linux-kernel - [PATCH v6 1/6] reiserfs: Switch to security_inode_init

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Date:   Wed, 23 Nov 2022 16:47:07 +0100
From:   Roberto Sassu <roberto.sassu@...weicloud.com>
To:     mark@...heh.com, jlbec@...lplan.org, joseph.qi@...ux.alibaba.com,
        zohar@...ux.ibm.com, dmitry.kasatkin@...il.com,
        paul@...l-moore.com, jmorris@...ei.org, serge@...lyn.com,
        stephen.smalley.work@...il.com, eparis@...isplace.org,
        casey@...aufler-ca.com
Cc:     ocfs2-devel@....oracle.com, reiserfs-devel@...r.kernel.org,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, selinux@...r.kernel.org,
        linux-kernel@...r.kernel.org, keescook@...omium.org,
        nicolas.bouchinet@...p-os.org,
        Roberto Sassu <roberto.sassu@...wei.com>
Subject: [PATCH v6 1/6] reiserfs: Switch to security_inode_init_security()

From: Roberto Sassu <roberto.sassu@...wei.com>

In preparation for removing security_old_inode_init_security(), switch to
security_inode_init_security().

Define the initxattrs callback reiserfs_initxattrs(), to populate the
name/value/len triple in the reiserfs_security_handle() with the first
xattr provided by LSMs. Make a copy of the xattr value, as
security_inode_init_security() frees it.

After the call to security_inode_init_security(), remove the check for
returning -EOPNOTSUPP, as security_inode_init_security() changes it to
zero.

Multiple xattrs are currently not supported, as the
reiserfs_security_handle structure is exported to user space. As a
consequence, even if EVM is invoked, it will not provide an xattr (if it
is not the first to set it, its xattr will be discarded; if it is the
first, it does not have xattrs to calculate the HMAC on).

Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
---
 fs/reiserfs/xattr_security.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/fs/reiserfs/xattr_security.c b/fs/reiserfs/xattr_security.c
index 857a65b05726..0ba96757681d 100644
--- a/fs/reiserfs/xattr_security.c
+++ b/fs/reiserfs/xattr_security.c
@@ -39,6 +39,22 @@ static bool security_list(struct dentry *dentry)
 	return !IS_PRIVATE(d_inode(dentry));
 }
 
+static int
+reiserfs_initxattrs(struct inode *inode, const struct xattr *xattr_array,
+		    void *fs_info)
+{
+	struct reiserfs_security_handle *sec = fs_info;
+
+	sec->value = kmemdup(xattr_array->value, xattr_array->value_len,
+			     GFP_KERNEL);
+	if (!sec->value)
+		return -ENOMEM;
+
+	sec->name = xattr_array->name;
+	sec->length = xattr_array->value_len;
+	return 0;
+}
+
 /* Initializes the security context for a new inode and returns the number
  * of blocks needed for the transaction. If successful, reiserfs_security
  * must be released using reiserfs_security_free when the caller is done. */
@@ -56,12 +72,9 @@ int reiserfs_security_init(struct inode *dir, struct inode *inode,
 	if (IS_PRIVATE(dir))
 		return 0;
 
-	error = security_old_inode_init_security(inode, dir, qstr, &sec->name,
-						 &sec->value, &sec->length);
+	error = security_inode_init_security(inode, dir, qstr,
+					     &reiserfs_initxattrs, sec);
 	if (error) {
-		if (error == -EOPNOTSUPP)
-			error = 0;
-
 		sec->name = NULL;
 		sec->value = NULL;
 		sec->length = 0;
-- 
2.25.1