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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 10:00:50 -0800
commitf077e88fc9f0befcf0441be2fed9516881ab02ef (patch)
tree75071c6d3e84f07f38592707615ac3a9bbc8c66c /include
parent096b0c8d7033ef56d4c0eb13a29865a021eedea5 (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 4836ba3c1cd8..dd4f91b99b04 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -63,6 +63,7 @@ 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)
@@ -87,6 +88,10 @@ static inline void put_user_ns(struct user_namespace *ns)
{
}
+static inline bool userns_may_setgroups(const struct user_namespace *ns)
+{
+ return true;
+}
#endif
#endif /* _LINUX_USER_H */