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Message-ID: <97ca7651b7ae9a0b6dce4d23c76af266fbd5642f.camel@linux.ibm.com>
Date: Mon, 06 Dec 2021 16:14:15 -0500
From: James Bottomley <jejb@...ux.ibm.com>
To: Stefan Berger <stefanb@...ux.ibm.com>,
linux-integrity@...r.kernel.org
Cc: zohar@...ux.ibm.com, serge@...lyn.com,
christian.brauner@...ntu.com, containers@...ts.linux.dev,
dmitry.kasatkin@...il.com, ebiederm@...ssion.com,
krzysztof.struczynski@...wei.com, roberto.sassu@...wei.com,
mpeters@...hat.com, lhinds@...hat.com, lsturman@...hat.com,
puiterwi@...hat.com, jamjoom@...ibm.com,
linux-kernel@...r.kernel.org, paul@...l-moore.com, rgb@...hat.com,
linux-security-module@...r.kernel.org, jmorris@...ei.org
Subject: Re: [PATCH v3 00/16] ima: Namespace IMA with audit support in IMA-ns
On Mon, 2021-12-06 at 12:25 -0500, Stefan Berger wrote:
[...]
> v3:
> - Further modifications to virtualized SecurityFS following James's
> posted patch
> - Dropping of early teardown for user_namespaces since not needed
> anymore
This is my incremental to this series that moves the namespaced
securityfs away from using a vfsmount and on to a root dentry instead,
meaning we can call the blocking notifier from fill_super as Christian
requested (and thus can remove the securityfs_notifier_sent indicator
since it's only called once).
James
---
>From 07b680d5fd59f5d3cea5580be25a2c9e08a01c3b Mon Sep 17 00:00:00 2001
From: James Bottomley <James.Bottomley@...senPartnership.com>
Date: Mon, 6 Dec 2021 20:27:00 +0000
Subject: [PATCH] Incremental for d_root
---
include/linux/user_namespace.h | 3 +-
security/inode.c | 55 +++++++++++++---------------------
2 files changed, 22 insertions(+), 36 deletions(-)
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 6b8bd060d8c4..03a0879376a0 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -104,8 +104,7 @@ struct user_namespace {
struct ima_namespace *ima_ns;
#endif
#ifdef CONFIG_SECURITYFS
- struct vfsmount *securityfs_mount;
- bool securityfs_notifier_sent;
+ struct dentry *securityfs_root;
#endif
} __randomize_layout;
diff --git a/security/inode.c b/security/inode.c
index 45211845fc31..f8b6cb3dfb87 100644
--- a/security/inode.c
+++ b/security/inode.c
@@ -24,6 +24,7 @@
#include <linux/magic.h>
#include <linux/user_namespace.h>
+static struct vfsmount *securityfs_mount;
static int securityfs_mount_count;
static BLOCKING_NOTIFIER_HEAD(securityfs_ns_notifier);
@@ -40,43 +41,24 @@ static const struct super_operations securityfs_super_operations = {
.free_inode = securityfs_free_inode,
};
-static struct file_system_type fs_type;
-
-static void securityfs_free_context(struct fs_context *fc)
-{
- struct user_namespace *ns = fc->user_ns;
-
- if (ns == &init_user_ns ||
- ns->securityfs_notifier_sent)
- return;
-
- ns->securityfs_notifier_sent = true;
-
- ns->securityfs_mount = vfs_kern_mount(&fs_type, SB_KERNMOUNT,
- fs_type.name, NULL);
- if (IS_ERR(ns->securityfs_mount)) {
- printk(KERN_ERR "kern mount on securityfs ERROR: %ld\n",
- PTR_ERR(ns->securityfs_mount));
- ns->securityfs_mount = NULL;
- return;
- }
-
- blocking_notifier_call_chain(&securityfs_ns_notifier,
- SECURITYFS_NS_ADD, fc->user_ns);
- mntput(ns->securityfs_mount);
-}
-
static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc)
{
static const struct tree_descr files[] = {{""}};
int error;
+ struct user_namespace *ns = fc->user_ns;
error = simple_fill_super(sb, SECURITYFS_MAGIC, files);
if (error)
return error;
+ ns->securityfs_root = dget(sb->s_root);
+
sb->s_op = &securityfs_super_operations;
+ if (ns != &init_user_ns)
+ blocking_notifier_call_chain(&securityfs_ns_notifier,
+ SECURITYFS_NS_ADD, ns);
+
return 0;
}
@@ -87,7 +69,6 @@ static int securityfs_get_tree(struct fs_context *fc)
static const struct fs_context_operations securityfs_context_ops = {
.get_tree = securityfs_get_tree,
- .free = securityfs_free_context,
};
static int securityfs_init_fs_context(struct fs_context *fc)
@@ -104,8 +85,10 @@ static void securityfs_kill_super(struct super_block *sb)
blocking_notifier_call_chain(&securityfs_ns_notifier,
SECURITYFS_NS_REMOVE,
sb->s_fs_info);
- ns->securityfs_notifier_sent = false;
- ns->securityfs_mount = NULL;
+
+ dput(ns->securityfs_root);
+ ns->securityfs_root = NULL;
+
kill_litter_super(sb);
}
@@ -174,14 +157,18 @@ static struct dentry *securityfs_create_dentry(const char *name, umode_t mode,
pr_debug("securityfs: creating file '%s'\n",name);
if (ns == &init_user_ns) {
- error = simple_pin_fs(&fs_type, &ns->securityfs_mount,
+ error = simple_pin_fs(&fs_type, &securityfs_mount,
&securityfs_mount_count);
if (error)
return ERR_PTR(error);
}
- if (!parent)
- parent = ns->securityfs_mount->mnt_root;
+ if (!parent) {
+ if (ns == &init_user_ns)
+ parent = securityfs_mount->mnt_root;
+ else
+ parent = ns->securityfs_root;
+ }
dir = d_inode(parent);
@@ -227,7 +214,7 @@ static struct dentry *securityfs_create_dentry(const char *name, umode_t mode,
out:
inode_unlock(dir);
if (ns == &init_user_ns)
- simple_release_fs(&ns->securityfs_mount,
+ simple_release_fs(&securityfs_mount,
&securityfs_mount_count);
return dentry;
}
@@ -371,7 +358,7 @@ void securityfs_remove(struct dentry *dentry)
}
inode_unlock(dir);
if (ns == &init_user_ns)
- simple_release_fs(&ns->securityfs_mount,
+ simple_release_fs(&securityfs_mount,
&securityfs_mount_count);
}
EXPORT_SYMBOL_GPL(securityfs_remove);
--
2.33.0
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