// SPDX-License-Identifier: GPL-2.0-only/* Copyright (c) 2019 Facebook */#include <linux/hash.h>#include <linux/bpf.h>#include <linux/filter.h>#include <linux/ftrace.h>#include <linux/rbtree_latch.h>#include <linux/perf_event.h>#include <linux/btf.h>#include <linux/rcupdate_trace.h>#include <linux/rcupdate_wait.h>#include <linux/module.h> /* dummy _ops. The verifier will operate on target program's ops. */const struct bpf_verifier_ops bpf_extension_verifier_ops = {};const struct bpf_prog_ops bpf_extension_prog_ops = {}; /* btf_vmlinux has ~22k attachable functions. 1k htab is enough. */#define TRAMPOLINE_HASH_BITS 10#define TRAMPOLINE_TABLE_SIZE (1 << TRAMPOLINE_HASH_BITS) static struct hlist_head trampoline_table[TRAMPOLINE_TABLE_SIZE]; /* serializes access to trampoline_table */static DEFINE_MUTEX(trampoline_mutex); void *bpf_jit_alloc_exec_page(void){ void *image; image = bpf_jit_alloc_exec(PAGE_SIZE); if (!image) return NULL; set_vm_flush_reset_perms(image); /* Keep image as writeable. The alternative is to keep flipping ro/rw * everytime new program is attached or detached. */ set_memory_x((long)image, 1); return image;} void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym){ ksym->start = (unsigned long) data; ksym->end = ksym->start + PAGE_SIZE; bpf_ksym_add(ksym); perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, PAGE_SIZE, false, ksym->name);} void bpf_image_ksym_del(struct bpf_ksym *ksym){ bpf_ksym_del(ksym); perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, PAGE_SIZE, true, ksym->name);} static struct bpf_trampoline *bpf_trampoline_lookup(u64 key){ struct bpf_trampoline *tr; struct hlist_head *head; int i; mutex_lock(&trampoline_mutex); head = &trampoline_table[hash_64(key, TRAMPOLINE_HASH_BITS)]; hlist_for_each_entry(tr, head, hlist) { if (tr->key == key) { refcount_inc(&tr->refcnt); goto out; } } tr = kzalloc(sizeof(*tr), GFP_KERNEL); if (!tr) goto out; tr->key = key; INIT_HLIST_NODE(&tr->hlist); hlist_add_head(&tr->hlist, head); refcount_set(&tr->refcnt, 1); mutex_init(&tr->mutex); for (i = 0; i < BPF_TRAMP_MAX; i++) INIT_HLIST_HEAD(&tr->progs_hlist[i]);out: mutex_unlock(&trampoline_mutex); return tr;} static int bpf_trampoline_module_get(struct bpf_trampoline *tr){ struct module *mod; int err = 0; preempt_disable(); mod = __module_text_address((unsigned long) tr->func.addr); if (mod && !try_module_get(mod)) err = -ENOENT; preempt_enable(); tr->mod = mod; return err;} static void bpf_trampoline_module_put(struct bpf_trampoline *tr){ module_put(tr->mod); tr->mod = NULL;} static int is_ftrace_location(void *ip){ long addr; addr = ftrace_location((long)ip); if (!addr) return 0; if (WARN_ON_ONCE(addr != (long)ip)) return -EFAULT; return 1;} static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr){ void *ip = tr->func.addr; int ret; if (tr->func.ftrace_managed) ret = unregister_ftrace_direct((long)ip, (long)old_addr); else ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, NULL); if (!ret) bpf_trampoline_module_put(tr); return ret;} static int modify_fentry(struct bpf_trampoline *tr, void *old_addr, void *new_addr){ void *ip = tr->func.addr; int ret; if (tr->func.ftrace_managed) ret = modify_ftrace_direct((long)ip, (long)old_addr, (long)new_addr); else ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, new_addr); return ret;} /* first time registering */static int register_fentry(struct bpf_trampoline *tr, void *new_addr){ void *ip = tr->func.addr; int ret; ret = is_ftrace_location(ip); if (ret < 0) return ret; tr->func.ftrace_managed = ret; if (bpf_trampoline_module_get(tr)) return -ENOENT; if (tr->func.ftrace_managed) ret = register_ftrace_direct((long)ip, (long)new_addr); else ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, NULL, new_addr); if (ret) bpf_trampoline_module_put(tr); return ret;} static struct bpf_tramp_progs *bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total){ const struct bpf_prog_aux *aux; struct bpf_tramp_progs *tprogs; struct bpf_prog **progs; int kind; *total = 0; tprogs = kcalloc(BPF_TRAMP_MAX, sizeof(*tprogs), GFP_KERNEL); if (!tprogs) return ERR_PTR(-ENOMEM); for (kind = 0; kind < BPF_TRAMP_MAX; kind++) { tprogs[kind].nr_progs = tr->progs_cnt[kind]; *total += tr->progs_cnt[kind]; progs = tprogs[kind].progs; hlist_for_each_entry(aux, &tr->progs_hlist[kind], tramp_hlist) *progs++ = aux->prog; } return tprogs;} static void __bpf_tramp_image_put_deferred(struct work_struct *work){ struct bpf_tramp_image *im; im = container_of(work, struct bpf_tramp_image, work); bpf_image_ksym_del(&im->ksym); bpf_jit_free_exec(im->image); bpf_jit_uncharge_modmem(1); percpu_ref_exit(&im->pcref); kfree_rcu(im, rcu);} /* callback, fexit step 3 or fentry step 2 */static void __bpf_tramp_image_put_rcu(struct rcu_head *rcu){ struct bpf_tramp_image *im; im = container_of(rcu, struct bpf_tramp_image, rcu); INIT_WORK(&im->work, __bpf_tramp_image_put_deferred); schedule_work(&im->work);} /* callback, fexit step 2. Called after percpu_ref_kill confirms. */static void __bpf_tramp_image_release(struct percpu_ref *pcref){ struct bpf_tramp_image *im; im = container_of(pcref, struct bpf_tramp_image, pcref); call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu);} /* callback, fexit or fentry step 1 */static void __bpf_tramp_image_put_rcu_tasks(struct rcu_head *rcu){ struct bpf_tramp_image *im; im = container_of(rcu, struct bpf_tramp_image, rcu); if (im->ip_after_call) /* the case of fmod_ret/fexit trampoline and CONFIG_PREEMPTION=y */ percpu_ref_kill(&im->pcref); else /* the case of fentry trampoline */ call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu);} static void bpf_tramp_image_put(struct bpf_tramp_image *im){ /* The trampoline image that calls original function is using: * rcu_read_lock_trace to protect sleepable bpf progs * rcu_read_lock to protect normal bpf progs * percpu_ref to protect trampoline itself * rcu tasks to protect trampoline asm not covered by percpu_ref * (which are few asm insns before __bpf_tramp_enter and * after __bpf_tramp_exit) * * The trampoline is unreachable before bpf_tramp_image_put(). * * First, patch the trampoline to avoid calling into fexit progs. * The progs will be freed even if the original function is still * executing or sleeping. * In case of CONFIG_PREEMPT=y use call_rcu_tasks() to wait on * first few asm instructions to execute and call into * __bpf_tramp_enter->percpu_ref_get. * Then use percpu_ref_kill to wait for the trampoline and the original * function to finish. * Then use call_rcu_tasks() to make sure few asm insns in * the trampoline epilogue are done as well. * * In !PREEMPT case the task that got interrupted in the first asm * insns won't go through an RCU quiescent state which the * percpu_ref_kill will be waiting for. Hence the first * call_rcu_tasks() is not necessary. */ if (im->ip_after_call) { int err = bpf_arch_text_poke(im->ip_after_call, BPF_MOD_JUMP, NULL, im->ip_epilogue); WARN_ON(err); if (IS_ENABLED(CONFIG_PREEMPTION)) call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu_tasks); else percpu_ref_kill(&im->pcref); return; } /* The trampoline without fexit and fmod_ret progs doesn't call original * function and doesn't use percpu_ref. * Use call_rcu_tasks_trace() to wait for sleepable progs to finish. * Then use call_rcu_tasks() to wait for the rest of trampoline asm * and normal progs. */ call_rcu_tasks_trace(&im->rcu, __bpf_tramp_image_put_rcu_tasks);} static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx){ struct bpf_tramp_image *im; struct bpf_ksym *ksym; void *image; int err = -ENOMEM; im = kzalloc(sizeof(*im), GFP_KERNEL); if (!im) goto out; err = bpf_jit_charge_modmem(1); if (err) goto out_free_im; err = -ENOMEM; im->image = image = bpf_jit_alloc_exec_page(); if (!image) goto out_uncharge; err = percpu_ref_init(&im->pcref, __bpf_tramp_image_release, 0, GFP_KERNEL); if (err) goto out_free_image; ksym = &im->ksym; INIT_LIST_HEAD_RCU(&ksym->lnode); snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu_%u", key, idx); bpf_image_ksym_add(image, ksym); return im; out_free_image: bpf_jit_free_exec(im->image);out_uncharge: bpf_jit_uncharge_modmem(1);out_free_im: kfree(im);out: return ERR_PTR(err);} static int bpf_trampoline_update(struct bpf_trampoline *tr){ struct bpf_tramp_image *im; struct bpf_tramp_progs *tprogs; u32 flags = BPF_TRAMP_F_RESTORE_REGS; int err, total; tprogs = bpf_trampoline_get_progs(tr, &total); if (IS_ERR(tprogs)) return PTR_ERR(tprogs); if (total == 0) { err = unregister_fentry(tr, tr->cur_image->image); bpf_tramp_image_put(tr->cur_image); tr->cur_image = NULL; tr->selector = 0; goto out; } im = bpf_tramp_image_alloc(tr->key, tr->selector); if (IS_ERR(im)) { err = PTR_ERR(im); goto out; } if (tprogs[BPF_TRAMP_FEXIT].nr_progs || tprogs[BPF_TRAMP_MODIFY_RETURN].nr_progs) flags = BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_SKIP_FRAME; err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE, &tr->func.model, flags, tprogs, tr->func.addr); if (err < 0) goto out; WARN_ON(tr->cur_image && tr->selector == 0); WARN_ON(!tr->cur_image && tr->selector); if (tr->cur_image) /* progs already running at this address */ err = modify_fentry(tr, tr->cur_image->image, im->image); else /* first time registering */ err = register_fentry(tr, im->image); if (err) goto out; if (tr->cur_image) bpf_tramp_image_put(tr->cur_image); tr->cur_image = im; tr->selector++;out: kfree(tprogs); return err;} static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog){ switch (prog->expected_attach_type) { case BPF_TRACE_FENTRY: return BPF_TRAMP_FENTRY; case BPF_MODIFY_RETURN: return BPF_TRAMP_MODIFY_RETURN; case BPF_TRACE_FEXIT: return BPF_TRAMP_FEXIT; case BPF_LSM_MAC: if (!prog->aux->attach_func_proto->type) /* The function returns void, we cannot modify its * return value. */ return BPF_TRAMP_FEXIT; else return BPF_TRAMP_MODIFY_RETURN; default: return BPF_TRAMP_REPLACE; }} int bpf_trampoline_link_prog(struct bpf_prog *prog, struct bpf_trampoline *tr){ enum bpf_tramp_prog_type kind; int err = 0; int cnt; kind = bpf_attach_type_to_tramp(prog); mutex_lock(&tr->mutex); if (tr->extension_prog) { /* cannot attach fentry/fexit if extension prog is attached. * cannot overwrite extension prog either. */ err = -EBUSY; goto out; } cnt = tr->progs_cnt[BPF_TRAMP_FENTRY] + tr->progs_cnt[BPF_TRAMP_FEXIT]; if (kind == BPF_TRAMP_REPLACE) { /* Cannot attach extension if fentry/fexit are in use. */ if (cnt) { err = -EBUSY; goto out; } tr->extension_prog = prog; err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, NULL, prog->bpf_func); goto out; } if (cnt >= BPF_MAX_TRAMP_PROGS) { err = -E2BIG; goto out; } if (!hlist_unhashed(&prog->aux->tramp_hlist)) { /* prog already linked */ err = -EBUSY; goto out; } hlist_add_head(&prog->aux->tramp_hlist, &tr->progs_hlist[kind]); tr->progs_cnt[kind]++; err = bpf_trampoline_update(tr); if (err) { hlist_del_init(&prog->aux->tramp_hlist); tr->progs_cnt[kind]--; }out: mutex_unlock(&tr->mutex); return err;} /* bpf_trampoline_unlink_prog() should never fail. */int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr){ enum bpf_tramp_prog_type kind; int err; kind = bpf_attach_type_to_tramp(prog); mutex_lock(&tr->mutex); if (kind == BPF_TRAMP_REPLACE) { WARN_ON_ONCE(!tr->extension_prog); err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, tr->extension_prog->bpf_func, NULL); tr->extension_prog = NULL; goto out; } hlist_del_init(&prog->aux->tramp_hlist); tr->progs_cnt[kind]--; err = bpf_trampoline_update(tr);out: mutex_unlock(&tr->mutex); return err;} struct bpf_trampoline *bpf_trampoline_get(u64 key, struct bpf_attach_target_info *tgt_info){ struct bpf_trampoline *tr; tr = bpf_trampoline_lookup(key); if (!tr) return NULL; mutex_lock(&tr->mutex); if (tr->func.addr) goto out; memcpy(&tr->func.model, &tgt_info->fmodel, sizeof(tgt_info->fmodel)); tr->func.addr = (void *)tgt_info->tgt_addr;out: mutex_unlock(&tr->mutex); return tr;} void bpf_trampoline_put(struct bpf_trampoline *tr){ if (!tr)Lines 1–500 of 646. 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// SPDX-License-Identifier: GPL-2.0-only /* Copyright (c) 2019 Facebook */ #include <linux/hash.h> #include <linux/bpf.h> #include <linux/filter.h> #include <linux/ftrace.h> #include <linux/rbtree_latch.h> #include <linux/perf_event.h> #include <linux/btf.h> #include <linux/rcupdate_trace.h> #include <linux/rcupdate_wait.h> #include <linux/module.h> /* dummy _ops. The verifier will operate on target program's ops. */ const struct bpf_verifier_ops bpf_extension_verifier_ops = { }; const struct bpf_prog_ops bpf_extension_prog_ops = { }; /* btf_vmlinux has ~22k attachable functions. 1k htab is enough. */ #define TRAMPOLINE_HASH_BITS 10 #define TRAMPOLINE_TABLE_SIZE (1 << TRAMPOLINE_HASH_BITS) static struct hlist_head trampoline_table[TRAMPOLINE_TABLE_SIZE]; /* serializes access to trampoline_table */ static DEFINE_MUTEX(trampoline_mutex); void *bpf_jit_alloc_exec_page(void) { void *image; image = bpf_jit_alloc_exec(PAGE_SIZE); if (!image) return NULL; set_vm_flush_reset_perms(image); /* Keep image as writeable. The alternative is to keep flipping ro/rw * everytime new program is attached or detached. */ set_memory_x((long)image, 1); return image; } void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym) { ksym->start = (unsigned long) data; ksym->end = ksym->start + PAGE_SIZE; bpf_ksym_add(ksym); perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, PAGE_SIZE, false, ksym->name); } void bpf_image_ksym_del(struct bpf_ksym *ksym) { bpf_ksym_del(ksym); perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, PAGE_SIZE, true, ksym->name); } static struct bpf_trampoline *bpf_trampoline_lookup(u64 key) { struct bpf_trampoline *tr; struct hlist_head *head; int i; mutex_lock(&trampoline_mutex); head = &trampoline_table[hash_64(key, TRAMPOLINE_HASH_BITS)]; hlist_for_each_entry(tr, head, hlist) { if (tr->key == key) { refcount_inc(&tr->refcnt); goto out; } } tr = kzalloc(sizeof(*tr), GFP_KERNEL); if (!tr) goto out; tr->key = key; INIT_HLIST_NODE(&tr->hlist); hlist_add_head(&tr->hlist, head); refcount_set(&tr->refcnt, 1); mutex_init(&tr->mutex); for (i = 0; i < BPF_TRAMP_MAX; i++) INIT_HLIST_HEAD(&tr->progs_hlist[i]); out: mutex_unlock(&trampoline_mutex); return tr; } static int bpf_trampoline_module_get(struct bpf_trampoline *tr) { struct module *mod; int err = 0; preempt_disable(); mod = __module_text_address((unsigned long) tr->func.addr); if (mod && !try_module_get(mod)) err = -ENOENT; preempt_enable(); tr->mod = mod; return err; } static void bpf_trampoline_module_put(struct bpf_trampoline *tr) { module_put(tr->mod); tr->mod = NULL; } static int is_ftrace_location(void *ip) { long addr; addr = ftrace_location((long)ip); if (!addr) return 0; if (WARN_ON_ONCE(addr != (long)ip)) return -EFAULT; return 1; } static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr) { void *ip = tr->func.addr; int ret; if (tr->func.ftrace_managed) ret = unregister_ftrace_direct((long)ip, (long)old_addr); else ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, NULL); if (!ret) bpf_trampoline_module_put(tr); return ret; } static int modify_fentry(struct bpf_trampoline *tr, void *old_addr, void *new_addr) { void *ip = tr->func.addr; int ret; if (tr->func.ftrace_managed) ret = modify_ftrace_direct((long)ip, (long)old_addr, (long)new_addr); else ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, new_addr); return ret; } /* first time registering */ static int register_fentry(struct bpf_trampoline *tr, void *new_addr) { void *ip = tr->func.addr; int ret; ret = is_ftrace_location(ip); if (ret < 0) return ret; tr->func.ftrace_managed = ret; if (bpf_trampoline_module_get(tr)) return -ENOENT; if (tr->func.ftrace_managed) ret = register_ftrace_direct((long)ip, (long)new_addr); else ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, NULL, new_addr); if (ret) bpf_trampoline_module_put(tr); return ret; } static struct bpf_tramp_progs * bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total) { const struct bpf_prog_aux *aux; struct bpf_tramp_progs *tprogs; struct bpf_prog **progs; int kind; *total = 0; tprogs = kcalloc(BPF_TRAMP_MAX, sizeof(*tprogs), GFP_KERNEL); if (!tprogs) return ERR_PTR(-ENOMEM); for (kind = 0; kind < BPF_TRAMP_MAX; kind++) { tprogs[kind].nr_progs = tr->progs_cnt[kind]; *total += tr->progs_cnt[kind]; progs = tprogs[kind].progs; hlist_for_each_entry(aux, &tr->progs_hlist[kind], tramp_hlist) *progs++ = aux->prog; } return tprogs; } static void __bpf_tramp_image_put_deferred(struct work_struct *work) { struct bpf_tramp_image *im; im = container_of(work, struct bpf_tramp_image, work); bpf_image_ksym_del(&im->ksym); bpf_jit_free_exec(im->image); bpf_jit_uncharge_modmem(1); percpu_ref_exit(&im->pcref); kfree_rcu(im, rcu); } /* callback, fexit step 3 or fentry step 2 */ static void __bpf_tramp_image_put_rcu(struct rcu_head *rcu) { struct bpf_tramp_image *im; im = container_of(rcu, struct bpf_tramp_image, rcu); INIT_WORK(&im->work, __bpf_tramp_image_put_deferred); schedule_work(&im->work); } /* callback, fexit step 2. Called after percpu_ref_kill confirms. */ static void __bpf_tramp_image_release(struct percpu_ref *pcref) { struct bpf_tramp_image *im; im = container_of(pcref, struct bpf_tramp_image, pcref); call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu); } /* callback, fexit or fentry step 1 */ static void __bpf_tramp_image_put_rcu_tasks(struct rcu_head *rcu) { struct bpf_tramp_image *im; im = container_of(rcu, struct bpf_tramp_image, rcu); if (im->ip_after_call) /* the case of fmod_ret/fexit trampoline and CONFIG_PREEMPTION=y */ percpu_ref_kill(&im->pcref); else /* the case of fentry trampoline */ call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu); } static void bpf_tramp_image_put(struct bpf_tramp_image *im) { /* The trampoline image that calls original function is using: * rcu_read_lock_trace to protect sleepable bpf progs * rcu_read_lock to protect normal bpf progs * percpu_ref to protect trampoline itself * rcu tasks to protect trampoline asm not covered by percpu_ref * (which are few asm insns before __bpf_tramp_enter and * after __bpf_tramp_exit) * * The trampoline is unreachable before bpf_tramp_image_put(). * * First, patch the trampoline to avoid calling into fexit progs. * The progs will be freed even if the original function is still * executing or sleeping. * In case of CONFIG_PREEMPT=y use call_rcu_tasks() to wait on * first few asm instructions to execute and call into * __bpf_tramp_enter->percpu_ref_get. * Then use percpu_ref_kill to wait for the trampoline and the original * function to finish. * Then use call_rcu_tasks() to make sure few asm insns in * the trampoline epilogue are done as well. * * In !PREEMPT case the task that got interrupted in the first asm * insns won't go through an RCU quiescent state which the * percpu_ref_kill will be waiting for. Hence the first * call_rcu_tasks() is not necessary. */ if (im->ip_after_call) { int err = bpf_arch_text_poke(im->ip_after_call, BPF_MOD_JUMP, NULL, im->ip_epilogue); WARN_ON(err); if (IS_ENABLED(CONFIG_PREEMPTION)) call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu_tasks); else percpu_ref_kill(&im->pcref); return; } /* The trampoline without fexit and fmod_ret progs doesn't call original * function and doesn't use percpu_ref. * Use call_rcu_tasks_trace() to wait for sleepable progs to finish. * Then use call_rcu_tasks() to wait for the rest of trampoline asm * and normal progs. */ call_rcu_tasks_trace(&im->rcu, __bpf_tramp_image_put_rcu_tasks); } static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx) { struct bpf_tramp_image *im; struct bpf_ksym *ksym; void *image; int err = -ENOMEM; im = kzalloc(sizeof(*im), GFP_KERNEL); if (!im) goto out; err = bpf_jit_charge_modmem(1); if (err) goto out_free_im; err = -ENOMEM; im->image = image = bpf_jit_alloc_exec_page(); if (!image) goto out_uncharge; err = percpu_ref_init(&im->pcref, __bpf_tramp_image_release, 0, GFP_KERNEL); if (err) goto out_free_image; ksym = &im->ksym; INIT_LIST_HEAD_RCU(&ksym->lnode); snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu_%u", key, idx); bpf_image_ksym_add(image, ksym); return im; out_free_image: bpf_jit_free_exec(im->image); out_uncharge: bpf_jit_uncharge_modmem(1); out_free_im: kfree(im); out: return ERR_PTR(err); } static int bpf_trampoline_update(struct bpf_trampoline *tr) { struct bpf_tramp_image *im; struct bpf_tramp_progs *tprogs; u32 flags = BPF_TRAMP_F_RESTORE_REGS; int err, total; tprogs = bpf_trampoline_get_progs(tr, &total); if (IS_ERR(tprogs)) return PTR_ERR(tprogs); if (total == 0) { err = unregister_fentry(tr, tr->cur_image->image); bpf_tramp_image_put(tr->cur_image); tr->cur_image = NULL; tr->selector = 0; goto out; } im = bpf_tramp_image_alloc(tr->key, tr->selector); if (IS_ERR(im)) { err = PTR_ERR(im); goto out; } if (tprogs[BPF_TRAMP_FEXIT].nr_progs || tprogs[BPF_TRAMP_MODIFY_RETURN].nr_progs) flags = BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_SKIP_FRAME; err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE, &tr->func.model, flags, tprogs, tr->func.addr); if (err < 0) goto out; WARN_ON(tr->cur_image && tr->selector == 0); WARN_ON(!tr->cur_image && tr->selector); if (tr->cur_image) /* progs already running at this address */ err = modify_fentry(tr, tr->cur_image->image, im->image); else /* first time registering */ err = register_fentry(tr, im->image); if (err) goto out; if (tr->cur_image) bpf_tramp_image_put(tr->cur_image); tr->cur_image = im; tr->selector++; out: kfree(tprogs); return err; } static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog) { switch (prog->expected_attach_type) { case BPF_TRACE_FENTRY: return BPF_TRAMP_FENTRY; case BPF_MODIFY_RETURN: return BPF_TRAMP_MODIFY_RETURN; case BPF_TRACE_FEXIT: return BPF_TRAMP_FEXIT; case BPF_LSM_MAC: if (!prog->aux->attach_func_proto->type) /* The function returns void, we cannot modify its * return value. */ return BPF_TRAMP_FEXIT; else return BPF_TRAMP_MODIFY_RETURN; default: return BPF_TRAMP_REPLACE; } } int bpf_trampoline_link_prog(struct bpf_prog *prog, struct bpf_trampoline *tr) { enum bpf_tramp_prog_type kind; int err = 0; int cnt; kind = bpf_attach_type_to_tramp(prog); mutex_lock(&tr->mutex); if (tr->extension_prog) { /* cannot attach fentry/fexit if extension prog is attached. * cannot overwrite extension prog either. */ err = -EBUSY; goto out; } cnt = tr->progs_cnt[BPF_TRAMP_FENTRY] + tr->progs_cnt[BPF_TRAMP_FEXIT]; if (kind == BPF_TRAMP_REPLACE) { /* Cannot attach extension if fentry/fexit are in use. */ if (cnt) { err = -EBUSY; goto out; } tr->extension_prog = prog; err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, NULL, prog->bpf_func); goto out; } if (cnt >= BPF_MAX_TRAMP_PROGS) { err = -E2BIG; goto out; } if (!hlist_unhashed(&prog->aux->tramp_hlist)) { /* prog already linked */ err = -EBUSY; goto out; } hlist_add_head(&prog->aux->tramp_hlist, &tr->progs_hlist[kind]); tr->progs_cnt[kind]++; err = bpf_trampoline_update(tr); if (err) { hlist_del_init(&prog->aux->tramp_hlist); tr->progs_cnt[kind]--; } out: mutex_unlock(&tr->mutex); return err; } /* bpf_trampoline_unlink_prog() should never fail. */ int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr) { enum bpf_tramp_prog_type kind; int err; kind = bpf_attach_type_to_tramp(prog); mutex_lock(&tr->mutex); if (kind == BPF_TRAMP_REPLACE) { WARN_ON_ONCE(!tr->extension_prog); err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, tr->extension_prog->bpf_func, NULL); tr->extension_prog = NULL; goto out; } hlist_del_init(&prog->aux->tramp_hlist); tr->progs_cnt[kind]--; err = bpf_trampoline_update(tr); out: mutex_unlock(&tr->mutex); return err; } struct bpf_trampoline *bpf_trampoline_get(u64 key, struct bpf_attach_target_info *tgt_info) { struct bpf_trampoline *tr; tr = bpf_trampoline_lookup(key); if (!tr) return NULL; mutex_lock(&tr->mutex); if (tr->func.addr) goto out; memcpy(&tr->func.model, &tgt_info->fmodel, sizeof(tgt_info->fmodel)); tr->func.addr = (void *)tgt_info->tgt_addr; out: mutex_unlock(&tr->mutex); return tr; } void bpf_trampoline_put(struct bpf_trampoline *tr) { if (!tr)