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-rw-r--r--include/linux/user_namespace.h18
-rw-r--r--kernel/fork.c2
-rw-r--r--kernel/ucount.c116
-rw-r--r--kernel/user_namespace.c11
4 files changed, 117 insertions, 30 deletions
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 6421cca2daa9..826de7a12a20 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -22,6 +22,7 @@ struct uid_gid_map { /* 64 bytes -- 1 cache line */
#define USERNS_INIT_FLAGS USERNS_SETGROUPS_ALLOWED
+struct ucounts;
struct user_namespace {
struct uid_gid_map uid_map;
struct uid_gid_map gid_map;
@@ -44,15 +45,24 @@ struct user_namespace {
struct ctl_table_set set;
struct ctl_table_header *sysctls;
#endif
+ struct ucounts *ucounts;
int max_user_namespaces;
+};
+
+struct ucounts {
+ struct hlist_node node;
+ struct user_namespace *ns;
+ kuid_t uid;
+ atomic_t count;
atomic_t user_namespaces;
};
extern struct user_namespace init_user_ns;
-extern bool setup_userns_sysctls(struct user_namespace *ns);
-extern void retire_userns_sysctls(struct user_namespace *ns);
-extern bool inc_user_namespaces(struct user_namespace *ns);
-extern void dec_user_namespaces(struct user_namespace *ns);
+
+bool setup_userns_sysctls(struct user_namespace *ns);
+void retire_userns_sysctls(struct user_namespace *ns);
+struct ucounts *inc_user_namespaces(struct user_namespace *ns, kuid_t uid);
+void dec_user_namespaces(struct ucounts *ucounts);
#ifdef CONFIG_USER_NS
diff --git a/kernel/fork.c b/kernel/fork.c
index daa6a82b4900..d8cde533ace3 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -322,7 +322,7 @@ void __init fork_init(void)
init_task.signal->rlim[RLIMIT_SIGPENDING] =
init_task.signal->rlim[RLIMIT_NPROC];
- init_user_ns.max_user_namespaces = max_threads;
+ init_user_ns.max_user_namespaces = max_threads/2;
}
int __weak arch_dup_task_struct(struct task_struct *dst,
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 6c2205c0befd..33c418718304 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -8,8 +8,20 @@
#include <linux/stat.h>
#include <linux/sysctl.h>
#include <linux/slab.h>
+#include <linux/hash.h>
#include <linux/user_namespace.h>
+#define UCOUNTS_HASHTABLE_BITS 10
+static struct hlist_head ucounts_hashtable[(1 << UCOUNTS_HASHTABLE_BITS)];
+static DEFINE_SPINLOCK(ucounts_lock);
+
+#define ucounts_hashfn(ns, uid) \
+ hash_long((unsigned long)__kuid_val(uid) + (unsigned long)(ns), \
+ UCOUNTS_HASHTABLE_BITS)
+#define ucounts_hashentry(ns, uid) \
+ (ucounts_hashtable + ucounts_hashfn(ns, uid))
+
+
#ifdef CONFIG_SYSCTL
static struct ctl_table_set *
set_lookup(struct ctl_table_root *root)
@@ -45,7 +57,7 @@ static struct ctl_table_root set_root = {
static int zero = 0;
static int int_max = INT_MAX;
-static struct ctl_table userns_table[] = {
+static struct ctl_table user_table[] = {
{
.procname = "max_user_namespaces",
.data = &init_user_ns.max_user_namespaces,
@@ -64,11 +76,11 @@ bool setup_userns_sysctls(struct user_namespace *ns)
#ifdef CONFIG_SYSCTL
struct ctl_table *tbl;
setup_sysctl_set(&ns->set, &set_root, set_is_seen);
- tbl = kmemdup(userns_table, sizeof(userns_table), GFP_KERNEL);
+ tbl = kmemdup(user_table, sizeof(user_table), GFP_KERNEL);
if (tbl) {
tbl[0].data = &ns->max_user_namespaces;
- ns->sysctls = __register_sysctl_table(&ns->set, "userns", tbl);
+ ns->sysctls = __register_sysctl_table(&ns->set, "user", tbl);
}
if (!ns->sysctls) {
kfree(tbl);
@@ -91,6 +103,61 @@ void retire_userns_sysctls(struct user_namespace *ns)
#endif
}
+static struct ucounts *find_ucounts(struct user_namespace *ns, kuid_t uid, struct hlist_head *hashent)
+{
+ struct ucounts *ucounts;
+
+ hlist_for_each_entry(ucounts, hashent, node) {
+ if (uid_eq(ucounts->uid, uid) && (ucounts->ns == ns))
+ return ucounts;
+ }
+ return NULL;
+}
+
+static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid)
+{
+ struct hlist_head *hashent = ucounts_hashentry(ns, uid);
+ struct ucounts *ucounts, *new;
+
+ spin_lock(&ucounts_lock);
+ ucounts = find_ucounts(ns, uid, hashent);
+ if (!ucounts) {
+ spin_unlock(&ucounts_lock);
+
+ new = kzalloc(sizeof(*new), GFP_KERNEL);
+ if (!new)
+ return NULL;
+
+ new->ns = ns;
+ new->uid = uid;
+ atomic_set(&new->count, 0);
+
+ spin_lock(&ucounts_lock);
+ ucounts = find_ucounts(ns, uid, hashent);
+ if (ucounts) {
+ kfree(new);
+ } else {
+ hlist_add_head(&new->node, hashent);
+ ucounts = new;
+ }
+ }
+ if (!atomic_add_unless(&ucounts->count, 1, INT_MAX))
+ ucounts = NULL;
+ spin_unlock(&ucounts_lock);
+ return ucounts;
+}
+
+static void put_ucounts(struct ucounts *ucounts)
+{
+ if (atomic_dec_and_test(&ucounts->count)) {
+ spin_lock(&ucounts_lock);
+ hlist_del_init(&ucounts->node);
+ spin_unlock(&ucounts_lock);
+
+ kfree(ucounts);
+ }
+}
+
static inline bool atomic_inc_below(atomic_t *v, int u)
{
int c, old;
@@ -105,44 +172,51 @@ static inline bool atomic_inc_below(atomic_t *v, int u)
}
}
-bool inc_user_namespaces(struct user_namespace *ns)
+struct ucounts *inc_user_namespaces(struct user_namespace *ns, kuid_t uid)
{
- struct user_namespace *pos, *bad;
- for (pos = ns; pos; pos = pos->parent) {
- int max = READ_ONCE(pos->max_user_namespaces);
- if (!atomic_inc_below(&pos->user_namespaces, max))
+ struct ucounts *ucounts, *iter, *bad;
+ struct user_namespace *tns;
+ ucounts = get_ucounts(ns, uid);
+ for (iter = ucounts; iter; iter = tns->ucounts) {
+ int max;
+ tns = iter->ns;
+ max = READ_ONCE(tns->max_user_namespaces);
+ if (!atomic_inc_below(&iter->user_namespaces, max))
goto fail;
}
- return true;
+ return ucounts;
fail:
- bad = pos;
- for (pos = ns; pos != bad; pos = pos->parent)
- atomic_dec(&pos->user_namespaces);
+ bad = iter;
+ for (iter = ucounts; iter != bad; iter = iter->ns->ucounts)
+ atomic_dec(&iter->user_namespaces);
- return false;
+ put_ucounts(ucounts);
+ return NULL;
}
-void dec_user_namespaces(struct user_namespace *ns)
+void dec_user_namespaces(struct ucounts *ucounts)
{
- struct user_namespace *pos;
- for (pos = ns; pos; pos = pos->parent) {
- int dec = atomic_dec_if_positive(&pos->user_namespaces);
+ struct ucounts *iter;
+ for (iter = ucounts; iter; iter = iter->ns->ucounts) {
+ int dec = atomic_dec_if_positive(&iter->user_namespaces);
WARN_ON_ONCE(dec < 0);
}
+ put_ucounts(ucounts);
}
+
static __init int user_namespace_sysctl_init(void)
{
#ifdef CONFIG_SYSCTL
- static struct ctl_table_header *userns_header;
+ static struct ctl_table_header *user_header;
static struct ctl_table empty[1];
/*
- * It is necessary to register the userns directory in the
+ * It is necessary to register the user directory in the
* default set so that registrations in the child sets work
* properly.
*/
- userns_header = register_sysctl("userns", empty);
- BUG_ON(!userns_header);
+ user_header = register_sysctl("user", empty);
+ BUG_ON(!user_header);
BUG_ON(!setup_userns_sysctls(&init_user_ns));
#endif
return 0;
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 7d87017a0040..58c67e5f851c 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -31,7 +31,6 @@ static bool new_idmap_permitted(const struct file *file,
struct uid_gid_map *map);
static void free_user_ns(struct work_struct *work);
-
static void set_cred_user_ns(struct cred *cred, struct user_namespace *user_ns)
{
/* Start with the same capabilities as init but useless for doing
@@ -64,13 +63,15 @@ int create_user_ns(struct cred *new)
struct user_namespace *ns, *parent_ns = new->user_ns;
kuid_t owner = new->euid;
kgid_t group = new->egid;
+ struct ucounts *ucounts;
int ret;
ret = -EUSERS;
if (parent_ns->level > 32)
goto fail;
- if (!inc_user_namespaces(parent_ns))
+ ucounts = inc_user_namespaces(parent_ns, owner);
+ if (!ucounts)
goto fail;
/*
@@ -110,6 +111,7 @@ int create_user_ns(struct cred *new)
ns->group = group;
INIT_WORK(&ns->work, free_user_ns);
ns->max_user_namespaces = INT_MAX;
+ ns->ucounts = ucounts;
/* Inherit USERNS_SETGROUPS_ALLOWED from our parent */
mutex_lock(&userns_state_mutex);
@@ -133,7 +135,7 @@ fail_keyring:
fail_free:
kmem_cache_free(user_ns_cachep, ns);
fail_dec:
- dec_user_namespaces(parent_ns);
+ dec_user_namespaces(ucounts);
fail:
return ret;
}
@@ -164,6 +166,7 @@ static void free_user_ns(struct work_struct *work)
container_of(work, struct user_namespace, work);
do {
+ struct ucounts *ucounts = ns->ucounts;
parent = ns->parent;
retire_userns_sysctls(ns);
#ifdef CONFIG_PERSISTENT_KEYRINGS
@@ -171,7 +174,7 @@ static void free_user_ns(struct work_struct *work)
#endif
ns_free_inum(&ns->ns);
kmem_cache_free(user_ns_cachep, ns);
- dec_user_namespaces(parent);
+ dec_user_namespaces(ucounts);
ns = parent;
} while (atomic_dec_and_test(&parent->count));
}