Re: [PATCH] selinux: bpf: check SBLABEL_MNT before isec init

[Paul Moore <paul@paul-moore.com>]

On Jul 30, 2026 Carlos Llamas <cmllamas@google.com> wrote:
> 
> selinux_inode_init_security() marks the isec as initialized before
> checking if mount labeling is supported (SBLABEL_MNT). This was fine
> until commit 9722955b5430 ("bpf: Add simple xattr support to bpffs"),
> where genfscon bpffs mounts fail the SBLABEL_MNT check as expected (no
> xattrs) and yet leave the isec->initialized. This breaks subsequent
> calls to inode_doinit_with_dentry().
> 
> Do the SBLABEL_MNT check before the inode security is initialized.
> 
> Cc: stable@vger.kernel.org
> Closes: https://lore.kernel.org/all/akWdcp6P0FkNDzBk@google.com/
> Fixes: 9722955b5430 ("bpf: Add simple xattr support to bpffs")
> Signed-off-by: Carlos Llamas <cmllamas@google.com>
> Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
> ---
>  security/selinux/hooks.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 8d6945edae7a..09a12eb8652c 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -2980,6 +2980,10 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
>  	if (rc)
>  		return rc;
>  
> +	if (!selinux_initialized() ||
> +	    !(sbsec->flags & SBLABEL_MNT))
> +		return -EOPNOTSUPP;

If we're moving this check, we should probably just move it to right
after we assign 'sbsec' at the top of the function.  The calls to
inode_mode_to_security() and selinux_determine_inode_label() aren't
doing anything useful in either the !selinux_initialized() or !SBLABEL_MNT
cases so let's avoid the unnecessary work.

>  	/* Possibly defer initialization to selinux_complete_init. */
>  	if (sbsec->flags & SE_SBINITIALIZED) {
>  		struct inode_security_struct *isec = selinux_inode(inode);
> @@ -2988,10 +2992,6 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
>  		isec->initialized = LABEL_INITIALIZED;
>  	}
>  
> -	if (!selinux_initialized() ||
> -	    !(sbsec->flags & SBLABEL_MNT))
> -		return -EOPNOTSUPP;
> -
>  	xattr = lsm_get_xattr_slot(xattrs, xattr_count);
>  	if (xattr) {
>  		rc = security_sid_to_context_force(newsid,
> -- 
> 2.55.0.508.g3f0d502094-goog

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