/**
* alloc_fs_context - Create a filesystem context.
* @fs_type: The filesystem type.
* @reference: The dentry from which this one derives (or NULL)
* @sb_flags: Filesystem/superblock flags (SB_*)
* @sb_flags_mask: Applicable members of @sb_flags
* @purpose: The purpose that this configuration shall be used for.
*
* Open a filesystem and create a mount context. The mount context is
* initialised with the supplied flags and, if a submount/automount from
* another superblock (referred to by @reference) is supplied, may have
* parameters such as namespaces copied across from that superblock.
*/
static struct fs_context *alloc_fs_context(struct file_system_type *fs_type,
struct dentry *reference,
unsigned int sb_flags,
unsigned int sb_flags_mask,
enum fs_context_purpose purpose)
{
int (*init_fs_context)(struct fs_context *);
struct fs_context *fc;
int ret = -ENOMEM;
fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL);
if (!fc)
return ERR_PTR(-ENOMEM);
fc->purpose = purpose;
fc->sb_flags = sb_flags;
fc->sb_flags_mask = sb_flags_mask;
fc->fs_type = get_filesystem(fs_type);
fc->cred = get_current_cred();
fc->net_ns = get_net(current->nsproxy->net_ns);
mutex_init(&fc->uapi_mutex);
switch (purpose) {
case FS_CONTEXT_FOR_MOUNT:
fc->user_ns = get_user_ns(fc->cred->user_ns);
break;
case FS_CONTEXT_FOR_SUBMOUNT:
fc->user_ns = get_user_ns(reference->d_sb->s_user_ns);
break;
case FS_CONTEXT_FOR_RECONFIGURE:
/* We don't pin any namespaces as the superblock's
* subscriptions cannot be changed at this point.
*/
atomic_inc(&reference->d_sb->s_active);
fc->root = dget(reference);
break;
}
/* TODO: Make all filesystems support this unconditionally */
init_fs_context = fc->fs_type->init_fs_context;
if (!init_fs_context)
init_fs_context = legacy_init_fs_context;
ret = init_fs_context(fc);
if (ret < 0)
goto err_fc;
fc->need_free = true;
return fc;
err_fc:
put_fs_context(fc);
return ERR_PTR(ret);
}
static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk,
struct ipc_namespace *old_ns)
{
struct ipc_namespace *ns;
int err;
ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
if (ns == NULL)
return ERR_PTR(-ENOMEM);
atomic_set(&ns->count, 1);
err = mq_init_ns(ns);
if (err) {
kfree(ns);
return ERR_PTR(err);
}
atomic_inc(&nr_ipc_ns);
sem_init_ns(ns);
msg_init_ns(ns);
shm_init_ns(ns);
/*
* msgmni has already been computed for the new ipc ns.
* Thus, do the ipcns creation notification before registering that
* new ipcns in the chain.
*/
ipcns_notify(IPCNS_CREATED);
register_ipcns_notifier(ns);
ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
return ns;
}
static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
struct ipc_namespace *old_ns)
{
struct ipc_namespace *ns;
int err;
ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
if (ns == NULL)
return ERR_PTR(-ENOMEM);
err = ns_alloc_inum(&ns->ns);
if (err) {
kfree(ns);
return ERR_PTR(err);
}
ns->ns.ops = &ipcns_operations;
atomic_set(&ns->count, 1);
ns->user_ns = get_user_ns(user_ns);
err = mq_init_ns(ns);
if (err) {
put_user_ns(ns->user_ns);
ns_free_inum(&ns->ns);
kfree(ns);
return ERR_PTR(err);
}
sem_init_ns(ns);
msg_init_ns(ns);
shm_init_ns(ns);
return ns;
}
/*
* Clone a new ns copying an original utsname, setting refcount to 1
* @old_ns: namespace to clone
* Return NULL on error (failure to kmalloc), new ns otherwise
*/
static struct uts_namespace *clone_uts_ns(struct task_struct *tsk,
struct uts_namespace *old_ns)
{
struct uts_namespace *ns;
ns = create_uts_ns();
if (!ns)
return ERR_PTR(-ENOMEM);
down_read(&uts_sem);
memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
up_read(&uts_sem);
return ns;
}
/*
* Clone a new ns copying an original utsname, setting refcount to 1
* @old_ns: namespace to clone
* Return ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise
*/
static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
struct uts_namespace *old_ns)
{
struct uts_namespace *ns;
int err;
ns = create_uts_ns();
if (!ns)
return ERR_PTR(-ENOMEM);
err = proc_alloc_inum(&ns->proc_inum);
if (err) {
kfree(ns);
return ERR_PTR(err);
}
down_read(&uts_sem);
memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
ns->user_ns = get_user_ns(user_ns);
up_read(&uts_sem);
return ns;
}
/**
* vfs_dup_fc_config: Duplicate a filesystem context.
* @src_fc: The context to copy.
*/
struct fs_context *vfs_dup_fs_context(struct fs_context *src_fc)
{
struct fs_context *fc;
int ret;
if (!src_fc->ops->dup)
return ERR_PTR(-EOPNOTSUPP);
fc = kmemdup(src_fc, sizeof(struct fs_context), GFP_KERNEL);
if (!fc)
return ERR_PTR(-ENOMEM);
mutex_init(&fc->uapi_mutex);
fc->fs_private = NULL;
fc->s_fs_info = NULL;
fc->source = NULL;
fc->security = NULL;
get_filesystem(fc->fs_type);
get_net(fc->net_ns);
get_user_ns(fc->user_ns);
get_cred(fc->cred);
if (fc->log)
refcount_inc(&fc->log->usage);
/* Can't call put until we've called ->dup */
ret = fc->ops->dup(fc, src_fc);
if (ret < 0)
goto err_fc;
ret = security_fs_context_dup(fc, src_fc);
if (ret < 0)
goto err_fc;
return fc;
err_fc:
put_fs_context(fc);
return ERR_PTR(ret);
}
