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[2620:137:e000::1:20]) by mx.google.com with ESMTP id a4-20020a17090680c400b0078e06df0d29si13396051ejx.705.2022.10.20.15.37.10; Thu, 20 Oct 2022 15:37:34 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229919AbiJTWYi (ORCPT + 99 others); Thu, 20 Oct 2022 18:24:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42754 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229834AbiJTWYe (ORCPT ); Thu, 20 Oct 2022 18:24:34 -0400 Received: from mail-qv1-f50.google.com (mail-qv1-f50.google.com [209.85.219.50]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4D7413FA0; Thu, 20 Oct 2022 15:24:30 -0700 (PDT) Received: by mail-qv1-f50.google.com with SMTP id y10so647733qvo.11; Thu, 20 Oct 2022 15:24:30 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=MsC6/XBmm3wKyT5T4NGf7K2mMWvAtqX37cD6zeDYKck=; b=fs5cWDjFErlEG6dGu7Xrz0lwWHSUeFeO3YDmR3uDj8iX/cZJa3K7HUVYjsngfAaxgs W0/K8Qn4qqZOrJzn6nGrURBd0knmwmhTvHyZVcTuFeKKwu/i/Vxog7Qq5g42OZbykbTa xa3Py25WPv7veDXVeKHdigChlS5Y3MaqZwejW1FSaSaXyEpiszx+8fox0Rc+GvmCHEM7 P1jiW+U+NEE+58GgTQM7PG01SCgCb6jZJyX2/wYOPKE5yltxSRchC/G04TWzZBmJzzFa ursYQAVlsWU6z1RoyAiAZV7E0227lMbNRg+p67IUvKyqLAYtZKpfsDbUz6okbU9MKKHL pSSg== X-Gm-Message-State: ACrzQf2Og1nL+xTepvp7fKL12gvSSDypypWShqOKTjit5IAzH3mhuLks YaUDrdY0hmq+zubn5orNLZ/UDRrhdVzpmQ== X-Received: by 2002:a0c:dd89:0:b0:4ba:f06d:6fda with SMTP id v9-20020a0cdd89000000b004baf06d6fdamr65415qvk.51.1666304669258; Thu, 20 Oct 2022 15:24:29 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::80b7]) by smtp.gmail.com with ESMTPSA id dt27-20020a05620a479b00b006b9c9b7db8bsm8524990qkb.82.2022.10.20.15.24.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Oct 2022 15:24:28 -0700 (PDT) From: David Vernet To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, tj@kernel.org, memxor@gmail.com Subject: [PATCH bpf-next v6 1/3] bpf: Allow trusted pointers to be passed to KF_TRUSTED_ARGS kfuncs Date: Thu, 20 Oct 2022 17:24:14 -0500 Message-Id: <20221020222416.3415511-2-void@manifault.com> X-Mailer: git-send-email 2.38.0 In-Reply-To: <20221020222416.3415511-1-void@manifault.com> References: <20221020222416.3415511-1-void@manifault.com> MIME-Version: 1.0 X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1747247908727229679?= X-GMAIL-MSGID: =?utf-8?q?1747247908727229679?= Kfuncs currently support specifying the KF_TRUSTED_ARGS flag to signal to the verifier that it should enforce that a BPF program passes it a "safe", trusted pointer. Currently, "safe" means that the pointer is either PTR_TO_CTX, or is refcounted. There may be cases, however, where the kernel passes a BPF program a safe / trusted pointer to an object that the BPF program wishes to use as a kptr, but because the object does not yet have a ref_obj_id from the perspective of the verifier, the program would be unable to pass it to a KF_ACQUIRE | KF_TRUSTED_ARGS kfunc. The solution is to expand the set of pointers that are considered trusted according to KF_TRUSTED_ARGS, so that programs can invoke kfuncs with these pointers without getting rejected by the verifier. There is already a PTR_UNTRUSTED flag that is set in some scenarios, such as when a BPF program reads a kptr directly from a map without performing a bpf_kptr_xchg() call. These pointers of course can and should be rejected by the verifier. Unfortunately, however, PTR_UNTRUSTED does not cover all the cases for safety that need to be addressed to adequately protect kfuncs. Specifically, pointers obtained by a BPF program "walking" a struct are _not_ considered PTR_UNTRUSTED according to BPF. For example, say that we were to add a kfunc called bpf_task_acquire(), with KF_ACQUIRE | KF_TRUSTED_ARGS, to acquire a struct task_struct *. If we only used PTR_UNTRUSTED to signal that a task was unsafe to pass to a kfunc, the verifier would mistakenly allow the following unsafe BPF program to be loaded: SEC("tp_btf/task_newtask") int BPF_PROG(unsafe_acquire_task, struct task_struct *task, u64 clone_flags) { struct task_struct *acquired, *nested; nested = task->last_wakee; /* Would not be rejected by the verifier. */ acquired = bpf_task_acquire(nested); if (!acquired) return 0; bpf_task_release(acquired); return 0; } To address this, this patch defines a new type flag called PTR_WALKED which tracks whether a PTR_TO_BTF_ID pointer was retrieved from walking a struct. A pointer passed directly from the kernel begins with (PTR_WALKED & type) == 0, meaning of course that it is not obtained from walking another struct. Any pointer received from walking that object, however, would inherit that flag and become a walked pointer. Additionally, because some kfuncs still only want BPF programs to be able to send them an arg that they "own" (i.e. which they own a refcount on) another kfunc arg flag called KF_OWNED_ARGS is added which is identical to KF_TRUSTED_ARGS, but imposes the stricter requirement that the arg must also have a refcount. A subsequent patch will add kfuncs for storing a task kfunc as a kptr, and then another patch will validate this feature by ensuring that the verifier rejects a kfunc invocation with a nested pointer. Signed-off-by: David Vernet --- Documentation/bpf/kfuncs.rst | 50 ++++++++++---- include/linux/bpf.h | 6 ++ include/linux/btf.h | 57 ++++++++++++++-- kernel/bpf/btf.c | 18 ++++- kernel/bpf/verifier.c | 66 ++++++++++++++----- net/bpf/test_run.c | 2 +- net/netfilter/nf_conntrack_bpf.c | 8 +-- net/netfilter/nf_nat_bpf.c | 2 +- .../selftests/bpf/prog_tests/map_kptr.c | 2 +- tools/testing/selftests/bpf/verifier/calls.c | 4 +- .../testing/selftests/bpf/verifier/map_kptr.c | 2 +- 11 files changed, 169 insertions(+), 48 deletions(-) diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst index 0f858156371d..8e2825150a8d 100644 --- a/Documentation/bpf/kfuncs.rst +++ b/Documentation/bpf/kfuncs.rst @@ -137,30 +137,54 @@ KF_ACQUIRE and KF_RET_NULL flags. -------------------------- The KF_TRUSTED_ARGS flag is used for kfuncs taking pointer arguments. It -indicates that the all pointer arguments will always have a guaranteed lifetime, -and pointers to kernel objects are always passed to helpers in their unmodified -form (as obtained from acquire kfuncs). +indicates that the all pointer arguments will always have a guaranteed +lifetime, and pointers to kernel objects are always passed to helpers in their +unmodified form (either as passed by the main kernel, or as obtained from +acquire kfuncs). -It can be used to enforce that a pointer to a refcounted object acquired from a -kfunc or BPF helper is passed as an argument to this kfunc without any -modifications (e.g. pointer arithmetic) such that it is trusted and points to -the original object. +It can be used to enforce that a safe pointer passed to the program by the +kernel, or a refcounted object acquired from a kfunc or BPF helper, is passed +as an argument to this kfunc without any modifications (e.g. pointer +arithmetic) such that it is trusted and points to the original object. Meanwhile, it is also allowed pass pointers to normal memory to such kfuncs, but those can have a non-zero offset. -This flag is often used for kfuncs that operate (change some property, perform -some operation) on an object that was obtained using an acquire kfunc. Such -kfuncs need an unchanged pointer to ensure the integrity of the operation being -performed on the expected object. +This flag is often used for kfuncs that receive a trusted pointer from the +kernel, and which do not require a reference to be held by the program. For +example, if there's a kernel object that was allocated by the main kernel, and +which the BPF program wishes to store in a map as a kptr, KF_TRUSTED_ARGS can +be used to ensure that the pointer is actually a trusted kernel pointer before +a reference is acquired on it in a KF_ACQUIRE kfunc. + +2.4.6 KF_OWNED_ARGS flag +------------------------ + +The KF_OWNED_ARGS flag is identical to the KF_TRUSTED_ARGS flag, though it is +more restrictive in that it also requires the BPF program to hold a reference +on the object. -2.4.6 KF_SLEEPABLE flag +In other words, it can be used to enforce that a pointer to a refcounted object +acquired from a kfunc or BPF helper is passed as an argument to this kfunc +without any modifications (e.g. pointer arithmetic) such that it is trusted and +points to the original object that was allocated or owned by the BPF program. + +This flag is often used for kfuncs that operate (change some property, perform +some operation) on an object that was obtained using an acquire kfunc. For +example, if an acquire kfunc allocates an object on behalf of a program, +KF_OWNED_ARGS would be an appropriate flag to specify for other kfuncs which +allow the program to mutate that object. KF_TRUSTED_ARGS, on the other hand, +would likely not be sufficiently restrictive as the kfunc does not want to +allow the BPF program to mutate another instance of the same object type which +was allocated by the main kernel. + +2.4.7 KF_SLEEPABLE flag ----------------------- The KF_SLEEPABLE flag is used for kfuncs that may sleep. Such kfuncs can only be called by sleepable BPF programs (BPF_F_SLEEPABLE). -2.4.7 KF_DESTRUCTIVE flag +2.4.8 KF_DESTRUCTIVE flag -------------------------- The KF_DESTRUCTIVE flag is used to indicate functions calling which is diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 9e7d46d16032..ccdbefd72a95 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -457,6 +457,12 @@ enum bpf_type_flag { /* Size is known at compile time. */ MEM_FIXED_SIZE = BIT(10 + BPF_BASE_TYPE_BITS), + /* PTR was obtained from walking a struct. This is used with + * PTR_TO_BTF_ID to determine whether the pointer is safe to pass to a + * kfunc with KF_TRUSTED_ARGS. + */ + PTR_WALKED = BIT(11 + BPF_BASE_TYPE_BITS), + __BPF_TYPE_FLAG_MAX, __BPF_TYPE_LAST_FLAG = __BPF_TYPE_FLAG_MAX - 1, }; diff --git a/include/linux/btf.h b/include/linux/btf.h index f9aababc5d78..7f5a438196a2 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -17,9 +17,48 @@ #define KF_RELEASE (1 << 1) /* kfunc is a release function */ #define KF_RET_NULL (1 << 2) /* kfunc returns a pointer that may be NULL */ #define KF_KPTR_GET (1 << 3) /* kfunc returns reference to a kptr */ -/* Trusted arguments are those which are meant to be referenced arguments with - * unchanged offset. It is used to enforce that pointers obtained from acquire - * kfuncs remain unmodified when being passed to helpers taking trusted args. +/* Trusted arguments are those which are meant to be guaranteed valid + * arguments, with an unchanged offset. It is used to enforce that pointers + * obtained from either acquire kfuncs or the main kernel remain unmodified + * when being passed to helpers taking trusted args. + * + * Consider, for example, the following task tracepoint: + * + * SEC("tp_btf/task_newtask") + * int BPF_PROG(new_task_tp, struct task_struct *task, u64 clone_flags) + * { + * ... + * } + * + * And the following kfunc: + * + * BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_RET_NULL | KF_TRUSTED_ARGS) + * + * All invocations to the kfunc must pass the unmodified, unwalked task: + * + * bpf_task_acquire(task); // Allowed + * bpf_task_acquire(task->last_wakee); // Rejected, walked task + * + * Users may also pass referenced tasks directly to the kfunc: + * + * struct task_struct *acquired; + * + * acquired = bpf_task_acquire(task); // Allowed, same as above + * bpf_task_acquire(acquired); // Allowed + * bpf_task_acquire(task); // Allowed + * bpf_task_acquire(acquired->last_wakee); // Rejected, walked task + * + * If users wish to only allow referenced objects to be passed to a kfunc, they + * may instead specify the KF_OWNED_ARGS flag. + */ +#define KF_TRUSTED_ARGS (1 << 4) /* kfunc only takes trusted pointer arguments */ +#define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ +#define KF_DESTRUCTIVE (1 << 6) /* kfunc performs destructive actions */ +/* Owned arguments are similar to trusted arguments, but are even more + * restrictive. Owned arguments are arguments which are "owned" by the BPF + * program, meaning it has acquired a reference to the object via an acquire + * kfunc. Just as with trusted arguments, the verifier enforces that owned + * arguments have an unchanged offset when they're passed to kfuncs. * * Consider * struct foo { @@ -36,7 +75,7 @@ * struct bar *b = alloc_bar(); // Acquire kfunc * * If a kfunc set_foo_data() wants to operate only on the allocated object, it - * will set the KF_TRUSTED_ARGS flag, which will prevent unsafe usage like: + * will set the KR_ARGS_OWNED flag, which will prevent unsafe usage like: * * set_foo_data(f, 42); // Allowed * set_foo_data(f->next, 42); // Rejected, non-referenced pointer @@ -47,10 +86,14 @@ * by looking at the type of the member at the offset, but due to the * requirement of trusted argument, this deduction will be strict and not done * for this case. + * + * Note as well that if tracepoints existed which took a struct foo *f argument + * that was passed from the kernel, the verifier would also reject + * set_foo_bar(f, 42) on it, as the BPF program had not acquired a reference on + * it. If the kfunc had instead specified KF_TRUSTED_ARGS, this would be + * permitted. */ -#define KF_TRUSTED_ARGS (1 << 4) /* kfunc only takes trusted pointer arguments */ -#define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ -#define KF_DESTRUCTIVE (1 << 6) /* kfunc performs destructive actions */ +#define KF_OWNED_ARGS (1 << 7) /* kfunc performs destructive actions */ /* * Return the name of the passed struct, if exists, or halt the build if for diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index eba603cec2c5..a3712abae108 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6227,7 +6227,7 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, bool processing_call) { enum bpf_prog_type prog_type = resolve_prog_type(env->prog); - bool rel = false, kptr_get = false, trusted_args = false; + bool rel = false, kptr_get = false, trusted_args = false, owned_args = false; bool sleepable = false; struct bpf_verifier_log *log = &env->log; u32 i, nargs, ref_id, ref_obj_id = 0; @@ -6265,7 +6265,8 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, /* Only kfunc can be release func */ rel = kfunc_meta->flags & KF_RELEASE; kptr_get = kfunc_meta->flags & KF_KPTR_GET; - trusted_args = kfunc_meta->flags & KF_TRUSTED_ARGS; + owned_args = kfunc_meta->flags & KF_OWNED_ARGS; + trusted_args = owned_args || (kfunc_meta->flags & KF_TRUSTED_ARGS); sleepable = kfunc_meta->flags & KF_SLEEPABLE; } @@ -6333,8 +6334,19 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, /* Check if argument must be a referenced pointer, args + i has * been verified to be a pointer (after skipping modifiers). * PTR_TO_CTX is ok without having non-zero ref_obj_id. + * + * All object pointers must be refcounted, other than: + * - PTR_TO_CTX + * - Trusted pointers (i.e. pointers with no type modifiers). + * Kfuncs that have specified KF_OWNED_ARGS require + * references even if a pointer is otherwise trusted. */ - if (is_kfunc && trusted_args && (obj_ptr && reg->type != PTR_TO_CTX) && !reg->ref_obj_id) { + if (is_kfunc && + trusted_args && + obj_ptr && + base_type(reg->type) != PTR_TO_CTX && + (owned_args || type_flag(reg->type)) && + !reg->ref_obj_id) { bpf_log(log, "R%d must be referenced\n", regno); return -EINVAL; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6f6d2d511c06..7b8b20feeb62 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -541,7 +541,7 @@ static bool is_cmpxchg_insn(const struct bpf_insn *insn) static const char *reg_type_str(struct bpf_verifier_env *env, enum bpf_reg_type type) { - char postfix[16] = {0}, prefix[32] = {0}; + char postfix[16] = {0}, prefix[64] = {0}; static const char * const str[] = { [NOT_INIT] = "?", [SCALAR_VALUE] = "scalar", @@ -573,16 +573,14 @@ static const char *reg_type_str(struct bpf_verifier_env *env, strncpy(postfix, "_or_null", 16); } - if (type & MEM_RDONLY) - strncpy(prefix, "rdonly_", 32); - if (type & MEM_ALLOC) - strncpy(prefix, "alloc_", 32); - if (type & MEM_USER) - strncpy(prefix, "user_", 32); - if (type & MEM_PERCPU) - strncpy(prefix, "percpu_", 32); - if (type & PTR_UNTRUSTED) - strncpy(prefix, "untrusted_", 32); + snprintf(prefix, sizeof(prefix), "%s%s%s%s%s%s", + type & MEM_RDONLY ? "rdonly_" : "", + type & MEM_ALLOC ? "alloc_" : "", + type & MEM_USER ? "user_" : "", + type & MEM_PERCPU ? "percpu_" : "", + type & PTR_UNTRUSTED ? "untrusted_" : "", + type & PTR_WALKED ? "walked_" : "" + ); snprintf(env->type_str_buf, TYPE_STR_BUF_LEN, "%s%s%s", prefix, str[base_type(type)], postfix); @@ -4558,6 +4556,9 @@ static int check_ptr_to_btf_access(struct bpf_verifier_env *env, if (type_flag(reg->type) & PTR_UNTRUSTED) flag |= PTR_UNTRUSTED; + /* Mark this and any future pointers as having been obtained from walking a struct. */ + flag |= PTR_WALKED; + if (atype == BPF_READ && value_regno >= 0) mark_btf_ld_reg(env, regs, value_regno, ret, reg->btf, btf_id, flag); @@ -5661,6 +5662,7 @@ static const struct bpf_reg_types btf_id_sock_common_types = { PTR_TO_TCP_SOCK, PTR_TO_XDP_SOCK, PTR_TO_BTF_ID, + PTR_TO_BTF_ID | PTR_WALKED, }, .btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON], }; @@ -5694,9 +5696,19 @@ static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } }; static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } }; static const struct bpf_reg_types alloc_mem_types = { .types = { PTR_TO_MEM | MEM_ALLOC } }; static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } }; -static const struct bpf_reg_types btf_ptr_types = { .types = { PTR_TO_BTF_ID } }; +static const struct bpf_reg_types btf_ptr_types = { + .types = { + PTR_TO_BTF_ID, + PTR_TO_BTF_ID | PTR_WALKED + }, +}; static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE } }; -static const struct bpf_reg_types percpu_btf_ptr_types = { .types = { PTR_TO_BTF_ID | MEM_PERCPU } }; +static const struct bpf_reg_types percpu_btf_ptr_types = { + .types = { + PTR_TO_BTF_ID | MEM_PERCPU, + PTR_TO_BTF_ID | MEM_PERCPU | PTR_WALKED, + } +}; static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } }; static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } }; static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } }; @@ -5860,6 +5872,7 @@ int check_func_arg_reg_off(struct bpf_verifier_env *env, * fixed offset. */ case PTR_TO_BTF_ID: + case PTR_TO_BTF_ID | PTR_WALKED: /* When referenced PTR_TO_BTF_ID is passed to release function, * it's fixed offset must be 0. In the other cases, fixed offset * can be non-zero. @@ -12136,8 +12149,30 @@ static bool reg_type_mismatch_ok(enum bpf_reg_type type) */ static bool reg_type_mismatch(enum bpf_reg_type src, enum bpf_reg_type prev) { - return src != prev && (!reg_type_mismatch_ok(src) || - !reg_type_mismatch_ok(prev)); + /* Compare only the base types of the registers, to avoid confusing the + * verifier with the following type of code: + * + * struct fib6_nh *fib6_nh; + * struct nexthop *nh; + * + * fib6_nh = &rt->fib6_nh[0]; + * + * nh = rt->nh; + * if (nh) + * fib6_nh = &nh->nh_info->fib6_nh; + * + * If we did not compare base types, the verifier would reject this + * because the register in the former branch will have PTR_TO_BTF_ID, + * whereas the latter branch will have PTR_TO_BTF_ID | PTR_WALKED. + * + * The safety of the memory access is validated in check_mem_access() + * before this function is called. The intention here is rather to + * prevent a program from doing something like using PTR_TO_BTF_ID in + * one path, and PTR_TO_CTX in another, as it would cause the + * convert_ctx_access() handling to be incorrect. + */ + return base_type(src) != base_type(prev) && + (!reg_type_mismatch_ok(src) || !reg_type_mismatch_ok(prev)); } static int do_check(struct bpf_verifier_env *env) @@ -13499,6 +13534,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) break; case PTR_TO_BTF_ID: case PTR_TO_BTF_ID | PTR_UNTRUSTED: + case PTR_TO_BTF_ID | PTR_WALKED: if (type == BPF_READ) { insn->code = BPF_LDX | BPF_PROBE_MEM | BPF_SIZE((insn)->code); diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 13d578ce2a09..a298bef13e12 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -758,7 +758,7 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_test_fail3) BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_pass1) BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail1) BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail2) -BTF_ID_FLAGS(func, bpf_kfunc_call_test_ref, KF_TRUSTED_ARGS) +BTF_ID_FLAGS(func, bpf_kfunc_call_test_ref, KF_OWNED_ARGS) BTF_ID_FLAGS(func, bpf_kfunc_call_test_destructive, KF_DESTRUCTIVE) BTF_SET8_END(test_sk_check_kfunc_ids) diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c index 8639e7efd0e2..ef937f4b4fe4 100644 --- a/net/netfilter/nf_conntrack_bpf.c +++ b/net/netfilter/nf_conntrack_bpf.c @@ -479,10 +479,10 @@ BTF_ID_FLAGS(func, bpf_skb_ct_alloc, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_skb_ct_lookup, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_ct_insert_entry, KF_ACQUIRE | KF_RET_NULL | KF_RELEASE) BTF_ID_FLAGS(func, bpf_ct_release, KF_RELEASE) -BTF_ID_FLAGS(func, bpf_ct_set_timeout, KF_TRUSTED_ARGS) -BTF_ID_FLAGS(func, bpf_ct_change_timeout, KF_TRUSTED_ARGS) -BTF_ID_FLAGS(func, bpf_ct_set_status, KF_TRUSTED_ARGS) -BTF_ID_FLAGS(func, bpf_ct_change_status, KF_TRUSTED_ARGS) +BTF_ID_FLAGS(func, bpf_ct_set_timeout, KF_OWNED_ARGS) +BTF_ID_FLAGS(func, bpf_ct_change_timeout, KF_OWNED_ARGS) +BTF_ID_FLAGS(func, bpf_ct_set_status, KF_OWNED_ARGS) +BTF_ID_FLAGS(func, bpf_ct_change_status, KF_OWNED_ARGS) BTF_SET8_END(nf_ct_kfunc_set) static const struct btf_kfunc_id_set nf_conntrack_kfunc_set = { diff --git a/net/netfilter/nf_nat_bpf.c b/net/netfilter/nf_nat_bpf.c index 0fa5a0bbb0ff..69d6668756c4 100644 --- a/net/netfilter/nf_nat_bpf.c +++ b/net/netfilter/nf_nat_bpf.c @@ -57,7 +57,7 @@ int bpf_ct_set_nat_info(struct nf_conn___init *nfct, __diag_pop() BTF_SET8_START(nf_nat_kfunc_set) -BTF_ID_FLAGS(func, bpf_ct_set_nat_info, KF_TRUSTED_ARGS) +BTF_ID_FLAGS(func, bpf_ct_set_nat_info, KF_OWNED_ARGS) BTF_SET8_END(nf_nat_kfunc_set) static const struct btf_kfunc_id_set nf_bpf_nat_kfunc_set = { diff --git a/tools/testing/selftests/bpf/prog_tests/map_kptr.c b/tools/testing/selftests/bpf/prog_tests/map_kptr.c index 0d66b1524208..1070ce936d32 100644 --- a/tools/testing/selftests/bpf/prog_tests/map_kptr.c +++ b/tools/testing/selftests/bpf/prog_tests/map_kptr.c @@ -20,7 +20,7 @@ struct { { "reject_bad_type_match", "invalid kptr access, R1 type=untrusted_ptr_prog_test_ref_kfunc" }, { "marked_as_untrusted_or_null", "R1 type=untrusted_ptr_or_null_ expected=percpu_ptr_" }, { "correct_btf_id_check_size", "access beyond struct prog_test_ref_kfunc at off 32 size 4" }, - { "inherit_untrusted_on_walk", "R1 type=untrusted_ptr_ expected=percpu_ptr_" }, + { "inherit_untrusted_on_walk", "R1 type=untrusted_walked_ptr_ expected=percpu_ptr_" }, { "reject_kptr_xchg_on_unref", "off=8 kptr isn't referenced kptr" }, { "reject_kptr_get_no_map_val", "arg#0 expected pointer to map value" }, { "reject_kptr_get_no_null_map_val", "arg#0 expected pointer to map value" }, diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c index e1a937277b54..3327b3e75ce8 100644 --- a/tools/testing/selftests/bpf/verifier/calls.c +++ b/tools/testing/selftests/bpf/verifier/calls.c @@ -181,7 +181,7 @@ }, .result_unpriv = REJECT, .result = REJECT, - .errstr = "negative offset ptr_ ptr R1 off=-4 disallowed", + .errstr = "negative offset walked_ptr_ ptr R1 off=-4 disallowed", }, { "calls: invalid kfunc call: PTR_TO_BTF_ID with variable offset", @@ -243,7 +243,7 @@ }, .result_unpriv = REJECT, .result = REJECT, - .errstr = "R1 must be referenced", + .errstr = "arg#0 pointer type STRUCT prog_test_ref_kfunc must point to scalar", }, { "calls: valid kfunc call: referenced arg needs refcounted PTR_TO_BTF_ID", diff --git a/tools/testing/selftests/bpf/verifier/map_kptr.c b/tools/testing/selftests/bpf/verifier/map_kptr.c index 6914904344c0..003bae55d79e 100644 --- a/tools/testing/selftests/bpf/verifier/map_kptr.c +++ b/tools/testing/selftests/bpf/verifier/map_kptr.c @@ -242,7 +242,7 @@ .prog_type = BPF_PROG_TYPE_SCHED_CLS, .fixup_map_kptr = { 1 }, .result = REJECT, - 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The possible use cases for doing this are plentiful. During tracing, for example, it would be useful to be able to collect some tasks that performed a certain operation, and then periodically summarize who they are, which cgroup they're in, how much CPU time they've utilized, etc. In order to enable this, this patch adds three new kfuncs: struct task_struct *bpf_task_acquire(struct task_struct *p); struct task_struct *bpf_task_kptr_get(struct task_struct **pp); void bpf_task_release(struct task_struct *p); A follow-on patch will add selftests validating these kfuncs. Signed-off-by: David Vernet --- kernel/bpf/helpers.c | 86 +++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 81 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index a6b04faed282..bf2b1679aea8 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1700,20 +1700,96 @@ bpf_base_func_proto(enum bpf_func_id func_id) } } -BTF_SET8_START(tracing_btf_ids) +__diag_push(); +__diag_ignore_all("-Wmissing-prototypes", + "Global functions as their definitions will be in vmlinux BTF"); + +/** + * bpf_task_acquire - Acquire a reference to a task. A task acquired by this + * kfunc which is not stored in a map as a kptr, must be released by calling + * bpf_task_release(). + * @p: The task on which a reference is being acquired. + */ +__used noinline +struct task_struct *bpf_task_acquire(struct task_struct *p) +{ + if (!p) + return NULL; + + refcount_inc(&p->rcu_users); + return p; +} + +/** + * bpf_task_kptr_get - Acquire a reference on a struct task_struct kptr. A task + * kptr acquired by this kfunc which is not subsequently stored in a map, must + * be released by calling bpf_task_release(). + * @pp: A pointer to a task kptr on which a reference is being acquired. + */ +__used noinline +struct task_struct *bpf_task_kptr_get(struct task_struct **pp) +{ + struct task_struct *p; + + rcu_read_lock(); + p = READ_ONCE(*pp); + if (p && !refcount_inc_not_zero(&p->rcu_users)) + p = NULL; + rcu_read_unlock(); + + return p; +} + +/** + * bpf_task_release - Release the reference acquired on a struct task_struct *. + * If this kfunc is invoked in an RCU read region, the task_struct is + * guaranteed to not be freed until the current grace period has ended, even if + * its refcount drops to 0. + * @p: The task on which a reference is being released. + */ +__used noinline void bpf_task_release(struct task_struct *p) +{ + if (!p) + return; + + put_task_struct_rcu_user(p); +} + +__diag_pop(); + +BTF_SET8_START(generic_kfunc_btf_ids) #ifdef CONFIG_KEXEC_CORE BTF_ID_FLAGS(func, crash_kexec, KF_DESTRUCTIVE) #endif -BTF_SET8_END(tracing_btf_ids) +BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS | KF_RET_NULL) +BTF_ID_FLAGS(func, bpf_task_kptr_get, KF_ACQUIRE | KF_KPTR_GET | KF_RET_NULL) +BTF_ID_FLAGS(func, bpf_task_release, KF_RELEASE) +BTF_SET8_END(generic_kfunc_btf_ids) -static const struct btf_kfunc_id_set tracing_kfunc_set = { +static const struct btf_kfunc_id_set generic_kfunc_set = { .owner = THIS_MODULE, - .set = &tracing_btf_ids, + .set = &generic_kfunc_btf_ids, }; +BTF_ID_LIST(generic_kfunc_dtor_ids) +BTF_ID(struct, task_struct) +BTF_ID(func, bpf_task_release) + static int __init kfunc_init(void) { - return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &tracing_kfunc_set); + int ret; + const struct btf_id_dtor_kfunc generic_kfunc_dtors[] = { + { + .btf_id = generic_kfunc_dtor_ids[0], + .kfunc_btf_id = generic_kfunc_dtor_ids[1] + }, + }; + + ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &generic_kfunc_set); + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &generic_kfunc_set); + return ret ?: register_btf_id_dtor_kfuncs(generic_kfunc_dtors, + ARRAY_SIZE(generic_kfunc_dtors), + THIS_MODULE); } late_initcall(kfunc_init); From patchwork Thu Oct 20 22:24:16 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Vernet X-Patchwork-Id: 6438 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:4242:0:0:0:0:0 with SMTP id s2csp353247wrr; Thu, 20 Oct 2022 15:38:15 -0700 (PDT) X-Google-Smtp-Source: AMsMyM6ae7SmEwE1qKppXyueQxWucGsUys8RzpA70hRJ+xeCo3LSd+WblEhaohI0lX47t7B0PpIS X-Received: by 2002:a17:907:74a:b0:77e:9455:b4e3 with SMTP id xc10-20020a170907074a00b0077e9455b4e3mr13082342ejb.471.1666305495657; Thu, 20 Oct 2022 15:38:15 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1666305495; cv=none; d=google.com; s=arc-20160816; b=n25KCW4INtu0o6/eSPpnbvE1assZZ7SYQDYDQZnsthmObz4mZSPiPwFPMIj0BmBBzy 8CipXHhIS7ER5URhfwdoLNiBXfl3Yd22r8LY148Vuu8NHaUZVyG4FB44JX70W5p73bXY KziRYySmt43FZeWGgE0aH8HTEI714Hwu2OOsYRq3w1gCL/rSzxl2Zo0q7Gj66LiBsOaJ rUGW7301GueEfH357N/ryLhhY/dgc0/n+OmRxvJ+fq+ZrDHphDJQ1SD9JwuWH/YIuZfC d/uiJdrISCIXt5TUdaoAZbBr+OR3ZMjBoJu83i5lfkdZsj9h/RwKdXBWo0TD5bTszwKF hXuw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from; bh=9aZ+OmfC3WqmwDr6Z61AifhCCaQltrdfxVaW4RspNfI=; b=D3qwriJ1+f1SoMo3caaLSgFUIiUXxLInexEQlmadBdaBwsoS7m5HhGM2XUT6YA+7a8 S10mwtLQAhBMZdD1HmDctps9FmBDYvcTx6TGbzUoASXnLgBuybTKVTrKnQVEI7qsWyUV fGzmlPc+lMHGOSY8SQlvD0Eu8JaTHqBUMHQAAWtV2YkUsZqSrCOfOjmFEz8psE4b6qV7 +eop933YLCVnzI8Yf3Wc4dXk8DU498Sfu5FIbPiTHIW9UMFDSOk1b38cI3zFv+MmrbN6 y3hLSftpeYCRgY3e6TyO8ZlgAEgOVZR/EdgY+bip0C+1Wecv1YOYPu54PY/74cZ8JMED v81Q== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id fk23-20020a056402399700b004608b4f28b7si2567353edb.106.2022.10.20.15.37.51; Thu, 20 Oct 2022 15:38:15 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229945AbiJTWYr (ORCPT + 99 others); Thu, 20 Oct 2022 18:24:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229535AbiJTWYg (ORCPT ); Thu, 20 Oct 2022 18:24:36 -0400 Received: from mail-qv1-f41.google.com (mail-qv1-f41.google.com [209.85.219.41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31571248C9; Thu, 20 Oct 2022 15:24:34 -0700 (PDT) Received: by mail-qv1-f41.google.com with SMTP id j8so667997qvo.6; Thu, 20 Oct 2022 15:24:34 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=9aZ+OmfC3WqmwDr6Z61AifhCCaQltrdfxVaW4RspNfI=; b=fLUWzI0tXmtIoPiZWK6hiOxIrxX+OWYRs73A7upuZ04hx7vVvSH/6gnVlSb6AXaTNS D5bPsLjnC59h/9S066naqwqZVb137kopCwMGTJboq8VIxtzCRPEB1dmVXBOnXrq2jIB/ SwL1JHry4GmPhVE/1v/amEE1h/MPxm3NOGdvf2HmxPh3yhHQL9Kv1tHjt6T0CZCijOQZ 14tvMYeBFHwJMR2F4yFAfalwyejazA+/+H4AIvOgwvXGLuvpudsRRdH3EGZngMfpCsy0 HDRKNTlhk+jPIp7O+eQE6oGdB6cuD302+Bmj7RMOil6qXk0UgOk2EtBdrC8elojntPmT Ch9w== X-Gm-Message-State: ACrzQf3cNu5UZiPx8c01zwMN2O3nuFQdJTLNbwzV0QQUq2LB2W0hZC6y /0SOZmtYPfqIcT1P5YDafIcqhOtVsthdvw== X-Received: by 2002:a0c:ab55:0:b0:4b9:4dd5:64ab with SMTP id i21-20020a0cab55000000b004b94dd564abmr3722464qvb.106.1666304672786; Thu, 20 Oct 2022 15:24:32 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::80b7]) by smtp.gmail.com with ESMTPSA id bi39-20020a05620a31a700b006eeb64da8b1sm7944171qkb.2.2022.10.20.15.24.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Oct 2022 15:24:32 -0700 (PDT) From: David Vernet To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, tj@kernel.org, memxor@gmail.com Subject: [PATCH bpf-next v6 3/3] bpf/selftests: Add selftests for new task kfuncs Date: Thu, 20 Oct 2022 17:24:16 -0500 Message-Id: <20221020222416.3415511-4-void@manifault.com> X-Mailer: git-send-email 2.38.0 In-Reply-To: <20221020222416.3415511-1-void@manifault.com> References: <20221020222416.3415511-1-void@manifault.com> MIME-Version: 1.0 X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1747247951703339660?= X-GMAIL-MSGID: =?utf-8?q?1747247951703339660?= A previous change added a series of kfuncs for storing struct task_struct objects as referenced kptrs. This patch adds a new task_kfunc test suite for validating their expected behavior. Signed-off-by: David Vernet --- tools/testing/selftests/bpf/DENYLIST.s390x | 1 + .../selftests/bpf/prog_tests/task_kfunc.c | 160 +++++++++ .../selftests/bpf/progs/task_kfunc_common.h | 81 +++++ .../selftests/bpf/progs/task_kfunc_failure.c | 315 ++++++++++++++++++ .../selftests/bpf/progs/task_kfunc_success.c | 132 ++++++++ 5 files changed, 689 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/task_kfunc.c create mode 100644 tools/testing/selftests/bpf/progs/task_kfunc_common.h create mode 100644 tools/testing/selftests/bpf/progs/task_kfunc_failure.c create mode 100644 tools/testing/selftests/bpf/progs/task_kfunc_success.c diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x index 520f12229b98..323a0e312b3d 100644 --- a/tools/testing/selftests/bpf/DENYLIST.s390x +++ b/tools/testing/selftests/bpf/DENYLIST.s390x @@ -52,6 +52,7 @@ skc_to_unix_sock # could not attach BPF object unexpecte socket_cookie # prog_attach unexpected error: -524 (trampoline) stacktrace_build_id # compare_map_keys stackid_hmap vs. stackmap err -2 errno 2 (?) tailcalls # tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls (?) +task_kfunc # JIT does not support calling kernel function task_local_storage # failed to auto-attach program 'trace_exit_creds': -524 (trampoline) test_bpffs # bpffs test failed 255 (iterator) test_bprm_opts # failed to auto-attach program 'secure_exec': -524 (trampoline) diff --git a/tools/testing/selftests/bpf/prog_tests/task_kfunc.c b/tools/testing/selftests/bpf/prog_tests/task_kfunc.c new file mode 100644 index 000000000000..0be90106fd96 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/task_kfunc.c @@ -0,0 +1,160 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ + +#define _GNU_SOURCE +#include +#include +#include + +#include "task_kfunc_failure.skel.h" +#include "task_kfunc_success.skel.h" + +static size_t log_buf_sz = 1 << 20; /* 1 MB */ +static char obj_log_buf[1048576]; + +static struct task_kfunc_success *open_load_task_kfunc_skel(void) +{ + struct task_kfunc_success *skel; + int err; + + skel = task_kfunc_success__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return NULL; + + skel->bss->pid = getpid(); + + err = task_kfunc_success__load(skel); + if (!ASSERT_OK(err, "skel_load")) + goto cleanup; + + return skel; + +cleanup: + task_kfunc_success__destroy(skel); + return NULL; +} + +static void run_success_test(const char *prog_name) +{ + struct task_kfunc_success *skel; + int status; + pid_t child_pid; + struct bpf_program *prog; + struct bpf_link *link = NULL; + + skel = open_load_task_kfunc_skel(); + if (!ASSERT_OK_PTR(skel, "open_load_skel")) + return; + + if (!ASSERT_OK(skel->bss->err, "pre_spawn_err")) + goto cleanup; + + prog = bpf_object__find_program_by_name(skel->obj, prog_name); + if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name")) + goto cleanup; + + link = bpf_program__attach(prog); + if (!ASSERT_OK_PTR(link, "attached_link")) + goto cleanup; + + child_pid = fork(); + if (!ASSERT_GT(child_pid, -1, "child_pid")) + goto cleanup; + if (child_pid == 0) + _exit(0); + waitpid(child_pid, &status, 0); + + ASSERT_OK(skel->bss->err, "post_wait_err"); + +cleanup: + bpf_link__destroy(link); + task_kfunc_success__destroy(skel); +} + +static const char * const success_tests[] = { + "test_task_acquire_release_argument", + "test_task_acquire_release_current", + "test_task_acquire_leave_in_map", + "test_task_xchg_release", + "test_task_get_release", +}; + +static struct { + const char *prog_name; + const char *expected_err_msg; +} failure_tests[] = { + {"task_kfunc_acquire_untrusted", "arg#0 pointer type STRUCT task_struct must point"}, + {"task_kfunc_acquire_fp", "arg#0 pointer type STRUCT task_struct must point"}, + {"task_kfunc_acquire_no_null_check", "arg#0 pointer type STRUCT task_struct must point"}, + {"task_kfunc_acquire_trusted_walked", "arg#0 pointer type STRUCT task_struct must point"}, + {"task_kfunc_acquire_null", "arg#0 pointer type STRUCT task_struct must point"}, + {"task_kfunc_acquire_unreleased", "Unreleased reference"}, + {"task_kfunc_get_non_kptr_param", "arg#0 expected pointer to map value"}, + {"task_kfunc_get_non_kptr_acquired", "arg#0 expected pointer to map value"}, + {"task_kfunc_get_null", "arg#0 expected pointer to map value"}, + {"task_kfunc_xchg_unreleased", "Unreleased reference"}, + {"task_kfunc_get_unreleased", "Unreleased reference"}, + {"task_kfunc_release_untrusted", "arg#0 pointer type STRUCT task_struct must point"}, + {"task_kfunc_release_fp", "arg#0 pointer type STRUCT task_struct must point"}, + {"task_kfunc_release_null", "arg#0 pointer type STRUCT task_struct must point"}, + {"task_kfunc_release_unacquired", "release kernel function bpf_task_release expects"}, +}; + +static void verify_fail(const char *prog_name, const char *expected_err_msg) +{ + LIBBPF_OPTS(bpf_object_open_opts, opts); + struct task_kfunc_failure *skel; + int err, i; + + opts.kernel_log_buf = obj_log_buf; + opts.kernel_log_size = log_buf_sz; + opts.kernel_log_level = 1; + + skel = task_kfunc_failure__open_opts(&opts); + if (!ASSERT_OK_PTR(skel, "task_kfunc_failure__open_opts")) + goto cleanup; + + skel->bss->pid = getpid(); + + for (i = 0; i < ARRAY_SIZE(failure_tests); i++) { + struct bpf_program *prog; + const char *curr_name = failure_tests[i].prog_name; + + prog = bpf_object__find_program_by_name(skel->obj, curr_name); + if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name")) + goto cleanup; + + bpf_program__set_autoload(prog, !strcmp(curr_name, prog_name)); + } + + err = task_kfunc_failure__load(skel); + if (!ASSERT_ERR(err, "unexpected load success")) + goto cleanup; + + if (!ASSERT_OK_PTR(strstr(obj_log_buf, expected_err_msg), "expected_err_msg")) { + fprintf(stderr, "Expected err_msg: %s\n", expected_err_msg); + fprintf(stderr, "Verifier output: %s\n", obj_log_buf); + } + +cleanup: + task_kfunc_failure__destroy(skel); +} + +void test_task_kfunc(void) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(success_tests); i++) { + if (!test__start_subtest(success_tests[i])) + continue; + + run_success_test(success_tests[i]); + } + + for (i = 0; i < ARRAY_SIZE(failure_tests); i++) { + if (!test__start_subtest(failure_tests[i].prog_name)) + continue; + + verify_fail(failure_tests[i].prog_name, failure_tests[i].expected_err_msg); + } +} diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_common.h b/tools/testing/selftests/bpf/progs/task_kfunc_common.h new file mode 100644 index 000000000000..a5bb7604505a --- /dev/null +++ b/tools/testing/selftests/bpf/progs/task_kfunc_common.h @@ -0,0 +1,81 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ + +#ifndef _TASK_KFUNC_COMMON_H +#define _TASK_KFUNC_COMMON_H + +#include +#include +#include +#include + +struct __tasks_kfunc_map_value { + struct task_struct __kptr_ref * task; +}; + +struct hash_map { + __uint(type, BPF_MAP_TYPE_HASH); + __type(key, int); + __type(value, struct __tasks_kfunc_map_value); + __uint(max_entries, 1); +} __tasks_kfunc_map SEC(".maps"); + +struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym; +struct task_struct *bpf_task_kptr_get(struct task_struct **pp) __ksym; +void bpf_task_release(struct task_struct *p) __ksym; + +/* The pid of the test process used to determine if a newly created task is the test task. */ +int pid; + +static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p) +{ + s32 pid; + long status; + + status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid); + if (status) + return NULL; + + return bpf_map_lookup_elem(&__tasks_kfunc_map, &pid); +} + +static inline int tasks_kfunc_map_insert(struct task_struct *p) +{ + struct __tasks_kfunc_map_value local, *v; + long status; + struct task_struct *acquired, *old; + s32 pid; + + status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid); + if (status) + return status; + + local.task = NULL; + status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST); + if (status) + return status; + + v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid); + if (!v) { + bpf_map_delete_elem(&__tasks_kfunc_map, &pid); + return status; + } + + acquired = bpf_task_acquire(p); + old = bpf_kptr_xchg(&v->task, acquired); + if (old) { + bpf_task_release(old); + return -EEXIST; + } + + return 0; +} + +static inline bool is_test_kfunc_task(void) +{ + int cur_pid = bpf_get_current_pid_tgid() >> 32; + + return pid == cur_pid; +} + +#endif /* _TASK_KFUNC_COMMON_H */ diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_failure.c b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c new file mode 100644 index 000000000000..892ee73a928c --- /dev/null +++ b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c @@ -0,0 +1,315 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ + +#include +#include +#include + +#include "task_kfunc_common.h" + +char _license[] SEC("license") = "GPL"; + +/* Prototype for all of the program trace events below: + * + * TRACE_EVENT(task_newtask, + * TP_PROTO(struct task_struct *p, u64 clone_flags) + */ + +static struct __tasks_kfunc_map_value *insert_lookup_task(struct task_struct *task) +{ + int status; + + status = tasks_kfunc_map_insert(task); + if (status) + return NULL; + + return tasks_kfunc_map_value_lookup(task); +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_acquire_untrusted, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired; + struct __tasks_kfunc_map_value *v; + + if (!is_test_kfunc_task()) + return 0; + + v = insert_lookup_task(task); + if (!v) + return 0; + + /* Can't invoke bpf_task_acquire() on an untrusted pointer. */ + acquired = bpf_task_acquire(v->task); + if (!acquired) + return 0; + + bpf_task_release(acquired); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_acquire_fp, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired, *stack_task = (struct task_struct *)&clone_flags; + + if (!is_test_kfunc_task()) + return 0; + + /* Can't invoke bpf_task_acquire() on a random frame pointer. */ + acquired = bpf_task_acquire((struct task_struct *)&stack_task); + if (!acquired) + return 0; + bpf_task_release(acquired); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_acquire_no_null_check, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired; + + if (!is_test_kfunc_task()) + return 0; + + acquired = bpf_task_acquire(task); + /* Can't release a bpf_task_acquire()'d task without a NULL check. */ + bpf_task_release(acquired); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_acquire_trusted_walked, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired; + + if (!is_test_kfunc_task()) + return 0; + + /* Can't invoke bpf_task_acquire() on a trusted pointer obtained from walking a struct. */ + acquired = bpf_task_acquire(task->last_wakee); + if (!acquired) + return 0; + bpf_task_release(acquired); + + return 0; +} + + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_acquire_null, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired; + + if (!is_test_kfunc_task()) + return 0; + + /* Can't invoke bpf_task_acquire() on a NULL pointer. */ + acquired = bpf_task_acquire(NULL); + if (!acquired) + return 0; + bpf_task_release(acquired); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_acquire_unreleased, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired; + + if (!is_test_kfunc_task()) + return 0; + + acquired = bpf_task_acquire(task); + + /* Acquired task is never released. */ + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_get_non_kptr_param, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr; + + if (!is_test_kfunc_task()) + return 0; + + /* Cannot use bpf_task_kptr_get() on a non-kptr, even on a valid task. */ + kptr = bpf_task_kptr_get(&task); + if (!kptr) + return 0; + + bpf_task_release(kptr); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_get_non_kptr_acquired, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr, *acquired; + + if (!is_test_kfunc_task()) + return 0; + + acquired = bpf_task_acquire(task); + if (!acquired) + return 0; + + /* Cannot use bpf_task_kptr_get() on a non-kptr, even if it was acquired. */ + kptr = bpf_task_kptr_get(&acquired); + bpf_task_release(acquired); + if (!kptr) + return 0; + + bpf_task_release(kptr); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_get_null, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr; + + if (!is_test_kfunc_task()) + return 0; + + /* Cannot use bpf_task_kptr_get() on a NULL pointer. */ + kptr = bpf_task_kptr_get(NULL); + if (!kptr) + return 0; + + bpf_task_release(kptr); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_xchg_unreleased, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr; + struct __tasks_kfunc_map_value *v; + + if (!is_test_kfunc_task()) + return 0; + + v = insert_lookup_task(task); + if (!v) + return 0; + + kptr = bpf_kptr_xchg(&v->task, NULL); + if (!kptr) + return 0; + + /* Kptr retrieved from map is never released. */ + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_get_unreleased, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr; + struct __tasks_kfunc_map_value *v; + + if (!is_test_kfunc_task()) + return 0; + + v = insert_lookup_task(task); + if (!v) + return 0; + + kptr = bpf_task_kptr_get(&v->task); + if (!kptr) + return 0; + + /* Kptr acquired above is never released. */ + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_release_untrusted, struct task_struct *task, u64 clone_flags) +{ + struct __tasks_kfunc_map_value *v; + + if (!is_test_kfunc_task()) + return 0; + + v = insert_lookup_task(task); + if (!v) + return 0; + + /* Can't invoke bpf_task_release() on an untrusted pointer. */ + bpf_task_release(v->task); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_release_fp, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired = (struct task_struct *)&clone_flags; + + if (!is_test_kfunc_task()) + return 0; + + /* Cannot release random frame pointer. */ + bpf_task_release(acquired); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_release_null, struct task_struct *task, u64 clone_flags) +{ + struct __tasks_kfunc_map_value local, *v; + long status; + struct task_struct *acquired, *old; + s32 pid; + + if (!is_test_kfunc_task()) + return 0; + + status = bpf_probe_read_kernel(&pid, sizeof(pid), &task->pid); + if (status) + return 0; + + local.task = NULL; + status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST); + if (status) + return status; + + v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid); + if (!v) + return status; + + acquired = bpf_task_acquire(task); + if (!acquired) + return 0; + + old = bpf_kptr_xchg(&v->task, acquired); + + /* old cannot be passed to bpf_task_release() without a NULL check. */ + bpf_task_release(old); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_release_unacquired, struct task_struct *task, u64 clone_flags) +{ + if (!is_test_kfunc_task()) + return 0; + + /* Cannot release trusted task pointer which was not acquired. */ + bpf_task_release(task); + + return 0; +} diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_success.c b/tools/testing/selftests/bpf/progs/task_kfunc_success.c new file mode 100644 index 000000000000..8d5c05b41d53 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/task_kfunc_success.c @@ -0,0 +1,132 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ + +#include +#include +#include + +#include "task_kfunc_common.h" + +char _license[] SEC("license") = "GPL"; + +int err; + +/* Prototype for all of the program trace events below: + * + * TRACE_EVENT(task_newtask, + * TP_PROTO(struct task_struct *p, u64 clone_flags) + */ + +static int test_acquire_release(struct task_struct *task) +{ + struct task_struct *acquired; + + acquired = bpf_task_acquire(task); + if (!acquired) { + err = 1; + return 0; + } + + bpf_task_release(acquired); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_task_acquire_release_argument, struct task_struct *task, u64 clone_flags) +{ + if (!is_test_kfunc_task()) + return 0; + + return test_acquire_release(task); +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_task_acquire_release_current, struct task_struct *task, u64 clone_flags) +{ + if (!is_test_kfunc_task()) + return 0; + + return test_acquire_release(bpf_get_current_task_btf()); +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_task_acquire_leave_in_map, struct task_struct *task, u64 clone_flags) +{ + long status; + + if (!is_test_kfunc_task()) + return 0; + + status = tasks_kfunc_map_insert(task); + if (status) + err = 1; + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_task_xchg_release, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr; + struct __tasks_kfunc_map_value *v; + long status; + + if (!is_test_kfunc_task()) + return 0; + + status = tasks_kfunc_map_insert(task); + if (status) { + err = 1; + return 0; + } + + v = tasks_kfunc_map_value_lookup(task); + if (!v) { + err = 2; + return 0; + } + + kptr = bpf_kptr_xchg(&v->task, NULL); + if (!kptr) { + err = 3; + return 0; + } + + bpf_task_release(kptr); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_task_get_release, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr; + struct __tasks_kfunc_map_value *v; + long status; + + if (!is_test_kfunc_task()) + return 0; + + status = tasks_kfunc_map_insert(task); + if (status) { + err = 1; + return 0; + } + + v = tasks_kfunc_map_value_lookup(task); + if (!v) { + err = 2; + return 0; + } + + kptr = bpf_task_kptr_get(&v->task); + if (!kptr) { + err = 3; + return 0; + } + + bpf_task_release(kptr); + + return 0; +}