diff options
Diffstat (limited to 'net/bpfilter')
| -rw-r--r-- | net/bpfilter/Kconfig | 16 | ||||
| -rw-r--r-- | net/bpfilter/Makefile | 32 | ||||
| -rw-r--r-- | net/bpfilter/bpfilter_kern.c | 114 | ||||
| -rw-r--r-- | net/bpfilter/main.c | 63 | ||||
| -rw-r--r-- | net/bpfilter/msgfmt.h | 17 |
5 files changed, 242 insertions, 0 deletions
diff --git a/net/bpfilter/Kconfig b/net/bpfilter/Kconfig new file mode 100644 index 000000000000..a948b072c28f --- /dev/null +++ b/net/bpfilter/Kconfig @@ -0,0 +1,16 @@ +menuconfig BPFILTER + bool "BPF based packet filtering framework (BPFILTER)" + default n + depends on NET && BPF && INET + help + This builds experimental bpfilter framework that is aiming to + provide netfilter compatible functionality via BPF + +if BPFILTER +config BPFILTER_UMH + tristate "bpfilter kernel module with user mode helper" + default m + help + This builds bpfilter kernel module with embedded user mode helper +endif + diff --git a/net/bpfilter/Makefile b/net/bpfilter/Makefile new file mode 100644 index 000000000000..aafa72001fcd --- /dev/null +++ b/net/bpfilter/Makefile @@ -0,0 +1,32 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Makefile for the Linux BPFILTER layer. +# + +hostprogs-y := bpfilter_umh +bpfilter_umh-objs := main.o +HOSTCFLAGS += -I. -Itools/include/ -Itools/include/uapi +HOSTCC := $(CC) + +ifeq ($(CONFIG_BPFILTER_UMH), y) +# builtin bpfilter_umh should be compiled with -static +# since rootfs isn't mounted at the time of __init +# function is called and do_execv won't find elf interpreter +HOSTLDFLAGS += -static +endif + +# a bit of elf magic to convert bpfilter_umh binary into a binary blob +# inside bpfilter_umh.o elf file referenced by +# _binary_net_bpfilter_bpfilter_umh_start symbol +# which bpfilter_kern.c passes further into umh blob loader at run-time +quiet_cmd_copy_umh = GEN $@ + cmd_copy_umh = echo ':' > $(obj)/.bpfilter_umh.o.cmd; \ + $(OBJCOPY) -I binary -O $(CONFIG_OUTPUT_FORMAT) \ + -B `$(OBJDUMP) -f $<|grep architecture|cut -d, -f1|cut -d' ' -f2` \ + --rename-section .data=.init.rodata $< $@ + +$(obj)/bpfilter_umh.o: $(obj)/bpfilter_umh + $(call cmd,copy_umh) + +obj-$(CONFIG_BPFILTER_UMH) += bpfilter.o +bpfilter-objs += bpfilter_kern.o bpfilter_umh.o 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"); diff --git a/net/bpfilter/main.c b/net/bpfilter/main.c new file mode 100644 index 000000000000..1317f108df8a --- /dev/null +++ b/net/bpfilter/main.c @@ -0,0 +1,63 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include <sys/uio.h> +#include <errno.h> +#include <stdio.h> +#include <sys/socket.h> +#include <fcntl.h> +#include <unistd.h> +#include "include/uapi/linux/bpf.h" +#include <asm/unistd.h> +#include "msgfmt.h" + +int debug_fd; + +static int handle_get_cmd(struct mbox_request *cmd) +{ + switch (cmd->cmd) { + case 0: + return 0; + default: + break; + } + return -ENOPROTOOPT; +} + +static int handle_set_cmd(struct mbox_request *cmd) +{ + return -ENOPROTOOPT; +} + +static void loop(void) +{ + while (1) { + struct mbox_request req; + struct mbox_reply reply; + int n; + + n = read(0, &req, sizeof(req)); + if (n != sizeof(req)) { + dprintf(debug_fd, "invalid request %d\n", n); + return; + } + + reply.status = req.is_set ? + handle_set_cmd(&req) : + handle_get_cmd(&req); + + n = write(1, &reply, sizeof(reply)); + if (n != sizeof(reply)) { + dprintf(debug_fd, "reply failed %d\n", n); + return; + } + } +} + +int main(void) +{ + debug_fd = open("/dev/console", 00000002); + dprintf(debug_fd, "Started bpfilter\n"); + loop(); + close(debug_fd); + return 0; +} diff --git a/net/bpfilter/msgfmt.h b/net/bpfilter/msgfmt.h new file mode 100644 index 000000000000..98d121c62945 --- /dev/null +++ b/net/bpfilter/msgfmt.h @@ -0,0 +1,17 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _NET_BPFILTER_MSGFMT_H +#define _NET_BPFILTER_MSGFMT_H + +struct mbox_request { + __u64 addr; + __u32 len; + __u32 is_set; + __u32 cmd; + __u32 pid; +}; + +struct mbox_reply { + __u32 status; +}; + +#endif |