diff options
author | David S. Miller <davem@davemloft.net> | 2021-03-26 01:31:22 +0300 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2021-03-26 01:31:22 +0300 |
commit | efd13b71a3fa31413f8d15342e01d44b60b0a432 (patch) | |
tree | 2ed1b299e25538c5a60485a1047507b49d3e0ecf /kernel/bpf | |
parent | 84c7f6c33f42a12eb036ebf0f0e3670799304120 (diff) | |
parent | 002322402dafd846c424ffa9240a937f49b48c42 (diff) | |
download | linux-efd13b71a3fa31413f8d15342e01d44b60b0a432.tar.xz |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf')
-rw-r--r-- | kernel/bpf/bpf_inode_storage.c | 2 | ||||
-rw-r--r-- | kernel/bpf/bpf_struct_ops.c | 2 | ||||
-rw-r--r-- | kernel/bpf/core.c | 4 | ||||
-rw-r--r-- | kernel/bpf/preload/bpf_preload_kern.c | 19 | ||||
-rw-r--r-- | kernel/bpf/syscall.c | 5 | ||||
-rw-r--r-- | kernel/bpf/trampoline.c | 218 | ||||
-rw-r--r-- | kernel/bpf/verifier.c | 37 |
7 files changed, 217 insertions, 70 deletions
diff --git a/kernel/bpf/bpf_inode_storage.c b/kernel/bpf/bpf_inode_storage.c index da753721457c..2921ca39a93e 100644 --- a/kernel/bpf/bpf_inode_storage.c +++ b/kernel/bpf/bpf_inode_storage.c @@ -109,7 +109,7 @@ static void *bpf_fd_inode_storage_lookup_elem(struct bpf_map *map, void *key) fd = *(int *)key; f = fget_raw(fd); if (!f) - return NULL; + return ERR_PTR(-EBADF); sdata = inode_storage_lookup(f->f_inode, map, true); fput(f); diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index 1a666a975416..70f6fd4fa305 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -430,7 +430,7 @@ static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, tprogs[BPF_TRAMP_FENTRY].progs[0] = prog; tprogs[BPF_TRAMP_FENTRY].nr_progs = 1; - err = arch_prepare_bpf_trampoline(image, + err = arch_prepare_bpf_trampoline(NULL, image, st_map->image + PAGE_SIZE, &st_ops->func_models[i], 0, tprogs, NULL); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 3a283bf97f2f..75244ecb2389 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -827,7 +827,7 @@ static int __init bpf_jit_charge_init(void) } pure_initcall(bpf_jit_charge_init); -static int bpf_jit_charge_modmem(u32 pages) +int bpf_jit_charge_modmem(u32 pages) { if (atomic_long_add_return(pages, &bpf_jit_current) > (bpf_jit_limit >> PAGE_SHIFT)) { @@ -840,7 +840,7 @@ static int bpf_jit_charge_modmem(u32 pages) return 0; } -static void bpf_jit_uncharge_modmem(u32 pages) +void bpf_jit_uncharge_modmem(u32 pages) { atomic_long_sub(pages, &bpf_jit_current); } diff --git a/kernel/bpf/preload/bpf_preload_kern.c b/kernel/bpf/preload/bpf_preload_kern.c index 79c5772465f1..53736e52c1df 100644 --- a/kernel/bpf/preload/bpf_preload_kern.c +++ b/kernel/bpf/preload/bpf_preload_kern.c @@ -60,9 +60,12 @@ static int finish(void) &magic, sizeof(magic), &pos); if (n != sizeof(magic)) return -EPIPE; + tgid = umd_ops.info.tgid; - wait_event(tgid->wait_pidfd, thread_group_exited(tgid)); - umd_ops.info.tgid = NULL; + if (tgid) { + wait_event(tgid->wait_pidfd, thread_group_exited(tgid)); + umd_cleanup_helper(&umd_ops.info); + } return 0; } @@ -80,10 +83,18 @@ static int __init load_umd(void) static void __exit fini_umd(void) { + struct pid *tgid; + bpf_preload_ops = NULL; + /* kill UMD in case it's still there due to earlier error */ - kill_pid(umd_ops.info.tgid, SIGKILL, 1); - umd_ops.info.tgid = NULL; + tgid = umd_ops.info.tgid; + if (tgid) { + kill_pid(tgid, SIGKILL, 1); + + wait_event(tgid->wait_pidfd, thread_group_exited(tgid)); + umd_cleanup_helper(&umd_ops.info); + } umd_unload_blob(&umd_ops.info); } late_initcall(load_umd); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index c859bc46d06c..250503482cda 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -854,6 +854,11 @@ static int map_create(union bpf_attr *attr) err = PTR_ERR(btf); goto free_map; } + if (btf_is_kernel(btf)) { + btf_put(btf); + err = -EACCES; + goto free_map; + } map->btf = btf; if (attr->btf_value_type_id) { diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 7bc3b3209224..1f3a4be4b175 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -57,19 +57,10 @@ void bpf_image_ksym_del(struct bpf_ksym *ksym) PAGE_SIZE, true, ksym->name); } -static void bpf_trampoline_ksym_add(struct bpf_trampoline *tr) -{ - struct bpf_ksym *ksym = &tr->ksym; - - snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu", tr->key); - bpf_image_ksym_add(tr->image, ksym); -} - static struct bpf_trampoline *bpf_trampoline_lookup(u64 key) { struct bpf_trampoline *tr; struct hlist_head *head; - void *image; int i; mutex_lock(&trampoline_mutex); @@ -84,14 +75,6 @@ static struct bpf_trampoline *bpf_trampoline_lookup(u64 key) if (!tr) goto out; - /* is_root was checked earlier. No need for bpf_jit_charge_modmem() */ - image = bpf_jit_alloc_exec_page(); - if (!image) { - kfree(tr); - tr = NULL; - goto out; - } - tr->key = key; INIT_HLIST_NODE(&tr->hlist); hlist_add_head(&tr->hlist, head); @@ -99,9 +82,6 @@ static struct bpf_trampoline *bpf_trampoline_lookup(u64 key) mutex_init(&tr->mutex); for (i = 0; i < BPF_TRAMP_MAX; i++) INIT_HLIST_HEAD(&tr->progs_hlist[i]); - tr->image = image; - INIT_LIST_HEAD_RCU(&tr->ksym.lnode); - bpf_trampoline_ksym_add(tr); out: mutex_unlock(&trampoline_mutex); return tr; @@ -185,10 +165,142 @@ bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total) 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) { - void *old_image = tr->image + ((tr->selector + 1) & 1) * PAGE_SIZE/2; - void *new_image = tr->image + (tr->selector & 1) * PAGE_SIZE/2; + struct bpf_tramp_image *im; struct bpf_tramp_progs *tprogs; u32 flags = BPF_TRAMP_F_RESTORE_REGS; int err, total; @@ -198,41 +310,42 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr) return PTR_ERR(tprogs); if (total == 0) { - err = unregister_fentry(tr, old_image); + 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; - /* Though the second half of trampoline page is unused a task could be - * preempted in the middle of the first half of trampoline and two - * updates to trampoline would change the code from underneath the - * preempted task. Hence wait for tasks to voluntarily schedule or go - * to userspace. - * The same trampoline can hold both sleepable and non-sleepable progs. - * synchronize_rcu_tasks_trace() is needed to make sure all sleepable - * programs finish executing. - * Wait for these two grace periods together. - */ - synchronize_rcu_mult(call_rcu_tasks, call_rcu_tasks_trace); - - err = arch_prepare_bpf_trampoline(new_image, new_image + PAGE_SIZE / 2, + 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; - if (tr->selector) + 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, old_image, new_image); + err = modify_fentry(tr, tr->cur_image->image, im->image); else /* first time registering */ - err = register_fentry(tr, new_image); + 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); @@ -364,17 +477,12 @@ void bpf_trampoline_put(struct bpf_trampoline *tr) goto out; if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[BPF_TRAMP_FEXIT]))) goto out; - bpf_image_ksym_del(&tr->ksym); - /* This code will be executed when all bpf progs (both sleepable and - * non-sleepable) went through - * bpf_prog_put()->call_rcu[_tasks_trace]()->bpf_prog_free_deferred(). - * Hence no need for another synchronize_rcu_tasks_trace() here, - * but synchronize_rcu_tasks() is still needed, since trampoline - * may not have had any sleepable programs and we need to wait - * for tasks to get out of trampoline code before freeing it. + /* This code will be executed even when the last bpf_tramp_image + * is alive. All progs are detached from the trampoline and the + * trampoline image is patched with jmp into epilogue to skip + * fexit progs. The fentry-only trampoline will be freed via + * multiple rcu callbacks. */ - synchronize_rcu_tasks(); - bpf_jit_free_exec(tr->image); hlist_del(&tr->hlist); kfree(tr); out: @@ -478,8 +586,18 @@ void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start) rcu_read_unlock_trace(); } +void notrace __bpf_tramp_enter(struct bpf_tramp_image *tr) +{ + percpu_ref_get(&tr->pcref); +} + +void notrace __bpf_tramp_exit(struct bpf_tramp_image *tr) +{ + percpu_ref_put(&tr->pcref); +} + int __weak -arch_prepare_bpf_trampoline(void *image, void *image_end, +arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *image_end, const struct btf_func_model *m, u32 flags, struct bpf_tramp_progs *tprogs, void *orig_call) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f9096b049cd6..999bf36ffeb1 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6045,10 +6045,14 @@ static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, { bool mask_to_left = (opcode == BPF_ADD && off_is_neg) || (opcode == BPF_SUB && !off_is_neg); - u32 off; + u32 off, max; switch (ptr_reg->type) { case PTR_TO_STACK: + /* Offset 0 is out-of-bounds, but acceptable start for the + * left direction, see BPF_REG_FP. + */ + max = MAX_BPF_STACK + mask_to_left; /* Indirect variable offset stack access is prohibited in * unprivileged mode so it's not handled here. */ @@ -6056,8 +6060,8 @@ static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, if (mask_to_left) *ptr_limit = MAX_BPF_STACK + off; else - *ptr_limit = -off; - return 0; + *ptr_limit = -off - 1; + return *ptr_limit >= max ? -ERANGE : 0; case PTR_TO_MAP_KEY: /* Currently, this code is not exercised as the only use * is bpf_for_each_map_elem() helper which requires @@ -6072,13 +6076,14 @@ static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, } return 0; case PTR_TO_MAP_VALUE: + max = ptr_reg->map_ptr->value_size; if (mask_to_left) { *ptr_limit = ptr_reg->umax_value + ptr_reg->off; } else { off = ptr_reg->smin_value + ptr_reg->off; - *ptr_limit = ptr_reg->map_ptr->value_size - off; + *ptr_limit = ptr_reg->map_ptr->value_size - off - 1; } - return 0; + return *ptr_limit >= max ? -ERANGE : 0; default: return -EINVAL; } @@ -6131,6 +6136,7 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env, u32 alu_state, alu_limit; struct bpf_reg_state tmp; bool ret; + int err; if (can_skip_alu_sanitation(env, insn)) return 0; @@ -6146,10 +6152,13 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env, alu_state |= ptr_is_dst_reg ? BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST; - if (retrieve_ptr_limit(ptr_reg, &alu_limit, opcode, off_is_neg)) - return 0; - if (update_alu_sanitation_state(aux, alu_state, alu_limit)) - return -EACCES; + err = retrieve_ptr_limit(ptr_reg, &alu_limit, opcode, off_is_neg); + if (err < 0) + return err; + + err = update_alu_sanitation_state(aux, alu_state, alu_limit); + if (err < 0) + return err; do_sim: /* Simulate and find potential out-of-bounds access under * speculative execution from truncation as a result of @@ -6301,7 +6310,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, case BPF_ADD: ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0); if (ret < 0) { - verbose(env, "R%d tried to add from different maps or paths\n", dst); + verbose(env, "R%d tried to add from different maps, paths, or prohibited types\n", dst); return ret; } /* We can take a fixed offset as long as it doesn't overflow @@ -6356,7 +6365,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, case BPF_SUB: ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0); if (ret < 0) { - verbose(env, "R%d tried to sub from different maps or paths\n", dst); + verbose(env, "R%d tried to sub from different maps, paths, or prohibited types\n", dst); return ret; } if (dst_reg == off_reg) { @@ -9276,6 +9285,10 @@ static int check_btf_info(struct bpf_verifier_env *env, btf = btf_get_by_fd(attr->prog_btf_fd); if (IS_ERR(btf)) return PTR_ERR(btf); + if (btf_is_kernel(btf)) { + btf_put(btf); + return -EACCES; + } env->prog->aux->btf = btf; err = check_btf_func(env, attr, uattr); @@ -11916,7 +11929,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env) off_reg = issrc ? insn->src_reg : insn->dst_reg; if (isneg) *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1); - *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit - 1); + *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit); *patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg); *patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg); *patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0); |