1 /* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
7 #include <linux/kernel.h>
8 #include <linux/types.h>
9 #include <linux/slab.h>
10 #include <linux/bpf.h>
11 #include <linux/filter.h>
12 #include <linux/uaccess.h>
13 #include <linux/ctype.h>
16 static DEFINE_PER_CPU(int, bpf_prog_active);
19 * trace_call_bpf - invoke BPF program
21 * @ctx: opaque context pointer
23 * kprobe handlers execute BPF programs via this helper.
24 * Can be used from static tracepoints in the future.
26 * Return: BPF programs always return an integer which is interpreted by
28 * 0 - return from kprobe (event is filtered out)
29 * 1 - store kprobe event into ring buffer
30 * Other values are reserved and currently alias to 1
32 unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx)
36 if (in_nmi()) /* not supported yet */
41 if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
43 * since some bpf program is already running on this cpu,
44 * don't call into another bpf program (same or different)
45 * and don't send kprobe event into ring-buffer,
53 ret = BPF_PROG_RUN(prog, ctx);
57 __this_cpu_dec(bpf_prog_active);
62 EXPORT_SYMBOL_GPL(trace_call_bpf);
64 static u64 bpf_probe_read(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
66 void *dst = (void *) (long) r1;
68 void *unsafe_ptr = (void *) (long) r3;
70 return probe_kernel_read(dst, unsafe_ptr, size);
73 static const struct bpf_func_proto bpf_probe_read_proto = {
74 .func = bpf_probe_read,
76 .ret_type = RET_INTEGER,
77 .arg1_type = ARG_PTR_TO_STACK,
78 .arg2_type = ARG_CONST_STACK_SIZE,
79 .arg3_type = ARG_ANYTHING,
83 * limited trace_printk()
84 * only %d %u %x %ld %lu %lx %lld %llu %llx %p %s conversion specifiers allowed
86 static u64 bpf_trace_printk(u64 r1, u64 fmt_size, u64 r3, u64 r4, u64 r5)
88 char *fmt = (char *) (long) r1;
89 bool str_seen = false;
97 * bpf_check()->check_func_arg()->check_stack_boundary()
98 * guarantees that fmt points to bpf program stack,
99 * fmt_size bytes of it were initialized and fmt_size > 0
101 if (fmt[--fmt_size] != 0)
104 /* check format string for allowed specifiers */
105 for (i = 0; i < fmt_size; i++) {
106 if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i]))
115 /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */
120 } else if (fmt[i] == 'p' || fmt[i] == 's') {
123 if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0)
126 if (fmt[i - 1] == 's') {
128 /* allow only one '%s' per fmt string */
147 strncpy_from_unsafe(buf,
148 (void *) (long) unsafe_addr,
159 if (fmt[i] != 'd' && fmt[i] != 'u' && fmt[i] != 'x')
164 return __trace_printk(1/* fake ip will not be printed */, fmt,
165 mod[0] == 2 ? r3 : mod[0] == 1 ? (long) r3 : (u32) r3,
166 mod[1] == 2 ? r4 : mod[1] == 1 ? (long) r4 : (u32) r4,
167 mod[2] == 2 ? r5 : mod[2] == 1 ? (long) r5 : (u32) r5);
170 static const struct bpf_func_proto bpf_trace_printk_proto = {
171 .func = bpf_trace_printk,
173 .ret_type = RET_INTEGER,
174 .arg1_type = ARG_PTR_TO_STACK,
175 .arg2_type = ARG_CONST_STACK_SIZE,
178 const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
181 * this program might be calling bpf_trace_printk,
182 * so allocate per-cpu printk buffers
184 trace_printk_init_buffers();
186 return &bpf_trace_printk_proto;
189 static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
191 struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
192 struct bpf_array *array = container_of(map, struct bpf_array, map);
193 struct perf_event *event;
195 if (unlikely(index >= array->map.max_entries))
198 event = (struct perf_event *)array->ptrs[index];
203 * we don't know if the function is run successfully by the
204 * return value. It can be judged in other places, such as
207 return perf_event_read_local(event);
210 const struct bpf_func_proto bpf_perf_event_read_proto = {
211 .func = bpf_perf_event_read,
213 .ret_type = RET_INTEGER,
214 .arg1_type = ARG_CONST_MAP_PTR,
215 .arg2_type = ARG_ANYTHING,
218 static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
221 case BPF_FUNC_map_lookup_elem:
222 return &bpf_map_lookup_elem_proto;
223 case BPF_FUNC_map_update_elem:
224 return &bpf_map_update_elem_proto;
225 case BPF_FUNC_map_delete_elem:
226 return &bpf_map_delete_elem_proto;
227 case BPF_FUNC_probe_read:
228 return &bpf_probe_read_proto;
229 case BPF_FUNC_ktime_get_ns:
230 return &bpf_ktime_get_ns_proto;
231 case BPF_FUNC_tail_call:
232 return &bpf_tail_call_proto;
233 case BPF_FUNC_get_current_pid_tgid:
234 return &bpf_get_current_pid_tgid_proto;
235 case BPF_FUNC_get_current_uid_gid:
236 return &bpf_get_current_uid_gid_proto;
237 case BPF_FUNC_get_current_comm:
238 return &bpf_get_current_comm_proto;
239 case BPF_FUNC_trace_printk:
240 return bpf_get_trace_printk_proto();
241 case BPF_FUNC_get_smp_processor_id:
242 return &bpf_get_smp_processor_id_proto;
243 case BPF_FUNC_perf_event_read:
244 return &bpf_perf_event_read_proto;
250 /* bpf+kprobe programs can access fields of 'struct pt_regs' */
251 static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type)
254 if (off < 0 || off >= sizeof(struct pt_regs))
257 /* only read is allowed */
258 if (type != BPF_READ)
261 /* disallow misaligned access */
268 static struct bpf_verifier_ops kprobe_prog_ops = {
269 .get_func_proto = kprobe_prog_func_proto,
270 .is_valid_access = kprobe_prog_is_valid_access,
273 static struct bpf_prog_type_list kprobe_tl = {
274 .ops = &kprobe_prog_ops,
275 .type = BPF_PROG_TYPE_KPROBE,
278 static int __init register_kprobe_prog_ops(void)
280 bpf_register_prog_type(&kprobe_tl);
283 late_initcall(register_kprobe_prog_ops);