/* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com * Copyright (c) 2016 Facebook * * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. */ #include #include #include #include #include #include #include #include #include "trace.h" /** * trace_call_bpf - invoke BPF program * @call: tracepoint event * @ctx: opaque context pointer * * kprobe handlers execute BPF programs via this helper. * Can be used from static tracepoints in the future. * * Return: BPF programs always return an integer which is interpreted by * kprobe handler as: * 0 - return from kprobe (event is filtered out) * 1 - store kprobe event into ring buffer * Other values are reserved and currently alias to 1 */ unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx) { unsigned int ret; if (in_nmi()) /* not supported yet */ return 1; preempt_disable(); if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) { /* * since some bpf program is already running on this cpu, * don't call into another bpf program (same or different) * and don't send kprobe event into ring-buffer, * so return zero here */ ret = 0; goto out; } /* * Instead of moving rcu_read_lock/rcu_dereference/rcu_read_unlock * to all call sites, we did a bpf_prog_array_valid() there to check * whether call->prog_array is empty or not, which is * a heurisitc to speed up execution. * * If bpf_prog_array_valid() fetched prog_array was * non-NULL, we go into trace_call_bpf() and do the actual * proper rcu_dereference() under RCU lock. * If it turns out that prog_array is NULL then, we bail out. * For the opposite, if the bpf_prog_array_valid() fetched pointer * was NULL, you'll skip the prog_array with the risk of missing * out of events when it was updated in between this and the * rcu_dereference() which is accepted risk. */ ret = BPF_PROG_RUN_ARRAY_CHECK(call->prog_array, ctx, BPF_PROG_RUN); out: __this_cpu_dec(bpf_prog_active); preempt_enable(); return ret; } EXPORT_SYMBOL_GPL(trace_call_bpf); BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr) { int ret; ret = probe_kernel_read(dst, unsafe_ptr, size); if (unlikely(ret < 0)) memset(dst, 0, size); return ret; } static const struct bpf_func_proto bpf_probe_read_proto = { .func = bpf_probe_read, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_UNINIT_MEM, .arg2_type = ARG_CONST_SIZE, .arg3_type = ARG_ANYTHING, }; BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src, u32, size) { /* * Ensure we're in user context which is safe for the helper to * run. This helper has no business in a kthread. * * access_ok() should prevent writing to non-user memory, but in * some situations (nommu, temporary switch, etc) access_ok() does * not provide enough validation, hence the check on KERNEL_DS. */ if (unlikely(in_interrupt() || current->flags & (PF_KTHREAD | PF_EXITING))) return -EPERM; if (unlikely(uaccess_kernel())) return -EPERM; if (!access_ok(VERIFY_WRITE, unsafe_ptr, size)) return -EPERM; return probe_kernel_write(unsafe_ptr, src, size); } static const struct bpf_func_proto bpf_probe_write_user_proto = { .func = bpf_probe_write_user, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_ANYTHING, .arg2_type = ARG_PTR_TO_MEM, .arg3_type = ARG_CONST_SIZE, }; static const struct bpf_func_proto *bpf_get_probe_write_proto(void) { pr_warn_ratelimited("%s[%d] is installing a program with bpf_probe_write_user helper that may corrupt user memory!", current->comm, task_pid_nr(current)); return &bpf_probe_write_user_proto; } /* * Only limited trace_printk() conversion specifiers allowed: * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %s */ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, u64, arg2, u64, arg3) { bool str_seen = false; int mod[3] = {}; int fmt_cnt = 0; u64 unsafe_addr; char buf[64]; int i; /* * bpf_check()->check_func_arg()->check_stack_boundary() * guarantees that fmt points to bpf program stack, * fmt_size bytes of it were initialized and fmt_size > 0 */ if (fmt[--fmt_size] != 0) return -EINVAL; /* check format string for allowed specifiers */ for (i = 0; i < fmt_size; i++) { if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) return -EINVAL; if (fmt[i] != '%') continue; if (fmt_cnt >= 3) return -EINVAL; /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */ i++; if (fmt[i] == 'l') { mod[fmt_cnt]++; i++; } else if (fmt[i] == 'p' || fmt[i] == 's') { mod[fmt_cnt]++; i++; if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0) return -EINVAL; fmt_cnt++; if (fmt[i - 1] == 's') { if (str_seen) /* allow only one '%s' per fmt string */ return -EINVAL; str_seen = true; switch (fmt_cnt) { case 1: unsafe_addr = arg1; arg1 = (long) buf; break; case 2: unsafe_addr = arg2; arg2 = (long) buf; break; case 3: unsafe_addr = arg3; arg3 = (long) buf; break; } buf[0] = 0; strncpy_from_unsafe(buf, (void *) (long) unsafe_addr, sizeof(buf)); } continue; } if (fmt[i] == 'l') { mod[fmt_cnt]++; i++; } if (fmt[i] != 'i' && fmt[i] != 'd' && fmt[i] != 'u' && fmt[i] != 'x') return -EINVAL; fmt_cnt++; } /* Horrid workaround for getting va_list handling working with different * argument type combinations generically for 32 and 64 bit archs. */ #define __BPF_TP_EMIT() __BPF_ARG3_TP() #define __BPF_TP(...) \ __trace_printk(1 /* Fake ip will not be printed. */, \ fmt, ##__VA_ARGS__) #define __BPF_ARG1_TP(...) \ ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64)) \ ? __BPF_TP(arg1, ##__VA_ARGS__) \ : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32)) \ ? __BPF_TP((long)arg1, ##__VA_ARGS__) \ : __BPF_TP((u32)arg1, ##__VA_ARGS__))) #define __BPF_ARG2_TP(...) \ ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64)) \ ? __BPF_ARG1_TP(arg2, ##__VA_ARGS__) \ : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32)) \ ? __BPF_ARG1_TP((long)arg2, ##__VA_ARGS__) \ : __BPF_ARG1_TP((u32)arg2, ##__VA_ARGS__))) #define __BPF_ARG3_TP(...) \ ((mod[2] == 2 || (mod[2] == 1 && __BITS_PER_LONG == 64)) \ ? __BPF_ARG2_TP(arg3, ##__VA_ARGS__) \ : ((mod[2] == 1 || (mod[2] == 0 && __BITS_PER_LONG == 32)) \ ? __BPF_ARG2_TP((long)arg3, ##__VA_ARGS__) \ : __BPF_ARG2_TP((u32)arg3, ##__VA_ARGS__))) return __BPF_TP_EMIT(); } static const struct bpf_func_proto bpf_trace_printk_proto = { .func = bpf_trace_printk, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_MEM, .arg2_type = ARG_CONST_SIZE, }; const struct bpf_func_proto *bpf_get_trace_printk_proto(void) { /* * this program might be calling bpf_trace_printk, * so allocate per-cpu printk buffers */ trace_printk_init_buffers(); return &bpf_trace_printk_proto; } static __always_inline int get_map_perf_counter(struct bpf_map *map, u64 flags, u64 *value, u64 *enabled, u64 *running) { struct bpf_array *array = container_of(map, struct bpf_array, map); unsigned int cpu = smp_processor_id(); u64 index = flags & BPF_F_INDEX_MASK; struct bpf_event_entry *ee; if (unlikely(flags & ~(BPF_F_INDEX_MASK))) return -EINVAL; if (index == BPF_F_CURRENT_CPU) index = cpu; if (unlikely(index >= array->map.max_entries)) return -E2BIG; ee = READ_ONCE(array->ptrs[index]); if (!ee) return -ENOENT; return perf_event_read_local(ee->event, value, enabled, running); } BPF_CALL_2(bpf_perf_event_read, struct bpf_map *, map, u64, flags) { u64 value = 0; int err; err = get_map_perf_counter(map, flags, &value, NULL, NULL); /* * this api is ugly since we miss [-22..-2] range of valid * counter values, but that's uapi */ if (err) return err; return value; } static const struct bpf_func_proto bpf_perf_event_read_proto = { .func = bpf_perf_event_read, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_CONST_MAP_PTR, .arg2_type = ARG_ANYTHING, }; BPF_CALL_4(bpf_perf_event_read_value, struct bpf_map *, map, u64, flags, struct bpf_perf_event_value *, buf, u32, size) { int err = -EINVAL; if (unlikely(size != sizeof(struct bpf_perf_event_value))) goto clear; err = get_map_perf_counter(map, flags, &buf->counter, &buf->enabled, &buf->running); if (unlikely(err)) goto clear; return 0; clear: memset(buf, 0, size); return err; } static const struct bpf_func_proto bpf_perf_event_read_value_proto = { .func = bpf_perf_event_read_value, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_CONST_MAP_PTR, .arg2_type = ARG_ANYTHING, .arg3_type = ARG_PTR_TO_UNINIT_MEM, .arg4_type = ARG_CONST_SIZE, }; static DEFINE_PER_CPU(struct perf_sample_data, bpf_sd); static __always_inline u64 __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map, u64 flags, struct perf_raw_record *raw) { struct bpf_array *array = container_of(map, struct bpf_array, map); struct perf_sample_data *sd = this_cpu_ptr(&bpf_sd); unsigned int cpu = smp_processor_id(); u64 index = flags & BPF_F_INDEX_MASK; struct bpf_event_entry *ee; struct perf_event *event; if (index == BPF_F_CURRENT_CPU) index = cpu; if (unlikely(index >= array->map.max_entries)) return -E2BIG; ee = READ_ONCE(array->ptrs[index]); if (!ee) return -ENOENT; event = ee->event; if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE || event->attr.config != PERF_COUNT_SW_BPF_OUTPUT)) return -EINVAL; if (unlikely(event->oncpu != cpu)) return -EOPNOTSUPP; perf_sample_data_init(sd, 0, 0); sd->raw = raw; perf_event_output(event, sd, regs); return 0; } BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map, u64, flags, void *, data, u64, size) { struct perf_raw_record raw = { .frag = { .size = size, .data = data, }, }; if (unlikely(flags & ~(BPF_F_INDEX_MASK))) return -EINVAL; return __bpf_perf_event_output(regs, map, flags, &raw); } static const struct bpf_func_proto bpf_perf_event_output_proto = { .func = bpf_perf_event_output, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_CONST_MAP_PTR, .arg3_type = ARG_ANYTHING, .arg4_type = ARG_PTR_TO_MEM, .arg5_type = ARG_CONST_SIZE, }; static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs); u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size, void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy) { struct pt_regs *regs = this_cpu_ptr(&bpf_pt_regs); struct perf_raw_frag frag = { .copy = ctx_copy, .size = ctx_size, .data = ctx, }; struct perf_raw_record raw = { .frag = { { .next = ctx_size ? &frag : NULL, }, .size = meta_size, .data = meta, }, }; perf_fetch_caller_regs(regs); return __bpf_perf_event_output(regs, map, flags, &raw); } BPF_CALL_0(bpf_get_current_task) { return (long) current; } static const struct bpf_func_proto bpf_get_current_task_proto = { .func = bpf_get_current_task, .gpl_only = true, .ret_type = RET_INTEGER, }; BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx) { struct bpf_array *array = container_of(map, struct bpf_array, map); struct cgroup *cgrp; if (unlikely(in_interrupt())) return -EINVAL; if (unlikely(idx >= array->map.max_entries)) return -E2BIG; cgrp = READ_ONCE(array->ptrs[idx]); if (unlikely(!cgrp)) return -EAGAIN; return task_under_cgroup_hierarchy(current, cgrp); } static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = { .func = bpf_current_task_under_cgroup, .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_CONST_MAP_PTR, .arg2_type = ARG_ANYTHING, }; BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size, const void *, unsafe_ptr) { int ret; /* * The strncpy_from_unsafe() call will likely not fill the entire * buffer, but that's okay in this circumstance as we're probing * arbitrary memory anyway similar to bpf_probe_read() and might * as well probe the stack. Thus, memory is explicitly cleared * only in error case, so that improper users ignoring return * code altogether don't copy garbage; otherwise length of string * is returned that can be used for bpf_perf_event_output() et al. */ ret = strncpy_from_unsafe(dst, unsafe_ptr, size); if (unlikely(ret < 0)) memset(dst, 0, size); return ret; } static const struct bpf_func_proto bpf_probe_read_str_proto = { .func = bpf_probe_read_str, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_UNINIT_MEM, .arg2_type = ARG_CONST_SIZE, .arg3_type = ARG_ANYTHING, }; static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id) { switch (func_id) { case BPF_FUNC_map_lookup_elem: return &bpf_map_lookup_elem_proto; case BPF_FUNC_map_update_elem: return &bpf_map_update_elem_proto; case BPF_FUNC_map_delete_elem: return &bpf_map_delete_elem_proto; case BPF_FUNC_probe_read: return &bpf_probe_read_proto; case BPF_FUNC_ktime_get_ns: return &bpf_ktime_get_ns_proto; case BPF_FUNC_tail_call: return &bpf_tail_call_proto; case BPF_FUNC_get_current_pid_tgid: return &bpf_get_current_pid_tgid_proto; case BPF_FUNC_get_current_task: return &bpf_get_current_task_proto; case BPF_FUNC_get_current_uid_gid: return &bpf_get_current_uid_gid_proto; case BPF_FUNC_get_current_comm: return &bpf_get_current_comm_proto; case BPF_FUNC_trace_printk: return bpf_get_trace_printk_proto(); case BPF_FUNC_get_smp_processor_id: return &bpf_get_smp_processor_id_proto; case BPF_FUNC_get_numa_node_id: return &bpf_get_numa_node_id_proto; case BPF_FUNC_perf_event_read: return &bpf_perf_event_read_proto; case BPF_FUNC_probe_write_user: return bpf_get_probe_write_proto(); case BPF_FUNC_current_task_under_cgroup: return &bpf_current_task_under_cgroup_proto; case BPF_FUNC_get_prandom_u32: return &bpf_get_prandom_u32_proto; case BPF_FUNC_probe_read_str: return &bpf_probe_read_str_proto; default: return NULL; } } static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id) { switch (func_id) { case BPF_FUNC_perf_event_output: return &bpf_perf_event_output_proto; case BPF_FUNC_get_stackid: return &bpf_get_stackid_proto; case BPF_FUNC_perf_event_read_value: return &bpf_perf_event_read_value_proto; default: return tracing_func_proto(func_id); } } /* bpf+kprobe programs can access fields of 'struct pt_regs' */ static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type, struct bpf_insn_access_aux *info) { if (off < 0 || off >= sizeof(struct pt_regs)) return false; if (type != BPF_READ) return false; if (off % size != 0) return false; /* * Assertion for 32 bit to make sure last 8 byte access * (BPF_DW) to the last 4 byte member is disallowed. */ if (off + size > sizeof(struct pt_regs)) return false; return true; } const struct bpf_verifier_ops kprobe_verifier_ops = { .get_func_proto = kprobe_prog_func_proto, .is_valid_access = kprobe_prog_is_valid_access, }; const struct bpf_prog_ops kprobe_prog_ops = { }; BPF_CALL_5(bpf_perf_event_output_tp, void *, tp_buff, struct bpf_map *, map, u64, flags, void *, data, u64, size) { struct pt_regs *regs = *(struct pt_regs **)tp_buff; /* * r1 points to perf tracepoint buffer where first 8 bytes are hidden * from bpf program and contain a pointer to 'struct pt_regs'. Fetch it * from there and call the same bpf_perf_event_output() helper inline. */ return ____bpf_perf_event_output(regs, map, flags, data, size); } static const struct bpf_func_proto bpf_perf_event_output_proto_tp = { .func = bpf_perf_event_output_tp, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_CONST_MAP_PTR, .arg3_type = ARG_ANYTHING, .arg4_type = ARG_PTR_TO_MEM, .arg5_type = ARG_CONST_SIZE, }; BPF_CALL_3(bpf_get_stackid_tp, void *, tp_buff, struct bpf_map *, map, u64, flags) { struct pt_regs *regs = *(struct pt_regs **)tp_buff; /* * Same comment as in bpf_perf_event_output_tp(), only that this time * the other helper's function body cannot be inlined due to being * external, thus we need to call raw helper function. */ return bpf_get_stackid((unsigned long) regs, (unsigned long) map, flags, 0, 0); } static const struct bpf_func_proto bpf_get_stackid_proto_tp = { .func = bpf_get_stackid_tp, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_CONST_MAP_PTR, .arg3_type = ARG_ANYTHING, }; BPF_CALL_3(bpf_perf_prog_read_value_tp, struct bpf_perf_event_data_kern *, ctx, struct bpf_perf_event_value *, buf, u32, size) { int err = -EINVAL; if (unlikely(size != sizeof(struct bpf_perf_event_value))) goto clear; err = perf_event_read_local(ctx->event, &buf->counter, &buf->enabled, &buf->running); if (unlikely(err)) goto clear; return 0; clear: memset(buf, 0, size); return err; } static const struct bpf_func_proto bpf_perf_prog_read_value_proto_tp = { .func = bpf_perf_prog_read_value_tp, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_PTR_TO_UNINIT_MEM, .arg3_type = ARG_CONST_SIZE, }; static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id) { switch (func_id) { case BPF_FUNC_perf_event_output: return &bpf_perf_event_output_proto_tp; case BPF_FUNC_get_stackid: return &bpf_get_stackid_proto_tp; case BPF_FUNC_perf_prog_read_value: return &bpf_perf_prog_read_value_proto_tp; default: return tracing_func_proto(func_id); } } static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type, struct bpf_insn_access_aux *info) { if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE) return false; if (type != BPF_READ) return false; if (off % size != 0) return false; BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(__u64)); return true; } const struct bpf_verifier_ops tracepoint_verifier_ops = { .get_func_proto = tp_prog_func_proto, .is_valid_access = tp_prog_is_valid_access, }; const struct bpf_prog_ops tracepoint_prog_ops = { }; static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type, struct bpf_insn_access_aux *info) { const int size_sp = FIELD_SIZEOF(struct bpf_perf_event_data, sample_period); if (off < 0 || off >= sizeof(struct bpf_perf_event_data)) return false; if (type != BPF_READ) return false; if (off % size != 0) return false; switch (off) { case bpf_ctx_range(struct bpf_perf_event_data, sample_period): bpf_ctx_record_field_size(info, size_sp); if (!bpf_ctx_narrow_access_ok(off, size, size_sp)) return false; break; default: if (size != sizeof(long)) return false; } return true; } static u32 pe_prog_convert_ctx_access(enum bpf_access_type type, const struct bpf_insn *si, struct bpf_insn *insn_buf, struct bpf_prog *prog, u32 *target_size) { struct bpf_insn *insn = insn_buf; switch (si->off) { case offsetof(struct bpf_perf_event_data, sample_period): *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern, data), si->dst_reg, si->src_reg, offsetof(struct bpf_perf_event_data_kern, data)); *insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg, bpf_target_off(struct perf_sample_data, period, 8, target_size)); break; default: *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern, regs), si->dst_reg, si->src_reg, offsetof(struct bpf_perf_event_data_kern, regs)); *insn++ = BPF_LDX_MEM(BPF_SIZEOF(long), si->dst_reg, si->dst_reg, si->off); break; } return insn - insn_buf; } const struct bpf_verifier_ops perf_event_verifier_ops = { .get_func_proto = tp_prog_func_proto, .is_valid_access = pe_prog_is_valid_access, .convert_ctx_access = pe_prog_convert_ctx_access, }; const struct bpf_prog_ops perf_event_prog_ops = { }; static DEFINE_MUTEX(bpf_event_mutex); int perf_event_attach_bpf_prog(struct perf_event *event, struct bpf_prog *prog) { struct bpf_prog_array __rcu *old_array; struct bpf_prog_array *new_array; int ret = -EEXIST; mutex_lock(&bpf_event_mutex); if (event->prog) goto out; old_array = rcu_dereference_protected(event->tp_event->prog_array, lockdep_is_held(&bpf_event_mutex)); ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array); if (ret < 0) goto out; /* set the new array to event->tp_event and set event->prog */ event->prog = prog; rcu_assign_pointer(event->tp_event->prog_array, new_array); bpf_prog_array_free(old_array); out: mutex_unlock(&bpf_event_mutex); return ret; } void perf_event_detach_bpf_prog(struct perf_event *event) { struct bpf_prog_array __rcu *old_array; struct bpf_prog_array *new_array; int ret; mutex_lock(&bpf_event_mutex); if (!event->prog) goto out; old_array = rcu_dereference_protected(event->tp_event->prog_array, lockdep_is_held(&bpf_event_mutex)); ret = bpf_prog_array_copy(old_array, event->prog, NULL, &new_array); if (ret < 0) { bpf_prog_array_delete_safe(old_array, event->prog); } else { rcu_assign_pointer(event->tp_event->prog_array, new_array); bpf_prog_array_free(old_array); } bpf_prog_put(event->prog); event->prog = NULL; out: mutex_unlock(&bpf_event_mutex); }