From 3b5378a79df12779c55e5e81bcd5dbf6238c216a Mon Sep 17 00:00:00 2001 From: Fancy Zhang Date: Sat, 4 Jul 2020 11:07:56 +0800 Subject: [PATCH] use bpftool-gen to generate skel --- execsnoop-kernel/execsnoop_kern.c | 2 +- execsnoop-kernel/execsnoop_kern_skel.h | 225 +++++++++++++++++++++++++ execsnoop-kernel/execsnoop_user_1.c | 69 ++++++++ execsnoop-kernel/readme.md | 18 +- 4 files changed, 312 insertions(+), 2 deletions(-) create mode 100644 execsnoop-kernel/execsnoop_kern_skel.h create mode 100644 execsnoop-kernel/execsnoop_user_1.c diff --git a/execsnoop-kernel/execsnoop_kern.c b/execsnoop-kernel/execsnoop_kern.c index b03fa07..fce5e08 100644 --- a/execsnoop-kernel/execsnoop_kern.c +++ b/execsnoop-kernel/execsnoop_kern.c @@ -52,7 +52,7 @@ int syscall_enter_execve(struct syscalls_enter_execve_args *ctx){ u64 id = bpf_get_current_pid_tgid(); pid = (pid_t)id; tgid = id >> 32; - uid = (__u32)bpf_get_current_uid_gid(); + uid = (u32)bpf_get_current_uid_gid(); struct event empty_event={}; if (bpf_map_update_elem(&records, &pid, &empty_event, BPF_NOEXIST)!=0) return 0; diff --git a/execsnoop-kernel/execsnoop_kern_skel.h b/execsnoop-kernel/execsnoop_kern_skel.h new file mode 100644 index 0000000..ecb38ed --- /dev/null +++ b/execsnoop-kernel/execsnoop_kern_skel.h @@ -0,0 +1,225 @@ +/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ + +/* THIS FILE IS AUTOGENERATED! */ +#ifndef __EXECSNOOP_KERN_SKEL_H__ +#define __EXECSNOOP_KERN_SKEL_H__ + +#include +#include + +struct execsnoop_kern { + struct bpf_object_skeleton *skeleton; + struct bpf_object *obj; + struct { + struct bpf_map *perf_events; + struct bpf_map *records; + } maps; + struct { + struct bpf_program *syscall_enter_execve; + struct bpf_program *syscall_exit_execve; + } progs; + struct { + struct bpf_link *syscall_enter_execve; + struct bpf_link *syscall_exit_execve; + } links; +}; + +static void +execsnoop_kern__destroy(struct execsnoop_kern *obj) +{ + if (!obj) + return; + if (obj->skeleton) + bpf_object__destroy_skeleton(obj->skeleton); + free(obj); +} + +static inline int +execsnoop_kern__create_skeleton(struct execsnoop_kern *obj); + +static inline struct execsnoop_kern * +execsnoop_kern__open_opts(const struct bpf_object_open_opts *opts) +{ + struct execsnoop_kern *obj; + + obj = (typeof(obj))calloc(1, sizeof(*obj)); + if (!obj) + return NULL; + if (execsnoop_kern__create_skeleton(obj)) + goto err; + if (bpf_object__open_skeleton(obj->skeleton, opts)) + goto err; + + return obj; +err: + execsnoop_kern__destroy(obj); + return NULL; +} + +static inline struct execsnoop_kern * +execsnoop_kern__open(void) +{ + return execsnoop_kern__open_opts(NULL); +} + +static inline int +execsnoop_kern__load(struct execsnoop_kern *obj) +{ + return bpf_object__load_skeleton(obj->skeleton); +} + +static inline struct execsnoop_kern * +execsnoop_kern__open_and_load(void) +{ + struct execsnoop_kern *obj; + + obj = execsnoop_kern__open(); + if (!obj) + return NULL; + if (execsnoop_kern__load(obj)) { + execsnoop_kern__destroy(obj); + return NULL; + } + return obj; +} + +static inline int +execsnoop_kern__attach(struct execsnoop_kern *obj) +{ + return bpf_object__attach_skeleton(obj->skeleton); +} + +static inline void +execsnoop_kern__detach(struct execsnoop_kern *obj) +{ + return bpf_object__detach_skeleton(obj->skeleton); +} + +static inline int +execsnoop_kern__create_skeleton(struct execsnoop_kern *obj) +{ + struct bpf_object_skeleton *s; + + s = (typeof(s))calloc(1, sizeof(*s)); + if (!s) + return -1; + obj->skeleton = s; + + s->sz = sizeof(*s); + s->name = "execsnoop_kern"; + s->obj = &obj->obj; + + /* maps */ + s->map_cnt = 2; + s->map_skel_sz = sizeof(*s->maps); + s->maps = (typeof(s->maps))calloc(s->map_cnt, s->map_skel_sz); + if (!s->maps) + goto err; + + s->maps[0].name = "perf_events"; + s->maps[0].map = &obj->maps.perf_events; + + s->maps[1].name = "records"; + s->maps[1].map = &obj->maps.records; + + /* programs */ + s->prog_cnt = 2; + s->prog_skel_sz = sizeof(*s->progs); + s->progs = (typeof(s->progs))calloc(s->prog_cnt, s->prog_skel_sz); + if (!s->progs) + goto err; + + s->progs[0].name = "syscall_enter_execve"; + s->progs[0].prog = &obj->progs.syscall_enter_execve; + s->progs[0].link = &obj->links.syscall_enter_execve; + + s->progs[1].name = "syscall_exit_execve"; + s->progs[1].prog = &obj->progs.syscall_exit_execve; + s->progs[1].link = &obj->links.syscall_exit_execve; + + s->data_sz = 2320; + s->data = (void *)"\ +\x7f\x45\x4c\x46\x02\x01\x01\0\0\0\0\0\0\0\0\0\x01\0\xf7\0\x01\0\0\0\0\0\0\0\0\ +\0\0\0\0\0\0\0\0\0\0\0\xd0\x05\0\0\0\0\0\0\0\0\0\0\x40\0\0\0\0\0\x40\0\x0d\0\ +\x01\0\x85\0\0\0\x0e\0\0\0\xbf\x06\0\0\0\0\0\0\x63\x6a\xfc\xff\0\0\0\0\x85\0\0\ +\0\x0f\0\0\0\xbf\x07\0\0\0\0\0\0\xb7\x01\0\0\0\0\0\0\x7b\x1a\xe8\xff\0\0\0\0\ +\x7b\x1a\xe0\xff\0\0\0\0\x7b\x1a\xd8\xff\0\0\0\0\x7b\x1a\xd0\xff\0\0\0\0\xbf\ +\xa2\0\0\0\0\0\0\x07\x02\0\0\xfc\xff\xff\xff\xbf\xa3\0\0\0\0\0\0\x07\x03\0\0\ 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b/execsnoop-kernel/execsnoop_user_1.c new file mode 100644 index 0000000..0b9fd63 --- /dev/null +++ b/execsnoop-kernel/execsnoop_user_1.c @@ -0,0 +1,69 @@ + +#include +#include +#include +#include "execsnoop_kern_skel.h" +// #include "bpf_load.h" + +#define TASK_COMM_LEN 16 +struct event { + char comm[TASK_COMM_LEN]; + pid_t pid; + pid_t tgid; + pid_t ppid; + uid_t uid; +}; + +#define PERF_BUFFER_PAGES 64 + +static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size) { + struct event *e=data; + printf("comm: %s, pid: %d, tgid: %d, ppid: %d, uid: %d\n",e->comm,e->pid,e->tgid,e->ppid,e->uid); +} + +int bump_memlock_rlimit(void) +{ + struct rlimit rlim_new = { + .rlim_cur = RLIM_INFINITY, + .rlim_max = RLIM_INFINITY, + }; + + return setrlimit(RLIMIT_MEMLOCK, &rlim_new); +} + + +int main(int argc, char **argv) { + struct perf_buffer_opts pb_opts = {}; + struct perf_buffer *pb; + int err; + + err = bump_memlock_rlimit(); + if (err) { + fprintf(stderr, "failed to increase rlimit: %d\n", err); + return 1; + } + + struct execsnoop_kern *obj=execsnoop_kern__open_and_load(); + if (!obj) { + fprintf(stderr, "failed to open and/or load BPF object\n"); + return 1; + } + + err = execsnoop_kern__attach(obj); + if (err) { + fprintf(stderr, "failed to attach BPF programs\n"); + return err; + } + + pb_opts.sample_cb = print_bpf_output; + pb = perf_buffer__new(bpf_map__fd(obj->maps.perf_events), PERF_BUFFER_PAGES, &pb_opts); + err = libbpf_get_error(pb); + if (err) { + printf("failed to setup perf_buffer: %d\n", err); + return 1; + } + + while ((err = perf_buffer__poll(pb, -1)) >= 0) {} + kill(0, SIGINT); + return err; +} diff --git a/execsnoop-kernel/readme.md b/execsnoop-kernel/readme.md index 531c7d7..f39c0cf 100644 --- a/execsnoop-kernel/readme.md +++ b/execsnoop-kernel/readme.md @@ -61,7 +61,7 @@ clang -nostdinc \ -Wno-gnu-variable-sized-type-not-at-end \ -Wno-address-of-packed-member -Wno-tautological-compare \ -Wno-unknown-warning-option \ - -fno-stack-protector -g \ + -fno-stack-protector \ -O2 -emit-llvm -c samples/bpf/execsnoop_kern.c \ -o - | llc -march=bpf -filetype=obj -o samples/bpf/execsnoop_kern.o ``` @@ -95,6 +95,22 @@ clang -nostdinc \ -lelf -lz ``` + + +## With bpftool + +- gen + +``` +bpftool gen skeleton execsnoop_kern.o > execsnoop_kern_skel.h +``` + +- build + +``` +gcc -Wall -O2 execsnoop_user_1.c -o execsnoop -Wl,-lbpf +``` + ## Some resources - [A thorough introduction to eBPF](https://lwn.net/Articles/740157/)