Babrou <ivan@...udflare.com>
To:     linux-fsdevel@...r.kernel.org
Cc:     kernel-team@...udflare.com, cgroups@...r.kernel.org,
        linux-kernel@...r.kernel.org, Amir Goldstein <amir73il@...il.com>,
        Michal Koutný <mkoutny@...e.com>,
        Ivan Babrou <ivan@...udflare.com>, Jan Kara <jack@...e.cz>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Tejun Heo <tj@...nel.org>
Subject: [PATCH v2] kernfs: attach uuid for every kernfs and report it in fsid

The following two commits added the same thing for tmpfs:

* commit 2b4db79618ad ("tmpfs: generate random sb->s_uuid")
* commit 59cda49ecf6c ("shmem: allow reporting fanotify events with file handles on tmpfs")

Having fsid allows using fanotify, which is especially handy for cgroups,
where one might be interested in knowing when they are created or removed.

Signed-off-by: Ivan Babrou <ivan@...udflare.com>
Acked-by: Jan Kara <jack@...e.cz>

---
v2: Added a missing static and an ack from Jan Kara
---
 fs/kernfs/mount.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index d49606accb07..930026842359 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -16,6 +16,8 @@
 #include <linux/namei.h>
 #include <linux/seq_file.h>
 #include <linux/exportfs.h>
+#include <linux/uuid.h>
+#include <linux/statfs.h>
 
 #include "kernfs-internal.h"
 
@@ -45,8 +47,15 @@ static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry)
 	return 0;
 }
 
+int kernfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	simple_statfs(dentry, buf);
+	buf->f_fsid = uuid_to_fsid(dentry->d_sb->s_uuid.b);
+	return 0;
+}
+
 const struct super_operations kernfs_sops = {
-	.statfs		= simple_statfs,
+	.statfs		= kernfs_statfs,
 	.drop_inode	= generic_delete_inode,
 	.evict_inode	= kernfs_evict_inode,
 
@@ -351,6 +360,8 @@ int kernfs_get_tree(struct fs_context *fc)
 		}
 		sb->s_flags |= SB_ACTIVE;
 
+		uuid_gen(&sb->s_uuid);
+
 		down_write(&root->kernfs_supers_rwsem);
 		list_add(&info->node, &info->root->supers);
 		up_write(&root->kernfs_supers_rwsem);
-- 
2.41.0