[RHEL7,COMMIT] kernel: add a helper to get an owning user namespace for a namespace

Submitted by Konstantin Khorenko on June 11, 2020, 4:20 p.m.

Details

Message ID 202006111620.05BGKAFo022062@finist-ce7.sw.ru
State New
Series "port nsfs from vz8"
Headers show

Commit Message

Konstantin Khorenko June 11, 2020, 4:20 p.m.
The commit is pushed to "branch-rh7-3.10.0-1127.10.1.vz7.162.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1127.10.1.vz7.162.2
------>
commit 8c1844a802e1d003e2092ed64895de0866914b59
Author: Andrey Vagin <avagin@openvz.org>
Date:   Thu Jun 11 19:20:09 2020 +0300

    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>
    
    (cherry picked from VZ8 commit bcac25a58bfc6bd79191ac5d7afb49bea96da8c9)
    
    https://jira.sw.ru/browse/PSBM-102357
    
    Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
    
    =====================
    Patchset description:
    port nsfs from vz8
    
    We have problems with /proc/pid/ns/name bind-mounts in CRIU
    
    1) Currently (without nsfs) such a bind mount have same superblock with
    /proc mount, but in case of nested pid-namespaces container can have
    multiple different /proc mounts and for ns-bind-mount we need to bind it
    from the right pidns. So we will need to enter proper pid-namespace to
    reopen ns-file fd from proper proc, it looks too complex.
    
    If we port nsfs ns-bind-mounts will be all on the same superblock which
    does not depend from procfs's we opened the ns-file on.
    
    2) Bigger problem will come then we will wan't to migrate ns-bind-mounts
    from non-nsfs to nsfs (vz8) kernel this would bring a lot of crutches,
    we will need to workaround the fact that before migration mounts were
    with same superblock and after migration they can't be.
    
    To overcome those we can port nsfs to vz7 and do ns-bind-mount support in
    a new world of nsfs, looks like it would be easier.
    
    First we need to revert all patches which depend from nsfs:
    
    8782a0069f1b proc: add a proc_show_path method to fix mountinfo
    b823f8df2fcb ms/tun: Add ioctl() TUNGETDEVNETNS cmd to allow obtaining real net ns of tun device
    302889fa2e3d ms/net: add an ioctl to get a socket network namespace
    7cb9e7ae7041 ms/tun: Add ioctl() SIOCGSKNS cmd to allow obtaining net ns of tun device
    ac08c64138ac nsfs: add ioctl to get a parent namespace
    a8e0dd94d5cd nsfs: add ioctl to get an owning user namespace for ns file descriptor
    93dca538d184 kernel: add a helper to get an owning user namespace for a namespace
    edaecdb8adac ms/pidns: expose task pid_ns_for_children to userspace
    2b151c3f8909 ms/ns: allow ns_entries to have custom symlink content
    
    Cherry-pick nsfs from VZ8:
    
    435d5f4bb2cc common object embedded into various struct ....ns
    58be28256d98 make mntns ->get()/->put()/->install()/->inum() work with &mnt_ns->ns
    ff24870f46d5 netns: switch ->get()/->put()/->install()/->inum() to working with &net->ns
    3c0411846118 switch the rest of proc_ns_operations to working with &...->ns
    64964528b24e make proc_ns_operations work with struct ns_common * instead of void *
    6344c433a452 new helpers: ns_alloc_inum/ns_free_inum
    33c429405a2c copy address of proc_ns_ops into ns_common
    f77c80142e1a bury struct proc_ns in fs/proc
    292662014509 dcache.c: call ->d_prune() regardless of d_unhashed()
    e149ed2b805f take the targets of /proc/*/ns/* symlinks to separate fs
    
    Cherry-pick part of reverted patches back from VZ8:
    
    bcac25a58bfc kernel: add a helper to get an owning user namespace for a namespace
    6786741dbf99 nsfs: add ioctl to get an owning user namespace for ns file descriptor
    a7306ed8d94a nsfs: add ioctl to get a parent namespace
    c62cce2caee5 net: add an ioctl to get a socket network namespace
    25b14e92af1a ns: allow ns_entries to have custom symlink content
    eaa0d190bfe1 pidns: expose task pid_ns_for_children to userspace
    
    Cherry-pick reverted patches back from MS (we also need them to vz8):
    
    75509fd88fbd nsfs: Add a show_path method to fix mountinfo
    24dce0800baa net: Export open_related_ns()
    d8d211a2a0c3 net: Make extern and export get_net_ns()
    f2780d6d7475 tun: Add ioctl() SIOCGSKNS cmd to allow obtaining net ns of tun device
    0c3e0e3bb623 tun: Add ioctl() TUNGETDEVNETNS cmd to allow obtaining real net ns of tun device
    073c516ff735 nsfs: mark dentry with DCACHE_RCUACCESS
    
    On this kernel I've runed zdtm, so the change should not break interfaces.
    
    https://jira.sw.ru/browse/PSBM-102357
    
    Al Viro (10):
      ms: common object embedded into various struct ....ns
      make mntns ->get()/->put()/->install()/->inum() work with &mnt_ns->ns
      netns: switch ->get()/->put()/->install()/->inum() to working with
        &net->ns
      switch the rest of proc_ns_operations to working with &...->ns
      make proc_ns_operations work with struct ns_common * instead of void *
      new helpers: ns_alloc_inum/ns_free_inum
      copy address of proc_ns_ops into ns_common
      bury struct proc_ns in fs/proc
      dcache.c: call ->d_prune() regardless of d_unhashed()
      take the targets of /proc/*/ns/* symlinks to separate fs
    
    Andrey Vagin (4):
      kernel: add a helper to get an owning user namespace for a namespace
      nsfs: add ioctl to get an owning user namespace for ns file descriptor
      nsfs: add ioctl to get a parent namespace
      net: add an ioctl to get a socket network namespace
    
    Cong Wang (1):
      nsfs: mark dentry with DCACHE_RCUACCESS
    
    Eric W. Biederman (1):
      nsfs: Add a show_path method to fix mountinfo
    
    Kirill Tkhai (6):
      ns: allow ns_entries to have custom symlink content
      pidns: expose task pid_ns_for_children to userspace
      net: Export open_related_ns()
      net: Make extern and export get_net_ns()
      tun: Add ioctl() SIOCGSKNS cmd to allow obtaining net ns of tun device
      tun: Add ioctl() TUNGETDEVNETNS cmd to allow obtaining real net ns of
        tun device
    
    Pavel Tikhomirov (10):
      Revert "proc: add a proc_show_path method to fix mountinfo"
      Revert "ms/tun: Add ioctl() TUNGETDEVNETNS cmd to allow obtaining real
        net ns of tun device"
      Revert "ms/net: add an ioctl to get a socket network namespace"
      Revert "ms/tun: Add ioctl() SIOCGSKNS cmd to allow obtaining net ns of
        tun device"
      Revert "nsfs: add ioctl to get a parent namespace"
      Revert "nsfs: add ioctl to get an owning user namespace for ns file
        descriptor"
      Revert "kernel: add a helper to get an owning user namespace for a
        namespace"
      Revert "ms/pidns: expose task pid_ns_for_children to userspace"
      Revert "ms/ns: allow ns_entries to have custom symlink content"
      userns: move EXPORT_SYMBOL closer to current_in_userns
---
 fs/namespace.c                 |  6 ++++++
 include/linux/proc_ns.h        |  1 +
 include/linux/user_namespace.h |  7 +++++++
 ipc/namespace.c                |  6 ++++++
 kernel/pid_namespace.c         |  6 ++++++
 kernel/user_namespace.c        | 24 ++++++++++++++++++++++++
 kernel/utsname.c               |  6 ++++++
 net/core/net_namespace.c       |  6 ++++++
 8 files changed, 62 insertions(+)

Patch hide | download patch | download mbox

diff --git a/fs/namespace.c b/fs/namespace.c
index ab4fcd9a5b1fd..0abfd7b85965b 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3908,10 +3908,16 @@  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 065d651fde7cb..c860e681d595a 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 30f05fa393f73..68fc165f3f626 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -120,6 +120,8 @@  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)
@@ -153,6 +155,11 @@  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 c8de38b0ee45f..b680c86feea73 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -190,10 +190,16 @@  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/pid_namespace.c b/kernel/pid_namespace.c
index da5c2a541f121..302b234f5b067 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -397,12 +397,18 @@  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 0208d67347b9d..fc388fbfad3f7 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -1079,12 +1079,36 @@  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 7ead888875b5e..68c1bb8443594 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -184,10 +184,16 @@  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 3e23dc6c09b0a..644e38948d102 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -1090,11 +1090,17 @@  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