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> 1600963a2eSSong 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 3300963a2eSSong Liu #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 3400963a2eSSong Liu static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex); 3500963a2eSSong Liu 3600963a2eSSong Liu static int bpf_tramp_ftrace_ops_func(struct ftrace_ops *ops, enum ftrace_ops_cmd cmd) 3700963a2eSSong Liu { 3800963a2eSSong Liu struct bpf_trampoline *tr = ops->private; 3900963a2eSSong Liu int ret = 0; 4000963a2eSSong Liu 4100963a2eSSong Liu if (cmd == FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_SELF) { 4200963a2eSSong Liu /* This is called inside register_ftrace_direct_multi(), so 4300963a2eSSong Liu * tr->mutex is already locked. 4400963a2eSSong Liu */ 4500963a2eSSong Liu lockdep_assert_held_once(&tr->mutex); 4600963a2eSSong Liu 4700963a2eSSong Liu /* Instead of updating the trampoline here, we propagate 4800963a2eSSong Liu * -EAGAIN to register_ftrace_direct_multi(). Then we can 4900963a2eSSong Liu * retry register_ftrace_direct_multi() after updating the 5000963a2eSSong Liu * trampoline. 5100963a2eSSong Liu */ 5200963a2eSSong Liu if ((tr->flags & BPF_TRAMP_F_CALL_ORIG) && 5300963a2eSSong Liu !(tr->flags & BPF_TRAMP_F_ORIG_STACK)) { 5400963a2eSSong Liu if (WARN_ON_ONCE(tr->flags & BPF_TRAMP_F_SHARE_IPMODIFY)) 5500963a2eSSong Liu return -EBUSY; 5600963a2eSSong Liu 5700963a2eSSong Liu tr->flags |= BPF_TRAMP_F_SHARE_IPMODIFY; 5800963a2eSSong Liu return -EAGAIN; 5900963a2eSSong Liu } 6000963a2eSSong Liu 6100963a2eSSong Liu return 0; 6200963a2eSSong Liu } 6300963a2eSSong Liu 6400963a2eSSong Liu /* The normal locking order is 6500963a2eSSong Liu * tr->mutex => direct_mutex (ftrace.c) => ftrace_lock (ftrace.c) 6600963a2eSSong Liu * 6700963a2eSSong Liu * The following two commands are called from 6800963a2eSSong Liu * 6900963a2eSSong Liu * prepare_direct_functions_for_ipmodify 7000963a2eSSong Liu * cleanup_direct_functions_after_ipmodify 7100963a2eSSong Liu * 7200963a2eSSong Liu * In both cases, direct_mutex is already locked. Use 7300963a2eSSong Liu * mutex_trylock(&tr->mutex) to avoid deadlock in race condition 7400963a2eSSong Liu * (something else is making changes to this same trampoline). 7500963a2eSSong Liu */ 7600963a2eSSong Liu if (!mutex_trylock(&tr->mutex)) { 7700963a2eSSong Liu /* sleep 1 ms to make sure whatever holding tr->mutex makes 7800963a2eSSong Liu * some progress. 7900963a2eSSong Liu */ 8000963a2eSSong Liu msleep(1); 8100963a2eSSong Liu return -EAGAIN; 8200963a2eSSong Liu } 8300963a2eSSong Liu 8400963a2eSSong Liu switch (cmd) { 8500963a2eSSong Liu case FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER: 8600963a2eSSong Liu tr->flags |= BPF_TRAMP_F_SHARE_IPMODIFY; 8700963a2eSSong Liu 8800963a2eSSong Liu if ((tr->flags & BPF_TRAMP_F_CALL_ORIG) && 8900963a2eSSong Liu !(tr->flags & BPF_TRAMP_F_ORIG_STACK)) 9000963a2eSSong Liu ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */); 9100963a2eSSong Liu break; 9200963a2eSSong Liu case FTRACE_OPS_CMD_DISABLE_SHARE_IPMODIFY_PEER: 9300963a2eSSong Liu tr->flags &= ~BPF_TRAMP_F_SHARE_IPMODIFY; 9400963a2eSSong Liu 9500963a2eSSong Liu if (tr->flags & BPF_TRAMP_F_ORIG_STACK) 9600963a2eSSong Liu ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */); 9700963a2eSSong Liu break; 9800963a2eSSong Liu default: 9900963a2eSSong Liu ret = -EINVAL; 10000963a2eSSong Liu break; 10114250fa4SYang Li } 10200963a2eSSong Liu 10300963a2eSSong Liu mutex_unlock(&tr->mutex); 10400963a2eSSong Liu return ret; 10500963a2eSSong Liu } 10600963a2eSSong Liu #endif 10700963a2eSSong 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 119a108f7dcSJiri Olsa void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym) 120a108f7dcSJiri Olsa { 121a108f7dcSJiri Olsa ksym->start = (unsigned long) data; 1227ac88ebaSJiri Olsa ksym->end = ksym->start + PAGE_SIZE; 123a108f7dcSJiri Olsa bpf_ksym_add(ksym); 124a108f7dcSJiri Olsa perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, 1257ac88ebaSJiri Olsa PAGE_SIZE, false, ksym->name); 126a108f7dcSJiri Olsa } 127a108f7dcSJiri Olsa 128a108f7dcSJiri Olsa void bpf_image_ksym_del(struct bpf_ksym *ksym) 129a108f7dcSJiri Olsa { 130a108f7dcSJiri Olsa bpf_ksym_del(ksym); 131a108f7dcSJiri Olsa perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, 1327ac88ebaSJiri Olsa PAGE_SIZE, true, ksym->name); 133a108f7dcSJiri Olsa } 134a108f7dcSJiri Olsa 135f7b12b6fSToke Høiland-Jørgensen static struct bpf_trampoline *bpf_trampoline_lookup(u64 key) 136fec56f58SAlexei Starovoitov { 137fec56f58SAlexei Starovoitov struct bpf_trampoline *tr; 138fec56f58SAlexei Starovoitov struct hlist_head *head; 139fec56f58SAlexei Starovoitov int i; 140fec56f58SAlexei Starovoitov 141fec56f58SAlexei Starovoitov mutex_lock(&trampoline_mutex); 142fec56f58SAlexei Starovoitov head = &trampoline_table[hash_64(key, TRAMPOLINE_HASH_BITS)]; 143fec56f58SAlexei Starovoitov hlist_for_each_entry(tr, head, hlist) { 144fec56f58SAlexei Starovoitov if (tr->key == key) { 145fec56f58SAlexei Starovoitov refcount_inc(&tr->refcnt); 146fec56f58SAlexei Starovoitov goto out; 147fec56f58SAlexei Starovoitov } 148fec56f58SAlexei Starovoitov } 149fec56f58SAlexei Starovoitov tr = kzalloc(sizeof(*tr), GFP_KERNEL); 150fec56f58SAlexei Starovoitov if (!tr) 151fec56f58SAlexei Starovoitov goto out; 15200963a2eSSong Liu #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 15300963a2eSSong Liu tr->fops = kzalloc(sizeof(struct ftrace_ops), GFP_KERNEL); 15400963a2eSSong Liu if (!tr->fops) { 15500963a2eSSong Liu kfree(tr); 15600963a2eSSong Liu tr = NULL; 15700963a2eSSong Liu goto out; 15800963a2eSSong Liu } 15900963a2eSSong Liu tr->fops->private = tr; 16000963a2eSSong Liu tr->fops->ops_func = bpf_tramp_ftrace_ops_func; 16100963a2eSSong Liu #endif 162fec56f58SAlexei Starovoitov 163fec56f58SAlexei Starovoitov tr->key = key; 164fec56f58SAlexei Starovoitov INIT_HLIST_NODE(&tr->hlist); 165fec56f58SAlexei Starovoitov hlist_add_head(&tr->hlist, head); 166fec56f58SAlexei Starovoitov refcount_set(&tr->refcnt, 1); 167fec56f58SAlexei Starovoitov mutex_init(&tr->mutex); 168fec56f58SAlexei Starovoitov for (i = 0; i < BPF_TRAMP_MAX; i++) 169fec56f58SAlexei Starovoitov INIT_HLIST_HEAD(&tr->progs_hlist[i]); 170fec56f58SAlexei Starovoitov out: 171fec56f58SAlexei Starovoitov mutex_unlock(&trampoline_mutex); 172fec56f58SAlexei Starovoitov return tr; 173fec56f58SAlexei Starovoitov } 174fec56f58SAlexei Starovoitov 175861de02eSJiri Olsa static int bpf_trampoline_module_get(struct bpf_trampoline *tr) 176861de02eSJiri Olsa { 177861de02eSJiri Olsa struct module *mod; 178861de02eSJiri Olsa int err = 0; 179861de02eSJiri Olsa 180861de02eSJiri Olsa preempt_disable(); 181861de02eSJiri Olsa mod = __module_text_address((unsigned long) tr->func.addr); 182861de02eSJiri Olsa if (mod && !try_module_get(mod)) 183861de02eSJiri Olsa err = -ENOENT; 184861de02eSJiri Olsa preempt_enable(); 185861de02eSJiri Olsa tr->mod = mod; 186861de02eSJiri Olsa return err; 187861de02eSJiri Olsa } 188861de02eSJiri Olsa 189861de02eSJiri Olsa static void bpf_trampoline_module_put(struct bpf_trampoline *tr) 190861de02eSJiri Olsa { 191861de02eSJiri Olsa module_put(tr->mod); 192861de02eSJiri Olsa tr->mod = NULL; 193861de02eSJiri Olsa } 194861de02eSJiri Olsa 195b91e014fSAlexei Starovoitov static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr) 196b91e014fSAlexei Starovoitov { 197b91e014fSAlexei Starovoitov void *ip = tr->func.addr; 198b91e014fSAlexei Starovoitov int ret; 199b91e014fSAlexei Starovoitov 200b91e014fSAlexei Starovoitov if (tr->func.ftrace_managed) 20100963a2eSSong Liu ret = unregister_ftrace_direct_multi(tr->fops, (long)old_addr); 202b91e014fSAlexei Starovoitov else 203b91e014fSAlexei Starovoitov ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, NULL); 204861de02eSJiri Olsa 205861de02eSJiri Olsa if (!ret) 206861de02eSJiri Olsa bpf_trampoline_module_put(tr); 207b91e014fSAlexei Starovoitov return ret; 208b91e014fSAlexei Starovoitov } 209b91e014fSAlexei Starovoitov 21000963a2eSSong Liu static int modify_fentry(struct bpf_trampoline *tr, void *old_addr, void *new_addr, 21100963a2eSSong Liu bool lock_direct_mutex) 212b91e014fSAlexei Starovoitov { 213b91e014fSAlexei Starovoitov void *ip = tr->func.addr; 214b91e014fSAlexei Starovoitov int ret; 215b91e014fSAlexei Starovoitov 21600963a2eSSong Liu if (tr->func.ftrace_managed) { 21700963a2eSSong Liu if (lock_direct_mutex) 21800963a2eSSong Liu ret = modify_ftrace_direct_multi(tr->fops, (long)new_addr); 219b91e014fSAlexei Starovoitov else 22000963a2eSSong Liu ret = modify_ftrace_direct_multi_nolock(tr->fops, (long)new_addr); 22100963a2eSSong Liu } else { 222b91e014fSAlexei Starovoitov ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, new_addr); 22300963a2eSSong Liu } 224b91e014fSAlexei Starovoitov return ret; 225b91e014fSAlexei Starovoitov } 226b91e014fSAlexei Starovoitov 227b91e014fSAlexei Starovoitov /* first time registering */ 228b91e014fSAlexei Starovoitov static int register_fentry(struct bpf_trampoline *tr, void *new_addr) 229b91e014fSAlexei Starovoitov { 230b91e014fSAlexei Starovoitov void *ip = tr->func.addr; 231aebfd125SPeter Zijlstra unsigned long faddr; 232b91e014fSAlexei Starovoitov int ret; 233b91e014fSAlexei Starovoitov 234aebfd125SPeter Zijlstra faddr = ftrace_location((unsigned long)ip); 2353b317abcSXu Kuohai if (faddr) { 2363b317abcSXu Kuohai if (!tr->fops) 2373b317abcSXu Kuohai return -ENOTSUPP; 238aebfd125SPeter Zijlstra tr->func.ftrace_managed = true; 2393b317abcSXu Kuohai } 240b91e014fSAlexei Starovoitov 241861de02eSJiri Olsa if (bpf_trampoline_module_get(tr)) 242861de02eSJiri Olsa return -ENOENT; 243861de02eSJiri Olsa 24400963a2eSSong Liu if (tr->func.ftrace_managed) { 245dc81f8d1SSong Liu ftrace_set_filter_ip(tr->fops, (unsigned long)ip, 0, 1); 24600963a2eSSong Liu ret = register_ftrace_direct_multi(tr->fops, (long)new_addr); 24700963a2eSSong Liu } else { 248b91e014fSAlexei Starovoitov ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, NULL, new_addr); 24900963a2eSSong Liu } 250861de02eSJiri Olsa 251861de02eSJiri Olsa if (ret) 252861de02eSJiri Olsa bpf_trampoline_module_put(tr); 253b91e014fSAlexei Starovoitov return ret; 254b91e014fSAlexei Starovoitov } 255b91e014fSAlexei Starovoitov 256f7e0beafSKui-Feng Lee static struct bpf_tramp_links * 2571e37392cSJiri Olsa bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_arg) 25888fd9e53SKP Singh { 259f7e0beafSKui-Feng Lee struct bpf_tramp_link *link; 260f7e0beafSKui-Feng Lee struct bpf_tramp_links *tlinks; 261f7e0beafSKui-Feng Lee struct bpf_tramp_link **links; 26288fd9e53SKP Singh int kind; 26388fd9e53SKP Singh 26488fd9e53SKP Singh *total = 0; 265f7e0beafSKui-Feng Lee tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL); 266f7e0beafSKui-Feng Lee if (!tlinks) 26788fd9e53SKP Singh return ERR_PTR(-ENOMEM); 26888fd9e53SKP Singh 26988fd9e53SKP Singh for (kind = 0; kind < BPF_TRAMP_MAX; kind++) { 270f7e0beafSKui-Feng Lee tlinks[kind].nr_links = tr->progs_cnt[kind]; 27188fd9e53SKP Singh *total += tr->progs_cnt[kind]; 272f7e0beafSKui-Feng Lee links = tlinks[kind].links; 27388fd9e53SKP Singh 274f7e0beafSKui-Feng Lee hlist_for_each_entry(link, &tr->progs_hlist[kind], tramp_hlist) { 275f7e0beafSKui-Feng Lee *ip_arg |= link->link.prog->call_get_func_ip; 276f7e0beafSKui-Feng Lee *links++ = link; 27788fd9e53SKP Singh } 2781e37392cSJiri Olsa } 279f7e0beafSKui-Feng Lee return tlinks; 28088fd9e53SKP Singh } 281fec56f58SAlexei Starovoitov 282e21aa341SAlexei Starovoitov static void __bpf_tramp_image_put_deferred(struct work_struct *work) 283e21aa341SAlexei Starovoitov { 284e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 285e21aa341SAlexei Starovoitov 286e21aa341SAlexei Starovoitov im = container_of(work, struct bpf_tramp_image, work); 287e21aa341SAlexei Starovoitov bpf_image_ksym_del(&im->ksym); 288e21aa341SAlexei Starovoitov bpf_jit_free_exec(im->image); 2893486beddSSong Liu bpf_jit_uncharge_modmem(PAGE_SIZE); 290e21aa341SAlexei Starovoitov percpu_ref_exit(&im->pcref); 291e21aa341SAlexei Starovoitov kfree_rcu(im, rcu); 292e21aa341SAlexei Starovoitov } 293e21aa341SAlexei Starovoitov 294e21aa341SAlexei Starovoitov /* callback, fexit step 3 or fentry step 2 */ 295e21aa341SAlexei Starovoitov static void __bpf_tramp_image_put_rcu(struct rcu_head *rcu) 296e21aa341SAlexei Starovoitov { 297e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 298e21aa341SAlexei Starovoitov 299e21aa341SAlexei Starovoitov im = container_of(rcu, struct bpf_tramp_image, rcu); 300e21aa341SAlexei Starovoitov INIT_WORK(&im->work, __bpf_tramp_image_put_deferred); 301e21aa341SAlexei Starovoitov schedule_work(&im->work); 302e21aa341SAlexei Starovoitov } 303e21aa341SAlexei Starovoitov 304e21aa341SAlexei Starovoitov /* callback, fexit step 2. Called after percpu_ref_kill confirms. */ 305e21aa341SAlexei Starovoitov static void __bpf_tramp_image_release(struct percpu_ref *pcref) 306e21aa341SAlexei Starovoitov { 307e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 308e21aa341SAlexei Starovoitov 309e21aa341SAlexei Starovoitov im = container_of(pcref, struct bpf_tramp_image, pcref); 310e21aa341SAlexei Starovoitov call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu); 311e21aa341SAlexei Starovoitov } 312e21aa341SAlexei Starovoitov 313e21aa341SAlexei Starovoitov /* callback, fexit or fentry step 1 */ 314e21aa341SAlexei Starovoitov static void __bpf_tramp_image_put_rcu_tasks(struct rcu_head *rcu) 315e21aa341SAlexei Starovoitov { 316e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 317e21aa341SAlexei Starovoitov 318e21aa341SAlexei Starovoitov im = container_of(rcu, struct bpf_tramp_image, rcu); 319e21aa341SAlexei Starovoitov if (im->ip_after_call) 320e21aa341SAlexei Starovoitov /* the case of fmod_ret/fexit trampoline and CONFIG_PREEMPTION=y */ 321e21aa341SAlexei Starovoitov percpu_ref_kill(&im->pcref); 322e21aa341SAlexei Starovoitov else 323e21aa341SAlexei Starovoitov /* the case of fentry trampoline */ 324e21aa341SAlexei Starovoitov call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu); 325e21aa341SAlexei Starovoitov } 326e21aa341SAlexei Starovoitov 327e21aa341SAlexei Starovoitov static void bpf_tramp_image_put(struct bpf_tramp_image *im) 328e21aa341SAlexei Starovoitov { 329e21aa341SAlexei Starovoitov /* The trampoline image that calls original function is using: 330e21aa341SAlexei Starovoitov * rcu_read_lock_trace to protect sleepable bpf progs 331e21aa341SAlexei Starovoitov * rcu_read_lock to protect normal bpf progs 332e21aa341SAlexei Starovoitov * percpu_ref to protect trampoline itself 333e21aa341SAlexei Starovoitov * rcu tasks to protect trampoline asm not covered by percpu_ref 334e21aa341SAlexei Starovoitov * (which are few asm insns before __bpf_tramp_enter and 335e21aa341SAlexei Starovoitov * after __bpf_tramp_exit) 336e21aa341SAlexei Starovoitov * 337e21aa341SAlexei Starovoitov * The trampoline is unreachable before bpf_tramp_image_put(). 338e21aa341SAlexei Starovoitov * 339e21aa341SAlexei Starovoitov * First, patch the trampoline to avoid calling into fexit progs. 340e21aa341SAlexei Starovoitov * The progs will be freed even if the original function is still 341e21aa341SAlexei Starovoitov * executing or sleeping. 342e21aa341SAlexei Starovoitov * In case of CONFIG_PREEMPT=y use call_rcu_tasks() to wait on 343e21aa341SAlexei Starovoitov * first few asm instructions to execute and call into 344e21aa341SAlexei Starovoitov * __bpf_tramp_enter->percpu_ref_get. 345e21aa341SAlexei Starovoitov * Then use percpu_ref_kill to wait for the trampoline and the original 346e21aa341SAlexei Starovoitov * function to finish. 347e21aa341SAlexei Starovoitov * Then use call_rcu_tasks() to make sure few asm insns in 348e21aa341SAlexei Starovoitov * the trampoline epilogue are done as well. 349e21aa341SAlexei Starovoitov * 350e21aa341SAlexei Starovoitov * In !PREEMPT case the task that got interrupted in the first asm 351e21aa341SAlexei Starovoitov * insns won't go through an RCU quiescent state which the 352e21aa341SAlexei Starovoitov * percpu_ref_kill will be waiting for. Hence the first 353e21aa341SAlexei Starovoitov * call_rcu_tasks() is not necessary. 354e21aa341SAlexei Starovoitov */ 355e21aa341SAlexei Starovoitov if (im->ip_after_call) { 356e21aa341SAlexei Starovoitov int err = bpf_arch_text_poke(im->ip_after_call, BPF_MOD_JUMP, 357e21aa341SAlexei Starovoitov NULL, im->ip_epilogue); 358e21aa341SAlexei Starovoitov WARN_ON(err); 359e21aa341SAlexei Starovoitov if (IS_ENABLED(CONFIG_PREEMPTION)) 360e21aa341SAlexei Starovoitov call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu_tasks); 361e21aa341SAlexei Starovoitov else 362e21aa341SAlexei Starovoitov percpu_ref_kill(&im->pcref); 363e21aa341SAlexei Starovoitov return; 364e21aa341SAlexei Starovoitov } 365e21aa341SAlexei Starovoitov 366e21aa341SAlexei Starovoitov /* The trampoline without fexit and fmod_ret progs doesn't call original 367e21aa341SAlexei Starovoitov * function and doesn't use percpu_ref. 368e21aa341SAlexei Starovoitov * Use call_rcu_tasks_trace() to wait for sleepable progs to finish. 369e21aa341SAlexei Starovoitov * Then use call_rcu_tasks() to wait for the rest of trampoline asm 370e21aa341SAlexei Starovoitov * and normal progs. 371e21aa341SAlexei Starovoitov */ 372e21aa341SAlexei Starovoitov call_rcu_tasks_trace(&im->rcu, __bpf_tramp_image_put_rcu_tasks); 373e21aa341SAlexei Starovoitov } 374e21aa341SAlexei Starovoitov 375e21aa341SAlexei Starovoitov static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx) 376e21aa341SAlexei Starovoitov { 377e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 378e21aa341SAlexei Starovoitov struct bpf_ksym *ksym; 379e21aa341SAlexei Starovoitov void *image; 380e21aa341SAlexei Starovoitov int err = -ENOMEM; 381e21aa341SAlexei Starovoitov 382e21aa341SAlexei Starovoitov im = kzalloc(sizeof(*im), GFP_KERNEL); 383e21aa341SAlexei Starovoitov if (!im) 384e21aa341SAlexei Starovoitov goto out; 385e21aa341SAlexei Starovoitov 3863486beddSSong Liu err = bpf_jit_charge_modmem(PAGE_SIZE); 387e21aa341SAlexei Starovoitov if (err) 388e21aa341SAlexei Starovoitov goto out_free_im; 389e21aa341SAlexei Starovoitov 390e21aa341SAlexei Starovoitov err = -ENOMEM; 3915b0d1c7bSSong Liu im->image = image = bpf_jit_alloc_exec(PAGE_SIZE); 392e21aa341SAlexei Starovoitov if (!image) 393e21aa341SAlexei Starovoitov goto out_uncharge; 3945b0d1c7bSSong Liu set_vm_flush_reset_perms(image); 395e21aa341SAlexei Starovoitov 396e21aa341SAlexei Starovoitov err = percpu_ref_init(&im->pcref, __bpf_tramp_image_release, 0, GFP_KERNEL); 397e21aa341SAlexei Starovoitov if (err) 398e21aa341SAlexei Starovoitov goto out_free_image; 399e21aa341SAlexei Starovoitov 400e21aa341SAlexei Starovoitov ksym = &im->ksym; 401e21aa341SAlexei Starovoitov INIT_LIST_HEAD_RCU(&ksym->lnode); 402e21aa341SAlexei Starovoitov snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu_%u", key, idx); 403e21aa341SAlexei Starovoitov bpf_image_ksym_add(image, ksym); 404e21aa341SAlexei Starovoitov return im; 405e21aa341SAlexei Starovoitov 406e21aa341SAlexei Starovoitov out_free_image: 407e21aa341SAlexei Starovoitov bpf_jit_free_exec(im->image); 408e21aa341SAlexei Starovoitov out_uncharge: 4093486beddSSong Liu bpf_jit_uncharge_modmem(PAGE_SIZE); 410e21aa341SAlexei Starovoitov out_free_im: 411e21aa341SAlexei Starovoitov kfree(im); 412e21aa341SAlexei Starovoitov out: 413e21aa341SAlexei Starovoitov return ERR_PTR(err); 414e21aa341SAlexei Starovoitov } 415e21aa341SAlexei Starovoitov 41600963a2eSSong Liu static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex) 417fec56f58SAlexei Starovoitov { 418e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 419f7e0beafSKui-Feng Lee struct bpf_tramp_links *tlinks; 42000963a2eSSong Liu u32 orig_flags = tr->flags; 4211e37392cSJiri Olsa bool ip_arg = false; 42288fd9e53SKP Singh int err, total; 423fec56f58SAlexei Starovoitov 424f7e0beafSKui-Feng Lee tlinks = bpf_trampoline_get_progs(tr, &total, &ip_arg); 425f7e0beafSKui-Feng Lee if (IS_ERR(tlinks)) 426f7e0beafSKui-Feng Lee return PTR_ERR(tlinks); 42788fd9e53SKP Singh 42888fd9e53SKP Singh if (total == 0) { 429e21aa341SAlexei Starovoitov err = unregister_fentry(tr, tr->cur_image->image); 430e21aa341SAlexei Starovoitov bpf_tramp_image_put(tr->cur_image); 431e21aa341SAlexei Starovoitov tr->cur_image = NULL; 432fec56f58SAlexei Starovoitov tr->selector = 0; 433fec56f58SAlexei Starovoitov goto out; 434fec56f58SAlexei Starovoitov } 435fec56f58SAlexei Starovoitov 436e21aa341SAlexei Starovoitov im = bpf_tramp_image_alloc(tr->key, tr->selector); 437e21aa341SAlexei Starovoitov if (IS_ERR(im)) { 438e21aa341SAlexei Starovoitov err = PTR_ERR(im); 439e21aa341SAlexei Starovoitov goto out; 440e21aa341SAlexei Starovoitov } 441e21aa341SAlexei Starovoitov 44200963a2eSSong Liu /* clear all bits except SHARE_IPMODIFY */ 44300963a2eSSong Liu tr->flags &= BPF_TRAMP_F_SHARE_IPMODIFY; 44400963a2eSSong Liu 445f7e0beafSKui-Feng Lee if (tlinks[BPF_TRAMP_FEXIT].nr_links || 44600963a2eSSong Liu tlinks[BPF_TRAMP_MODIFY_RETURN].nr_links) { 447535a57a7SXu Kuohai /* NOTE: BPF_TRAMP_F_RESTORE_REGS and BPF_TRAMP_F_SKIP_FRAME 448535a57a7SXu Kuohai * should not be set together. 449535a57a7SXu Kuohai */ 45000963a2eSSong Liu tr->flags |= BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_SKIP_FRAME; 45100963a2eSSong Liu } else { 45200963a2eSSong Liu tr->flags |= BPF_TRAMP_F_RESTORE_REGS; 45300963a2eSSong Liu } 454fec56f58SAlexei Starovoitov 4551e37392cSJiri Olsa if (ip_arg) 45600963a2eSSong Liu tr->flags |= BPF_TRAMP_F_IP_ARG; 45700963a2eSSong Liu 45800963a2eSSong Liu #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 45900963a2eSSong Liu again: 46000963a2eSSong Liu if ((tr->flags & BPF_TRAMP_F_SHARE_IPMODIFY) && 46100963a2eSSong Liu (tr->flags & BPF_TRAMP_F_CALL_ORIG)) 46200963a2eSSong Liu tr->flags |= BPF_TRAMP_F_ORIG_STACK; 46300963a2eSSong Liu #endif 4641e37392cSJiri Olsa 465e21aa341SAlexei Starovoitov err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE, 46600963a2eSSong Liu &tr->func.model, tr->flags, tlinks, 467fec56f58SAlexei Starovoitov tr->func.addr); 46885d33df3SMartin KaFai Lau if (err < 0) 469fec56f58SAlexei Starovoitov goto out; 470fec56f58SAlexei Starovoitov 4715b0d1c7bSSong Liu set_memory_ro((long)im->image, 1); 4725b0d1c7bSSong Liu set_memory_x((long)im->image, 1); 4735b0d1c7bSSong Liu 474e21aa341SAlexei Starovoitov WARN_ON(tr->cur_image && tr->selector == 0); 475e21aa341SAlexei Starovoitov WARN_ON(!tr->cur_image && tr->selector); 476e21aa341SAlexei Starovoitov if (tr->cur_image) 477fec56f58SAlexei Starovoitov /* progs already running at this address */ 47800963a2eSSong Liu err = modify_fentry(tr, tr->cur_image->image, im->image, lock_direct_mutex); 479fec56f58SAlexei Starovoitov else 480fec56f58SAlexei Starovoitov /* first time registering */ 481e21aa341SAlexei Starovoitov err = register_fentry(tr, im->image); 48200963a2eSSong Liu 48300963a2eSSong Liu #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 48400963a2eSSong Liu if (err == -EAGAIN) { 48500963a2eSSong Liu /* -EAGAIN from bpf_tramp_ftrace_ops_func. Now 48600963a2eSSong Liu * BPF_TRAMP_F_SHARE_IPMODIFY is set, we can generate the 48700963a2eSSong Liu * trampoline again, and retry register. 48800963a2eSSong Liu */ 48900963a2eSSong Liu /* reset fops->func and fops->trampoline for re-register */ 49000963a2eSSong Liu tr->fops->func = NULL; 49100963a2eSSong Liu tr->fops->trampoline = 0; 49200963a2eSSong Liu goto again; 49300963a2eSSong Liu } 49400963a2eSSong Liu #endif 495fec56f58SAlexei Starovoitov if (err) 496fec56f58SAlexei Starovoitov goto out; 49700963a2eSSong Liu 498e21aa341SAlexei Starovoitov if (tr->cur_image) 499e21aa341SAlexei Starovoitov bpf_tramp_image_put(tr->cur_image); 500e21aa341SAlexei Starovoitov tr->cur_image = im; 501fec56f58SAlexei Starovoitov tr->selector++; 502fec56f58SAlexei Starovoitov out: 50300963a2eSSong Liu /* If any error happens, restore previous flags */ 50400963a2eSSong Liu if (err) 50500963a2eSSong Liu tr->flags = orig_flags; 506f7e0beafSKui-Feng Lee kfree(tlinks); 507fec56f58SAlexei Starovoitov return err; 508fec56f58SAlexei Starovoitov } 509fec56f58SAlexei Starovoitov 5109e4e01dfSKP Singh static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog) 511fec56f58SAlexei Starovoitov { 5129e4e01dfSKP Singh switch (prog->expected_attach_type) { 513fec56f58SAlexei Starovoitov case BPF_TRACE_FENTRY: 514fec56f58SAlexei Starovoitov return BPF_TRAMP_FENTRY; 515ae240823SKP Singh case BPF_MODIFY_RETURN: 516ae240823SKP Singh return BPF_TRAMP_MODIFY_RETURN; 517be8704ffSAlexei Starovoitov case BPF_TRACE_FEXIT: 518fec56f58SAlexei Starovoitov return BPF_TRAMP_FEXIT; 5199e4e01dfSKP Singh case BPF_LSM_MAC: 5209e4e01dfSKP Singh if (!prog->aux->attach_func_proto->type) 5219e4e01dfSKP Singh /* The function returns void, we cannot modify its 5229e4e01dfSKP Singh * return value. 5239e4e01dfSKP Singh */ 5249e4e01dfSKP Singh return BPF_TRAMP_FEXIT; 5259e4e01dfSKP Singh else 5269e4e01dfSKP Singh return BPF_TRAMP_MODIFY_RETURN; 527be8704ffSAlexei Starovoitov default: 528be8704ffSAlexei Starovoitov return BPF_TRAMP_REPLACE; 529fec56f58SAlexei Starovoitov } 530fec56f58SAlexei Starovoitov } 531fec56f58SAlexei Starovoitov 532af3f4134SStanislav Fomichev static int __bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr) 533fec56f58SAlexei Starovoitov { 534fec56f58SAlexei Starovoitov enum bpf_tramp_prog_type kind; 535f7e0beafSKui-Feng Lee struct bpf_tramp_link *link_exiting; 536fec56f58SAlexei Starovoitov int err = 0; 537a2aa95b7SYuntao Wang int cnt = 0, i; 538fec56f58SAlexei Starovoitov 539f7e0beafSKui-Feng Lee kind = bpf_attach_type_to_tramp(link->link.prog); 540af3f4134SStanislav Fomichev if (tr->extension_prog) 541be8704ffSAlexei Starovoitov /* cannot attach fentry/fexit if extension prog is attached. 542be8704ffSAlexei Starovoitov * cannot overwrite extension prog either. 543be8704ffSAlexei Starovoitov */ 544af3f4134SStanislav Fomichev return -EBUSY; 545a2aa95b7SYuntao Wang 546a2aa95b7SYuntao Wang for (i = 0; i < BPF_TRAMP_MAX; i++) 547a2aa95b7SYuntao Wang cnt += tr->progs_cnt[i]; 548a2aa95b7SYuntao Wang 549be8704ffSAlexei Starovoitov if (kind == BPF_TRAMP_REPLACE) { 550be8704ffSAlexei Starovoitov /* Cannot attach extension if fentry/fexit are in use. */ 551af3f4134SStanislav Fomichev if (cnt) 552af3f4134SStanislav Fomichev return -EBUSY; 553f7e0beafSKui-Feng Lee tr->extension_prog = link->link.prog; 554af3f4134SStanislav Fomichev return bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, NULL, 555f7e0beafSKui-Feng Lee link->link.prog->bpf_func); 556be8704ffSAlexei Starovoitov } 557af3f4134SStanislav Fomichev if (cnt >= BPF_MAX_TRAMP_LINKS) 558af3f4134SStanislav Fomichev return -E2BIG; 559af3f4134SStanislav Fomichev if (!hlist_unhashed(&link->tramp_hlist)) 560fec56f58SAlexei Starovoitov /* prog already linked */ 561af3f4134SStanislav Fomichev return -EBUSY; 562f7e0beafSKui-Feng Lee hlist_for_each_entry(link_exiting, &tr->progs_hlist[kind], tramp_hlist) { 563f7e0beafSKui-Feng Lee if (link_exiting->link.prog != link->link.prog) 564f7e0beafSKui-Feng Lee continue; 565f7e0beafSKui-Feng Lee /* prog already linked */ 566af3f4134SStanislav Fomichev return -EBUSY; 567f7e0beafSKui-Feng Lee } 568f7e0beafSKui-Feng Lee 569f7e0beafSKui-Feng Lee hlist_add_head(&link->tramp_hlist, &tr->progs_hlist[kind]); 570fec56f58SAlexei Starovoitov tr->progs_cnt[kind]++; 57100963a2eSSong Liu err = bpf_trampoline_update(tr, true /* lock_direct_mutex */); 572fec56f58SAlexei Starovoitov if (err) { 573f7e0beafSKui-Feng Lee hlist_del_init(&link->tramp_hlist); 574fec56f58SAlexei Starovoitov tr->progs_cnt[kind]--; 575fec56f58SAlexei Starovoitov } 576af3f4134SStanislav Fomichev return err; 577af3f4134SStanislav Fomichev } 578af3f4134SStanislav Fomichev 579af3f4134SStanislav Fomichev int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr) 580af3f4134SStanislav Fomichev { 581af3f4134SStanislav Fomichev int err; 582af3f4134SStanislav Fomichev 583af3f4134SStanislav Fomichev mutex_lock(&tr->mutex); 584af3f4134SStanislav Fomichev err = __bpf_trampoline_link_prog(link, tr); 585fec56f58SAlexei Starovoitov mutex_unlock(&tr->mutex); 586fec56f58SAlexei Starovoitov return err; 587fec56f58SAlexei Starovoitov } 588fec56f58SAlexei Starovoitov 589af3f4134SStanislav Fomichev static int __bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr) 590fec56f58SAlexei Starovoitov { 591fec56f58SAlexei Starovoitov enum bpf_tramp_prog_type kind; 592fec56f58SAlexei Starovoitov int err; 593fec56f58SAlexei Starovoitov 594f7e0beafSKui-Feng Lee kind = bpf_attach_type_to_tramp(link->link.prog); 595be8704ffSAlexei Starovoitov if (kind == BPF_TRAMP_REPLACE) { 596be8704ffSAlexei Starovoitov WARN_ON_ONCE(!tr->extension_prog); 597be8704ffSAlexei Starovoitov err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, 598be8704ffSAlexei Starovoitov tr->extension_prog->bpf_func, NULL); 599be8704ffSAlexei Starovoitov tr->extension_prog = NULL; 600af3f4134SStanislav Fomichev return err; 601be8704ffSAlexei Starovoitov } 602f7e0beafSKui-Feng Lee hlist_del_init(&link->tramp_hlist); 603fec56f58SAlexei Starovoitov tr->progs_cnt[kind]--; 60400963a2eSSong Liu return bpf_trampoline_update(tr, true /* lock_direct_mutex */); 605af3f4134SStanislav Fomichev } 606af3f4134SStanislav Fomichev 607af3f4134SStanislav Fomichev /* bpf_trampoline_unlink_prog() should never fail. */ 608af3f4134SStanislav Fomichev int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr) 609af3f4134SStanislav Fomichev { 610af3f4134SStanislav Fomichev int err; 611af3f4134SStanislav Fomichev 612af3f4134SStanislav Fomichev mutex_lock(&tr->mutex); 613af3f4134SStanislav Fomichev err = __bpf_trampoline_unlink_prog(link, tr); 614fec56f58SAlexei Starovoitov mutex_unlock(&tr->mutex); 615fec56f58SAlexei Starovoitov return err; 616fec56f58SAlexei Starovoitov } 617fec56f58SAlexei Starovoitov 6183908fcddSStanislav Fomichev #if defined(CONFIG_CGROUP_BPF) && defined(CONFIG_BPF_LSM) 61969fd337aSStanislav Fomichev static void bpf_shim_tramp_link_release(struct bpf_link *link) 62069fd337aSStanislav Fomichev { 62169fd337aSStanislav Fomichev struct bpf_shim_tramp_link *shim_link = 62269fd337aSStanislav Fomichev container_of(link, struct bpf_shim_tramp_link, link.link); 62369fd337aSStanislav Fomichev 62469fd337aSStanislav Fomichev /* paired with 'shim_link->trampoline = tr' in bpf_trampoline_link_cgroup_shim */ 62569fd337aSStanislav Fomichev if (!shim_link->trampoline) 62669fd337aSStanislav Fomichev return; 62769fd337aSStanislav Fomichev 62869fd337aSStanislav Fomichev WARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->link, shim_link->trampoline)); 62969fd337aSStanislav Fomichev bpf_trampoline_put(shim_link->trampoline); 63069fd337aSStanislav Fomichev } 63169fd337aSStanislav Fomichev 63269fd337aSStanislav Fomichev static void bpf_shim_tramp_link_dealloc(struct bpf_link *link) 63369fd337aSStanislav Fomichev { 63469fd337aSStanislav Fomichev struct bpf_shim_tramp_link *shim_link = 63569fd337aSStanislav Fomichev container_of(link, struct bpf_shim_tramp_link, link.link); 63669fd337aSStanislav Fomichev 63769fd337aSStanislav Fomichev kfree(shim_link); 63869fd337aSStanislav Fomichev } 63969fd337aSStanislav Fomichev 64069fd337aSStanislav Fomichev static const struct bpf_link_ops bpf_shim_tramp_link_lops = { 64169fd337aSStanislav Fomichev .release = bpf_shim_tramp_link_release, 64269fd337aSStanislav Fomichev .dealloc = bpf_shim_tramp_link_dealloc, 64369fd337aSStanislav Fomichev }; 64469fd337aSStanislav Fomichev 64569fd337aSStanislav Fomichev static struct bpf_shim_tramp_link *cgroup_shim_alloc(const struct bpf_prog *prog, 64669fd337aSStanislav Fomichev bpf_func_t bpf_func, 64769fd337aSStanislav Fomichev int cgroup_atype) 64869fd337aSStanislav Fomichev { 64969fd337aSStanislav Fomichev struct bpf_shim_tramp_link *shim_link = NULL; 65069fd337aSStanislav Fomichev struct bpf_prog *p; 65169fd337aSStanislav Fomichev 65269fd337aSStanislav Fomichev shim_link = kzalloc(sizeof(*shim_link), GFP_USER); 65369fd337aSStanislav Fomichev if (!shim_link) 65469fd337aSStanislav Fomichev return NULL; 65569fd337aSStanislav Fomichev 65669fd337aSStanislav Fomichev p = bpf_prog_alloc(1, 0); 65769fd337aSStanislav Fomichev if (!p) { 65869fd337aSStanislav Fomichev kfree(shim_link); 65969fd337aSStanislav Fomichev return NULL; 66069fd337aSStanislav Fomichev } 66169fd337aSStanislav Fomichev 66269fd337aSStanislav Fomichev p->jited = false; 66369fd337aSStanislav Fomichev p->bpf_func = bpf_func; 66469fd337aSStanislav Fomichev 66569fd337aSStanislav Fomichev p->aux->cgroup_atype = cgroup_atype; 66669fd337aSStanislav Fomichev p->aux->attach_func_proto = prog->aux->attach_func_proto; 66769fd337aSStanislav Fomichev p->aux->attach_btf_id = prog->aux->attach_btf_id; 66869fd337aSStanislav Fomichev p->aux->attach_btf = prog->aux->attach_btf; 66969fd337aSStanislav Fomichev btf_get(p->aux->attach_btf); 67069fd337aSStanislav Fomichev p->type = BPF_PROG_TYPE_LSM; 67169fd337aSStanislav Fomichev p->expected_attach_type = BPF_LSM_MAC; 67269fd337aSStanislav Fomichev bpf_prog_inc(p); 67369fd337aSStanislav Fomichev bpf_link_init(&shim_link->link.link, BPF_LINK_TYPE_UNSPEC, 67469fd337aSStanislav Fomichev &bpf_shim_tramp_link_lops, p); 675c0e19f2cSStanislav Fomichev bpf_cgroup_atype_get(p->aux->attach_btf_id, cgroup_atype); 67669fd337aSStanislav Fomichev 67769fd337aSStanislav Fomichev return shim_link; 67869fd337aSStanislav Fomichev } 67969fd337aSStanislav Fomichev 68069fd337aSStanislav Fomichev static struct bpf_shim_tramp_link *cgroup_shim_find(struct bpf_trampoline *tr, 68169fd337aSStanislav Fomichev bpf_func_t bpf_func) 68269fd337aSStanislav Fomichev { 68369fd337aSStanislav Fomichev struct bpf_tramp_link *link; 68469fd337aSStanislav Fomichev int kind; 68569fd337aSStanislav Fomichev 68669fd337aSStanislav Fomichev for (kind = 0; kind < BPF_TRAMP_MAX; kind++) { 68769fd337aSStanislav Fomichev hlist_for_each_entry(link, &tr->progs_hlist[kind], tramp_hlist) { 68869fd337aSStanislav Fomichev struct bpf_prog *p = link->link.prog; 68969fd337aSStanislav Fomichev 69069fd337aSStanislav Fomichev if (p->bpf_func == bpf_func) 69169fd337aSStanislav Fomichev return container_of(link, struct bpf_shim_tramp_link, link); 69269fd337aSStanislav Fomichev } 69369fd337aSStanislav Fomichev } 69469fd337aSStanislav Fomichev 69569fd337aSStanislav Fomichev return NULL; 69669fd337aSStanislav Fomichev } 69769fd337aSStanislav Fomichev 69869fd337aSStanislav Fomichev int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog, 69969fd337aSStanislav Fomichev int cgroup_atype) 70069fd337aSStanislav Fomichev { 70169fd337aSStanislav Fomichev struct bpf_shim_tramp_link *shim_link = NULL; 70269fd337aSStanislav Fomichev struct bpf_attach_target_info tgt_info = {}; 70369fd337aSStanislav Fomichev struct bpf_trampoline *tr; 70469fd337aSStanislav Fomichev bpf_func_t bpf_func; 70569fd337aSStanislav Fomichev u64 key; 70669fd337aSStanislav Fomichev int err; 70769fd337aSStanislav Fomichev 70869fd337aSStanislav Fomichev err = bpf_check_attach_target(NULL, prog, NULL, 70969fd337aSStanislav Fomichev prog->aux->attach_btf_id, 71069fd337aSStanislav Fomichev &tgt_info); 71169fd337aSStanislav Fomichev if (err) 71269fd337aSStanislav Fomichev return err; 71369fd337aSStanislav Fomichev 71469fd337aSStanislav Fomichev key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, 71569fd337aSStanislav Fomichev prog->aux->attach_btf_id); 71669fd337aSStanislav Fomichev 71769fd337aSStanislav Fomichev bpf_lsm_find_cgroup_shim(prog, &bpf_func); 71869fd337aSStanislav Fomichev tr = bpf_trampoline_get(key, &tgt_info); 71969fd337aSStanislav Fomichev if (!tr) 72069fd337aSStanislav Fomichev return -ENOMEM; 72169fd337aSStanislav Fomichev 72269fd337aSStanislav Fomichev mutex_lock(&tr->mutex); 72369fd337aSStanislav Fomichev 72469fd337aSStanislav Fomichev shim_link = cgroup_shim_find(tr, bpf_func); 72569fd337aSStanislav Fomichev if (shim_link) { 72669fd337aSStanislav Fomichev /* Reusing existing shim attached by the other program. */ 72769fd337aSStanislav Fomichev bpf_link_inc(&shim_link->link.link); 72869fd337aSStanislav Fomichev 72969fd337aSStanislav Fomichev mutex_unlock(&tr->mutex); 73069fd337aSStanislav Fomichev bpf_trampoline_put(tr); /* bpf_trampoline_get above */ 73169fd337aSStanislav Fomichev return 0; 73269fd337aSStanislav Fomichev } 73369fd337aSStanislav Fomichev 73469fd337aSStanislav Fomichev /* Allocate and install new shim. */ 73569fd337aSStanislav Fomichev 73669fd337aSStanislav Fomichev shim_link = cgroup_shim_alloc(prog, bpf_func, cgroup_atype); 73769fd337aSStanislav Fomichev if (!shim_link) { 73869fd337aSStanislav Fomichev err = -ENOMEM; 73969fd337aSStanislav Fomichev goto err; 74069fd337aSStanislav Fomichev } 74169fd337aSStanislav Fomichev 74269fd337aSStanislav Fomichev err = __bpf_trampoline_link_prog(&shim_link->link, tr); 74369fd337aSStanislav Fomichev if (err) 74469fd337aSStanislav Fomichev goto err; 74569fd337aSStanislav Fomichev 74669fd337aSStanislav Fomichev shim_link->trampoline = tr; 74769fd337aSStanislav Fomichev /* note, we're still holding tr refcnt from above */ 74869fd337aSStanislav Fomichev 74969fd337aSStanislav Fomichev mutex_unlock(&tr->mutex); 75069fd337aSStanislav Fomichev 75169fd337aSStanislav Fomichev return 0; 75269fd337aSStanislav Fomichev err: 75369fd337aSStanislav Fomichev mutex_unlock(&tr->mutex); 75469fd337aSStanislav Fomichev 75569fd337aSStanislav Fomichev if (shim_link) 75669fd337aSStanislav Fomichev bpf_link_put(&shim_link->link.link); 75769fd337aSStanislav Fomichev 75869fd337aSStanislav Fomichev /* have to release tr while _not_ holding its mutex */ 75969fd337aSStanislav Fomichev bpf_trampoline_put(tr); /* bpf_trampoline_get above */ 76069fd337aSStanislav Fomichev 76169fd337aSStanislav Fomichev return err; 76269fd337aSStanislav Fomichev } 76369fd337aSStanislav Fomichev 76469fd337aSStanislav Fomichev void bpf_trampoline_unlink_cgroup_shim(struct bpf_prog *prog) 76569fd337aSStanislav Fomichev { 76669fd337aSStanislav Fomichev struct bpf_shim_tramp_link *shim_link = NULL; 76769fd337aSStanislav Fomichev struct bpf_trampoline *tr; 76869fd337aSStanislav Fomichev bpf_func_t bpf_func; 76969fd337aSStanislav Fomichev u64 key; 77069fd337aSStanislav Fomichev 77169fd337aSStanislav Fomichev key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, 77269fd337aSStanislav Fomichev prog->aux->attach_btf_id); 77369fd337aSStanislav Fomichev 77469fd337aSStanislav Fomichev bpf_lsm_find_cgroup_shim(prog, &bpf_func); 77569fd337aSStanislav Fomichev tr = bpf_trampoline_lookup(key); 77669fd337aSStanislav Fomichev if (WARN_ON_ONCE(!tr)) 77769fd337aSStanislav Fomichev return; 77869fd337aSStanislav Fomichev 77969fd337aSStanislav Fomichev mutex_lock(&tr->mutex); 78069fd337aSStanislav Fomichev shim_link = cgroup_shim_find(tr, bpf_func); 78169fd337aSStanislav Fomichev mutex_unlock(&tr->mutex); 78269fd337aSStanislav Fomichev 78369fd337aSStanislav Fomichev if (shim_link) 78469fd337aSStanislav Fomichev bpf_link_put(&shim_link->link.link); 78569fd337aSStanislav Fomichev 78669fd337aSStanislav Fomichev bpf_trampoline_put(tr); /* bpf_trampoline_lookup above */ 78769fd337aSStanislav Fomichev } 78869fd337aSStanislav Fomichev #endif 78969fd337aSStanislav Fomichev 790f7b12b6fSToke Høiland-Jørgensen struct bpf_trampoline *bpf_trampoline_get(u64 key, 791f7b12b6fSToke Høiland-Jørgensen struct bpf_attach_target_info *tgt_info) 792f7b12b6fSToke Høiland-Jørgensen { 793f7b12b6fSToke Høiland-Jørgensen struct bpf_trampoline *tr; 794f7b12b6fSToke Høiland-Jørgensen 795f7b12b6fSToke Høiland-Jørgensen tr = bpf_trampoline_lookup(key); 796f7b12b6fSToke Høiland-Jørgensen if (!tr) 797f7b12b6fSToke Høiland-Jørgensen return NULL; 798f7b12b6fSToke Høiland-Jørgensen 799f7b12b6fSToke Høiland-Jørgensen mutex_lock(&tr->mutex); 800f7b12b6fSToke Høiland-Jørgensen if (tr->func.addr) 801f7b12b6fSToke Høiland-Jørgensen goto out; 802f7b12b6fSToke Høiland-Jørgensen 803f7b12b6fSToke Høiland-Jørgensen memcpy(&tr->func.model, &tgt_info->fmodel, sizeof(tgt_info->fmodel)); 804f7b12b6fSToke Høiland-Jørgensen tr->func.addr = (void *)tgt_info->tgt_addr; 805f7b12b6fSToke Høiland-Jørgensen out: 806f7b12b6fSToke Høiland-Jørgensen mutex_unlock(&tr->mutex); 807f7b12b6fSToke Høiland-Jørgensen return tr; 808f7b12b6fSToke Høiland-Jørgensen } 809f7b12b6fSToke Høiland-Jørgensen 810fec56f58SAlexei Starovoitov void bpf_trampoline_put(struct bpf_trampoline *tr) 811fec56f58SAlexei Starovoitov { 812a2aa95b7SYuntao Wang int i; 813a2aa95b7SYuntao Wang 814fec56f58SAlexei Starovoitov if (!tr) 815fec56f58SAlexei Starovoitov return; 816fec56f58SAlexei Starovoitov mutex_lock(&trampoline_mutex); 817fec56f58SAlexei Starovoitov if (!refcount_dec_and_test(&tr->refcnt)) 818fec56f58SAlexei Starovoitov goto out; 819fec56f58SAlexei Starovoitov WARN_ON_ONCE(mutex_is_locked(&tr->mutex)); 820a2aa95b7SYuntao Wang 821a2aa95b7SYuntao Wang for (i = 0; i < BPF_TRAMP_MAX; i++) 822a2aa95b7SYuntao Wang if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[i]))) 823fec56f58SAlexei Starovoitov goto out; 824a2aa95b7SYuntao Wang 825e21aa341SAlexei Starovoitov /* This code will be executed even when the last bpf_tramp_image 826e21aa341SAlexei Starovoitov * is alive. All progs are detached from the trampoline and the 827e21aa341SAlexei Starovoitov * trampoline image is patched with jmp into epilogue to skip 828e21aa341SAlexei Starovoitov * fexit progs. The fentry-only trampoline will be freed via 829e21aa341SAlexei Starovoitov * multiple rcu callbacks. 8301e6c62a8SAlexei Starovoitov */ 831fec56f58SAlexei Starovoitov hlist_del(&tr->hlist); 83262d468e5SJiri Olsa if (tr->fops) { 83362d468e5SJiri Olsa ftrace_free_filter(tr->fops); 83400963a2eSSong Liu kfree(tr->fops); 83562d468e5SJiri Olsa } 836fec56f58SAlexei Starovoitov kfree(tr); 837fec56f58SAlexei Starovoitov out: 838fec56f58SAlexei Starovoitov mutex_unlock(&trampoline_mutex); 839fec56f58SAlexei Starovoitov } 840fec56f58SAlexei Starovoitov 841ca06f55bSAlexei Starovoitov #define NO_START_TIME 1 842856c02dbSSong Liu static __always_inline u64 notrace bpf_prog_start_time(void) 843f2dd3b39SAlexei Starovoitov { 844f2dd3b39SAlexei Starovoitov u64 start = NO_START_TIME; 845f2dd3b39SAlexei Starovoitov 846ca06f55bSAlexei Starovoitov if (static_branch_unlikely(&bpf_stats_enabled_key)) { 847f2dd3b39SAlexei Starovoitov start = sched_clock(); 848ca06f55bSAlexei Starovoitov if (unlikely(!start)) 849ca06f55bSAlexei Starovoitov start = NO_START_TIME; 850ca06f55bSAlexei Starovoitov } 851f2dd3b39SAlexei Starovoitov return start; 852f2dd3b39SAlexei Starovoitov } 853f2dd3b39SAlexei Starovoitov 854fb7dd8bcSAndrii Nakryiko /* The logic is similar to bpf_prog_run(), but with an explicit 85502ad0596SDavid Miller * rcu_read_lock() and migrate_disable() which are required 85602ad0596SDavid Miller * for the trampoline. The macro is split into 857f2dd3b39SAlexei Starovoitov * call __bpf_prog_enter 858fec56f58SAlexei Starovoitov * call prog->bpf_func 859fec56f58SAlexei Starovoitov * call __bpf_prog_exit 860ca06f55bSAlexei Starovoitov * 861ca06f55bSAlexei Starovoitov * __bpf_prog_enter returns: 862ca06f55bSAlexei Starovoitov * 0 - skip execution of the bpf prog 863ca06f55bSAlexei Starovoitov * 1 - execute bpf prog 8648fb33b60SZhen Lei * [2..MAX_U64] - execute bpf prog and record execution time. 865ca06f55bSAlexei Starovoitov * This is start time. 866fec56f58SAlexei Starovoitov */ 867e384c7b7SKui-Feng Lee u64 notrace __bpf_prog_enter(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx) 868dcce11d5SJules Irenge __acquires(RCU) 869fec56f58SAlexei Starovoitov { 870fec56f58SAlexei Starovoitov rcu_read_lock(); 87102ad0596SDavid Miller migrate_disable(); 872e384c7b7SKui-Feng Lee 873e384c7b7SKui-Feng Lee run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx); 874e384c7b7SKui-Feng Lee 875c89e843aSHou Tao if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) { 87605b24ff9SJiri Olsa bpf_prog_inc_misses_counter(prog); 877ca06f55bSAlexei Starovoitov return 0; 8789ed9e9baSAlexei Starovoitov } 879f2dd3b39SAlexei Starovoitov return bpf_prog_start_time(); 880fec56f58SAlexei Starovoitov } 881fec56f58SAlexei Starovoitov 882f2dd3b39SAlexei Starovoitov static void notrace update_prog_stats(struct bpf_prog *prog, 883f2dd3b39SAlexei Starovoitov u64 start) 884fec56f58SAlexei Starovoitov { 885fec56f58SAlexei Starovoitov struct bpf_prog_stats *stats; 886fec56f58SAlexei Starovoitov 887fec56f58SAlexei Starovoitov if (static_branch_unlikely(&bpf_stats_enabled_key) && 888f2dd3b39SAlexei Starovoitov /* static_key could be enabled in __bpf_prog_enter* 889f2dd3b39SAlexei Starovoitov * and disabled in __bpf_prog_exit*. 890fec56f58SAlexei Starovoitov * And vice versa. 891f2dd3b39SAlexei Starovoitov * Hence check that 'start' is valid. 892fec56f58SAlexei Starovoitov */ 893f2dd3b39SAlexei Starovoitov start > NO_START_TIME) { 894d979617aSEric Dumazet unsigned long flags; 895d979617aSEric Dumazet 896700d4796SAlexei Starovoitov stats = this_cpu_ptr(prog->stats); 897d979617aSEric Dumazet flags = u64_stats_update_begin_irqsave(&stats->syncp); 89861a0abaeSEric Dumazet u64_stats_inc(&stats->cnt); 89961a0abaeSEric Dumazet u64_stats_add(&stats->nsecs, sched_clock() - start); 900d979617aSEric Dumazet u64_stats_update_end_irqrestore(&stats->syncp, flags); 901fec56f58SAlexei Starovoitov } 902f2dd3b39SAlexei Starovoitov } 903f2dd3b39SAlexei Starovoitov 904e384c7b7SKui-Feng Lee void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start, struct bpf_tramp_run_ctx *run_ctx) 905f2dd3b39SAlexei Starovoitov __releases(RCU) 906f2dd3b39SAlexei Starovoitov { 907e384c7b7SKui-Feng Lee bpf_reset_run_ctx(run_ctx->saved_run_ctx); 908e384c7b7SKui-Feng Lee 909f2dd3b39SAlexei Starovoitov update_prog_stats(prog, start); 910c89e843aSHou Tao this_cpu_dec(*(prog->active)); 91102ad0596SDavid Miller migrate_enable(); 912fec56f58SAlexei Starovoitov rcu_read_unlock(); 913fec56f58SAlexei Starovoitov } 914fec56f58SAlexei Starovoitov 91569fd337aSStanislav Fomichev u64 notrace __bpf_prog_enter_lsm_cgroup(struct bpf_prog *prog, 91669fd337aSStanislav Fomichev struct bpf_tramp_run_ctx *run_ctx) 91769fd337aSStanislav Fomichev __acquires(RCU) 91869fd337aSStanislav Fomichev { 91969fd337aSStanislav Fomichev /* Runtime stats are exported via actual BPF_LSM_CGROUP 92069fd337aSStanislav Fomichev * programs, not the shims. 92169fd337aSStanislav Fomichev */ 92269fd337aSStanislav Fomichev rcu_read_lock(); 92369fd337aSStanislav Fomichev migrate_disable(); 92469fd337aSStanislav Fomichev 92569fd337aSStanislav Fomichev run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx); 92669fd337aSStanislav Fomichev 92769fd337aSStanislav Fomichev return NO_START_TIME; 92869fd337aSStanislav Fomichev } 92969fd337aSStanislav Fomichev 93069fd337aSStanislav Fomichev void notrace __bpf_prog_exit_lsm_cgroup(struct bpf_prog *prog, u64 start, 93169fd337aSStanislav Fomichev struct bpf_tramp_run_ctx *run_ctx) 93269fd337aSStanislav Fomichev __releases(RCU) 93369fd337aSStanislav Fomichev { 93469fd337aSStanislav Fomichev bpf_reset_run_ctx(run_ctx->saved_run_ctx); 93569fd337aSStanislav Fomichev 93669fd337aSStanislav Fomichev migrate_enable(); 93769fd337aSStanislav Fomichev rcu_read_unlock(); 93869fd337aSStanislav Fomichev } 93969fd337aSStanislav Fomichev 940e384c7b7SKui-Feng Lee u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx) 9411e6c62a8SAlexei Starovoitov { 9421e6c62a8SAlexei Starovoitov rcu_read_lock_trace(); 943031d6e02SAlexei Starovoitov migrate_disable(); 944f56407faSAlexei Starovoitov might_fault(); 945e384c7b7SKui-Feng Lee 946c89e843aSHou Tao if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) { 94705b24ff9SJiri Olsa bpf_prog_inc_misses_counter(prog); 948ca06f55bSAlexei Starovoitov return 0; 9499ed9e9baSAlexei Starovoitov } 950e384c7b7SKui-Feng Lee 951e384c7b7SKui-Feng Lee run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx); 952e384c7b7SKui-Feng Lee 953f2dd3b39SAlexei Starovoitov return bpf_prog_start_time(); 9541e6c62a8SAlexei Starovoitov } 9551e6c62a8SAlexei Starovoitov 956e384c7b7SKui-Feng Lee void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start, 957e384c7b7SKui-Feng Lee struct bpf_tramp_run_ctx *run_ctx) 9581e6c62a8SAlexei Starovoitov { 959e384c7b7SKui-Feng Lee bpf_reset_run_ctx(run_ctx->saved_run_ctx); 960e384c7b7SKui-Feng Lee 961f2dd3b39SAlexei Starovoitov update_prog_stats(prog, start); 962c89e843aSHou Tao this_cpu_dec(*(prog->active)); 963031d6e02SAlexei Starovoitov migrate_enable(); 9641e6c62a8SAlexei Starovoitov rcu_read_unlock_trace(); 9651e6c62a8SAlexei Starovoitov } 9661e6c62a8SAlexei Starovoitov 967*64696c40SMartin KaFai Lau u64 notrace __bpf_prog_enter_struct_ops(struct bpf_prog *prog, 968*64696c40SMartin KaFai Lau struct bpf_tramp_run_ctx *run_ctx) 969*64696c40SMartin KaFai Lau __acquires(RCU) 970*64696c40SMartin KaFai Lau { 971*64696c40SMartin KaFai Lau rcu_read_lock(); 972*64696c40SMartin KaFai Lau migrate_disable(); 973*64696c40SMartin KaFai Lau 974*64696c40SMartin KaFai Lau run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx); 975*64696c40SMartin KaFai Lau 976*64696c40SMartin KaFai Lau return bpf_prog_start_time(); 977*64696c40SMartin KaFai Lau } 978*64696c40SMartin KaFai Lau 979*64696c40SMartin KaFai Lau void notrace __bpf_prog_exit_struct_ops(struct bpf_prog *prog, u64 start, 980*64696c40SMartin KaFai Lau struct bpf_tramp_run_ctx *run_ctx) 981*64696c40SMartin KaFai Lau __releases(RCU) 982*64696c40SMartin KaFai Lau { 983*64696c40SMartin KaFai Lau bpf_reset_run_ctx(run_ctx->saved_run_ctx); 984*64696c40SMartin KaFai Lau 985*64696c40SMartin KaFai Lau update_prog_stats(prog, start); 986*64696c40SMartin KaFai Lau migrate_enable(); 987*64696c40SMartin KaFai Lau rcu_read_unlock(); 988*64696c40SMartin KaFai Lau } 989*64696c40SMartin KaFai Lau 990e21aa341SAlexei Starovoitov void notrace __bpf_tramp_enter(struct bpf_tramp_image *tr) 991e21aa341SAlexei Starovoitov { 992e21aa341SAlexei Starovoitov percpu_ref_get(&tr->pcref); 993e21aa341SAlexei Starovoitov } 994e21aa341SAlexei Starovoitov 995e21aa341SAlexei Starovoitov void notrace __bpf_tramp_exit(struct bpf_tramp_image *tr) 996e21aa341SAlexei Starovoitov { 997e21aa341SAlexei Starovoitov percpu_ref_put(&tr->pcref); 998e21aa341SAlexei Starovoitov } 999e21aa341SAlexei Starovoitov 1000fec56f58SAlexei Starovoitov int __weak 1001e21aa341SAlexei Starovoitov arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *image_end, 100285d33df3SMartin KaFai Lau const struct btf_func_model *m, u32 flags, 1003f7e0beafSKui-Feng Lee struct bpf_tramp_links *tlinks, 1004fec56f58SAlexei Starovoitov void *orig_call) 1005fec56f58SAlexei Starovoitov { 1006fec56f58SAlexei Starovoitov return -ENOTSUPP; 1007fec56f58SAlexei Starovoitov } 1008fec56f58SAlexei Starovoitov 1009fec56f58SAlexei Starovoitov static int __init init_trampolines(void) 1010fec56f58SAlexei Starovoitov { 1011fec56f58SAlexei Starovoitov int i; 1012fec56f58SAlexei Starovoitov 1013fec56f58SAlexei Starovoitov for (i = 0; i < TRAMPOLINE_TABLE_SIZE; i++) 1014fec56f58SAlexei Starovoitov INIT_HLIST_HEAD(&trampoline_table[i]); 1015fec56f58SAlexei Starovoitov return 0; 1016fec56f58SAlexei Starovoitov } 1017fec56f58SAlexei Starovoitov late_initcall(init_trampolines); 1018