static int populate_bpffs(struct dentry *parent)
{
struct bpf_preload_info objs[BPF_PRELOAD_LINKS] = {};
- struct bpf_link *links[BPF_PRELOAD_LINKS] = {};
int err = 0, i;
/* grab the mutex to make sure the kernel interactions with bpf_preload
- * UMD are serialized
+ * are serialized
*/
mutex_lock(&bpf_preload_lock);
if (!bpf_preload_mod_get())
goto out;
- if (!bpf_preload_ops->info.tgid) {
- /* preload() will start UMD that will load BPF iterator programs */
- err = bpf_preload_ops->preload(objs);
- if (err)
+ err = bpf_preload_ops->preload(objs);
+ if (err)
+ goto out_put;
+ for (i = 0; i < BPF_PRELOAD_LINKS; i++) {
+ bpf_link_inc(objs[i].link);
+ err = bpf_iter_link_pin_kernel(parent,
+ objs[i].link_name, objs[i].link);
+ if (err) {
+ bpf_link_put(objs[i].link);
goto out_put;
- for (i = 0; i < BPF_PRELOAD_LINKS; i++) {
- links[i] = bpf_link_by_id(objs[i].link_id);
- if (IS_ERR(links[i])) {
- err = PTR_ERR(links[i]);
- goto out_put;
- }
}
- for (i = 0; i < BPF_PRELOAD_LINKS; i++) {
- err = bpf_iter_link_pin_kernel(parent,
- objs[i].link_name, links[i]);
- if (err)
- goto out_put;
- /* do not unlink successfully pinned links even
- * if later link fails to pin
- */
- links[i] = NULL;
- }
- /* finish() will tell UMD process to exit */
- err = bpf_preload_ops->finish();
- if (err)
- goto out_put;
}
out_put:
bpf_preload_mod_put();
out:
mutex_unlock(&bpf_preload_lock);
- for (i = 0; i < BPF_PRELOAD_LINKS && err; i++)
- if (!IS_ERR_OR_NULL(links[i]))
- bpf_link_put(links[i]);
return err;
}
if BPF_PRELOAD
config BPF_PRELOAD_UMD
- tristate "bpf_preload kernel module with user mode driver"
- depends on CC_CAN_LINK
- depends on m || CC_CAN_LINK_STATIC
+ tristate "bpf_preload kernel module"
default m
help
- This builds bpf_preload kernel module with embedded user mode driver.
+ This builds bpf_preload kernel module with embedded BPF programs for
+ introspection in bpffs.
endif
LIBBPF_SRCS = $(srctree)/tools/lib/bpf/
LIBBPF_INCLUDE = $(LIBBPF_SRCS)/..
-userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi \
- -I $(LIBBPF_INCLUDE) -Wno-unused-result
-
-userprogs := bpf_preload_umd
-
-bpf_preload_umd-objs := iterators/iterators.o
-
-$(obj)/bpf_preload_umd:
-
-$(obj)/bpf_preload_umd_blob.o: $(obj)/bpf_preload_umd
-
obj-$(CONFIG_BPF_PRELOAD_UMD) += bpf_preload.o
-bpf_preload-objs += bpf_preload_kern.o bpf_preload_umd_blob.o
+CFLAGS_bpf_preload_kern.o += -I $(LIBBPF_INCLUDE)
+bpf_preload-objs += bpf_preload_kern.o
#ifndef _BPF_PRELOAD_H
#define _BPF_PRELOAD_H
-#include <linux/usermode_driver.h>
-#include "iterators/bpf_preload_common.h"
+struct bpf_preload_info {
+ char link_name[16];
+ struct bpf_link *link;
+};
struct bpf_preload_ops {
- struct umd_info info;
int (*preload)(struct bpf_preload_info *);
- int (*finish)(void);
struct module *owner;
};
extern struct bpf_preload_ops *bpf_preload_ops;
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/module.h>
-#include <linux/pid.h>
-#include <linux/fs.h>
-#include <linux/sched/signal.h>
#include "bpf_preload.h"
+#include "iterators/iterators.lskel.h"
-extern char bpf_preload_umd_start;
-extern char bpf_preload_umd_end;
+static struct bpf_link *maps_link, *progs_link;
+static struct iterators_bpf *skel;
-static int preload(struct bpf_preload_info *obj);
-static int finish(void);
+static void free_links_and_skel(void)
+{
+ if (!IS_ERR_OR_NULL(maps_link))
+ bpf_link_put(maps_link);
+ if (!IS_ERR_OR_NULL(progs_link))
+ bpf_link_put(progs_link);
+ iterators_bpf__destroy(skel);
+}
+
+static int preload(struct bpf_preload_info *obj)
+{
+ strlcpy(obj[0].link_name, "maps.debug", sizeof(obj[0].link_name));
+ obj[0].link = maps_link;
+ strlcpy(obj[1].link_name, "progs.debug", sizeof(obj[1].link_name));
+ obj[1].link = progs_link;
+ return 0;
+}
-static struct bpf_preload_ops umd_ops = {
- .info.driver_name = "bpf_preload",
+static struct bpf_preload_ops ops = {
.preload = preload,
- .finish = finish,
.owner = THIS_MODULE,
};
-static int preload(struct bpf_preload_info *obj)
+static int load_skel(void)
{
- int magic = BPF_PRELOAD_START;
- loff_t pos = 0;
- int i, err;
- ssize_t n;
+ int err;
- err = fork_usermode_driver(&umd_ops.info);
+ skel = iterators_bpf__open();
+ if (!skel)
+ return -ENOMEM;
+ err = iterators_bpf__load(skel);
if (err)
- return err;
-
- /* send the start magic to let UMD proceed with loading BPF progs */
- n = kernel_write(umd_ops.info.pipe_to_umh,
- &magic, sizeof(magic), &pos);
- if (n != sizeof(magic))
- return -EPIPE;
-
- /* receive bpf_link IDs and names from UMD */
- pos = 0;
- for (i = 0; i < BPF_PRELOAD_LINKS; i++) {
- n = kernel_read(umd_ops.info.pipe_from_umh,
- &obj[i], sizeof(*obj), &pos);
- if (n != sizeof(*obj))
- return -EPIPE;
+ goto out;
+ err = iterators_bpf__attach(skel);
+ if (err)
+ goto out;
+ maps_link = bpf_link_get_from_fd(skel->links.dump_bpf_map_fd);
+ if (IS_ERR(maps_link)) {
+ err = PTR_ERR(maps_link);
+ goto out;
}
- return 0;
-}
-
-static int finish(void)
-{
- int magic = BPF_PRELOAD_END;
- struct pid *tgid;
- loff_t pos = 0;
- ssize_t n;
-
- /* send the last magic to UMD. It will do a normal exit. */
- n = kernel_write(umd_ops.info.pipe_to_umh,
- &magic, sizeof(magic), &pos);
- if (n != sizeof(magic))
- return -EPIPE;
-
- tgid = umd_ops.info.tgid;
- if (tgid) {
- wait_event(tgid->wait_pidfd, thread_group_exited(tgid));
- umd_cleanup_helper(&umd_ops.info);
+ progs_link = bpf_link_get_from_fd(skel->links.dump_bpf_prog_fd);
+ if (IS_ERR(progs_link)) {
+ err = PTR_ERR(progs_link);
+ goto out;
}
return 0;
+out:
+ free_links_and_skel();
+ return err;
}
-static int __init load_umd(void)
+static int __init load(void)
{
int err;
- err = umd_load_blob(&umd_ops.info, &bpf_preload_umd_start,
- &bpf_preload_umd_end - &bpf_preload_umd_start);
+ err = load_skel();
if (err)
return err;
- bpf_preload_ops = &umd_ops;
+ bpf_preload_ops = &ops;
return err;
}
-static void __exit fini_umd(void)
+static void __exit fini(void)
{
- struct pid *tgid;
-
bpf_preload_ops = NULL;
-
- /* kill UMD in case it's still there due to earlier error */
- tgid = umd_ops.info.tgid;
- if (tgid) {
- kill_pid(tgid, SIGKILL, 1);
-
- wait_event(tgid->wait_pidfd, thread_group_exited(tgid));
- umd_cleanup_helper(&umd_ops.info);
- }
- umd_unload_blob(&umd_ops.info);
+ free_links_and_skel();
}
-late_initcall(load_umd);
-module_exit(fini_umd);
+late_initcall(load);
+module_exit(fini);
MODULE_LICENSE("GPL");
+++ /dev/null
-/* SPDX-License-Identifier: GPL-2.0 */
- .section .init.rodata, "a"
- .global bpf_preload_umd_start
-bpf_preload_umd_start:
- .incbin "kernel/bpf/preload/bpf_preload_umd"
- .global bpf_preload_umd_end
-bpf_preload_umd_end:
+++ /dev/null
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _BPF_PRELOAD_COMMON_H
-#define _BPF_PRELOAD_COMMON_H
-
-#define BPF_PRELOAD_START 0x5555
-#define BPF_PRELOAD_END 0xAAAA
-
-struct bpf_preload_info {
- char link_name[16];
- int link_id;
-};
-
-#endif
+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0
-/* Copyright (c) 2020 Facebook */
-#include <errno.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <sys/resource.h>
-#include <bpf/libbpf.h>
-#include <bpf/bpf.h>
-#include <sys/mount.h>
-#include "iterators.lskel.h"
-#include "bpf_preload_common.h"
-
-int to_kernel = -1;
-int from_kernel = 0;
-
-static int __bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len)
-{
- union bpf_attr attr;
- int err;
-
- memset(&attr, 0, sizeof(attr));
- attr.info.bpf_fd = bpf_fd;
- attr.info.info_len = *info_len;
- attr.info.info = (long) info;
-
- err = skel_sys_bpf(BPF_OBJ_GET_INFO_BY_FD, &attr, sizeof(attr));
- if (!err)
- *info_len = attr.info.info_len;
- return err;
-}
-
-static int send_link_to_kernel(int link_fd, const char *link_name)
-{
- struct bpf_preload_info obj = {};
- struct bpf_link_info info = {};
- __u32 info_len = sizeof(info);
- int err;
-
- err = __bpf_obj_get_info_by_fd(link_fd, &info, &info_len);
- if (err)
- return err;
- obj.link_id = info.id;
- if (strlen(link_name) >= sizeof(obj.link_name))
- return -E2BIG;
- strcpy(obj.link_name, link_name);
- if (write(to_kernel, &obj, sizeof(obj)) != sizeof(obj))
- return -EPIPE;
- return 0;
-}
-
-int main(int argc, char **argv)
-{
- struct iterators_bpf *skel;
- int err, magic;
- int debug_fd;
-
- debug_fd = open("/dev/console", O_WRONLY | O_NOCTTY | O_CLOEXEC);
- if (debug_fd < 0)
- return 1;
- to_kernel = dup(1);
- close(1);
- dup(debug_fd);
- /* now stdin and stderr point to /dev/console */
-
- read(from_kernel, &magic, sizeof(magic));
- if (magic != BPF_PRELOAD_START) {
- printf("bad start magic %d\n", magic);
- return 1;
- }
- /* libbpf opens BPF object and loads it into the kernel */
- skel = iterators_bpf__open_and_load();
- if (!skel) {
- /* iterators.skel.h is little endian.
- * libbpf doesn't support automatic little->big conversion
- * of BPF bytecode yet.
- * The program load will fail in such case.
- */
- printf("Failed load could be due to wrong endianness\n");
- return 1;
- }
- err = iterators_bpf__attach(skel);
- if (err)
- goto cleanup;
-
- /* send two bpf_link IDs with names to the kernel */
- err = send_link_to_kernel(skel->links.dump_bpf_map_fd, "maps.debug");
- if (err)
- goto cleanup;
- err = send_link_to_kernel(skel->links.dump_bpf_prog_fd, "progs.debug");
- if (err)
- goto cleanup;
-
- /* The kernel will proceed with pinnging the links in bpffs.
- * UMD will wait on read from pipe.
- */
- read(from_kernel, &magic, sizeof(magic));
- if (magic != BPF_PRELOAD_END) {
- printf("bad final magic %d\n", magic);
- err = -EINVAL;
- }
-cleanup:
- iterators_bpf__destroy(skel);
-
- return err != 0;
-}
bpf_link_free(link);
}
}
+EXPORT_SYMBOL(bpf_link_put);
static int bpf_link_release(struct inode *inode, struct file *filp)
{
return link;
}
+EXPORT_SYMBOL(bpf_link_get_from_fd);
struct bpf_tracing_link {
struct bpf_link link;
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