From c9e7c76d70fa50582ca96759829c93d0dd024662 Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Mon, 21 Sep 2020 15:36:51 +0100 Subject: [PATCH] xfrm: Provide API to register translator module Add a skeleton for xfrm_compat module and provide API to register it in xfrm_state.ko. struct xfrm_translator will have function pointers to translate messages received from 32-bit userspace or to be sent to it from 64-bit kernel. module_get()/module_put() are used instead of rcu_read_lock() as the module will vmalloc() memory for translation. The new API is registered with xfrm_state module, not with xfrm_user as the former needs translator for user_policy set by setsockopt() and xfrm_user already uses functions from xfrm_state. Signed-off-by: Dmitry Safonov Signed-off-by: Steffen Klassert --- include/net/xfrm.h | 19 +++++++++++++ net/xfrm/Kconfig | 10 +++++++ net/xfrm/Makefile | 1 + net/xfrm/xfrm_compat.c | 29 ++++++++++++++++++++ net/xfrm/xfrm_state.c | 60 ++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 119 insertions(+) create mode 100644 net/xfrm/xfrm_compat.c diff --git a/include/net/xfrm.h b/include/net/xfrm.h index 2737d24ec244..fe2e3717da14 100644 --- a/include/net/xfrm.h +++ b/include/net/xfrm.h @@ -2000,6 +2000,25 @@ static inline int xfrm_tunnel_check(struct sk_buff *skb, struct xfrm_state *x, return 0; } +struct xfrm_translator { + struct module *owner; +}; + +#if IS_ENABLED(CONFIG_XFRM_USER_COMPAT) +extern int xfrm_register_translator(struct xfrm_translator *xtr); +extern int xfrm_unregister_translator(struct xfrm_translator *xtr); +extern struct xfrm_translator *xfrm_get_translator(void); +extern void xfrm_put_translator(struct xfrm_translator *xtr); +#else +static inline struct xfrm_translator *xfrm_get_translator(void) +{ + return NULL; +} +static inline void xfrm_put_translator(struct xfrm_translator *xtr) +{ +} +#endif + #if IS_ENABLED(CONFIG_IPV6) static inline bool xfrm6_local_dontfrag(const struct sock *sk) { diff --git a/net/xfrm/Kconfig b/net/xfrm/Kconfig index 5b9a5ab48111..e79b48dab61b 100644 --- a/net/xfrm/Kconfig +++ b/net/xfrm/Kconfig @@ -28,6 +28,16 @@ config XFRM_USER If unsure, say Y. +config XFRM_USER_COMPAT + tristate "Compatible ABI support" + depends on XFRM_USER && COMPAT_FOR_U64_ALIGNMENT + select WANT_COMPAT_NETLINK_MESSAGES + help + Transformation(XFRM) user configuration interface like IPsec + used by compatible Linux applications. + + If unsure, say N. + config XFRM_INTERFACE tristate "Transformation virtual interface" depends on XFRM && IPV6 diff --git a/net/xfrm/Makefile b/net/xfrm/Makefile index 2d4bb4b9f75e..494aa744bfb9 100644 --- a/net/xfrm/Makefile +++ b/net/xfrm/Makefile @@ -9,6 +9,7 @@ obj-$(CONFIG_XFRM) := xfrm_policy.o xfrm_state.o xfrm_hash.o \ obj-$(CONFIG_XFRM_STATISTICS) += xfrm_proc.o obj-$(CONFIG_XFRM_ALGO) += xfrm_algo.o obj-$(CONFIG_XFRM_USER) += xfrm_user.o +obj-$(CONFIG_XFRM_USER_COMPAT) += xfrm_compat.o obj-$(CONFIG_XFRM_IPCOMP) += xfrm_ipcomp.o obj-$(CONFIG_XFRM_INTERFACE) += xfrm_interface.o obj-$(CONFIG_XFRM_ESPINTCP) += espintcp.o diff --git a/net/xfrm/xfrm_compat.c b/net/xfrm/xfrm_compat.c new file mode 100644 index 000000000000..f01d9af41c55 --- /dev/null +++ b/net/xfrm/xfrm_compat.c @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * XFRM compat layer + * Author: Dmitry Safonov + * Based on code and translator idea by: Florian Westphal + */ +#include +#include +#include + +static struct xfrm_translator xfrm_translator = { + .owner = THIS_MODULE, +}; + +static int __init xfrm_compat_init(void) +{ + return xfrm_register_translator(&xfrm_translator); +} + +static void __exit xfrm_compat_exit(void) +{ + xfrm_unregister_translator(&xfrm_translator); +} + +module_init(xfrm_compat_init); +module_exit(xfrm_compat_exit); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Dmitry Safonov"); +MODULE_DESCRIPTION("XFRM 32-bit compatibility layer"); diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index 69520ad3d83b..cc206ca3df78 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -2264,6 +2264,66 @@ static bool km_is_alive(const struct km_event *c) return is_alive; } +#if IS_ENABLED(CONFIG_XFRM_USER_COMPAT) +static DEFINE_SPINLOCK(xfrm_translator_lock); +static struct xfrm_translator __rcu *xfrm_translator; + +struct xfrm_translator *xfrm_get_translator(void) +{ + struct xfrm_translator *xtr; + + rcu_read_lock(); + xtr = rcu_dereference(xfrm_translator); + if (unlikely(!xtr)) + goto out; + if (!try_module_get(xtr->owner)) + xtr = NULL; +out: + rcu_read_unlock(); + return xtr; +} +EXPORT_SYMBOL_GPL(xfrm_get_translator); + +void xfrm_put_translator(struct xfrm_translator *xtr) +{ + module_put(xtr->owner); +} +EXPORT_SYMBOL_GPL(xfrm_put_translator); + +int xfrm_register_translator(struct xfrm_translator *xtr) +{ + int err = 0; + + spin_lock_bh(&xfrm_translator_lock); + if (unlikely(xfrm_translator != NULL)) + err = -EEXIST; + else + rcu_assign_pointer(xfrm_translator, xtr); + spin_unlock_bh(&xfrm_translator_lock); + + return err; +} +EXPORT_SYMBOL_GPL(xfrm_register_translator); + +int xfrm_unregister_translator(struct xfrm_translator *xtr) +{ + int err = 0; + + spin_lock_bh(&xfrm_translator_lock); + if (likely(xfrm_translator != NULL)) { + if (rcu_access_pointer(xfrm_translator) != xtr) + err = -EINVAL; + else + RCU_INIT_POINTER(xfrm_translator, NULL); + } + spin_unlock_bh(&xfrm_translator_lock); + synchronize_rcu(); + + return err; +} +EXPORT_SYMBOL_GPL(xfrm_unregister_translator); +#endif + int xfrm_user_policy(struct sock *sk, int optname, sockptr_t optval, int optlen) { int err;