diff options
| -rw-r--r-- | include/linux/user_namespace.h | 4 | ||||
| -rw-r--r-- | kernel/Makefile | 2 | ||||
| -rw-r--r-- | kernel/ucount.c | 99 | ||||
| -rw-r--r-- | kernel/user_namespace.c | 18 |
4 files changed, 120 insertions, 3 deletions
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index 4e79b3c64dee..e5697eaf6bf9 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -40,6 +40,10 @@ struct user_namespace { struct rw_semaphore persistent_keyring_register_sem; #endif struct work_struct work; +#ifdef CONFIG_SYSCTL + struct ctl_table_set set; + struct ctl_table_header *sysctls; +#endif }; extern struct user_namespace init_user_ns; diff --git a/kernel/Makefile b/kernel/Makefile index e2ec54e2b952..eb26e12c6c2a 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -9,7 +9,7 @@ obj-y = fork.o exec_domain.o panic.o \ extable.o params.o \ kthread.o sys_ni.o nsproxy.o \ notifier.o ksysfs.o cred.o reboot.o \ - async.o range.o smpboot.o + async.o range.o smpboot.o ucount.o obj-$(CONFIG_MULTIUSER) += groups.o diff --git a/kernel/ucount.c b/kernel/ucount.c new file mode 100644 index 000000000000..cbde1dc87851 --- /dev/null +++ b/kernel/ucount.c @@ -0,0 +1,99 @@ +/* + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation, version 2 of the + * License. + */ + +#include <linux/stat.h> +#include <linux/sysctl.h> +#include <linux/slab.h> +#include <linux/user_namespace.h> + +#ifdef CONFIG_SYSCTL +static struct ctl_table_set * +set_lookup(struct ctl_table_root *root) +{ + return ¤t_user_ns()->set; +} + +static int set_is_seen(struct ctl_table_set *set) +{ + return ¤t_user_ns()->set == set; +} + +static int set_permissions(struct ctl_table_header *head, + struct ctl_table *table) +{ + struct user_namespace *user_ns = + container_of(head->set, struct user_namespace, set); + int mode; + + /* Allow users with CAP_SYS_RESOURCE unrestrained access */ + if (ns_capable(user_ns, CAP_SYS_RESOURCE)) + mode = (table->mode & S_IRWXU) >> 6; + else + /* Allow all others at most read-only access */ + mode = table->mode & S_IROTH; + return (mode << 6) | (mode << 3) | mode; +} + +static struct ctl_table_root set_root = { + .lookup = set_lookup, + .permissions = set_permissions, +}; + +static struct ctl_table userns_table[] = { + { } +}; +#endif /* CONFIG_SYSCTL */ + +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); + if (tbl) { + ns->sysctls = __register_sysctl_table(&ns->set, "userns", tbl); + } + if (!ns->sysctls) { + kfree(tbl); + retire_sysctl_set(&ns->set); + return false; + } +#endif + return true; +} + +void retire_userns_sysctls(struct user_namespace *ns) +{ +#ifdef CONFIG_SYSCTL + struct ctl_table *tbl; + + tbl = ns->sysctls->ctl_table_arg; + unregister_sysctl_table(ns->sysctls); + retire_sysctl_set(&ns->set); + kfree(tbl); +#endif +} + +static __init int user_namespace_sysctl_init(void) +{ +#ifdef CONFIG_SYSCTL + static struct ctl_table_header *userns_header; + static struct ctl_table empty[1]; + /* + * It is necessary to register the userns directory in the + * default set so that registrations in the child sets work + * properly. + */ + userns_header = register_sysctl("userns", empty); + BUG_ON(!userns_header); + BUG_ON(!setup_userns_sysctls(&init_user_ns)); +#endif + return 0; +} +subsys_initcall(user_namespace_sysctl_init); + + diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 5247cdb24e62..a63332253c7e 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -23,6 +23,9 @@ #include <linux/projid.h> #include <linux/fs_struct.h> +extern bool setup_userns_sysctls(struct user_namespace *ns); +extern void retire_userns_sysctls(struct user_namespace *ns); + static struct kmem_cache *user_ns_cachep __read_mostly; static DEFINE_MUTEX(userns_state_mutex); @@ -109,12 +112,22 @@ int create_user_ns(struct cred *new) ns->flags = parent_ns->flags; mutex_unlock(&userns_state_mutex); - set_cred_user_ns(new, ns); - #ifdef CONFIG_PERSISTENT_KEYRINGS init_rwsem(&ns->persistent_keyring_register_sem); #endif + ret = -ENOMEM; + if (!setup_userns_sysctls(ns)) + goto fail_keyring; + + set_cred_user_ns(new, ns); return 0; +fail_keyring: +#ifdef CONFIG_PERSISTENT_KEYRINGS + key_put(ns->persistent_keyring_register); +#endif + ns_free_inum(&ns->ns); + kmem_cache_free(user_ns_cachep, ns); + return ret; } int unshare_userns(unsigned long unshare_flags, struct cred **new_cred) @@ -144,6 +157,7 @@ static void free_user_ns(struct work_struct *work) do { parent = ns->parent; + retire_userns_sysctls(ns); #ifdef CONFIG_PERSISTENT_KEYRINGS key_put(ns->persistent_keyring_register); #endif |