From: ebiederm@xmission•com (Eric W. Biederman)
To: David Miller <davem@davemloft•net>
Cc: Serge Hallyn <serue@us•ibm.com>,
Linux Containers <containers@lists•osdl.org>,
Daniel Lezcano <daniel.lezcano@free•fr>, <netdev@vger•kernel.org>,
Pavel Emelyanov <xemul@parallels•com>
Subject: [PATCH 2/8] user_ns: Introduce user_nsmap_uid and user_ns_map_gid.
Date: Sun, 13 Jun 2010 06:28:03 -0700 [thread overview]
Message-ID: <m17hm3hxjw.fsf_-_@fess.ebiederm.org> (raw)
In-Reply-To: <m1d3vvhxlj.fsf@fess.ebiederm.org> (Eric W. Biederman's message of "Sun\, 13 Jun 2010 06\:27\:04 -0700")
Define what happens when a we view a uid from one user_namespace
in another user_namepece.
- If the user namespaces are the same no mapping is necessary.
- For most cases of difference use overflowuid and overflowgid,
the uid and gid currently used for 16bit apis when we have a 32bit uid
that does fit in 16bits. Effectively the situation is the same,
we want to return a uid or gid that is not assigned to any user.
- For the case when we happen to be mapping the uid or gid of the
creator of the target user namespace use uid 0 and gid as confusing
that user with root is not a problem.
Signed-off-by: Eric W. Biederman <ebiederm@xmission•com>
---
include/linux/user_namespace.h | 14 ++++++++++++
kernel/user_namespace.c | 44 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 58 insertions(+), 0 deletions(-)
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index cc4f453..8178156 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -36,6 +36,9 @@ static inline void put_user_ns(struct user_namespace *ns)
kref_put(&ns->kref, free_user_ns);
}
+uid_t user_ns_map_uid(struct user_namespace *to, const struct cred *cred, uid_t uid);
+gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t gid);
+
#else
static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
@@ -52,6 +55,17 @@ static inline void put_user_ns(struct user_namespace *ns)
{
}
+static inline uid_t user_ns_map_uid(struct user_namespace *to,
+ const struct cred *cred, uid_t uid)
+{
+ return uid;
+}
+static inline gid_t user_ns_map_gid(struct user_namespace *to,
+ const struct cred *cred, gid_t gid)
+{
+ return gid;
+}
+
#endif
#endif /* _LINUX_USER_H */
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 076c7c8..825abfb 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -9,6 +9,7 @@
#include <linux/nsproxy.h>
#include <linux/slab.h>
#include <linux/user_namespace.h>
+#include <linux/highuid.h>
#include <linux/cred.h>
/*
@@ -82,3 +83,46 @@ void free_user_ns(struct kref *kref)
schedule_work(&ns->destroyer);
}
EXPORT_SYMBOL(free_user_ns);
+
+uid_t user_ns_map_uid(struct user_namespace *to, const struct cred *cred, uid_t uid)
+{
+ struct user_namespace *tmp;
+
+ if (likely(to == cred->user->user_ns))
+ return uid;
+
+
+ /* Is cred->user the creator of the target user_ns
+ * or the creator of one of it's parents?
+ */
+ for ( tmp = to; tmp != &init_user_ns;
+ tmp = tmp->creator->user_ns ) {
+ if (cred->user == tmp->creator) {
+ return (uid_t)0;
+ }
+ }
+
+ /* No useful relationship so no mapping */
+ return overflowuid;
+}
+
+gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t gid)
+{
+ struct user_namespace *tmp;
+
+ if (likely(to == cred->user->user_ns))
+ return gid;
+
+ /* Is cred->user the creator of the target user_ns
+ * or the creator of one of it's parents?
+ */
+ for ( tmp = to; tmp != &init_user_ns;
+ tmp = tmp->creator->user_ns ) {
+ if (cred->user == tmp->creator) {
+ return (gid_t)0;
+ }
+ }
+
+ /* No useful relationship so no mapping */
+ return overflowgid;
+}
--
1.6.5.2.143.g8cc62
next prev parent reply other threads:[~2010-06-13 13:28 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-13 13:25 [PATCH 0/8] Support unix domain sockets across namespaces Eric W. Biederman
2010-06-13 13:27 ` [PATCH 1/8] scm: Reorder scm_cookie Eric W. Biederman
2010-06-13 13:28 ` Eric W. Biederman [this message]
[not found] ` <m17hm3hxjw.fsf_-_-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2010-06-15 8:02 ` [PATCH 2/8] user_ns: Introduce user_nsmap_uid and user_ns_map_gid Pavel Emelyanov
2010-06-15 22:37 ` Eric W. Biederman
2010-06-15 20:58 ` Serge E. Hallyn
2010-06-15 8:00 ` [PATCH 1/8] scm: Reorder scm_cookie Pavel Emelyanov
2010-06-13 13:28 ` [PATCH 3/8] sock: Introduce cred_to_ucred Eric W. Biederman
2010-06-15 8:03 ` Pavel Emelyanov
2010-06-13 13:30 ` [PATCH 4/8] af_unix: Allow SO_PEERCRED to work across namespaces Eric W. Biederman
2010-06-14 13:37 ` Daniel Lezcano
2010-06-15 8:04 ` Pavel Emelyanov
2010-06-13 13:31 ` [PATCH 5/8] af_netlink: Add needed scm_destroy after scm_send Eric W. Biederman
2010-06-14 13:37 ` Daniel Lezcano
2010-06-15 8:06 ` Pavel Emelyanov
2010-06-13 13:32 ` [PATCH 6/8] scm: Capture the full credentials of the scm sender Eric W. Biederman
2010-06-15 8:08 ` Pavel Emelyanov
2010-06-15 9:53 ` Eric W. Biederman
2010-06-15 21:45 ` Serge E. Hallyn
2010-06-15 22:08 ` Eric W. Biederman
2010-06-16 4:47 ` Serge E. Hallyn
2010-06-13 13:34 ` [PATCH 7/8] af_unix: Allow credentials to work across user and pid namespaces Eric W. Biederman
[not found] ` <m17hm3giom.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2010-06-15 8:11 ` Pavel Emelyanov
2010-06-13 13:35 ` [PATCH 8/8] af_unix: Allow connecting to sockets in other network namespaces Eric W. Biederman
2010-06-14 13:37 ` Daniel Lezcano
[not found] ` <m11vcbgimj.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2010-06-15 8:12 ` Pavel Emelyanov
2010-06-16 22:15 ` [PATCH 0/8] Support unix domain sockets across namespaces David Miller
2010-06-16 23:17 ` David Miller
2010-06-16 23:32 ` Eric W. Biederman
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