diff options
Diffstat (limited to 'net/bpfilter/bpfilter_kern.c')
-rw-r--r-- | net/bpfilter/bpfilter_kern.c | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c new file mode 100644 index 000000000000..b13d058f8c34 --- /dev/null +++ b/net/bpfilter/bpfilter_kern.c @@ -0,0 +1,114 @@ +// SPDX-License-Identifier: GPL-2.0 +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/init.h> +#include <linux/module.h> +#include <linux/umh.h> +#include <linux/bpfilter.h> +#include <linux/sched.h> +#include <linux/sched/signal.h> +#include <linux/fs.h> +#include <linux/file.h> +#include "msgfmt.h" + +#define UMH_start _binary_net_bpfilter_bpfilter_umh_start +#define UMH_end _binary_net_bpfilter_bpfilter_umh_end + +extern char UMH_start; +extern char UMH_end; + +static struct umh_info info; +/* since ip_getsockopt() can run in parallel, serialize access to umh */ +static DEFINE_MUTEX(bpfilter_lock); + +static void shutdown_umh(struct umh_info *info) +{ + struct task_struct *tsk; + + tsk = pid_task(find_vpid(info->pid), PIDTYPE_PID); + if (tsk) + force_sig(SIGKILL, tsk); + fput(info->pipe_to_umh); + fput(info->pipe_from_umh); +} + +static void __stop_umh(void) +{ + if (IS_ENABLED(CONFIG_INET) && + bpfilter_process_sockopt) { + bpfilter_process_sockopt = NULL; + shutdown_umh(&info); + } +} + +static void stop_umh(void) +{ + mutex_lock(&bpfilter_lock); + __stop_umh(); + mutex_unlock(&bpfilter_lock); +} + +static int __bpfilter_process_sockopt(struct sock *sk, int optname, + char __user *optval, + unsigned int optlen, bool is_set) +{ + struct mbox_request req; + struct mbox_reply reply; + loff_t pos; + ssize_t n; + int ret; + + req.is_set = is_set; + req.pid = current->pid; + req.cmd = optname; + req.addr = (long)optval; + req.len = optlen; + mutex_lock(&bpfilter_lock); + n = __kernel_write(info.pipe_to_umh, &req, sizeof(req), &pos); + if (n != sizeof(req)) { + pr_err("write fail %zd\n", n); + __stop_umh(); + ret = -EFAULT; + goto out; + } + pos = 0; + n = kernel_read(info.pipe_from_umh, &reply, sizeof(reply), &pos); + if (n != sizeof(reply)) { + pr_err("read fail %zd\n", n); + __stop_umh(); + ret = -EFAULT; + goto out; + } + ret = reply.status; +out: + mutex_unlock(&bpfilter_lock); + return ret; +} + +static int __init load_umh(void) +{ + int err; + + /* fork usermode process */ + err = fork_usermode_blob(&UMH_start, &UMH_end - &UMH_start, &info); + if (err) + return err; + pr_info("Loaded bpfilter_umh pid %d\n", info.pid); + + /* health check that usermode process started correctly */ + if (__bpfilter_process_sockopt(NULL, 0, 0, 0, 0) != 0) { + stop_umh(); + return -EFAULT; + } + if (IS_ENABLED(CONFIG_INET)) + bpfilter_process_sockopt = &__bpfilter_process_sockopt; + + return 0; +} + +static void __exit fini_umh(void) +{ + stop_umh(); +} +module_init(load_umh); +module_exit(fini_umh); +MODULE_LICENSE("GPL"); |