kernel/bpf/helpers.c

   1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
   2  *
   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.
   6  *
   7  * This program is distributed in the hope that it will be useful, but
   8  * WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  10  * General Public License for more details.
  11  */
  12 #include <linux/bpf.h>
  13 #include <linux/rcupdate.h>
  14 #include <linux/random.h>
  15 #include <linux/smp.h>
  16 #include <linux/topology.h>
  17 #include <linux/ktime.h>
  18 #include <linux/sched.h>
  19 #include <linux/uidgid.h>
  20 #include <linux/filter.h>
  21
  22 /* If kernel subsystem is allowing eBPF programs to call this function,
  23  * inside its own verifier_ops->get_func_proto() callback it should return
  24  * bpf_map_lookup_elem_proto, so that verifier can properly check the arguments
  25  *
  26  * Different map implementations will rely on rcu in map methods
  27  * lookup/update/delete, therefore eBPF programs must run under rcu lock
  28  * if program is allowed to access maps, so check rcu_read_lock_held in
  29  * all three functions.
  30  */
  31 BPF_CALL_2(bpf_map_lookup_elem, struct bpf_map *, map, void *, key)
  32 {
  33         WARN_ON_ONCE(!rcu_read_lock_held());
  34         return (unsigned long) map->ops->map_lookup_elem(map, key);
  35 }
  36
  37 const struct bpf_func_proto bpf_map_lookup_elem_proto = {
  38         .func           = bpf_map_lookup_elem,
  39         .gpl_only       = false,
  40         .pkt_access     = true,
  41         .ret_type       = RET_PTR_TO_MAP_VALUE_OR_NULL,
  42         .arg1_type      = ARG_CONST_MAP_PTR,
  43         .arg2_type      = ARG_PTR_TO_MAP_KEY,
  44 };
  45
  46 BPF_CALL_4(bpf_map_update_elem, struct bpf_map *, map, void *, key,
  47            void *, value, u64, flags)
  48 {
  49         WARN_ON_ONCE(!rcu_read_lock_held());
  50         return map->ops->map_update_elem(map, key, value, flags);
  51 }
  52
  53 const struct bpf_func_proto bpf_map_update_elem_proto = {
  54         .func           = bpf_map_update_elem,
  55         .gpl_only       = false,
  56         .pkt_access     = true,
  57         .ret_type       = RET_INTEGER,
  58         .arg1_type      = ARG_CONST_MAP_PTR,
  59         .arg2_type      = ARG_PTR_TO_MAP_KEY,
  60         .arg3_type      = ARG_PTR_TO_MAP_VALUE,
  61         .arg4_type      = ARG_ANYTHING,
  62 };
  63
  64 BPF_CALL_2(bpf_map_delete_elem, struct bpf_map *, map, void *, key)
  65 {
  66         WARN_ON_ONCE(!rcu_read_lock_held());
  67         return map->ops->map_delete_elem(map, key);
  68 }
  69
  70 const struct bpf_func_proto bpf_map_delete_elem_proto = {
  71         .func           = bpf_map_delete_elem,
  72         .gpl_only       = false,
  73         .pkt_access     = true,
  74         .ret_type       = RET_INTEGER,
  75         .arg1_type      = ARG_CONST_MAP_PTR,
  76         .arg2_type      = ARG_PTR_TO_MAP_KEY,
  77 };
  78
  79 const struct bpf_func_proto bpf_get_prandom_u32_proto = {
  80         .func           = bpf_user_rnd_u32,
  81         .gpl_only       = false,
  82         .ret_type       = RET_INTEGER,
  83 };
  84
  85 BPF_CALL_0(bpf_get_smp_processor_id)
  86 {
  87         return smp_processor_id();
  88 }
  89
  90 const struct bpf_func_proto bpf_get_smp_processor_id_proto = {
  91         .func           = bpf_get_smp_processor_id,
  92         .gpl_only       = false,
  93         .ret_type       = RET_INTEGER,
  94 };
  95
  96 BPF_CALL_0(bpf_get_numa_node_id)
  97 {
  98         return numa_node_id();
  99 }
 100
 101 const struct bpf_func_proto bpf_get_numa_node_id_proto = {
 102         .func           = bpf_get_numa_node_id,
 103         .gpl_only       = false,
 104         .ret_type       = RET_INTEGER,
 105 };
 106
 107 BPF_CALL_0(bpf_ktime_get_ns)
 108 {
 109         /* NMI safe access to clock monotonic */
 110         return ktime_get_mono_fast_ns();
 111 }
 112
 113 const struct bpf_func_proto bpf_ktime_get_ns_proto = {
 114         .func           = bpf_ktime_get_ns,
 115         .gpl_only       = true,
 116         .ret_type       = RET_INTEGER,
 117 };
 118
 119 BPF_CALL_0(bpf_get_current_pid_tgid)
 120 {
 121         struct task_struct *task = current;
 122
 123         if (unlikely(!task))
 124                 return -EINVAL;
 125
 126         return (u64) task->tgid << 32 | task->pid;
 127 }
 128
 129 const struct bpf_func_proto bpf_get_current_pid_tgid_proto = {
 130         .func           = bpf_get_current_pid_tgid,
 131         .gpl_only       = false,
 132         .ret_type       = RET_INTEGER,
 133 };
 134
 135 BPF_CALL_0(bpf_get_current_uid_gid)
 136 {
 137         struct task_struct *task = current;
 138         kuid_t uid;
 139         kgid_t gid;
 140
 141         if (unlikely(!task))
 142                 return -EINVAL;
 143
 144         current_uid_gid(&uid, &gid);
 145         return (u64) from_kgid(&init_user_ns, gid) << 32 |
 146                      from_kuid(&init_user_ns, uid);
 147 }
 148
 149 const struct bpf_func_proto bpf_get_current_uid_gid_proto = {
 150         .func           = bpf_get_current_uid_gid,
 151         .gpl_only       = false,
 152         .ret_type       = RET_INTEGER,
 153 };
 154
 155 BPF_CALL_2(bpf_get_current_comm, char *, buf, u32, size)
 156 {
 157         struct task_struct *task = current;
 158
 159         if (unlikely(!task))
 160                 goto err_clear;
 161
 162         strncpy(buf, task->comm, size);
 163
 164         /* Verifier guarantees that size > 0. For task->comm exceeding
 165          * size, guarantee that buf is %NUL-terminated. Unconditionally
 166          * done here to save the size test.
 167          */
 168         buf[size - 1] = 0;
 169         return 0;
 170 err_clear:
 171         memset(buf, 0, size);
 172         return -EINVAL;
 173 }
 174
 175 const struct bpf_func_proto bpf_get_current_comm_proto = {
 176         .func           = bpf_get_current_comm,
 177         .gpl_only       = false,
 178         .ret_type       = RET_INTEGER,
 179         .arg1_type      = ARG_PTR_TO_RAW_STACK,
 180         .arg2_type      = ARG_CONST_STACK_SIZE,
 181 };