>From nobody Mon Sep 17 00:00:00 2001
From: Serge E. Hallyn <[EMAIL PROTECTED]>
Date: Thu, 5 Apr 2007 13:00:47 -0400
Subject: [PATCH 2/6] user namespace : add unshare
Changelog: Fix !CONFIG_USER_NS clone with CLONE_NEWUSER so it returns -EINVAL
rather than 0, so that userspace knows they didn't get a new user
namespace.
Cc: Serge E. Hallyn <[EMAIL PROTECTED]>
Cc: Herbert Poetzl <[EMAIL PROTECTED]>
Cc: Kirill Korotaev <[EMAIL PROTECTED]>
Cc: "Eric W. Biederman" <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Serge E. Hallyn <[EMAIL PROTECTED]>
---
include/linux/sched.h | 1 +
include/linux/user_namespace.h | 5 +++-
kernel/fork.c | 2 +-
kernel/nsproxy.c | 10 +++++++--
kernel/user_namespace.c | 46 +++++++++++++++++++++++++++++++++++++++-
5 files changed, 59 insertions(+), 5 deletions(-)
4ddd1e8f0539d843e998ea26d0c6c9cb751cbf3e
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 259d0a5..ad19efa 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -26,6 +26,7 @@ #define CLONE_CHILD_SETTID 0x01000000 /*
#define CLONE_STOPPED 0x02000000 /* Start in stopped state */
#define CLONE_NEWUTS 0x04000000 /* New utsname group? */
#define CLONE_NEWIPC 0x08000000 /* New ipcs */
+#define CLONE_NEWUSER 0x10000000 /* New user namespace */
/*
* Scheduling policies
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index c2debd8..9044456 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -45,7 +45,10 @@ static inline struct user_namespace *get
static inline struct user_namespace *copy_user_ns(int flags,
struct user_namespace *old_ns)
{
- return 0;
+ if (flags & CLONE_NEWUSER)
+ return ERR_PTR(-EINVAL);
+
+ return NULL;
}
static inline void put_user_ns(struct user_namespace *ns)
diff --git a/kernel/fork.c b/kernel/fork.c
index c20137e..123bc93 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1581,7 +1581,7 @@ asmlinkage long sys_unshare(unsigned lon
err = -EINVAL;
if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
- CLONE_NEWUTS|CLONE_NEWIPC))
+ CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWUSER))
goto bad_unshare_out;
if ((err = unshare_thread(unshare_flags)))
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 1ea8a73..fb00706 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -121,7 +121,7 @@ int copy_namespaces(int flags, struct ta
get_nsproxy(old_ns);
- if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC)))
+ if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
CLONE_NEWUSER)))
return 0;
if (!capable(CAP_SYS_ADMIN)) {
@@ -168,9 +168,15 @@ int unshare_nsproxy_namespaces(unsigned
struct nsproxy *old_ns = current->nsproxy;
int err = 0;
- if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC)))
+ if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
+ CLONE_NEWUSER)))
return 0;
+#ifndef CONFIG_USER_NS
+ if (unshare_flags & CLONE_NEWUSER)
+ return -EINVAL;
+#endif
+
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 3d79642..89a27e8 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -21,6 +21,45 @@ EXPORT_SYMBOL_GPL(init_user_ns);
#ifdef CONFIG_USER_NS
+/*
+ * Clone a new ns copying an original user ns, setting refcount to 1
+ * @old_ns: namespace to clone
+ * Return NULL on error (failure to kmalloc), new ns otherwise
+ */
+static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
+{
+ struct user_namespace *ns;
+ struct user_struct *new_user;
+ int n;
+
+ ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
+ if (!ns)
+ return NULL;
+
+ kref_init(&ns->kref);
+
+ for (n = 0; n < UIDHASH_SZ; ++n)
+ INIT_LIST_HEAD(ns->uidhash_table + n);
+
+ /* Insert new root user. */
+ ns->root_user = alloc_uid(ns, 0);
+ if (!ns->root_user) {
+ kfree(ns);
+ return NULL;
+ }
+
+ /* Reset current->user with a new one */
+ new_user = alloc_uid(ns, current->uid);
+ if (!new_user) {
+ free_uid(ns->root_user);
+ kfree(ns);
+ return NULL;
+ }
+
+ switch_uid(new_user);
+ return ns;
+}
+
struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
{
struct user_namespace *new_ns;
@@ -28,7 +67,12 @@ struct user_namespace * copy_user_ns(int
BUG_ON(!old_ns);
get_user_ns(old_ns);
- new_ns = old_ns;
+ if (!(flags & CLONE_NEWUSER))
+ return old_ns;
+
+ new_ns = clone_user_ns(old_ns);
+
+ put_user_ns(old_ns);
return new_ns;
}
--
1.3.2
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