Namespaces

Per-process Namespaces. More...

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Detailed Description

Per-process Namespaces.

The per-process namespace system allows each process to have its own view of the filesystem hierarchy, by having each process store its own set of mountpoints instead of having a global set of mountpoints.

Propagation

When a new mount or bind is created in a namespace, it is only added to that specific namespace. However, its possible to propagate mounts to children and/or parent namespaces using mount flags (mount_flags_t), this allows those namespaces to also see the new mount or bind.

Data Structures
struct	namespace_mount_t
struct	namespace_t
struct	namespace_mount
	A mount in a namespace. More...
struct	namespace_t
	Namespace structure. More...

Functions
void	namespace_init (namespace_t *ns)
	Initializes a namespace.
void	namespace_deinit (namespace_t *ns)
	Clear and deinitialize a namespace.
uint64_t	namespace_set_parent (namespace_t *ns, namespace_t *parent)
	Sets the parent of a namespace and inherits all mounts from the parent.
uint64_t	namespace_traverse (namespace_t *ns, path_t *path)
	If the given path is a mountpoint in the namespace, traverse to the mounted filesystem, else no-op.
mount_t *	namespace_mount (namespace_t *ns, path_t *target, const char *deviceName, const char *fsName, mount_flags_t flags, mode_t mode, void *private)
	Mount a filesystem in a namespace.
mount_t *	namespace_bind (namespace_t *ns, dentry_t *source, path_t *target, mount_flags_t flags, mode_t mode)
	Bind a source dentry to a target path in a namespace.
uint64_t	namespace_get_root_path (namespace_t *ns, path_t *out)
	Get the root path of a namespace.
void	namespace_clear (namespace_t *ns)
	Clears all mounts from a namespace.

Function Documentation

namespace_init()

void namespace_init

(

namespace_t *

ns

)

Initializes a namespace.

Parameters

ns	The namespace to initialize.
parent	The parent namespace to inherit all mounts from, can be NULL to create an empty namespace.

Definition at line 100 of file namespace.c.

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namespace_deinit()

void namespace_deinit

(

namespace_t *

ns

)

Clear and deinitialize a namespace.

Parameters

ns	The namespace to deinitialize.

Definition at line 111 of file namespace.c.

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namespace_set_parent()

uint64_t namespace_set_parent	(	namespace_t *	ns,
		namespace_t *	parent
	)

Sets the parent of a namespace and inherits all mounts from the parent.

Parameters

ns	The namespace to set the parent of.
parent	The new parent namespace.

Returns

On success, 0. On failure, ERR and errno is set to:

• EINVAL: Invalid parameters.
• EBUSY: The namespace already has a parent.
• ENOMEM: Out of memory.

Definition at line 123 of file namespace.c.

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namespace_traverse()

uint64_t namespace_traverse	(	namespace_t *	ns,
		path_t *	path
	)

If the given path is a mountpoint in the namespace, traverse to the mounted filesystem, else no-op.

Parameters

ns	The namespace to traverse in.
path	The mountpoint path to traverse, will be updated to the new path if traversed.

Returns

On success, 0. On failure, ERR and errno is set to:

• EINVAL: Invalid parameters.

Definition at line 163 of file namespace.c.

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namespace_mount()

mount_t * namespace_mount	(	namespace_t *	ns,
		path_t *	target,
		const char *	deviceName,
		const char *	fsName,
		mount_flags_t	flags,
		mode_t	mode,
		void *	private
	)

Mount a filesystem in a namespace.

Parameters

ns	The namespace to mount in.
deviceName	The device name, or VFS_DEVICE_NAME_NONE for no device.
target	The target path to mount to.
fsName	The filesystem name.
flags	Mount flags.
mode	The maximum allowed permissions for files/directories opened under this mount.
private	Private data for the filesystem's mount function.

Returns

On success, the new mount. On failure, returns NULL and errno is set to:

• EINVAL: Invalid parameters.
• EXDEV: The target path is not visible in the namespace.
• ENODEV: The specified filesystem does not exist.
• EBUSY: Attempt to mount to already existing root.
• ENOMEM: Out of memory.
• ENOENT: The root does not exist or the target is negative.
• Other errors as returned by the filesystem's mount() function or mount_new().

Definition at line 191 of file namespace.c.

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namespace_bind()

mount_t * namespace_bind	(	namespace_t *	ns,
		dentry_t *	source,
		path_t *	target,
		mount_flags_t	flags,
		mode_t	mode
	)

Bind a source dentry to a target path in a namespace.

Parameters

ns	The namespace to mount in.
source	The source dentry to bind from, could be either a file or directory and from any filesystem.
target	The target path to bind to.
flags	Mount flags.
mode	The maximum allowed permissions for files/directories opened under this mount.

Returns

On success, the new mount. On failure, returns NULL and errno is set to:

• EINVAL: Invalid parameters.
• ENOMEM: Out of memory.
• Other errors as returned by mount_new().

Definition at line 259 of file namespace.c.

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namespace_get_root_path()

uint64_t namespace_get_root_path	(	namespace_t *	ns,
		path_t *	out
	)

Get the root path of a namespace.

Parameters

ns	The namespace, can be NULL to get the kernel process's namespace root.
out	The output root path.

Returns

On success, 0. On failure, ERR and errno is set to:

• EINVAL: Invalid parameters.
• ENOENT: The namespace has no root mount.

Definition at line 286 of file namespace.c.

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namespace_clear()

void namespace_clear

(

namespace_t *

ns

)

Clears all mounts from a namespace.

Note

The parent of the namespace will inherit all child namespaces of the deinitialized namespace.

Parameters

ns	The namespace to clear.

Definition at line 306 of file namespace.c.

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