#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)
.permissions = set_permissions,
};
-static struct ctl_table userns_table[] = {
+static int zero = 0;
+static int int_max = INT_MAX;
+#define UCOUNT_ENTRY(name) \
+ { \
+ .procname = name, \
+ .maxlen = sizeof(int), \
+ .mode = 0644, \
+ .proc_handler = proc_dointvec_minmax, \
+ .extra1 = &zero, \
+ .extra2 = &int_max, \
+ }
+static struct ctl_table user_table[] = {
+ UCOUNT_ENTRY("max_user_namespaces"),
+ UCOUNT_ENTRY("max_pid_namespaces"),
+ UCOUNT_ENTRY("max_uts_namespaces"),
+ UCOUNT_ENTRY("max_ipc_namespaces"),
+ UCOUNT_ENTRY("max_net_namespaces"),
+ UCOUNT_ENTRY("max_mnt_namespaces"),
+ UCOUNT_ENTRY("max_cgroup_namespaces"),
{ }
};
#endif /* CONFIG_SYSCTL */
#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) {
- ns->sysctls = __register_sysctl_table(&ns->set, "userns", tbl);
+ int i;
+ for (i = 0; i < UCOUNT_COUNTS; i++) {
+ tbl[i].data = &ns->ucount_max[i];
+ }
+ ns->sysctls = __register_sysctl_table(&ns->set, "user", tbl);
}
if (!ns->sysctls) {
kfree(tbl);
#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;
+ c = atomic_read(v);
+ for (;;) {
+ if (unlikely(c >= u))
+ return false;
+ old = atomic_cmpxchg(v, c, c+1);
+ if (likely(old == c))
+ return true;
+ c = old;
+ }
+}
+
+struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid,
+ enum ucount_type type)
+{
+ 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->ucount_max[type]);
+ if (!atomic_inc_below(&iter->ucount[type], max))
+ goto fail;
+ }
+ return ucounts;
+fail:
+ bad = iter;
+ for (iter = ucounts; iter != bad; iter = iter->ns->ucounts)
+ atomic_dec(&iter->ucount[type]);
+
+ put_ucounts(ucounts);
+ return NULL;
+}
+
+void dec_ucount(struct ucounts *ucounts, enum ucount_type type)
+{
+ struct ucounts *iter;
+ for (iter = ucounts; iter; iter = iter->ns->ucounts) {
+ int dec = atomic_dec_if_positive(&iter->ucount[type]);
+ 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;
projects / cascardo / linux.git / blobdiff