On Wed, Aug 24, 2022 at 11:09:50AM +0100, David Howells wrote:
What's the reason for difference between selinux and smack instances of
context_init? The former allocates only on submount, the latter -
unconditionally...
> +static int selinux_fs_context_init(struct fs_context *fc,
> + struct dentry *reference)
> +{
> + const struct superblock_security_struct *sbsec;
> + const struct inode_security_struct *root_isec;
> + struct selinux_mnt_opts *opts;
> +
> + if (fc->purpose == FS_CONTEXT_FOR_SUBMOUNT) {
> + opts = kzalloc(sizeof(*opts), GFP_KERNEL);
> + if (!opts)
> + return -ENOMEM;
> +
> + root_isec = backing_inode_security(reference->d_sb->s_root);
> + sbsec = selinux_superblock(reference->d_sb);
> + if (sbsec->flags & FSCONTEXT_MNT)
> + opts->fscontext_sid = sbsec->sid;
> + if (sbsec->flags & CONTEXT_MNT)
> + opts->context_sid = sbsec->mntpoint_sid;
> + if (sbsec->flags & DEFCONTEXT_MNT)
> + opts->defcontext_sid = sbsec->def_sid;
> + fc->security = opts;
> + }
> +
> + return 0;
> +}
> +/**
> + * smack_fs_context_init - Initialise security data for a filesystem context
> + * @fc: The filesystem context.
> + * @reference: Reference dentry (automount/reconfigure) or NULL
> + *
> + * Returns 0 on success or -ENOMEM on error.
> + */
> +static int smack_fs_context_init(struct fs_context *fc,
> + struct dentry *reference)
> +{
> + struct superblock_smack *sbsp;
> + struct smack_mnt_opts *ctx;
> + struct inode_smack *isp;
> +
> + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> + if (!ctx)
> + return -ENOMEM;
> + fc->security = ctx;
> +
> + if (fc->purpose == FS_CONTEXT_FOR_SUBMOUNT) {
> + sbsp = smack_superblock(reference->d_sb);
> + isp = smack_inode(reference->d_sb->s_root->d_inode);
