2022-12-01 11:00:47

by Roberto Sassu

Subject: [PATCH v7 1/6] reiserfs: Switch to security_inode_init_security()

From: Roberto Sassu <[email protected]>

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 <[email protected]>
Reviewed-by: Casey Schaufler <[email protected]>
---
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

2023-02-17 19:48:21

by Mimi Zohar

Subject: Re: [PATCH v7 1/6] reiserfs: Switch to security_inode_init_security()

On Thu, 2022-12-01 at 11:41 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <[email protected]>
>
> 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 <[email protected]>
> Reviewed-by: Casey Schaufler <[email protected]>

Now that commit 572302af1258 ("reiserfs: Add missing calls to
reiserfs_security_free()") is upstreamed, please include a dependency
comment.

Reviewed-by: Mimi Zohar <[email protected]>

> ---
> 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;