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Date: Tue, 6 Sep 2016 00:47:13 -0700
From: Andrei Vagin <avagin@...nvz.org>
To: "Eric W. Biederman" <ebiederm@...ssion.com>,
containers@...ts.linux-foundation.org
Cc: linux-api@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org, Andrey Vagin <avagin@...nvz.org>,
James Bottomley <James.Bottomley@...senPartnership.com>,
"Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>,
"W. Trevor King" <wking@...mily.us>,
Alexander Viro <viro@...iv.linux.org.uk>,
Serge Hallyn <serge.hallyn@...onical.com>
Subject: [PATCH 1/4] kernel: add a helper to get an owning user namespace for a namespace
From: Andrey Vagin <avagin@...nvz.org>
Return -EPERM if an owning user namespace is outside of a process
current user namespace.
v2: In a first version ns_get_owner returned ENOENT for init_user_ns.
This special cases was removed from this version. There is nothing
outside of init_user_ns, so we can return EPERM.
v3: rename ns->get_owner() to ns->owner(). get_* usually means that it
grabs a reference.
Acked-by: Serge Hallyn <serge@...lyn.com>
Signed-off-by: Andrei Vagin <avagin@...nvz.org>
---
fs/namespace.c | 6 ++++++
include/linux/proc_ns.h | 1 +
include/linux/user_namespace.h | 7 +++++++
ipc/namespace.c | 6 ++++++
kernel/cgroup.c | 6 ++++++
kernel/pid_namespace.c | 6 ++++++
kernel/user_namespace.c | 24 ++++++++++++++++++++++++
kernel/utsname.c | 6 ++++++
net/core/net_namespace.c | 6 ++++++
9 files changed, 68 insertions(+)
diff --git a/fs/namespace.c b/fs/namespace.c
index 491b8f3..dd27ce4 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3368,10 +3368,16 @@ static int mntns_install(struct nsproxy *nsproxy, struct ns_common *ns)
return 0;
}
+static struct user_namespace *mntns_owner(struct ns_common *ns)
+{
+ return to_mnt_ns(ns)->user_ns;
+}
+
const struct proc_ns_operations mntns_operations = {
.name = "mnt",
.type = CLONE_NEWNS,
.get = mntns_get,
.put = mntns_put,
.install = mntns_install,
+ .owner = mntns_owner,
};
diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index de0e771..ca85a43 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -18,6 +18,7 @@ struct proc_ns_operations {
struct ns_common *(*get)(struct task_struct *task);
void (*put)(struct ns_common *ns);
int (*install)(struct nsproxy *nsproxy, struct ns_common *ns);
+ struct user_namespace *(*owner)(struct ns_common *ns);
};
extern const struct proc_ns_operations netns_operations;
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 30ffe10..eb209d4 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -106,6 +106,8 @@ extern ssize_t proc_setgroups_write(struct file *, const char __user *, size_t,
extern int proc_setgroups_show(struct seq_file *m, void *v);
extern bool userns_may_setgroups(const struct user_namespace *ns);
extern bool current_in_userns(const struct user_namespace *target_ns);
+
+struct ns_common *ns_get_owner(struct ns_common *ns);
#else
static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
@@ -139,6 +141,11 @@ static inline bool current_in_userns(const struct user_namespace *target_ns)
{
return true;
}
+
+static inline struct ns_common *ns_get_owner(struct ns_common *ns)
+{
+ return ERR_PTR(-EPERM);
+}
#endif
#endif /* _LINUX_USER_H */
diff --git a/ipc/namespace.c b/ipc/namespace.c
index 7309142..465c981 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -188,10 +188,16 @@ static int ipcns_install(struct nsproxy *nsproxy, struct ns_common *new)
return 0;
}
+static struct user_namespace *ipcns_owner(struct ns_common *ns)
+{
+ return to_ipc_ns(ns)->user_ns;
+}
+
const struct proc_ns_operations ipcns_operations = {
.name = "ipc",
.type = CLONE_NEWIPC,
.get = ipcns_get,
.put = ipcns_put,
.install = ipcns_install,
+ .owner = ipcns_owner,
};
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e9e4427..2665b58 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -6421,12 +6421,18 @@ static void cgroupns_put(struct ns_common *ns)
put_cgroup_ns(to_cg_ns(ns));
}
+static struct user_namespace *cgroupns_owner(struct ns_common *ns)
+{
+ return to_cg_ns(ns)->user_ns;
+}
+
const struct proc_ns_operations cgroupns_operations = {
.name = "cgroup",
.type = CLONE_NEWCGROUP,
.get = cgroupns_get,
.put = cgroupns_put,
.install = cgroupns_install,
+ .owner = cgroupns_owner,
};
static __init int cgroup_namespaces_init(void)
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 30a7f33..c18f0f4f 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -405,12 +405,18 @@ static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns)
return 0;
}
+static struct user_namespace *pidns_owner(struct ns_common *ns)
+{
+ return to_pid_ns(ns)->user_ns;
+}
+
const struct proc_ns_operations pidns_operations = {
.name = "pid",
.type = CLONE_NEWPID,
.get = pidns_get,
.put = pidns_put,
.install = pidns_install,
+ .owner = pidns_owner,
};
static __init int pid_namespaces_init(void)
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 0edafe3..42a64d5 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -1050,12 +1050,36 @@ static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns)
return commit_creds(cred);
}
+struct ns_common *ns_get_owner(struct ns_common *ns)
+{
+ struct user_namespace *my_user_ns = current_user_ns();
+ struct user_namespace *owner, *p;
+
+ /* See if the owner is in the current user namespace */
+ owner = p = ns->ops->owner(ns);
+ for (;;) {
+ if (!p)
+ return ERR_PTR(-EPERM);
+ if (p == my_user_ns)
+ break;
+ p = p->parent;
+ }
+
+ return &get_user_ns(owner)->ns;
+}
+
+static struct user_namespace *userns_owner(struct ns_common *ns)
+{
+ return to_user_ns(ns)->parent;
+}
+
const struct proc_ns_operations userns_operations = {
.name = "user",
.type = CLONE_NEWUSER,
.get = userns_get,
.put = userns_put,
.install = userns_install,
+ .owner = userns_owner,
};
static __init int user_namespaces_init(void)
diff --git a/kernel/utsname.c b/kernel/utsname.c
index f3b0bb4..0795e97 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -154,10 +154,16 @@ static int utsns_install(struct nsproxy *nsproxy, struct ns_common *new)
return 0;
}
+static struct user_namespace *utsns_owner(struct ns_common *ns)
+{
+ return to_uts_ns(ns)->user_ns;
+}
+
const struct proc_ns_operations utsns_operations = {
.name = "uts",
.type = CLONE_NEWUTS,
.get = utsns_get,
.put = utsns_put,
.install = utsns_install,
+ .owner = utsns_owner,
};
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 3e2812a..8619e89 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -1016,11 +1016,17 @@ static int netns_install(struct nsproxy *nsproxy, struct ns_common *ns)
return 0;
}
+static struct user_namespace *netns_owner(struct ns_common *ns)
+{
+ return to_net_ns(ns)->user_ns;
+}
+
const struct proc_ns_operations netns_operations = {
.name = "net",
.type = CLONE_NEWNET,
.get = netns_get,
.put = netns_put,
.install = netns_install,
+ .owner = netns_owner,
};
#endif
--
2.5.5
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