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-rw-r--r--kernel/user_namespace.c62
1 files changed, 48 insertions, 14 deletions
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 2b042c4..8b65083 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) &&
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