On 07/13/2016 10:44 AM, Vivek Goyal wrote:
> A file is being copied up for overlay file system. Prepare a new set of
> creds and set create_sid appropriately so that new file is created with
> appropriate label.
>
> Overlay inode has right label for both context and non-context mount
> cases. In case of non-context mount, overlay inode will have the label
> of lower file and in case of context mount, overlay inode will have
> the label from context= mount option.
>
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Acked-by: Stephen Smalley <sds@xxxxxxxxxxxxx>
> ---
> security/selinux/hooks.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index a86d537..c82ee54 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -3270,6 +3270,26 @@ static void selinux_inode_getsecid(struct inode *inode, u32 *secid)
> *secid = isec->sid;
> }
>
> +static int selinux_inode_copy_up(struct dentry *src, struct cred **new)
> +{
> + u32 sid;
> + struct task_security_struct *tsec;
> + struct cred *new_creds = *new;
> +
> + if (new_creds == NULL) {
> + new_creds = prepare_creds();
> + if (!new_creds)
> + return -ENOMEM;
> + }
> +
> + tsec = new_creds->security;
> + /* Get label from overlay inode and set it in create_sid */
> + selinux_inode_getsecid(d_inode(src), &sid);
> + tsec->create_sid = sid;
> + *new = new_creds;
> + return 0;
> +}
> +
> /* file security operations */
>
> static int selinux_revalidate_file_permission(struct file *file, int mask)
> @@ -6056,6 +6076,7 @@ static struct security_hook_list selinux_hooks[] = {
> LSM_HOOK_INIT(inode_setsecurity, selinux_inode_setsecurity),
> LSM_HOOK_INIT(inode_listsecurity, selinux_inode_listsecurity),
> LSM_HOOK_INIT(inode_getsecid, selinux_inode_getsecid),
> + LSM_HOOK_INIT(inode_copy_up, selinux_inode_copy_up),
>
> LSM_HOOK_INIT(file_permission, selinux_file_permission),
> LSM_HOOK_INIT(file_alloc_security, selinux_file_alloc_security),
>
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