[RH7,1/3] kernel: add a helper to get an owning user namespace for a namespace

Submitted by Pavel Tikhomirov on Nov. 29, 2017, 12:47 p.m.

Details

Message ID 20171129124707.25875-2-ptikhomirov@virtuozzo.com
State New
Series "ioctl: port NS_GET_USERNS and NS_GET_PARENT"
Headers show

Commit Message

Pavel Tikhomirov Nov. 29, 2017, 12:47 p.m.
Changes:
We don't have ns_common, so instead use pointer to namespace,
and where needed also pass proc_ns_operations.
We don't have cgroupns_operations so skip it's hunk.
Initial patch doesn't add pidns_owner to pidns_for_children_operations,
as there were no such thing in ms in a time of patch, do it.

https://jira.sw.ru/browse/PSBM-57362

ms commit bcac25a58bfc ("kernel: add a helper to get an owning user
namespace for a namespace")

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@hallyn.com>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
---
 fs/namespace.c                 |  7 +++++++
 include/linux/proc_ns.h        |  1 +
 include/linux/user_namespace.h |  9 +++++++++
 ipc/namespace.c                |  7 +++++++
 kernel/pid_namespace.c         |  8 ++++++++
 kernel/user_namespace.c        | 25 +++++++++++++++++++++++++
 kernel/utsname.c               |  7 +++++++
 net/core/net_namespace.c       |  7 +++++++
 8 files changed, 71 insertions(+)

Patch hide | download patch | download mbox

diff --git a/fs/namespace.c b/fs/namespace.c
index c2489dd2f520..46b521b8d16a 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3537,6 +3537,12 @@  static unsigned int mntns_inum(void *ns)
 	return mnt_ns->proc_inum;
 }
 
+static struct user_namespace *mntns_owner(void *ns)
+{
+	struct mnt_namespace *mnt_ns = ns;
+	return mnt_ns->user_ns;
+}
+
 const struct proc_ns_operations mntns_operations = {
 	.name		= "mnt",
 	.type		= CLONE_NEWNS,
@@ -3544,4 +3550,5 @@  const struct proc_ns_operations mntns_operations = {
 	.put		= mntns_put,
 	.install	= mntns_install,
 	.inum		= mntns_inum,
+	.owner		= mntns_owner,
 };
diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index 8deba57cbb45..3f71f8e1aa18 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -16,6 +16,7 @@  struct proc_ns_operations {
 	void (*put)(void *ns);
 	int (*install)(struct nsproxy *nsproxy, void *ns);
 	unsigned int (*inum)(void *ns);
+	struct user_namespace *(*owner)(void *ns);
 };
 
 struct proc_ns {
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index ba9e7ab12de4..35b0160ae4d9 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -27,6 +27,8 @@  struct uid_gid_map {	/* 64 bytes -- 1 cache line */
 
 struct ucounts;
 
+struct proc_ns_operations;
+
 enum ucount_type {
 	UCOUNT_USER_NAMESPACES,
 	UCOUNT_PID_NAMESPACES,
@@ -118,6 +120,8 @@  extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t,
 extern ssize_t proc_setgroups_write(struct file *, const char __user *, size_t, loff_t *);
 extern int proc_setgroups_show(struct seq_file *m, void *v);
 extern bool userns_may_setgroups(const struct user_namespace *ns);
+
+void *ns_get_owner(void *ns, const struct proc_ns_operations *ns_ops);
 #else
 
 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
@@ -146,6 +150,11 @@  static inline bool userns_may_setgroups(const struct user_namespace *ns)
 {
 	return true;
 }
+static inline void *ns_get_owner(void *ns,
+		const struct proc_ns_operations *ns_ops)
+{
+	return ERR_PTR(-EPERM);
+}
 #endif
 
 void update_mnt_policy(struct user_namespace *userns);
diff --git a/ipc/namespace.c b/ipc/namespace.c
index f4cc0ef2d8ac..d2eac5005be0 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -213,6 +213,12 @@  static unsigned int ipcns_inum(void *vp)
 	return ns->proc_inum;
 }
 
+static struct user_namespace *ipcns_owner(void *ns)
+{
+	struct ipc_namespace *ipc_ns = ns;
+	return ipc_ns->user_ns;
+}
+
 const struct proc_ns_operations ipcns_operations = {
 	.name		= "ipc",
 	.type		= CLONE_NEWIPC,
@@ -220,4 +226,5 @@  const struct proc_ns_operations ipcns_operations = {
 	.put		= ipcns_put,
 	.install	= ipcns_install,
 	.inum		= ipcns_inum,
+	.owner		= ipcns_owner,
 };
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 3728139e7e54..1bab842a8e1e 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -420,6 +420,12 @@  static unsigned int pidns_inum(void *ns)
 	return pid_ns->proc_inum;
 }
 
+static struct user_namespace *pidns_owner(void *ns)
+{
+	struct pid_namespace *pid_ns = ns;
+	return pid_ns->user_ns;
+}
+
 const struct proc_ns_operations pidns_operations = {
 	.name		= "pid",
 	.type		= CLONE_NEWPID,
@@ -427,6 +433,7 @@  const struct proc_ns_operations pidns_operations = {
 	.put		= pidns_put,
 	.install	= pidns_install,
 	.inum		= pidns_inum,
+	.owner		= pidns_owner,
 };
 
 const struct proc_ns_operations pidns_for_children_operations = {
@@ -437,6 +444,7 @@  const struct proc_ns_operations pidns_for_children_operations = {
 	.put		= pidns_put,
 	.install	= pidns_install,
 	.inum		= pidns_inum,
+	.owner		= pidns_owner,
 };
 
 static __init int pid_namespaces_init(void)
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 69fb5c095966..9b145831e07c 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -1064,6 +1064,30 @@  static unsigned int userns_inum(void *ns)
 	return user_ns->proc_inum;
 }
 
+void *ns_get_owner(void *ns, const struct proc_ns_operations *ns_ops)
+{
+	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);
+}
+
+static struct user_namespace *userns_owner(void *ns)
+{
+	struct user_namespace *user_ns = ns;
+	return user_ns->parent;
+}
+
 const struct proc_ns_operations userns_operations = {
 	.name		= "user",
 	.type		= CLONE_NEWUSER,
@@ -1071,6 +1095,7 @@  const struct proc_ns_operations userns_operations = {
 	.put		= userns_put,
 	.install	= userns_install,
 	.inum		= userns_inum,
+	.owner		= userns_owner,
 };
 
 static __init int user_namespaces_init(void)
diff --git a/kernel/utsname.c b/kernel/utsname.c
index ec7adcdca386..1414b9e57822 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -184,6 +184,12 @@  static unsigned int utsns_inum(void *vp)
 	return ns->proc_inum;
 }
 
+static struct user_namespace *utsns_owner(void *ns)
+{
+	struct uts_namespace *uts_ns = ns;
+	return uts_ns->user_ns;
+}
+
 const struct proc_ns_operations utsns_operations = {
 	.name		= "uts",
 	.type		= CLONE_NEWUTS,
@@ -191,4 +197,5 @@  const struct proc_ns_operations utsns_operations = {
 	.put		= utsns_put,
 	.install	= utsns_install,
 	.inum		= utsns_inum,
+	.owner		= utsns_owner,
 };
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 6602c292743d..757d7b5f2ae3 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -1060,6 +1060,12 @@  static unsigned int netns_inum(void *ns)
 	return net->proc_inum;
 }
 
+static struct user_namespace *netns_owner(void *ns)
+{
+	struct net *net_ns = ns;
+	return net_ns->user_ns;
+}
+
 const struct proc_ns_operations netns_operations = {
 	.name		= "net",
 	.type		= CLONE_NEWNET,
@@ -1067,5 +1073,6 @@  const struct proc_ns_operations netns_operations = {
 	.put		= netns_put,
 	.install	= netns_install,
 	.inum		= netns_inum,
+	.owner		= netns_owner,
 };
 #endif