diff options
Diffstat (limited to 'userns-Don-t-allow-setgroups-until-a-gid-mapping-has.patch')
| -rw-r--r-- | userns-Don-t-allow-setgroups-until-a-gid-mapping-has.patch | 98 |
1 files changed, 0 insertions, 98 deletions
diff --git a/userns-Don-t-allow-setgroups-until-a-gid-mapping-has.patch b/userns-Don-t-allow-setgroups-until-a-gid-mapping-has.patch deleted file mode 100644 index 81217d2a5..000000000 --- a/userns-Don-t-allow-setgroups-until-a-gid-mapping-has.patch +++ /dev/null @@ -1,98 +0,0 @@ -From: "Eric W. Biederman" <ebiederm@xmission.com> -Date: Fri, 5 Dec 2014 18:01:11 -0600 -Subject: [PATCH] userns: Don't allow setgroups until a gid mapping has been - setablished - -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. - -Cc: stable@vger.kernel.org -Reviewed-by: Andy Lutomirski <luto@amacapital.net> -Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> ---- - include/linux/user_namespace.h | 5 +++++ - kernel/groups.c | 4 +++- - kernel/user_namespace.c | 14 ++++++++++++++ - 3 files changed, 22 insertions(+), 1 deletion(-) - -diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h -index e95372654f09..8d493083486a 100644 ---- a/include/linux/user_namespace.h -+++ b/include/linux/user_namespace.h -@@ -63,6 +63,7 @@ extern const 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 */ -diff --git a/kernel/groups.c b/kernel/groups.c -index 02d8a251c476..664411f171b5 100644 ---- a/kernel/groups.c -+++ b/kernel/groups.c -@@ -6,6 +6,7 @@ - #include <linux/slab.h> - #include <linux/security.h> - #include <linux/syscalls.h> -+#include <linux/user_namespace.h> - #include <asm/uaccess.h> - - /* init to 2 - one for init_task, one to ensure it is never freed */ -@@ -217,7 +218,8 @@ bool may_setgroups(void) - { - struct user_namespace *user_ns = current_user_ns(); - -- return ns_capable(user_ns, CAP_SETGID); -+ return ns_capable(user_ns, CAP_SETGID) && -+ userns_may_setgroups(user_ns); - } - - /* -diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c -index b99c862a2e3f..27c8dab48c07 100644 ---- a/kernel/user_namespace.c -+++ b/kernel/user_namespace.c -@@ -843,6 +843,20 @@ static bool new_idmap_permitted(const struct file *file, - return false; - } - -+bool userns_may_setgroups(const struct user_namespace *ns) -+{ -+ bool allowed; -+ -+ mutex_lock(&id_map_mutex); -+ /* It is not safe to use setgroups until a gid mapping in -+ * the user namespace has been established. -+ */ -+ allowed = ns->gid_map.nr_extents != 0; -+ mutex_unlock(&id_map_mutex); -+ -+ return allowed; -+} -+ - static void *userns_get(struct task_struct *task) - { - struct user_namespace *user_ns; --- -2.1.0 - |