[PATCH 01/27] userns: pass const uid_gid_map in lookup helpers

[Christian Brauner]

map_id_down(), map_id_up() and map_id_range_up() search the extents
of an idmapping and never modify it. Let all relevant helpers pass a
const struct uid_gid_map. Callers can now pass pass struct mnt_idmap as
const and pass down &idmap->uid_map and &idmap->gid_map.

No functional changes.

Signed-off-by: Christian Brauner (Amutable) <brauner at kernel.org>
---
 include/linux/uidgid.h  | 12 ++++++------
 kernel/user_namespace.c | 28 ++++++++++++++--------------
 2 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/include/linux/uidgid.h b/include/linux/uidgid.h
index 2dc767e08f54..02403629b49f 100644
--- a/include/linux/uidgid.h
+++ b/include/linux/uidgid.h
@@ -130,9 +130,9 @@ static inline bool kgid_has_mapping(struct user_namespace *ns, kgid_t gid)
 	return from_kgid(ns, gid) != (gid_t) -1;
 }
 
-u32 map_id_down(struct uid_gid_map *map, u32 id);
-u32 map_id_up(struct uid_gid_map *map, u32 id);
-u32 map_id_range_up(struct uid_gid_map *map, u32 id, u32 count);
+u32 map_id_down(const struct uid_gid_map *map, u32 id);
+u32 map_id_up(const struct uid_gid_map *map, u32 id);
+u32 map_id_range_up(const struct uid_gid_map *map, u32 id, u32 count);
 
 #else
 
@@ -182,17 +182,17 @@ static inline bool kgid_has_mapping(struct user_namespace *ns, kgid_t gid)
 	return gid_valid(gid);
 }
 
-static inline u32 map_id_down(struct uid_gid_map *map, u32 id)
+static inline u32 map_id_down(const struct uid_gid_map *map, u32 id)
 {
 	return id;
 }
 
-static inline u32 map_id_range_up(struct uid_gid_map *map, u32 id, u32 count)
+static inline u32 map_id_range_up(const struct uid_gid_map *map, u32 id, u32 count)
 {
 	return id;
 }
 
-static inline u32 map_id_up(struct uid_gid_map *map, u32 id)
+static inline u32 map_id_up(const struct uid_gid_map *map, u32 id)
 {
 	return id;
 }
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 0bed462e9b2a..55b6bd75624b 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -278,8 +278,8 @@ static int cmp_map_id(const void *k, const void *e)
  * map_id_range_down_max - Find idmap via binary search in ordered idmap array.
  * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS.
  */
-static struct uid_gid_extent *
-map_id_range_down_max(unsigned extents, struct uid_gid_map *map, u32 id, u32 count)
+static const struct uid_gid_extent *
+map_id_range_down_max(unsigned extents, const struct uid_gid_map *map, u32 id, u32 count)
 {
 	struct idmap_key key;
 
@@ -296,8 +296,8 @@ map_id_range_down_max(unsigned extents, struct uid_gid_map *map, u32 id, u32 cou
  * Can only be called if number of mappings is equal or less than
  * UID_GID_MAP_MAX_BASE_EXTENTS.
  */
-static struct uid_gid_extent *
-map_id_range_down_base(unsigned extents, struct uid_gid_map *map, u32 id, u32 count)
+static const struct uid_gid_extent *
+map_id_range_down_base(unsigned extents, const struct uid_gid_map *map, u32 id, u32 count)
 {
 	unsigned idx;
 	u32 first, last, id2;
@@ -315,9 +315,9 @@ map_id_range_down_base(unsigned extents, struct uid_gid_map *map, u32 id, u32 co
 	return NULL;
 }
 
-static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count)
+static u32 map_id_range_down(const struct uid_gid_map *map, u32 id, u32 count)
 {
-	struct uid_gid_extent *extent;
+	const struct uid_gid_extent *extent;
 	unsigned extents = map->nr_extents;
 	smp_rmb();
 
@@ -335,7 +335,7 @@ static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count)
 	return id;
 }
 
-u32 map_id_down(struct uid_gid_map *map, u32 id)
+u32 map_id_down(const struct uid_gid_map *map, u32 id)
 {
 	return map_id_range_down(map, id, 1);
 }
@@ -345,8 +345,8 @@ u32 map_id_down(struct uid_gid_map *map, u32 id)
  * Can only be called if number of mappings is equal or less than
  * UID_GID_MAP_MAX_BASE_EXTENTS.
  */
-static struct uid_gid_extent *
-map_id_range_up_base(unsigned extents, struct uid_gid_map *map, u32 id, u32 count)
+static const struct uid_gid_extent *
+map_id_range_up_base(unsigned extents, const struct uid_gid_map *map, u32 id, u32 count)
 {
 	unsigned idx;
 	u32 first, last, id2;
@@ -368,8 +368,8 @@ map_id_range_up_base(unsigned extents, struct uid_gid_map *map, u32 id, u32 coun
  * map_id_up_max - Find idmap via binary search in ordered idmap array.
  * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS.
  */
-static struct uid_gid_extent *
-map_id_range_up_max(unsigned extents, struct uid_gid_map *map, u32 id, u32 count)
+static const struct uid_gid_extent *
+map_id_range_up_max(unsigned extents, const struct uid_gid_map *map, u32 id, u32 count)
 {
 	struct idmap_key key;
 
@@ -381,9 +381,9 @@ map_id_range_up_max(unsigned extents, struct uid_gid_map *map, u32 id, u32 count
 		       sizeof(struct uid_gid_extent), cmp_map_id);
 }
 
-u32 map_id_range_up(struct uid_gid_map *map, u32 id, u32 count)
+u32 map_id_range_up(const struct uid_gid_map *map, u32 id, u32 count)
 {
-	struct uid_gid_extent *extent;
+	const struct uid_gid_extent *extent;
 	unsigned extents = map->nr_extents;
 	smp_rmb();
 
@@ -401,7 +401,7 @@ u32 map_id_range_up(struct uid_gid_map *map, u32 id, u32 count)
 	return id;
 }
 
-u32 map_id_up(struct uid_gid_map *map, u32 id)
+u32 map_id_up(const struct uid_gid_map *map, u32 id)
 {
 	return map_id_range_up(map, id, 1);
 }

-- 
2.53.0