Commit ffcdc4c6 authored by Alexander Mikhalitsyn's avatar Alexander Mikhalitsyn Committed by Miklos Szeredi
Browse files

fs/mnt_idmapping: introduce an invalid_mnt_idmap 

Link: https://lore.kernel.org/linux-fsdevel/20240904-baugrube-erhoben-b3c1c49a2645@brauner/


Suggested-by: default avatarChristian Brauner <brauner@kernel.org>
Signed-off-by: default avatarAlexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Reviewed-by: default avatarChristian Brauner <brauner@kernel.org>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 0c679382

fs/mnt_idmapping.c

+20 −2
Original line number Diff line number Diff line
@@ -32,6 +32,15 @@ struct mnt_idmap nop_mnt_idmap = { 
};

EXPORT_SYMBOL_GPL(nop_mnt_idmap);



/*

 * Carries the invalid idmapping of a full 0-4294967295 {g,u}id range.

 * This means that all {g,u}ids are mapped to INVALID_VFS{G,U}ID.

 */

struct mnt_idmap invalid_mnt_idmap = {

	.count	= REFCOUNT_INIT(1),

};

EXPORT_SYMBOL_GPL(invalid_mnt_idmap);



/**

 * initial_idmapping - check whether this is the initial mapping

 * @ns: idmapping to check
@@ -75,6 +84,8 @@ vfsuid_t make_vfsuid(struct mnt_idmap *idmap, 


	if (idmap == &nop_mnt_idmap)

		return VFSUIDT_INIT(kuid);

	if (idmap == &invalid_mnt_idmap)

		return INVALID_VFSUID;

	if (initial_idmapping(fs_userns))

		uid = __kuid_val(kuid);

	else
@@ -112,6 +123,8 @@ vfsgid_t make_vfsgid(struct mnt_idmap *idmap, 


	if (idmap == &nop_mnt_idmap)

		return VFSGIDT_INIT(kgid);

	if (idmap == &invalid_mnt_idmap)

		return INVALID_VFSGID;

	if (initial_idmapping(fs_userns))

		gid = __kgid_val(kgid);

	else
@@ -140,6 +153,8 @@ kuid_t from_vfsuid(struct mnt_idmap *idmap, 


	if (idmap == &nop_mnt_idmap)

		return AS_KUIDT(vfsuid);

	if (idmap == &invalid_mnt_idmap)

		return INVALID_UID;

	uid = map_id_up(&idmap->uid_map, __vfsuid_val(vfsuid));

	if (uid == (uid_t)-1)

		return INVALID_UID;
@@ -167,6 +182,8 @@ kgid_t from_vfsgid(struct mnt_idmap *idmap, 


	if (idmap == &nop_mnt_idmap)

		return AS_KGIDT(vfsgid);

	if (idmap == &invalid_mnt_idmap)

		return INVALID_GID;

	gid = map_id_up(&idmap->gid_map, __vfsgid_val(vfsgid));

	if (gid == (gid_t)-1)

		return INVALID_GID;
@@ -296,7 +313,7 @@ struct mnt_idmap *alloc_mnt_idmap(struct user_namespace *mnt_userns) 
 */

struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap)

{

	if (idmap != &nop_mnt_idmap)

	if (idmap != &nop_mnt_idmap && idmap != &invalid_mnt_idmap)

		refcount_inc(&idmap->count);



	return idmap;
@@ -312,7 +329,8 @@ EXPORT_SYMBOL_GPL(mnt_idmap_get); 
 */

void mnt_idmap_put(struct mnt_idmap *idmap)

{

	if (idmap != &nop_mnt_idmap && refcount_dec_and_test(&idmap->count))

	if (idmap != &nop_mnt_idmap && idmap != &invalid_mnt_idmap &&

	    refcount_dec_and_test(&idmap->count))

		free_mnt_idmap(idmap);

}

EXPORT_SYMBOL_GPL(mnt_idmap_put);

include/linux/mnt_idmapping.h

+1 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ struct mnt_idmap; 
struct user_namespace;



extern struct mnt_idmap nop_mnt_idmap;

extern struct mnt_idmap invalid_mnt_idmap;

extern struct user_namespace init_user_ns;



typedef struct {