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authorEric W. Biederman <ebiederm@xmission.com>2016-08-08 22:11:25 +0300
committerEric W. Biederman <ebiederm@xmission.com>2016-08-08 22:42:02 +0300
commitf7af3d1c03136275b876f58644599b120cf4ffdd (patch)
treeca152c99d9a25b1bad1ddf1b1ea4026e8da6e7cb
parentf333c700c6100b53050980986be922bb21466e29 (diff)
downloadlinux-f7af3d1c03136275b876f58644599b120cf4ffdd.tar.xz
utsns: Add a limit on the number of uts namespaces
Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
-rw-r--r--include/linux/user_namespace.h1
-rw-r--r--include/linux/utsname.h1
-rw-r--r--kernel/ucount.c1
-rw-r--r--kernel/utsname.c34
4 files changed, 32 insertions, 5 deletions
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 9ee94827728d..f9df7dd2609a 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -27,6 +27,7 @@ struct ucounts;
enum ucount_type {
UCOUNT_USER_NAMESPACES,
UCOUNT_PID_NAMESPACES,
+ UCOUNT_UTS_NAMESPACES,
UCOUNT_COUNTS,
};
diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index 5093f58ae192..60f0bb83b313 100644
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -24,6 +24,7 @@ struct uts_namespace {
struct kref kref;
struct new_utsname name;
struct user_namespace *user_ns;
+ struct ucounts *ucounts;
struct ns_common ns;
};
extern struct uts_namespace init_uts_ns;
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 66eca94e4ada..866850e2eb92 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -69,6 +69,7 @@ static int int_max = INT_MAX;
static struct ctl_table user_table[] = {
UCOUNT_ENTRY("max_user_namespaces"),
UCOUNT_ENTRY("max_pid_namespaces"),
+ UCOUNT_ENTRY("max_uts_namespaces"),
{ }
};
#endif /* CONFIG_SYSCTL */
diff --git a/kernel/utsname.c b/kernel/utsname.c
index 831ea7108232..f3b0bb4ac3ba 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -17,6 +17,16 @@
#include <linux/user_namespace.h>
#include <linux/proc_ns.h>
+static struct ucounts *inc_uts_namespaces(struct user_namespace *ns)
+{
+ return inc_ucount(ns, current_euid(), UCOUNT_UTS_NAMESPACES);
+}
+
+static void dec_uts_namespaces(struct ucounts *ucounts)
+{
+ dec_ucount(ucounts, UCOUNT_UTS_NAMESPACES);
+}
+
static struct uts_namespace *create_uts_ns(void)
{
struct uts_namespace *uts_ns;
@@ -36,18 +46,24 @@ static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
struct uts_namespace *old_ns)
{
struct uts_namespace *ns;
+ struct ucounts *ucounts;
int err;
+ err = -ENFILE;
+ ucounts = inc_uts_namespaces(user_ns);
+ if (!ucounts)
+ goto fail;
+
+ err = -ENOMEM;
ns = create_uts_ns();
if (!ns)
- return ERR_PTR(-ENOMEM);
+ goto fail_dec;
err = ns_alloc_inum(&ns->ns);
- if (err) {
- kfree(ns);
- return ERR_PTR(err);
- }
+ if (err)
+ goto fail_free;
+ ns->ucounts = ucounts;
ns->ns.ops = &utsns_operations;
down_read(&uts_sem);
@@ -55,6 +71,13 @@ static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
ns->user_ns = get_user_ns(user_ns);
up_read(&uts_sem);
return ns;
+
+fail_free:
+ kfree(ns);
+fail_dec:
+ dec_uts_namespaces(ucounts);
+fail:
+ return ERR_PTR(err);
}
/*
@@ -85,6 +108,7 @@ void free_uts_ns(struct kref *kref)
struct uts_namespace *ns;
ns = container_of(kref, struct uts_namespace, kref);
+ dec_uts_namespaces(ns->ucounts);
put_user_ns(ns->user_ns);
ns_free_inum(&ns->ns);
kfree(ns);