diff options
Diffstat (limited to 'kernel/user_namespace.c')
| -rw-r--r-- | kernel/user_namespace.c | 62 |
1 files changed, 48 insertions, 14 deletions
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 2b042c42fbc..8b650837083 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -78,7 +78,7 @@ int create_user_ns(struct cred *new) return ret; } - kref_init(&ns->kref); + atomic_set(&ns->count, 1); /* Leave the new->user_ns reference with the new user namespace. */ ns->parent = parent_ns; ns->owner = owner; @@ -104,15 +104,16 @@ int unshare_userns(unsigned long unshare_flags, struct cred **new_cred) return create_user_ns(cred); } -void free_user_ns(struct kref *kref) +void free_user_ns(struct user_namespace *ns) { - struct user_namespace *parent, *ns = - container_of(kref, struct user_namespace, kref); + struct user_namespace *parent; - parent = ns->parent; - proc_free_inum(ns->proc_inum); - kmem_cache_free(user_ns_cachep, ns); - put_user_ns(parent); + do { + parent = ns->parent; + proc_free_inum(ns->proc_inum); + kmem_cache_free(user_ns_cachep, ns); + ns = parent; + } while (atomic_dec_and_test(&parent->count)); } EXPORT_SYMBOL(free_user_ns); @@ -519,6 +520,42 @@ struct seq_operations proc_projid_seq_operations = { .show = projid_m_show, }; +static bool mappings_overlap(struct uid_gid_map *new_map, struct uid_gid_extent *extent) +{ + u32 upper_first, lower_first, upper_last, lower_last; + unsigned idx; + + upper_first = extent->first; + lower_first = extent->lower_first; + upper_last = upper_first + extent->count - 1; + lower_last = lower_first + extent->count - 1; + + for (idx = 0; idx < new_map->nr_extents; idx++) { + u32 prev_upper_first, prev_lower_first; + u32 prev_upper_last, prev_lower_last; + struct uid_gid_extent *prev; + + prev = &new_map->extent[idx]; + + prev_upper_first = prev->first; + prev_lower_first = prev->lower_first; + prev_upper_last = prev_upper_first + prev->count - 1; + prev_lower_last = prev_lower_first + prev->count - 1; + + /* Does the upper range intersect a previous extent? */ + if ((prev_upper_first <= upper_last) && + (prev_upper_last >= upper_first)) + return true; + + /* Does the lower range intersect a previous extent? */ + if ((prev_lower_first <= lower_last) && + (prev_lower_last >= lower_first)) + return true; + } + return false; +} + + static DEFINE_MUTEX(id_map_mutex); static ssize_t map_write(struct file *file, const char __user *buf, @@ -531,7 +568,7 @@ static ssize_t map_write(struct file *file, const char __user *buf, struct user_namespace *ns = seq->private; struct uid_gid_map new_map; unsigned idx; - struct uid_gid_extent *extent, *last = NULL; + struct uid_gid_extent *extent = NULL; unsigned long page = 0; char *kbuf, *pos, *next_line; ssize_t ret = -EINVAL; @@ -634,14 +671,11 @@ static ssize_t map_write(struct file *file, const char __user *buf, if ((extent->lower_first + extent->count) <= extent->lower_first) goto out; - /* For now only accept extents that are strictly in order */ - if (last && - (((last->first + last->count) > extent->first) || - ((last->lower_first + last->count) > extent->lower_first))) + /* Do the ranges in extent overlap any previous extents? */ + if (mappings_overlap(&new_map, extent)) goto out; new_map.nr_extents++; - last = extent; /* Fail if the file contains too many extents */ if ((new_map.nr_extents == UID_GID_MAP_MAX_EXTENTS) && |