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| author | Eric W. Biederman <ebiederm@xmission.com> | 2014-12-05 18:01:11 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-01-08 09:58:16 -0800 |
| commit | fc9b65e3d7703e6d63875b0b233bbe26a4a513ba (patch) | |
| tree | 7686f17848a927d80398803eab339cb9084343ed /include | |
| parent | b8a0441b542f6d6bd6fda46cc735ae71392cb845 (diff) | |
| download | lwn-fc9b65e3d7703e6d63875b0b233bbe26a4a513ba.tar.gz lwn-fc9b65e3d7703e6d63875b0b233bbe26a4a513ba.zip | |
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.h | 5 |
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); |