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authorEric W. Biederman <ebiederm@xmission.com>2014-12-05 18:01:11 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-01-08 09:58:16 -0800
commitfc9b65e3d7703e6d63875b0b233bbe26a4a513ba (patch)
tree7686f17848a927d80398803eab339cb9084343ed /include
parentb8a0441b542f6d6bd6fda46cc735ae71392cb845 (diff)
userns: Don't allow setgroups until a gid mapping has been setablished
commit 273d2c67c3e179adb1e74f403d1e9a06e3f841b5 upstream. setgroups is unique in not needing a valid mapping before it can be called, in the case of setgroups(0, NULL) which drops all supplemental groups. The design of the user namespace assumes that CAP_SETGID can not actually be used until a gid mapping is established. Therefore add a helper function to see if the user namespace gid mapping has been established and call that function in the setgroups permission check. This is part of the fix for CVE-2014-8989, being able to drop groups without privilege using user namespaces. Reviewed-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/user_namespace.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 14105c26a836..648cf88c5d6d 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -59,6 +59,7 @@ extern struct seq_operations proc_projid_seq_operations;
extern ssize_t proc_uid_map_write(struct file *, const char __user *, size_t, loff_t *);
extern ssize_t proc_gid_map_write(struct file *, const char __user *, size_t, loff_t *);
extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t, loff_t *);
+extern bool userns_may_setgroups(const struct user_namespace *ns);
#else
static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
@@ -83,6 +84,10 @@ static inline void put_user_ns(struct user_namespace *ns)
{
}
+static inline bool userns_may_setgroups(const struct user_namespace *ns)
+{
+ return true;
+}
#endif
void update_mnt_policy(struct user_namespace *userns);