On Fri, Dec 10, 2021 at 02:47:31PM -0500, Stefan Berger wrote:
> Extend 'securityfs' for support of IMA namespacing so that each
> IMA (user) namespace can have its own front-end for showing the currently
> active policy, the measurement list, number of violations and so on.
>
> Drop the addition dentry reference and simplify cleanup to work without
> the additional reference. This enables simple cleanup of dentries upon
> umount.
>
> Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
> Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> ---
> security/inode.c | 14 ++++----------
> 1 file changed, 4 insertions(+), 10 deletions(-)
>
> diff --git a/security/inode.c b/security/inode.c
> index fee01ff4d831..c77ae8ecc464 100644
> --- a/security/inode.c
> +++ b/security/inode.c
> @@ -54,7 +54,7 @@ static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc)
>
> static int securityfs_get_tree(struct fs_context *fc)
> {
> - return get_tree_single(fc, securityfs_fill_super);
> + return get_tree_keyed(fc, securityfs_fill_super, fc->user_ns);
> }
>
> static const struct fs_context_operations securityfs_context_ops = {
> @@ -72,6 +72,7 @@ static struct file_system_type fs_type = {
> .name = "securityfs",
> .init_fs_context = securityfs_init_fs_context,
> .kill_sb = kill_litter_super,
> + .fs_flags = FS_USERNS_MOUNT,
> };
>
> /**
> @@ -168,7 +169,6 @@ static struct dentry *securityfs_create_dentry(const char *name, umode_t mode,
> inode->i_fop = fops;
> }
> d_instantiate(dentry, inode);
> - dget(dentry);
> inode_unlock(dir);
> return dentry;
>
> @@ -306,23 +306,17 @@ EXPORT_SYMBOL_GPL(securityfs_create_symlink);
> void securityfs_remove(struct dentry *dentry)
> {
> struct user_namespace *ns;
> - struct inode *dir;
>
> if (!dentry || IS_ERR(dentry))
> return;
>
> ns = dentry->d_sb->s_user_ns;
>
> - dir = d_inode(dentry->d_parent);
> - inode_lock(dir);
> if (simple_positive(dentry)) {
> - if (d_is_dir(dentry))
> - simple_rmdir(dir, dentry);
> - else
> - simple_unlink(dir, dentry);
> + d_delete(dentry);
> dput(dentry);
In
https://lore.kernel.org/lkml/20211210114934.tacjnwryihrsx6ln@wittgenstein
I explained why d_delete()+d_put() only is wrong and how to fix it.
