| Message ID | 20200218143411.2389182-6-christian.brauner@ubuntu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | user_namespace: introduce fsid mappings | expand |
On Tue, Feb 18, 2020 at 03:33:51PM +0100, Christian Brauner wrote: > Refactor map_write() to prepare for adding fsid mappings support. This mainly > factors out various open-coded parts into helpers that can be reused in the > follow up patch. > > Cc: Jann Horn <jannh@google.com> > Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Acked-by: Serge Hallyn <serge@hallyn.com> > --- > /* v2 */ > patch not present > > /* v3 */ > patch added > - Jann Horn <jannh@google.com>: > - Split changes to map_write() to implement fsid mappings into three separate > patches: basic fsid helpers, preparatory changes to map_write(), actual > fsid mapping support in map_write(). > --- > kernel/user_namespace.c | 117 +++++++++++++++++++++++++--------------- > 1 file changed, 74 insertions(+), 43 deletions(-) > > diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c > index 2cfd1e519cc4..e91141262bcc 100644 > --- a/kernel/user_namespace.c > +++ b/kernel/user_namespace.c > @@ -1038,10 +1038,10 @@ static int cmp_extents_reverse(const void *a, const void *b) > } > > /** > - * sort_idmaps - Sorts an array of idmap entries. > + * sort_map - Sorts an array of idmap entries. > * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. > */ > -static int sort_idmaps(struct uid_gid_map *map) > +static int sort_map(struct uid_gid_map *map) > { > if (map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) > return 0; > @@ -1064,6 +1064,71 @@ static int sort_idmaps(struct uid_gid_map *map) > return 0; > } > > +static int sort_idmaps(struct uid_gid_map *map) > +{ > + return sort_map(map); > +} > + > +static int map_from_parent(struct uid_gid_map *new_map, > + struct uid_gid_map *parent_map) > +{ > + unsigned idx; > + > + /* Map the lower ids from the parent user namespace to the > + * kernel global id space. > + */ > + for (idx = 0; idx < new_map->nr_extents; idx++) { > + struct uid_gid_extent *e; > + u32 lower_first; > + > + if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) > + e = &new_map->extent[idx]; > + else > + e = &new_map->forward[idx]; > + > + lower_first = map_id_range_down(parent_map, e->lower_first, e->count); > + > + /* Fail if we can not map the specified extent to > + * the kernel global id space. > + */ > + if (lower_first == (u32)-1) > + return -EPERM; > + > + e->lower_first = lower_first; > + } > + > + return 0; > +} > + > +static int map_into_kids(struct uid_gid_map *id_map, > + struct uid_gid_map *parent_id_map) > +{ > + return map_from_parent(id_map, parent_id_map); > +} > + > +static void install_idmaps(struct uid_gid_map *id_map, > + struct uid_gid_map *new_id_map) > +{ > + if (new_id_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) { > + memcpy(id_map->extent, new_id_map->extent, > + new_id_map->nr_extents * sizeof(new_id_map->extent[0])); > + } else { > + id_map->forward = new_id_map->forward; > + id_map->reverse = new_id_map->reverse; > + } > +} > + > +static void free_idmaps(struct uid_gid_map *new_id_map) > +{ > + if (new_id_map->nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { > + kfree(new_id_map->forward); > + kfree(new_id_map->reverse); > + new_id_map->forward = NULL; > + new_id_map->reverse = NULL; > + new_id_map->nr_extents = 0; > + } > +} > + > static ssize_t map_write(struct file *file, const char __user *buf, > size_t count, loff_t *ppos, > int cap_setid, > @@ -1073,7 +1138,6 @@ static ssize_t map_write(struct file *file, const char __user *buf, > struct seq_file *seq = file->private_data; > struct user_namespace *ns = seq->private; > struct uid_gid_map new_map; > - unsigned idx; > struct uid_gid_extent extent; > char *kbuf = NULL, *pos, *next_line; > ssize_t ret; > @@ -1191,61 +1255,28 @@ static ssize_t map_write(struct file *file, const char __user *buf, > if (!new_idmap_permitted(file, ns, cap_setid, &new_map)) > goto out; > > - ret = -EPERM; > - /* Map the lower ids from the parent user namespace to the > - * kernel global id space. > - */ > - for (idx = 0; idx < new_map.nr_extents; idx++) { > - struct uid_gid_extent *e; > - u32 lower_first; > - > - if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) > - e = &new_map.extent[idx]; > - else > - e = &new_map.forward[idx]; > - > - lower_first = map_id_range_down(parent_map, > - e->lower_first, > - e->count); > - > - /* Fail if we can not map the specified extent to > - * the kernel global id space. > - */ > - if (lower_first == (u32) -1) > - goto out; > - > - e->lower_first = lower_first; > - } > + ret = map_into_kids(&new_map, parent_map); > + if (ret) > + goto out; > > /* > * If we want to use binary search for lookup, this clones the extent > * array and sorts both copies. > */ > ret = sort_idmaps(&new_map); > - if (ret < 0) > + if (ret) > goto out; > > /* Install the map */ > - if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) { > - memcpy(map->extent, new_map.extent, > - new_map.nr_extents * sizeof(new_map.extent[0])); > - } else { > - map->forward = new_map.forward; > - map->reverse = new_map.reverse; > - } > + install_idmaps(map, &new_map); > smp_wmb(); > map->nr_extents = new_map.nr_extents; > > *ppos = count; > ret = count; > out: > - if (ret < 0 && new_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { > - kfree(new_map.forward); > - kfree(new_map.reverse); > - map->forward = NULL; > - map->reverse = NULL; > - map->nr_extents = 0; > - } > + if (ret < 0) > + free_idmaps(&new_map); > > mutex_unlock(&userns_state_mutex); > kfree(kbuf); > -- > 2.25.0
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 2cfd1e519cc4..e91141262bcc 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -1038,10 +1038,10 @@ static int cmp_extents_reverse(const void *a, const void *b) } /** - * sort_idmaps - Sorts an array of idmap entries. + * sort_map - Sorts an array of idmap entries. * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. */ -static int sort_idmaps(struct uid_gid_map *map) +static int sort_map(struct uid_gid_map *map) { if (map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) return 0; @@ -1064,6 +1064,71 @@ static int sort_idmaps(struct uid_gid_map *map) return 0; } +static int sort_idmaps(struct uid_gid_map *map) +{ + return sort_map(map); +} + +static int map_from_parent(struct uid_gid_map *new_map, + struct uid_gid_map *parent_map) +{ + unsigned idx; + + /* Map the lower ids from the parent user namespace to the + * kernel global id space. + */ + for (idx = 0; idx < new_map->nr_extents; idx++) { + struct uid_gid_extent *e; + u32 lower_first; + + if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) + e = &new_map->extent[idx]; + else + e = &new_map->forward[idx]; + + lower_first = map_id_range_down(parent_map, e->lower_first, e->count); + + /* Fail if we can not map the specified extent to + * the kernel global id space. + */ + if (lower_first == (u32)-1) + return -EPERM; + + e->lower_first = lower_first; + } + + return 0; +} + +static int map_into_kids(struct uid_gid_map *id_map, + struct uid_gid_map *parent_id_map) +{ + return map_from_parent(id_map, parent_id_map); +} + +static void install_idmaps(struct uid_gid_map *id_map, + struct uid_gid_map *new_id_map) +{ + if (new_id_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) { + memcpy(id_map->extent, new_id_map->extent, + new_id_map->nr_extents * sizeof(new_id_map->extent[0])); + } else { + id_map->forward = new_id_map->forward; + id_map->reverse = new_id_map->reverse; + } +} + +static void free_idmaps(struct uid_gid_map *new_id_map) +{ + if (new_id_map->nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { + kfree(new_id_map->forward); + kfree(new_id_map->reverse); + new_id_map->forward = NULL; + new_id_map->reverse = NULL; + new_id_map->nr_extents = 0; + } +} + static ssize_t map_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos, int cap_setid, @@ -1073,7 +1138,6 @@ static ssize_t map_write(struct file *file, const char __user *buf, struct seq_file *seq = file->private_data; struct user_namespace *ns = seq->private; struct uid_gid_map new_map; - unsigned idx; struct uid_gid_extent extent; char *kbuf = NULL, *pos, *next_line; ssize_t ret; @@ -1191,61 +1255,28 @@ static ssize_t map_write(struct file *file, const char __user *buf, if (!new_idmap_permitted(file, ns, cap_setid, &new_map)) goto out; - ret = -EPERM; - /* Map the lower ids from the parent user namespace to the - * kernel global id space. - */ - for (idx = 0; idx < new_map.nr_extents; idx++) { - struct uid_gid_extent *e; - u32 lower_first; - - if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) - e = &new_map.extent[idx]; - else - e = &new_map.forward[idx]; - - lower_first = map_id_range_down(parent_map, - e->lower_first, - e->count); - - /* Fail if we can not map the specified extent to - * the kernel global id space. - */ - if (lower_first == (u32) -1) - goto out; - - e->lower_first = lower_first; - } + ret = map_into_kids(&new_map, parent_map); + if (ret) + goto out; /* * If we want to use binary search for lookup, this clones the extent * array and sorts both copies. */ ret = sort_idmaps(&new_map); - if (ret < 0) + if (ret) goto out; /* Install the map */ - if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) { - memcpy(map->extent, new_map.extent, - new_map.nr_extents * sizeof(new_map.extent[0])); - } else { - map->forward = new_map.forward; - map->reverse = new_map.reverse; - } + install_idmaps(map, &new_map); smp_wmb(); map->nr_extents = new_map.nr_extents; *ppos = count; ret = count; out: - if (ret < 0 && new_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { - kfree(new_map.forward); - kfree(new_map.reverse); - map->forward = NULL; - map->reverse = NULL; - map->nr_extents = 0; - } + if (ret < 0) + free_idmaps(&new_map); mutex_unlock(&userns_state_mutex); kfree(kbuf);
Refactor map_write() to prepare for adding fsid mappings support. This mainly factors out various open-coded parts into helpers that can be reused in the follow up patch. Cc: Jann Horn <jannh@google.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> --- /* v2 */ patch not present /* v3 */ patch added - Jann Horn <jannh@google.com>: - Split changes to map_write() to implement fsid mappings into three separate patches: basic fsid helpers, preparatory changes to map_write(), actual fsid mapping support in map_write(). --- kernel/user_namespace.c | 117 +++++++++++++++++++++++++--------------- 1 file changed, 74 insertions(+), 43 deletions(-)