[Devel] [PATCH RHEL7 COMMIT] kernel: add a helper to get an owning user namespace for a namespace
Konstantin Khorenko
khorenko at virtuozzo.com
Thu Dec 7 13:40:13 MSK 2017
The commit is pushed to "branch-rh7-3.10.0-693.11.1.vz7.39.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.11.1.vz7.39.1
------>
commit c3b7dd8bb650c9981a931ae248605c7eb35bd08f
Author: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
Date: Thu Dec 7 13:40:13 2017 +0300
kernel: add a helper to get an owning user namespace for a namespace
Patchset description:
ioctl: port NS_GET_USERNS and NS_GET_PARENT
Need these to be able to enter owner's userns of mountnamespace to have
privileges to unmount everything, to uncover dumpable overmounted
mounts. NS_GET_PARENT is not a must here but it is nice to have it too
for criu.
https://jira.sw.ru/browse/PSBM-57362
Rework mainstream patches as we don't have nsfs and ns_common.
Other option can be porting 10 more patches:
5d826c847b34 ("new helper: readlink_copy()")
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")
e149ed2b805f ("take the targets of /proc/*/ns/* symlinks to separate fs")
And re-applying on top of them:
25b14e92af1a ("ns: allow ns_entries to have custom symlink content")
And porting fix as new version uses rcu:
073c516ff735 ("nsfs: mark dentry with DCACHE_RCUACCESS")
But still ioctls won't apply to clean after it, so I think complete
rework here is a better option.
Pavel Tikhomirov (3):
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
============================
This patch description:
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 at hallyn.com>
Signed-off-by: Andrei Vagin <avagin at openvz.org>
Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>
Signed-off-by: Pavel Tikhomirov <ptikhomirov at 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(+)
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
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