1fec56f58SAlexei Starovoitov // SPDX-License-Identifier: GPL-2.0-only 2fec56f58SAlexei Starovoitov /* Copyright (c) 2019 Facebook */ 3fec56f58SAlexei Starovoitov #include <linux/hash.h> 4fec56f58SAlexei Starovoitov #include <linux/bpf.h> 5fec56f58SAlexei Starovoitov #include <linux/filter.h> 6b91e014fSAlexei Starovoitov #include <linux/ftrace.h> 7e9b4e606SJiri Olsa #include <linux/rbtree_latch.h> 8a108f7dcSJiri Olsa #include <linux/perf_event.h> 99e4e01dfSKP Singh #include <linux/btf.h> 101e6c62a8SAlexei Starovoitov #include <linux/rcupdate_trace.h> 111e6c62a8SAlexei Starovoitov #include <linux/rcupdate_wait.h> 12861de02eSJiri Olsa #include <linux/module.h> 13856c02dbSSong Liu #include <linux/static_call.h> 1469fd337aSStanislav Fomichev #include <linux/bpf_verifier.h> 1569fd337aSStanislav Fomichev #include <linux/bpf_lsm.h> 16*00963a2eSSong Liu #include <linux/delay.h> 17fec56f58SAlexei Starovoitov 18be8704ffSAlexei Starovoitov /* dummy _ops. The verifier will operate on target program's ops. */ 19be8704ffSAlexei Starovoitov const struct bpf_verifier_ops bpf_extension_verifier_ops = { 20be8704ffSAlexei Starovoitov }; 21be8704ffSAlexei Starovoitov const struct bpf_prog_ops bpf_extension_prog_ops = { 22be8704ffSAlexei Starovoitov }; 23be8704ffSAlexei Starovoitov 24fec56f58SAlexei Starovoitov /* btf_vmlinux has ~22k attachable functions. 1k htab is enough. */ 25fec56f58SAlexei Starovoitov #define TRAMPOLINE_HASH_BITS 10 26fec56f58SAlexei Starovoitov #define TRAMPOLINE_TABLE_SIZE (1 << TRAMPOLINE_HASH_BITS) 27fec56f58SAlexei Starovoitov 28fec56f58SAlexei Starovoitov static struct hlist_head trampoline_table[TRAMPOLINE_TABLE_SIZE]; 29fec56f58SAlexei Starovoitov 307ac88ebaSJiri Olsa /* serializes access to trampoline_table */ 31fec56f58SAlexei Starovoitov static DEFINE_MUTEX(trampoline_mutex); 32fec56f58SAlexei Starovoitov 33*00963a2eSSong Liu #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 34*00963a2eSSong Liu static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex); 35*00963a2eSSong Liu 36*00963a2eSSong Liu static int bpf_tramp_ftrace_ops_func(struct ftrace_ops *ops, enum ftrace_ops_cmd cmd) 37*00963a2eSSong Liu { 38*00963a2eSSong Liu struct bpf_trampoline *tr = ops->private; 39*00963a2eSSong Liu int ret = 0; 40*00963a2eSSong Liu 41*00963a2eSSong Liu if (cmd == FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_SELF) { 42*00963a2eSSong Liu /* This is called inside register_ftrace_direct_multi(), so 43*00963a2eSSong Liu * tr->mutex is already locked. 44*00963a2eSSong Liu */ 45*00963a2eSSong Liu lockdep_assert_held_once(&tr->mutex); 46*00963a2eSSong Liu 47*00963a2eSSong Liu /* Instead of updating the trampoline here, we propagate 48*00963a2eSSong Liu * -EAGAIN to register_ftrace_direct_multi(). Then we can 49*00963a2eSSong Liu * retry register_ftrace_direct_multi() after updating the 50*00963a2eSSong Liu * trampoline. 51*00963a2eSSong Liu */ 52*00963a2eSSong Liu if ((tr->flags & BPF_TRAMP_F_CALL_ORIG) && 53*00963a2eSSong Liu !(tr->flags & BPF_TRAMP_F_ORIG_STACK)) { 54*00963a2eSSong Liu if (WARN_ON_ONCE(tr->flags & BPF_TRAMP_F_SHARE_IPMODIFY)) 55*00963a2eSSong Liu return -EBUSY; 56*00963a2eSSong Liu 57*00963a2eSSong Liu tr->flags |= BPF_TRAMP_F_SHARE_IPMODIFY; 58*00963a2eSSong Liu return -EAGAIN; 59*00963a2eSSong Liu } 60*00963a2eSSong Liu 61*00963a2eSSong Liu return 0; 62*00963a2eSSong Liu } 63*00963a2eSSong Liu 64*00963a2eSSong Liu /* The normal locking order is 65*00963a2eSSong Liu * tr->mutex => direct_mutex (ftrace.c) => ftrace_lock (ftrace.c) 66*00963a2eSSong Liu * 67*00963a2eSSong Liu * The following two commands are called from 68*00963a2eSSong Liu * 69*00963a2eSSong Liu * prepare_direct_functions_for_ipmodify 70*00963a2eSSong Liu * cleanup_direct_functions_after_ipmodify 71*00963a2eSSong Liu * 72*00963a2eSSong Liu * In both cases, direct_mutex is already locked. Use 73*00963a2eSSong Liu * mutex_trylock(&tr->mutex) to avoid deadlock in race condition 74*00963a2eSSong Liu * (something else is making changes to this same trampoline). 75*00963a2eSSong Liu */ 76*00963a2eSSong Liu if (!mutex_trylock(&tr->mutex)) { 77*00963a2eSSong Liu /* sleep 1 ms to make sure whatever holding tr->mutex makes 78*00963a2eSSong Liu * some progress. 79*00963a2eSSong Liu */ 80*00963a2eSSong Liu msleep(1); 81*00963a2eSSong Liu return -EAGAIN; 82*00963a2eSSong Liu } 83*00963a2eSSong Liu 84*00963a2eSSong Liu switch (cmd) { 85*00963a2eSSong Liu case FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER: 86*00963a2eSSong Liu tr->flags |= BPF_TRAMP_F_SHARE_IPMODIFY; 87*00963a2eSSong Liu 88*00963a2eSSong Liu if ((tr->flags & BPF_TRAMP_F_CALL_ORIG) && 89*00963a2eSSong Liu !(tr->flags & BPF_TRAMP_F_ORIG_STACK)) 90*00963a2eSSong Liu ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */); 91*00963a2eSSong Liu break; 92*00963a2eSSong Liu case FTRACE_OPS_CMD_DISABLE_SHARE_IPMODIFY_PEER: 93*00963a2eSSong Liu tr->flags &= ~BPF_TRAMP_F_SHARE_IPMODIFY; 94*00963a2eSSong Liu 95*00963a2eSSong Liu if (tr->flags & BPF_TRAMP_F_ORIG_STACK) 96*00963a2eSSong Liu ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */); 97*00963a2eSSong Liu break; 98*00963a2eSSong Liu default: 99*00963a2eSSong Liu ret = -EINVAL; 100*00963a2eSSong Liu break; 101*00963a2eSSong Liu }; 102*00963a2eSSong Liu 103*00963a2eSSong Liu mutex_unlock(&tr->mutex); 104*00963a2eSSong Liu return ret; 105*00963a2eSSong Liu } 106*00963a2eSSong Liu #endif 107*00963a2eSSong Liu 108f92c1e18SJiri Olsa bool bpf_prog_has_trampoline(const struct bpf_prog *prog) 109f92c1e18SJiri Olsa { 110f92c1e18SJiri Olsa enum bpf_attach_type eatype = prog->expected_attach_type; 1112fcc8241SKui-Feng Lee enum bpf_prog_type ptype = prog->type; 112f92c1e18SJiri Olsa 1132fcc8241SKui-Feng Lee return (ptype == BPF_PROG_TYPE_TRACING && 1142fcc8241SKui-Feng Lee (eatype == BPF_TRACE_FENTRY || eatype == BPF_TRACE_FEXIT || 1152fcc8241SKui-Feng Lee eatype == BPF_MODIFY_RETURN)) || 1162fcc8241SKui-Feng Lee (ptype == BPF_PROG_TYPE_LSM && eatype == BPF_LSM_MAC); 117f92c1e18SJiri Olsa } 118f92c1e18SJiri Olsa 1197ac88ebaSJiri Olsa void *bpf_jit_alloc_exec_page(void) 12098e8627eSBjörn Töpel { 12198e8627eSBjörn Töpel void *image; 12298e8627eSBjörn Töpel 12398e8627eSBjörn Töpel image = bpf_jit_alloc_exec(PAGE_SIZE); 12498e8627eSBjörn Töpel if (!image) 12598e8627eSBjörn Töpel return NULL; 12698e8627eSBjörn Töpel 12798e8627eSBjörn Töpel set_vm_flush_reset_perms(image); 12898e8627eSBjörn Töpel /* Keep image as writeable. The alternative is to keep flipping ro/rw 12998e8627eSBjörn Töpel * every time new program is attached or detached. 13098e8627eSBjörn Töpel */ 13198e8627eSBjörn Töpel set_memory_x((long)image, 1); 13298e8627eSBjörn Töpel return image; 13398e8627eSBjörn Töpel } 13498e8627eSBjörn Töpel 135a108f7dcSJiri Olsa void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym) 136a108f7dcSJiri Olsa { 137a108f7dcSJiri Olsa ksym->start = (unsigned long) data; 1387ac88ebaSJiri Olsa ksym->end = ksym->start + PAGE_SIZE; 139a108f7dcSJiri Olsa bpf_ksym_add(ksym); 140a108f7dcSJiri Olsa perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, 1417ac88ebaSJiri Olsa PAGE_SIZE, false, ksym->name); 142a108f7dcSJiri Olsa } 143a108f7dcSJiri Olsa 144a108f7dcSJiri Olsa void bpf_image_ksym_del(struct bpf_ksym *ksym) 145a108f7dcSJiri Olsa { 146a108f7dcSJiri Olsa bpf_ksym_del(ksym); 147a108f7dcSJiri Olsa perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, 1487ac88ebaSJiri Olsa PAGE_SIZE, true, ksym->name); 149a108f7dcSJiri Olsa } 150a108f7dcSJiri Olsa 151f7b12b6fSToke Høiland-Jørgensen static struct bpf_trampoline *bpf_trampoline_lookup(u64 key) 152fec56f58SAlexei Starovoitov { 153fec56f58SAlexei Starovoitov struct bpf_trampoline *tr; 154fec56f58SAlexei Starovoitov struct hlist_head *head; 155fec56f58SAlexei Starovoitov int i; 156fec56f58SAlexei Starovoitov 157fec56f58SAlexei Starovoitov mutex_lock(&trampoline_mutex); 158fec56f58SAlexei Starovoitov head = &trampoline_table[hash_64(key, TRAMPOLINE_HASH_BITS)]; 159fec56f58SAlexei Starovoitov hlist_for_each_entry(tr, head, hlist) { 160fec56f58SAlexei Starovoitov if (tr->key == key) { 161fec56f58SAlexei Starovoitov refcount_inc(&tr->refcnt); 162fec56f58SAlexei Starovoitov goto out; 163fec56f58SAlexei Starovoitov } 164fec56f58SAlexei Starovoitov } 165fec56f58SAlexei Starovoitov tr = kzalloc(sizeof(*tr), GFP_KERNEL); 166fec56f58SAlexei Starovoitov if (!tr) 167fec56f58SAlexei Starovoitov goto out; 168*00963a2eSSong Liu #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 169*00963a2eSSong Liu tr->fops = kzalloc(sizeof(struct ftrace_ops), GFP_KERNEL); 170*00963a2eSSong Liu if (!tr->fops) { 171*00963a2eSSong Liu kfree(tr); 172*00963a2eSSong Liu tr = NULL; 173*00963a2eSSong Liu goto out; 174*00963a2eSSong Liu } 175*00963a2eSSong Liu tr->fops->private = tr; 176*00963a2eSSong Liu tr->fops->ops_func = bpf_tramp_ftrace_ops_func; 177*00963a2eSSong Liu #endif 178fec56f58SAlexei Starovoitov 179fec56f58SAlexei Starovoitov tr->key = key; 180fec56f58SAlexei Starovoitov INIT_HLIST_NODE(&tr->hlist); 181fec56f58SAlexei Starovoitov hlist_add_head(&tr->hlist, head); 182fec56f58SAlexei Starovoitov refcount_set(&tr->refcnt, 1); 183fec56f58SAlexei Starovoitov mutex_init(&tr->mutex); 184fec56f58SAlexei Starovoitov for (i = 0; i < BPF_TRAMP_MAX; i++) 185fec56f58SAlexei Starovoitov INIT_HLIST_HEAD(&tr->progs_hlist[i]); 186fec56f58SAlexei Starovoitov out: 187fec56f58SAlexei Starovoitov mutex_unlock(&trampoline_mutex); 188fec56f58SAlexei Starovoitov return tr; 189fec56f58SAlexei Starovoitov } 190fec56f58SAlexei Starovoitov 191861de02eSJiri Olsa static int bpf_trampoline_module_get(struct bpf_trampoline *tr) 192861de02eSJiri Olsa { 193861de02eSJiri Olsa struct module *mod; 194861de02eSJiri Olsa int err = 0; 195861de02eSJiri Olsa 196861de02eSJiri Olsa preempt_disable(); 197861de02eSJiri Olsa mod = __module_text_address((unsigned long) tr->func.addr); 198861de02eSJiri Olsa if (mod && !try_module_get(mod)) 199861de02eSJiri Olsa err = -ENOENT; 200861de02eSJiri Olsa preempt_enable(); 201861de02eSJiri Olsa tr->mod = mod; 202861de02eSJiri Olsa return err; 203861de02eSJiri Olsa } 204861de02eSJiri Olsa 205861de02eSJiri Olsa static void bpf_trampoline_module_put(struct bpf_trampoline *tr) 206861de02eSJiri Olsa { 207861de02eSJiri Olsa module_put(tr->mod); 208861de02eSJiri Olsa tr->mod = NULL; 209861de02eSJiri Olsa } 210861de02eSJiri Olsa 211b91e014fSAlexei Starovoitov static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr) 212b91e014fSAlexei Starovoitov { 213b91e014fSAlexei Starovoitov void *ip = tr->func.addr; 214b91e014fSAlexei Starovoitov int ret; 215b91e014fSAlexei Starovoitov 216b91e014fSAlexei Starovoitov if (tr->func.ftrace_managed) 217*00963a2eSSong Liu ret = unregister_ftrace_direct_multi(tr->fops, (long)old_addr); 218b91e014fSAlexei Starovoitov else 219b91e014fSAlexei Starovoitov ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, NULL); 220861de02eSJiri Olsa 221861de02eSJiri Olsa if (!ret) 222861de02eSJiri Olsa bpf_trampoline_module_put(tr); 223b91e014fSAlexei Starovoitov return ret; 224b91e014fSAlexei Starovoitov } 225b91e014fSAlexei Starovoitov 226*00963a2eSSong Liu static int modify_fentry(struct bpf_trampoline *tr, void *old_addr, void *new_addr, 227*00963a2eSSong Liu bool lock_direct_mutex) 228b91e014fSAlexei Starovoitov { 229b91e014fSAlexei Starovoitov void *ip = tr->func.addr; 230b91e014fSAlexei Starovoitov int ret; 231b91e014fSAlexei Starovoitov 232*00963a2eSSong Liu if (tr->func.ftrace_managed) { 233*00963a2eSSong Liu if (lock_direct_mutex) 234*00963a2eSSong Liu ret = modify_ftrace_direct_multi(tr->fops, (long)new_addr); 235b91e014fSAlexei Starovoitov else 236*00963a2eSSong Liu ret = modify_ftrace_direct_multi_nolock(tr->fops, (long)new_addr); 237*00963a2eSSong Liu } else { 238b91e014fSAlexei Starovoitov ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, new_addr); 239*00963a2eSSong Liu } 240b91e014fSAlexei Starovoitov return ret; 241b91e014fSAlexei Starovoitov } 242b91e014fSAlexei Starovoitov 243b91e014fSAlexei Starovoitov /* first time registering */ 244b91e014fSAlexei Starovoitov static int register_fentry(struct bpf_trampoline *tr, void *new_addr) 245b91e014fSAlexei Starovoitov { 246b91e014fSAlexei Starovoitov void *ip = tr->func.addr; 247aebfd125SPeter Zijlstra unsigned long faddr; 248b91e014fSAlexei Starovoitov int ret; 249b91e014fSAlexei Starovoitov 250aebfd125SPeter Zijlstra faddr = ftrace_location((unsigned long)ip); 251aebfd125SPeter Zijlstra if (faddr) 252aebfd125SPeter Zijlstra tr->func.ftrace_managed = true; 253b91e014fSAlexei Starovoitov 254861de02eSJiri Olsa if (bpf_trampoline_module_get(tr)) 255861de02eSJiri Olsa return -ENOENT; 256861de02eSJiri Olsa 257*00963a2eSSong Liu if (tr->func.ftrace_managed) { 258*00963a2eSSong Liu ftrace_set_filter_ip(tr->fops, (unsigned long)ip, 0, 0); 259*00963a2eSSong Liu ret = register_ftrace_direct_multi(tr->fops, (long)new_addr); 260*00963a2eSSong Liu } else { 261b91e014fSAlexei Starovoitov ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, NULL, new_addr); 262*00963a2eSSong Liu } 263861de02eSJiri Olsa 264861de02eSJiri Olsa if (ret) 265861de02eSJiri Olsa bpf_trampoline_module_put(tr); 266b91e014fSAlexei Starovoitov return ret; 267b91e014fSAlexei Starovoitov } 268b91e014fSAlexei Starovoitov 269f7e0beafSKui-Feng Lee static struct bpf_tramp_links * 2701e37392cSJiri Olsa bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_arg) 27188fd9e53SKP Singh { 272f7e0beafSKui-Feng Lee struct bpf_tramp_link *link; 273f7e0beafSKui-Feng Lee struct bpf_tramp_links *tlinks; 274f7e0beafSKui-Feng Lee struct bpf_tramp_link **links; 27588fd9e53SKP Singh int kind; 27688fd9e53SKP Singh 27788fd9e53SKP Singh *total = 0; 278f7e0beafSKui-Feng Lee tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL); 279f7e0beafSKui-Feng Lee if (!tlinks) 28088fd9e53SKP Singh return ERR_PTR(-ENOMEM); 28188fd9e53SKP Singh 28288fd9e53SKP Singh for (kind = 0; kind < BPF_TRAMP_MAX; kind++) { 283f7e0beafSKui-Feng Lee tlinks[kind].nr_links = tr->progs_cnt[kind]; 28488fd9e53SKP Singh *total += tr->progs_cnt[kind]; 285f7e0beafSKui-Feng Lee links = tlinks[kind].links; 28688fd9e53SKP Singh 287f7e0beafSKui-Feng Lee hlist_for_each_entry(link, &tr->progs_hlist[kind], tramp_hlist) { 288f7e0beafSKui-Feng Lee *ip_arg |= link->link.prog->call_get_func_ip; 289f7e0beafSKui-Feng Lee *links++ = link; 29088fd9e53SKP Singh } 2911e37392cSJiri Olsa } 292f7e0beafSKui-Feng Lee return tlinks; 29388fd9e53SKP Singh } 294fec56f58SAlexei Starovoitov 295e21aa341SAlexei Starovoitov static void __bpf_tramp_image_put_deferred(struct work_struct *work) 296e21aa341SAlexei Starovoitov { 297e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 298e21aa341SAlexei Starovoitov 299e21aa341SAlexei Starovoitov im = container_of(work, struct bpf_tramp_image, work); 300e21aa341SAlexei Starovoitov bpf_image_ksym_del(&im->ksym); 301e21aa341SAlexei Starovoitov bpf_jit_free_exec(im->image); 3023486beddSSong Liu bpf_jit_uncharge_modmem(PAGE_SIZE); 303e21aa341SAlexei Starovoitov percpu_ref_exit(&im->pcref); 304e21aa341SAlexei Starovoitov kfree_rcu(im, rcu); 305e21aa341SAlexei Starovoitov } 306e21aa341SAlexei Starovoitov 307e21aa341SAlexei Starovoitov /* callback, fexit step 3 or fentry step 2 */ 308e21aa341SAlexei Starovoitov static void __bpf_tramp_image_put_rcu(struct rcu_head *rcu) 309e21aa341SAlexei Starovoitov { 310e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 311e21aa341SAlexei Starovoitov 312e21aa341SAlexei Starovoitov im = container_of(rcu, struct bpf_tramp_image, rcu); 313e21aa341SAlexei Starovoitov INIT_WORK(&im->work, __bpf_tramp_image_put_deferred); 314e21aa341SAlexei Starovoitov schedule_work(&im->work); 315e21aa341SAlexei Starovoitov } 316e21aa341SAlexei Starovoitov 317e21aa341SAlexei Starovoitov /* callback, fexit step 2. Called after percpu_ref_kill confirms. */ 318e21aa341SAlexei Starovoitov static void __bpf_tramp_image_release(struct percpu_ref *pcref) 319e21aa341SAlexei Starovoitov { 320e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 321e21aa341SAlexei Starovoitov 322e21aa341SAlexei Starovoitov im = container_of(pcref, struct bpf_tramp_image, pcref); 323e21aa341SAlexei Starovoitov call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu); 324e21aa341SAlexei Starovoitov } 325e21aa341SAlexei Starovoitov 326e21aa341SAlexei Starovoitov /* callback, fexit or fentry step 1 */ 327e21aa341SAlexei Starovoitov static void __bpf_tramp_image_put_rcu_tasks(struct rcu_head *rcu) 328e21aa341SAlexei Starovoitov { 329e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 330e21aa341SAlexei Starovoitov 331e21aa341SAlexei Starovoitov im = container_of(rcu, struct bpf_tramp_image, rcu); 332e21aa341SAlexei Starovoitov if (im->ip_after_call) 333e21aa341SAlexei Starovoitov /* the case of fmod_ret/fexit trampoline and CONFIG_PREEMPTION=y */ 334e21aa341SAlexei Starovoitov percpu_ref_kill(&im->pcref); 335e21aa341SAlexei Starovoitov else 336e21aa341SAlexei Starovoitov /* the case of fentry trampoline */ 337e21aa341SAlexei Starovoitov call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu); 338e21aa341SAlexei Starovoitov } 339e21aa341SAlexei Starovoitov 340e21aa341SAlexei Starovoitov static void bpf_tramp_image_put(struct bpf_tramp_image *im) 341e21aa341SAlexei Starovoitov { 342e21aa341SAlexei Starovoitov /* The trampoline image that calls original function is using: 343e21aa341SAlexei Starovoitov * rcu_read_lock_trace to protect sleepable bpf progs 344e21aa341SAlexei Starovoitov * rcu_read_lock to protect normal bpf progs 345e21aa341SAlexei Starovoitov * percpu_ref to protect trampoline itself 346e21aa341SAlexei Starovoitov * rcu tasks to protect trampoline asm not covered by percpu_ref 347e21aa341SAlexei Starovoitov * (which are few asm insns before __bpf_tramp_enter and 348e21aa341SAlexei Starovoitov * after __bpf_tramp_exit) 349e21aa341SAlexei Starovoitov * 350e21aa341SAlexei Starovoitov * The trampoline is unreachable before bpf_tramp_image_put(). 351e21aa341SAlexei Starovoitov * 352e21aa341SAlexei Starovoitov * First, patch the trampoline to avoid calling into fexit progs. 353e21aa341SAlexei Starovoitov * The progs will be freed even if the original function is still 354e21aa341SAlexei Starovoitov * executing or sleeping. 355e21aa341SAlexei Starovoitov * In case of CONFIG_PREEMPT=y use call_rcu_tasks() to wait on 356e21aa341SAlexei Starovoitov * first few asm instructions to execute and call into 357e21aa341SAlexei Starovoitov * __bpf_tramp_enter->percpu_ref_get. 358e21aa341SAlexei Starovoitov * Then use percpu_ref_kill to wait for the trampoline and the original 359e21aa341SAlexei Starovoitov * function to finish. 360e21aa341SAlexei Starovoitov * Then use call_rcu_tasks() to make sure few asm insns in 361e21aa341SAlexei Starovoitov * the trampoline epilogue are done as well. 362e21aa341SAlexei Starovoitov * 363e21aa341SAlexei Starovoitov * In !PREEMPT case the task that got interrupted in the first asm 364e21aa341SAlexei Starovoitov * insns won't go through an RCU quiescent state which the 365e21aa341SAlexei Starovoitov * percpu_ref_kill will be waiting for. Hence the first 366e21aa341SAlexei Starovoitov * call_rcu_tasks() is not necessary. 367e21aa341SAlexei Starovoitov */ 368e21aa341SAlexei Starovoitov if (im->ip_after_call) { 369e21aa341SAlexei Starovoitov int err = bpf_arch_text_poke(im->ip_after_call, BPF_MOD_JUMP, 370e21aa341SAlexei Starovoitov NULL, im->ip_epilogue); 371e21aa341SAlexei Starovoitov WARN_ON(err); 372e21aa341SAlexei Starovoitov if (IS_ENABLED(CONFIG_PREEMPTION)) 373e21aa341SAlexei Starovoitov call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu_tasks); 374e21aa341SAlexei Starovoitov else 375e21aa341SAlexei Starovoitov percpu_ref_kill(&im->pcref); 376e21aa341SAlexei Starovoitov return; 377e21aa341SAlexei Starovoitov } 378e21aa341SAlexei Starovoitov 379e21aa341SAlexei Starovoitov /* The trampoline without fexit and fmod_ret progs doesn't call original 380e21aa341SAlexei Starovoitov * function and doesn't use percpu_ref. 381e21aa341SAlexei Starovoitov * Use call_rcu_tasks_trace() to wait for sleepable progs to finish. 382e21aa341SAlexei Starovoitov * Then use call_rcu_tasks() to wait for the rest of trampoline asm 383e21aa341SAlexei Starovoitov * and normal progs. 384e21aa341SAlexei Starovoitov */ 385e21aa341SAlexei Starovoitov call_rcu_tasks_trace(&im->rcu, __bpf_tramp_image_put_rcu_tasks); 386e21aa341SAlexei Starovoitov } 387e21aa341SAlexei Starovoitov 388e21aa341SAlexei Starovoitov static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx) 389e21aa341SAlexei Starovoitov { 390e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 391e21aa341SAlexei Starovoitov struct bpf_ksym *ksym; 392e21aa341SAlexei Starovoitov void *image; 393e21aa341SAlexei Starovoitov int err = -ENOMEM; 394e21aa341SAlexei Starovoitov 395e21aa341SAlexei Starovoitov im = kzalloc(sizeof(*im), GFP_KERNEL); 396e21aa341SAlexei Starovoitov if (!im) 397e21aa341SAlexei Starovoitov goto out; 398e21aa341SAlexei Starovoitov 3993486beddSSong Liu err = bpf_jit_charge_modmem(PAGE_SIZE); 400e21aa341SAlexei Starovoitov if (err) 401e21aa341SAlexei Starovoitov goto out_free_im; 402e21aa341SAlexei Starovoitov 403e21aa341SAlexei Starovoitov err = -ENOMEM; 404e21aa341SAlexei Starovoitov im->image = image = bpf_jit_alloc_exec_page(); 405e21aa341SAlexei Starovoitov if (!image) 406e21aa341SAlexei Starovoitov goto out_uncharge; 407e21aa341SAlexei Starovoitov 408e21aa341SAlexei Starovoitov err = percpu_ref_init(&im->pcref, __bpf_tramp_image_release, 0, GFP_KERNEL); 409e21aa341SAlexei Starovoitov if (err) 410e21aa341SAlexei Starovoitov goto out_free_image; 411e21aa341SAlexei Starovoitov 412e21aa341SAlexei Starovoitov ksym = &im->ksym; 413e21aa341SAlexei Starovoitov INIT_LIST_HEAD_RCU(&ksym->lnode); 414e21aa341SAlexei Starovoitov snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu_%u", key, idx); 415e21aa341SAlexei Starovoitov bpf_image_ksym_add(image, ksym); 416e21aa341SAlexei Starovoitov return im; 417e21aa341SAlexei Starovoitov 418e21aa341SAlexei Starovoitov out_free_image: 419e21aa341SAlexei Starovoitov bpf_jit_free_exec(im->image); 420e21aa341SAlexei Starovoitov out_uncharge: 4213486beddSSong Liu bpf_jit_uncharge_modmem(PAGE_SIZE); 422e21aa341SAlexei Starovoitov out_free_im: 423e21aa341SAlexei Starovoitov kfree(im); 424e21aa341SAlexei Starovoitov out: 425e21aa341SAlexei Starovoitov return ERR_PTR(err); 426e21aa341SAlexei Starovoitov } 427e21aa341SAlexei Starovoitov 428*00963a2eSSong Liu static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex) 429fec56f58SAlexei Starovoitov { 430e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 431f7e0beafSKui-Feng Lee struct bpf_tramp_links *tlinks; 432*00963a2eSSong Liu u32 orig_flags = tr->flags; 4331e37392cSJiri Olsa bool ip_arg = false; 43488fd9e53SKP Singh int err, total; 435fec56f58SAlexei Starovoitov 436f7e0beafSKui-Feng Lee tlinks = bpf_trampoline_get_progs(tr, &total, &ip_arg); 437f7e0beafSKui-Feng Lee if (IS_ERR(tlinks)) 438f7e0beafSKui-Feng Lee return PTR_ERR(tlinks); 43988fd9e53SKP Singh 44088fd9e53SKP Singh if (total == 0) { 441e21aa341SAlexei Starovoitov err = unregister_fentry(tr, tr->cur_image->image); 442e21aa341SAlexei Starovoitov bpf_tramp_image_put(tr->cur_image); 443e21aa341SAlexei Starovoitov tr->cur_image = NULL; 444fec56f58SAlexei Starovoitov tr->selector = 0; 445fec56f58SAlexei Starovoitov goto out; 446fec56f58SAlexei Starovoitov } 447fec56f58SAlexei Starovoitov 448e21aa341SAlexei Starovoitov im = bpf_tramp_image_alloc(tr->key, tr->selector); 449e21aa341SAlexei Starovoitov if (IS_ERR(im)) { 450e21aa341SAlexei Starovoitov err = PTR_ERR(im); 451e21aa341SAlexei Starovoitov goto out; 452e21aa341SAlexei Starovoitov } 453e21aa341SAlexei Starovoitov 454*00963a2eSSong Liu /* clear all bits except SHARE_IPMODIFY */ 455*00963a2eSSong Liu tr->flags &= BPF_TRAMP_F_SHARE_IPMODIFY; 456*00963a2eSSong Liu 457f7e0beafSKui-Feng Lee if (tlinks[BPF_TRAMP_FEXIT].nr_links || 458*00963a2eSSong Liu tlinks[BPF_TRAMP_MODIFY_RETURN].nr_links) { 459535a57a7SXu Kuohai /* NOTE: BPF_TRAMP_F_RESTORE_REGS and BPF_TRAMP_F_SKIP_FRAME 460535a57a7SXu Kuohai * should not be set together. 461535a57a7SXu Kuohai */ 462*00963a2eSSong Liu tr->flags |= BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_SKIP_FRAME; 463*00963a2eSSong Liu } else { 464*00963a2eSSong Liu tr->flags |= BPF_TRAMP_F_RESTORE_REGS; 465*00963a2eSSong Liu } 466fec56f58SAlexei Starovoitov 4671e37392cSJiri Olsa if (ip_arg) 468*00963a2eSSong Liu tr->flags |= BPF_TRAMP_F_IP_ARG; 469*00963a2eSSong Liu 470*00963a2eSSong Liu #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 471*00963a2eSSong Liu again: 472*00963a2eSSong Liu if ((tr->flags & BPF_TRAMP_F_SHARE_IPMODIFY) && 473*00963a2eSSong Liu (tr->flags & BPF_TRAMP_F_CALL_ORIG)) 474*00963a2eSSong Liu tr->flags |= BPF_TRAMP_F_ORIG_STACK; 475*00963a2eSSong Liu #endif 4761e37392cSJiri Olsa 477e21aa341SAlexei Starovoitov err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE, 478*00963a2eSSong Liu &tr->func.model, tr->flags, tlinks, 479fec56f58SAlexei Starovoitov tr->func.addr); 48085d33df3SMartin KaFai Lau if (err < 0) 481fec56f58SAlexei Starovoitov goto out; 482fec56f58SAlexei Starovoitov 483e21aa341SAlexei Starovoitov WARN_ON(tr->cur_image && tr->selector == 0); 484e21aa341SAlexei Starovoitov WARN_ON(!tr->cur_image && tr->selector); 485e21aa341SAlexei Starovoitov if (tr->cur_image) 486fec56f58SAlexei Starovoitov /* progs already running at this address */ 487*00963a2eSSong Liu err = modify_fentry(tr, tr->cur_image->image, im->image, lock_direct_mutex); 488fec56f58SAlexei Starovoitov else 489fec56f58SAlexei Starovoitov /* first time registering */ 490e21aa341SAlexei Starovoitov err = register_fentry(tr, im->image); 491*00963a2eSSong Liu 492*00963a2eSSong Liu #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 493*00963a2eSSong Liu if (err == -EAGAIN) { 494*00963a2eSSong Liu /* -EAGAIN from bpf_tramp_ftrace_ops_func. Now 495*00963a2eSSong Liu * BPF_TRAMP_F_SHARE_IPMODIFY is set, we can generate the 496*00963a2eSSong Liu * trampoline again, and retry register. 497*00963a2eSSong Liu */ 498*00963a2eSSong Liu /* reset fops->func and fops->trampoline for re-register */ 499*00963a2eSSong Liu tr->fops->func = NULL; 500*00963a2eSSong Liu tr->fops->trampoline = 0; 501*00963a2eSSong Liu goto again; 502*00963a2eSSong Liu } 503*00963a2eSSong Liu #endif 504fec56f58SAlexei Starovoitov if (err) 505fec56f58SAlexei Starovoitov goto out; 506*00963a2eSSong Liu 507e21aa341SAlexei Starovoitov if (tr->cur_image) 508e21aa341SAlexei Starovoitov bpf_tramp_image_put(tr->cur_image); 509e21aa341SAlexei Starovoitov tr->cur_image = im; 510fec56f58SAlexei Starovoitov tr->selector++; 511fec56f58SAlexei Starovoitov out: 512*00963a2eSSong Liu /* If any error happens, restore previous flags */ 513*00963a2eSSong Liu if (err) 514*00963a2eSSong Liu tr->flags = orig_flags; 515f7e0beafSKui-Feng Lee kfree(tlinks); 516fec56f58SAlexei Starovoitov return err; 517fec56f58SAlexei Starovoitov } 518fec56f58SAlexei Starovoitov 5199e4e01dfSKP Singh static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog) 520fec56f58SAlexei Starovoitov { 5219e4e01dfSKP Singh switch (prog->expected_attach_type) { 522fec56f58SAlexei Starovoitov case BPF_TRACE_FENTRY: 523fec56f58SAlexei Starovoitov return BPF_TRAMP_FENTRY; 524ae240823SKP Singh case BPF_MODIFY_RETURN: 525ae240823SKP Singh return BPF_TRAMP_MODIFY_RETURN; 526be8704ffSAlexei Starovoitov case BPF_TRACE_FEXIT: 527fec56f58SAlexei Starovoitov return BPF_TRAMP_FEXIT; 5289e4e01dfSKP Singh case BPF_LSM_MAC: 5299e4e01dfSKP Singh if (!prog->aux->attach_func_proto->type) 5309e4e01dfSKP Singh /* The function returns void, we cannot modify its 5319e4e01dfSKP Singh * return value. 5329e4e01dfSKP Singh */ 5339e4e01dfSKP Singh return BPF_TRAMP_FEXIT; 5349e4e01dfSKP Singh else 5359e4e01dfSKP Singh return BPF_TRAMP_MODIFY_RETURN; 536be8704ffSAlexei Starovoitov default: 537be8704ffSAlexei Starovoitov return BPF_TRAMP_REPLACE; 538fec56f58SAlexei Starovoitov } 539fec56f58SAlexei Starovoitov } 540fec56f58SAlexei Starovoitov 541af3f4134SStanislav Fomichev static int __bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr) 542fec56f58SAlexei Starovoitov { 543fec56f58SAlexei Starovoitov enum bpf_tramp_prog_type kind; 544f7e0beafSKui-Feng Lee struct bpf_tramp_link *link_exiting; 545fec56f58SAlexei Starovoitov int err = 0; 546a2aa95b7SYuntao Wang int cnt = 0, i; 547fec56f58SAlexei Starovoitov 548f7e0beafSKui-Feng Lee kind = bpf_attach_type_to_tramp(link->link.prog); 549af3f4134SStanislav Fomichev if (tr->extension_prog) 550be8704ffSAlexei Starovoitov /* cannot attach fentry/fexit if extension prog is attached. 551be8704ffSAlexei Starovoitov * cannot overwrite extension prog either. 552be8704ffSAlexei Starovoitov */ 553af3f4134SStanislav Fomichev return -EBUSY; 554a2aa95b7SYuntao Wang 555a2aa95b7SYuntao Wang for (i = 0; i < BPF_TRAMP_MAX; i++) 556a2aa95b7SYuntao Wang cnt += tr->progs_cnt[i]; 557a2aa95b7SYuntao Wang 558be8704ffSAlexei Starovoitov if (kind == BPF_TRAMP_REPLACE) { 559be8704ffSAlexei Starovoitov /* Cannot attach extension if fentry/fexit are in use. */ 560af3f4134SStanislav Fomichev if (cnt) 561af3f4134SStanislav Fomichev return -EBUSY; 562f7e0beafSKui-Feng Lee tr->extension_prog = link->link.prog; 563af3f4134SStanislav Fomichev return bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, NULL, 564f7e0beafSKui-Feng Lee link->link.prog->bpf_func); 565be8704ffSAlexei Starovoitov } 566af3f4134SStanislav Fomichev if (cnt >= BPF_MAX_TRAMP_LINKS) 567af3f4134SStanislav Fomichev return -E2BIG; 568af3f4134SStanislav Fomichev if (!hlist_unhashed(&link->tramp_hlist)) 569fec56f58SAlexei Starovoitov /* prog already linked */ 570af3f4134SStanislav Fomichev return -EBUSY; 571f7e0beafSKui-Feng Lee hlist_for_each_entry(link_exiting, &tr->progs_hlist[kind], tramp_hlist) { 572f7e0beafSKui-Feng Lee if (link_exiting->link.prog != link->link.prog) 573f7e0beafSKui-Feng Lee continue; 574f7e0beafSKui-Feng Lee /* prog already linked */ 575af3f4134SStanislav Fomichev return -EBUSY; 576f7e0beafSKui-Feng Lee } 577f7e0beafSKui-Feng Lee 578f7e0beafSKui-Feng Lee hlist_add_head(&link->tramp_hlist, &tr->progs_hlist[kind]); 579fec56f58SAlexei Starovoitov tr->progs_cnt[kind]++; 580*00963a2eSSong Liu err = bpf_trampoline_update(tr, true /* lock_direct_mutex */); 581fec56f58SAlexei Starovoitov if (err) { 582f7e0beafSKui-Feng Lee hlist_del_init(&link->tramp_hlist); 583fec56f58SAlexei Starovoitov tr->progs_cnt[kind]--; 584fec56f58SAlexei Starovoitov } 585af3f4134SStanislav Fomichev return err; 586af3f4134SStanislav Fomichev } 587af3f4134SStanislav Fomichev 588af3f4134SStanislav Fomichev int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr) 589af3f4134SStanislav Fomichev { 590af3f4134SStanislav Fomichev int err; 591af3f4134SStanislav Fomichev 592af3f4134SStanislav Fomichev mutex_lock(&tr->mutex); 593af3f4134SStanislav Fomichev err = __bpf_trampoline_link_prog(link, tr); 594fec56f58SAlexei Starovoitov mutex_unlock(&tr->mutex); 595fec56f58SAlexei Starovoitov return err; 596fec56f58SAlexei Starovoitov } 597fec56f58SAlexei Starovoitov 598af3f4134SStanislav Fomichev static int __bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr) 599fec56f58SAlexei Starovoitov { 600fec56f58SAlexei Starovoitov enum bpf_tramp_prog_type kind; 601fec56f58SAlexei Starovoitov int err; 602fec56f58SAlexei Starovoitov 603f7e0beafSKui-Feng Lee kind = bpf_attach_type_to_tramp(link->link.prog); 604be8704ffSAlexei Starovoitov if (kind == BPF_TRAMP_REPLACE) { 605be8704ffSAlexei Starovoitov WARN_ON_ONCE(!tr->extension_prog); 606be8704ffSAlexei Starovoitov err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, 607be8704ffSAlexei Starovoitov tr->extension_prog->bpf_func, NULL); 608be8704ffSAlexei Starovoitov tr->extension_prog = NULL; 609af3f4134SStanislav Fomichev return err; 610be8704ffSAlexei Starovoitov } 611f7e0beafSKui-Feng Lee hlist_del_init(&link->tramp_hlist); 612fec56f58SAlexei Starovoitov tr->progs_cnt[kind]--; 613*00963a2eSSong Liu return bpf_trampoline_update(tr, true /* lock_direct_mutex */); 614af3f4134SStanislav Fomichev } 615af3f4134SStanislav Fomichev 616af3f4134SStanislav Fomichev /* bpf_trampoline_unlink_prog() should never fail. */ 617af3f4134SStanislav Fomichev int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr) 618af3f4134SStanislav Fomichev { 619af3f4134SStanislav Fomichev int err; 620af3f4134SStanislav Fomichev 621af3f4134SStanislav Fomichev mutex_lock(&tr->mutex); 622af3f4134SStanislav Fomichev err = __bpf_trampoline_unlink_prog(link, tr); 623fec56f58SAlexei Starovoitov mutex_unlock(&tr->mutex); 624fec56f58SAlexei Starovoitov return err; 625fec56f58SAlexei Starovoitov } 626fec56f58SAlexei Starovoitov 6273908fcddSStanislav Fomichev #if defined(CONFIG_CGROUP_BPF) && defined(CONFIG_BPF_LSM) 62869fd337aSStanislav Fomichev static void bpf_shim_tramp_link_release(struct bpf_link *link) 62969fd337aSStanislav Fomichev { 63069fd337aSStanislav Fomichev struct bpf_shim_tramp_link *shim_link = 63169fd337aSStanislav Fomichev container_of(link, struct bpf_shim_tramp_link, link.link); 63269fd337aSStanislav Fomichev 63369fd337aSStanislav Fomichev /* paired with 'shim_link->trampoline = tr' in bpf_trampoline_link_cgroup_shim */ 63469fd337aSStanislav Fomichev if (!shim_link->trampoline) 63569fd337aSStanislav Fomichev return; 63669fd337aSStanislav Fomichev 63769fd337aSStanislav Fomichev WARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->link, shim_link->trampoline)); 63869fd337aSStanislav Fomichev bpf_trampoline_put(shim_link->trampoline); 63969fd337aSStanislav Fomichev } 64069fd337aSStanislav Fomichev 64169fd337aSStanislav Fomichev static void bpf_shim_tramp_link_dealloc(struct bpf_link *link) 64269fd337aSStanislav Fomichev { 64369fd337aSStanislav Fomichev struct bpf_shim_tramp_link *shim_link = 64469fd337aSStanislav Fomichev container_of(link, struct bpf_shim_tramp_link, link.link); 64569fd337aSStanislav Fomichev 64669fd337aSStanislav Fomichev kfree(shim_link); 64769fd337aSStanislav Fomichev } 64869fd337aSStanislav Fomichev 64969fd337aSStanislav Fomichev static const struct bpf_link_ops bpf_shim_tramp_link_lops = { 65069fd337aSStanislav Fomichev .release = bpf_shim_tramp_link_release, 65169fd337aSStanislav Fomichev .dealloc = bpf_shim_tramp_link_dealloc, 65269fd337aSStanislav Fomichev }; 65369fd337aSStanislav Fomichev 65469fd337aSStanislav Fomichev static struct bpf_shim_tramp_link *cgroup_shim_alloc(const struct bpf_prog *prog, 65569fd337aSStanislav Fomichev bpf_func_t bpf_func, 65669fd337aSStanislav Fomichev int cgroup_atype) 65769fd337aSStanislav Fomichev { 65869fd337aSStanislav Fomichev struct bpf_shim_tramp_link *shim_link = NULL; 65969fd337aSStanislav Fomichev struct bpf_prog *p; 66069fd337aSStanislav Fomichev 66169fd337aSStanislav Fomichev shim_link = kzalloc(sizeof(*shim_link), GFP_USER); 66269fd337aSStanislav Fomichev if (!shim_link) 66369fd337aSStanislav Fomichev return NULL; 66469fd337aSStanislav Fomichev 66569fd337aSStanislav Fomichev p = bpf_prog_alloc(1, 0); 66669fd337aSStanislav Fomichev if (!p) { 66769fd337aSStanislav Fomichev kfree(shim_link); 66869fd337aSStanislav Fomichev return NULL; 66969fd337aSStanislav Fomichev } 67069fd337aSStanislav Fomichev 67169fd337aSStanislav Fomichev p->jited = false; 67269fd337aSStanislav Fomichev p->bpf_func = bpf_func; 67369fd337aSStanislav Fomichev 67469fd337aSStanislav Fomichev p->aux->cgroup_atype = cgroup_atype; 67569fd337aSStanislav Fomichev p->aux->attach_func_proto = prog->aux->attach_func_proto; 67669fd337aSStanislav Fomichev p->aux->attach_btf_id = prog->aux->attach_btf_id; 67769fd337aSStanislav Fomichev p->aux->attach_btf = prog->aux->attach_btf; 67869fd337aSStanislav Fomichev btf_get(p->aux->attach_btf); 67969fd337aSStanislav Fomichev p->type = BPF_PROG_TYPE_LSM; 68069fd337aSStanislav Fomichev p->expected_attach_type = BPF_LSM_MAC; 68169fd337aSStanislav Fomichev bpf_prog_inc(p); 68269fd337aSStanislav Fomichev bpf_link_init(&shim_link->link.link, BPF_LINK_TYPE_UNSPEC, 68369fd337aSStanislav Fomichev &bpf_shim_tramp_link_lops, p); 684c0e19f2cSStanislav Fomichev bpf_cgroup_atype_get(p->aux->attach_btf_id, cgroup_atype); 68569fd337aSStanislav Fomichev 68669fd337aSStanislav Fomichev return shim_link; 68769fd337aSStanislav Fomichev } 68869fd337aSStanislav Fomichev 68969fd337aSStanislav Fomichev static struct bpf_shim_tramp_link *cgroup_shim_find(struct bpf_trampoline *tr, 69069fd337aSStanislav Fomichev bpf_func_t bpf_func) 69169fd337aSStanislav Fomichev { 69269fd337aSStanislav Fomichev struct bpf_tramp_link *link; 69369fd337aSStanislav Fomichev int kind; 69469fd337aSStanislav Fomichev 69569fd337aSStanislav Fomichev for (kind = 0; kind < BPF_TRAMP_MAX; kind++) { 69669fd337aSStanislav Fomichev hlist_for_each_entry(link, &tr->progs_hlist[kind], tramp_hlist) { 69769fd337aSStanislav Fomichev struct bpf_prog *p = link->link.prog; 69869fd337aSStanislav Fomichev 69969fd337aSStanislav Fomichev if (p->bpf_func == bpf_func) 70069fd337aSStanislav Fomichev return container_of(link, struct bpf_shim_tramp_link, link); 70169fd337aSStanislav Fomichev } 70269fd337aSStanislav Fomichev } 70369fd337aSStanislav Fomichev 70469fd337aSStanislav Fomichev return NULL; 70569fd337aSStanislav Fomichev } 70669fd337aSStanislav Fomichev 70769fd337aSStanislav Fomichev int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog, 70869fd337aSStanislav Fomichev int cgroup_atype) 70969fd337aSStanislav Fomichev { 71069fd337aSStanislav Fomichev struct bpf_shim_tramp_link *shim_link = NULL; 71169fd337aSStanislav Fomichev struct bpf_attach_target_info tgt_info = {}; 71269fd337aSStanislav Fomichev struct bpf_trampoline *tr; 71369fd337aSStanislav Fomichev bpf_func_t bpf_func; 71469fd337aSStanislav Fomichev u64 key; 71569fd337aSStanislav Fomichev int err; 71669fd337aSStanislav Fomichev 71769fd337aSStanislav Fomichev err = bpf_check_attach_target(NULL, prog, NULL, 71869fd337aSStanislav Fomichev prog->aux->attach_btf_id, 71969fd337aSStanislav Fomichev &tgt_info); 72069fd337aSStanislav Fomichev if (err) 72169fd337aSStanislav Fomichev return err; 72269fd337aSStanislav Fomichev 72369fd337aSStanislav Fomichev key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, 72469fd337aSStanislav Fomichev prog->aux->attach_btf_id); 72569fd337aSStanislav Fomichev 72669fd337aSStanislav Fomichev bpf_lsm_find_cgroup_shim(prog, &bpf_func); 72769fd337aSStanislav Fomichev tr = bpf_trampoline_get(key, &tgt_info); 72869fd337aSStanislav Fomichev if (!tr) 72969fd337aSStanislav Fomichev return -ENOMEM; 73069fd337aSStanislav Fomichev 73169fd337aSStanislav Fomichev mutex_lock(&tr->mutex); 73269fd337aSStanislav Fomichev 73369fd337aSStanislav Fomichev shim_link = cgroup_shim_find(tr, bpf_func); 73469fd337aSStanislav Fomichev if (shim_link) { 73569fd337aSStanislav Fomichev /* Reusing existing shim attached by the other program. */ 73669fd337aSStanislav Fomichev bpf_link_inc(&shim_link->link.link); 73769fd337aSStanislav Fomichev 73869fd337aSStanislav Fomichev mutex_unlock(&tr->mutex); 73969fd337aSStanislav Fomichev bpf_trampoline_put(tr); /* bpf_trampoline_get above */ 74069fd337aSStanislav Fomichev return 0; 74169fd337aSStanislav Fomichev } 74269fd337aSStanislav Fomichev 74369fd337aSStanislav Fomichev /* Allocate and install new shim. */ 74469fd337aSStanislav Fomichev 74569fd337aSStanislav Fomichev shim_link = cgroup_shim_alloc(prog, bpf_func, cgroup_atype); 74669fd337aSStanislav Fomichev if (!shim_link) { 74769fd337aSStanislav Fomichev err = -ENOMEM; 74869fd337aSStanislav Fomichev goto err; 74969fd337aSStanislav Fomichev } 75069fd337aSStanislav Fomichev 75169fd337aSStanislav Fomichev err = __bpf_trampoline_link_prog(&shim_link->link, tr); 75269fd337aSStanislav Fomichev if (err) 75369fd337aSStanislav Fomichev goto err; 75469fd337aSStanislav Fomichev 75569fd337aSStanislav Fomichev shim_link->trampoline = tr; 75669fd337aSStanislav Fomichev /* note, we're still holding tr refcnt from above */ 75769fd337aSStanislav Fomichev 75869fd337aSStanislav Fomichev mutex_unlock(&tr->mutex); 75969fd337aSStanislav Fomichev 76069fd337aSStanislav Fomichev return 0; 76169fd337aSStanislav Fomichev err: 76269fd337aSStanislav Fomichev mutex_unlock(&tr->mutex); 76369fd337aSStanislav Fomichev 76469fd337aSStanislav Fomichev if (shim_link) 76569fd337aSStanislav Fomichev bpf_link_put(&shim_link->link.link); 76669fd337aSStanislav Fomichev 76769fd337aSStanislav Fomichev /* have to release tr while _not_ holding its mutex */ 76869fd337aSStanislav Fomichev bpf_trampoline_put(tr); /* bpf_trampoline_get above */ 76969fd337aSStanislav Fomichev 77069fd337aSStanislav Fomichev return err; 77169fd337aSStanislav Fomichev } 77269fd337aSStanislav Fomichev 77369fd337aSStanislav Fomichev void bpf_trampoline_unlink_cgroup_shim(struct bpf_prog *prog) 77469fd337aSStanislav Fomichev { 77569fd337aSStanislav Fomichev struct bpf_shim_tramp_link *shim_link = NULL; 77669fd337aSStanislav Fomichev struct bpf_trampoline *tr; 77769fd337aSStanislav Fomichev bpf_func_t bpf_func; 77869fd337aSStanislav Fomichev u64 key; 77969fd337aSStanislav Fomichev 78069fd337aSStanislav Fomichev key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, 78169fd337aSStanislav Fomichev prog->aux->attach_btf_id); 78269fd337aSStanislav Fomichev 78369fd337aSStanislav Fomichev bpf_lsm_find_cgroup_shim(prog, &bpf_func); 78469fd337aSStanislav Fomichev tr = bpf_trampoline_lookup(key); 78569fd337aSStanislav Fomichev if (WARN_ON_ONCE(!tr)) 78669fd337aSStanislav Fomichev return; 78769fd337aSStanislav Fomichev 78869fd337aSStanislav Fomichev mutex_lock(&tr->mutex); 78969fd337aSStanislav Fomichev shim_link = cgroup_shim_find(tr, bpf_func); 79069fd337aSStanislav Fomichev mutex_unlock(&tr->mutex); 79169fd337aSStanislav Fomichev 79269fd337aSStanislav Fomichev if (shim_link) 79369fd337aSStanislav Fomichev bpf_link_put(&shim_link->link.link); 79469fd337aSStanislav Fomichev 79569fd337aSStanislav Fomichev bpf_trampoline_put(tr); /* bpf_trampoline_lookup above */ 79669fd337aSStanislav Fomichev } 79769fd337aSStanislav Fomichev #endif 79869fd337aSStanislav Fomichev 799f7b12b6fSToke Høiland-Jørgensen struct bpf_trampoline *bpf_trampoline_get(u64 key, 800f7b12b6fSToke Høiland-Jørgensen struct bpf_attach_target_info *tgt_info) 801f7b12b6fSToke Høiland-Jørgensen { 802f7b12b6fSToke Høiland-Jørgensen struct bpf_trampoline *tr; 803f7b12b6fSToke Høiland-Jørgensen 804f7b12b6fSToke Høiland-Jørgensen tr = bpf_trampoline_lookup(key); 805f7b12b6fSToke Høiland-Jørgensen if (!tr) 806f7b12b6fSToke Høiland-Jørgensen return NULL; 807f7b12b6fSToke Høiland-Jørgensen 808f7b12b6fSToke Høiland-Jørgensen mutex_lock(&tr->mutex); 809f7b12b6fSToke Høiland-Jørgensen if (tr->func.addr) 810f7b12b6fSToke Høiland-Jørgensen goto out; 811f7b12b6fSToke Høiland-Jørgensen 812f7b12b6fSToke Høiland-Jørgensen memcpy(&tr->func.model, &tgt_info->fmodel, sizeof(tgt_info->fmodel)); 813f7b12b6fSToke Høiland-Jørgensen tr->func.addr = (void *)tgt_info->tgt_addr; 814f7b12b6fSToke Høiland-Jørgensen out: 815f7b12b6fSToke Høiland-Jørgensen mutex_unlock(&tr->mutex); 816f7b12b6fSToke Høiland-Jørgensen return tr; 817f7b12b6fSToke Høiland-Jørgensen } 818f7b12b6fSToke Høiland-Jørgensen 819fec56f58SAlexei Starovoitov void bpf_trampoline_put(struct bpf_trampoline *tr) 820fec56f58SAlexei Starovoitov { 821a2aa95b7SYuntao Wang int i; 822a2aa95b7SYuntao Wang 823fec56f58SAlexei Starovoitov if (!tr) 824fec56f58SAlexei Starovoitov return; 825fec56f58SAlexei Starovoitov mutex_lock(&trampoline_mutex); 826fec56f58SAlexei Starovoitov if (!refcount_dec_and_test(&tr->refcnt)) 827fec56f58SAlexei Starovoitov goto out; 828fec56f58SAlexei Starovoitov WARN_ON_ONCE(mutex_is_locked(&tr->mutex)); 829a2aa95b7SYuntao Wang 830a2aa95b7SYuntao Wang for (i = 0; i < BPF_TRAMP_MAX; i++) 831a2aa95b7SYuntao Wang if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[i]))) 832fec56f58SAlexei Starovoitov goto out; 833a2aa95b7SYuntao Wang 834e21aa341SAlexei Starovoitov /* This code will be executed even when the last bpf_tramp_image 835e21aa341SAlexei Starovoitov * is alive. All progs are detached from the trampoline and the 836e21aa341SAlexei Starovoitov * trampoline image is patched with jmp into epilogue to skip 837e21aa341SAlexei Starovoitov * fexit progs. The fentry-only trampoline will be freed via 838e21aa341SAlexei Starovoitov * multiple rcu callbacks. 8391e6c62a8SAlexei Starovoitov */ 840fec56f58SAlexei Starovoitov hlist_del(&tr->hlist); 841*00963a2eSSong Liu kfree(tr->fops); 842fec56f58SAlexei Starovoitov kfree(tr); 843fec56f58SAlexei Starovoitov out: 844fec56f58SAlexei Starovoitov mutex_unlock(&trampoline_mutex); 845fec56f58SAlexei Starovoitov } 846fec56f58SAlexei Starovoitov 847ca06f55bSAlexei Starovoitov #define NO_START_TIME 1 848856c02dbSSong Liu static __always_inline u64 notrace bpf_prog_start_time(void) 849f2dd3b39SAlexei Starovoitov { 850f2dd3b39SAlexei Starovoitov u64 start = NO_START_TIME; 851f2dd3b39SAlexei Starovoitov 852ca06f55bSAlexei Starovoitov if (static_branch_unlikely(&bpf_stats_enabled_key)) { 853f2dd3b39SAlexei Starovoitov start = sched_clock(); 854ca06f55bSAlexei Starovoitov if (unlikely(!start)) 855ca06f55bSAlexei Starovoitov start = NO_START_TIME; 856ca06f55bSAlexei Starovoitov } 857f2dd3b39SAlexei Starovoitov return start; 858f2dd3b39SAlexei Starovoitov } 859f2dd3b39SAlexei Starovoitov 8609ed9e9baSAlexei Starovoitov static void notrace inc_misses_counter(struct bpf_prog *prog) 8619ed9e9baSAlexei Starovoitov { 8629ed9e9baSAlexei Starovoitov struct bpf_prog_stats *stats; 8630e3135d3SHe Fengqing unsigned int flags; 8649ed9e9baSAlexei Starovoitov 8659ed9e9baSAlexei Starovoitov stats = this_cpu_ptr(prog->stats); 8660e3135d3SHe Fengqing flags = u64_stats_update_begin_irqsave(&stats->syncp); 86761a0abaeSEric Dumazet u64_stats_inc(&stats->misses); 8680e3135d3SHe Fengqing u64_stats_update_end_irqrestore(&stats->syncp, flags); 8699ed9e9baSAlexei Starovoitov } 8709ed9e9baSAlexei Starovoitov 871fb7dd8bcSAndrii Nakryiko /* The logic is similar to bpf_prog_run(), but with an explicit 87202ad0596SDavid Miller * rcu_read_lock() and migrate_disable() which are required 87302ad0596SDavid Miller * for the trampoline. The macro is split into 874f2dd3b39SAlexei Starovoitov * call __bpf_prog_enter 875fec56f58SAlexei Starovoitov * call prog->bpf_func 876fec56f58SAlexei Starovoitov * call __bpf_prog_exit 877ca06f55bSAlexei Starovoitov * 878ca06f55bSAlexei Starovoitov * __bpf_prog_enter returns: 879ca06f55bSAlexei Starovoitov * 0 - skip execution of the bpf prog 880ca06f55bSAlexei Starovoitov * 1 - execute bpf prog 8818fb33b60SZhen Lei * [2..MAX_U64] - execute bpf prog and record execution time. 882ca06f55bSAlexei Starovoitov * This is start time. 883fec56f58SAlexei Starovoitov */ 884e384c7b7SKui-Feng Lee u64 notrace __bpf_prog_enter(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx) 885dcce11d5SJules Irenge __acquires(RCU) 886fec56f58SAlexei Starovoitov { 887fec56f58SAlexei Starovoitov rcu_read_lock(); 88802ad0596SDavid Miller migrate_disable(); 889e384c7b7SKui-Feng Lee 890e384c7b7SKui-Feng Lee run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx); 891e384c7b7SKui-Feng Lee 8929ed9e9baSAlexei Starovoitov if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1)) { 8939ed9e9baSAlexei Starovoitov inc_misses_counter(prog); 894ca06f55bSAlexei Starovoitov return 0; 8959ed9e9baSAlexei Starovoitov } 896f2dd3b39SAlexei Starovoitov return bpf_prog_start_time(); 897fec56f58SAlexei Starovoitov } 898fec56f58SAlexei Starovoitov 899f2dd3b39SAlexei Starovoitov static void notrace update_prog_stats(struct bpf_prog *prog, 900f2dd3b39SAlexei Starovoitov u64 start) 901fec56f58SAlexei Starovoitov { 902fec56f58SAlexei Starovoitov struct bpf_prog_stats *stats; 903fec56f58SAlexei Starovoitov 904fec56f58SAlexei Starovoitov if (static_branch_unlikely(&bpf_stats_enabled_key) && 905f2dd3b39SAlexei Starovoitov /* static_key could be enabled in __bpf_prog_enter* 906f2dd3b39SAlexei Starovoitov * and disabled in __bpf_prog_exit*. 907fec56f58SAlexei Starovoitov * And vice versa. 908f2dd3b39SAlexei Starovoitov * Hence check that 'start' is valid. 909fec56f58SAlexei Starovoitov */ 910f2dd3b39SAlexei Starovoitov start > NO_START_TIME) { 911d979617aSEric Dumazet unsigned long flags; 912d979617aSEric Dumazet 913700d4796SAlexei Starovoitov stats = this_cpu_ptr(prog->stats); 914d979617aSEric Dumazet flags = u64_stats_update_begin_irqsave(&stats->syncp); 91561a0abaeSEric Dumazet u64_stats_inc(&stats->cnt); 91661a0abaeSEric Dumazet u64_stats_add(&stats->nsecs, sched_clock() - start); 917d979617aSEric Dumazet u64_stats_update_end_irqrestore(&stats->syncp, flags); 918fec56f58SAlexei Starovoitov } 919f2dd3b39SAlexei Starovoitov } 920f2dd3b39SAlexei Starovoitov 921e384c7b7SKui-Feng Lee void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start, struct bpf_tramp_run_ctx *run_ctx) 922f2dd3b39SAlexei Starovoitov __releases(RCU) 923f2dd3b39SAlexei Starovoitov { 924e384c7b7SKui-Feng Lee bpf_reset_run_ctx(run_ctx->saved_run_ctx); 925e384c7b7SKui-Feng Lee 926f2dd3b39SAlexei Starovoitov update_prog_stats(prog, start); 927ca06f55bSAlexei Starovoitov __this_cpu_dec(*(prog->active)); 92802ad0596SDavid Miller migrate_enable(); 929fec56f58SAlexei Starovoitov rcu_read_unlock(); 930fec56f58SAlexei Starovoitov } 931fec56f58SAlexei Starovoitov 93269fd337aSStanislav Fomichev u64 notrace __bpf_prog_enter_lsm_cgroup(struct bpf_prog *prog, 93369fd337aSStanislav Fomichev struct bpf_tramp_run_ctx *run_ctx) 93469fd337aSStanislav Fomichev __acquires(RCU) 93569fd337aSStanislav Fomichev { 93669fd337aSStanislav Fomichev /* Runtime stats are exported via actual BPF_LSM_CGROUP 93769fd337aSStanislav Fomichev * programs, not the shims. 93869fd337aSStanislav Fomichev */ 93969fd337aSStanislav Fomichev rcu_read_lock(); 94069fd337aSStanislav Fomichev migrate_disable(); 94169fd337aSStanislav Fomichev 94269fd337aSStanislav Fomichev run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx); 94369fd337aSStanislav Fomichev 94469fd337aSStanislav Fomichev return NO_START_TIME; 94569fd337aSStanislav Fomichev } 94669fd337aSStanislav Fomichev 94769fd337aSStanislav Fomichev void notrace __bpf_prog_exit_lsm_cgroup(struct bpf_prog *prog, u64 start, 94869fd337aSStanislav Fomichev struct bpf_tramp_run_ctx *run_ctx) 94969fd337aSStanislav Fomichev __releases(RCU) 95069fd337aSStanislav Fomichev { 95169fd337aSStanislav Fomichev bpf_reset_run_ctx(run_ctx->saved_run_ctx); 95269fd337aSStanislav Fomichev 95369fd337aSStanislav Fomichev migrate_enable(); 95469fd337aSStanislav Fomichev rcu_read_unlock(); 95569fd337aSStanislav Fomichev } 95669fd337aSStanislav Fomichev 957e384c7b7SKui-Feng Lee u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx) 9581e6c62a8SAlexei Starovoitov { 9591e6c62a8SAlexei Starovoitov rcu_read_lock_trace(); 960031d6e02SAlexei Starovoitov migrate_disable(); 961f56407faSAlexei Starovoitov might_fault(); 962e384c7b7SKui-Feng Lee 9639ed9e9baSAlexei Starovoitov if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1)) { 9649ed9e9baSAlexei Starovoitov inc_misses_counter(prog); 965ca06f55bSAlexei Starovoitov return 0; 9669ed9e9baSAlexei Starovoitov } 967e384c7b7SKui-Feng Lee 968e384c7b7SKui-Feng Lee run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx); 969e384c7b7SKui-Feng Lee 970f2dd3b39SAlexei Starovoitov return bpf_prog_start_time(); 9711e6c62a8SAlexei Starovoitov } 9721e6c62a8SAlexei Starovoitov 973e384c7b7SKui-Feng Lee void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start, 974e384c7b7SKui-Feng Lee struct bpf_tramp_run_ctx *run_ctx) 9751e6c62a8SAlexei Starovoitov { 976e384c7b7SKui-Feng Lee bpf_reset_run_ctx(run_ctx->saved_run_ctx); 977e384c7b7SKui-Feng Lee 978f2dd3b39SAlexei Starovoitov update_prog_stats(prog, start); 979ca06f55bSAlexei Starovoitov __this_cpu_dec(*(prog->active)); 980031d6e02SAlexei Starovoitov migrate_enable(); 9811e6c62a8SAlexei Starovoitov rcu_read_unlock_trace(); 9821e6c62a8SAlexei Starovoitov } 9831e6c62a8SAlexei Starovoitov 984e21aa341SAlexei Starovoitov void notrace __bpf_tramp_enter(struct bpf_tramp_image *tr) 985e21aa341SAlexei Starovoitov { 986e21aa341SAlexei Starovoitov percpu_ref_get(&tr->pcref); 987e21aa341SAlexei Starovoitov } 988e21aa341SAlexei Starovoitov 989e21aa341SAlexei Starovoitov void notrace __bpf_tramp_exit(struct bpf_tramp_image *tr) 990e21aa341SAlexei Starovoitov { 991e21aa341SAlexei Starovoitov percpu_ref_put(&tr->pcref); 992e21aa341SAlexei Starovoitov } 993e21aa341SAlexei Starovoitov 994fec56f58SAlexei Starovoitov int __weak 995e21aa341SAlexei Starovoitov arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *image_end, 99685d33df3SMartin KaFai Lau const struct btf_func_model *m, u32 flags, 997f7e0beafSKui-Feng Lee struct bpf_tramp_links *tlinks, 998fec56f58SAlexei Starovoitov void *orig_call) 999fec56f58SAlexei Starovoitov { 1000fec56f58SAlexei Starovoitov return -ENOTSUPP; 1001fec56f58SAlexei Starovoitov } 1002fec56f58SAlexei Starovoitov 1003fec56f58SAlexei Starovoitov static int __init init_trampolines(void) 1004fec56f58SAlexei Starovoitov { 1005fec56f58SAlexei Starovoitov int i; 1006fec56f58SAlexei Starovoitov 1007fec56f58SAlexei Starovoitov for (i = 0; i < TRAMPOLINE_TABLE_SIZE; i++) 1008fec56f58SAlexei Starovoitov INIT_HLIST_HEAD(&trampoline_table[i]); 1009fec56f58SAlexei Starovoitov return 0; 1010fec56f58SAlexei Starovoitov } 1011fec56f58SAlexei Starovoitov late_initcall(init_trampolines); 1012