From patchwork Mon Apr 8 08:09:27 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Benjamin Tissoires X-Patchwork-Id: 13620721 X-Patchwork-Delegate: bpf@iogearbox.net Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 504B2383A0; Mon, 8 Apr 2024 08:09:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712563799; cv=none; b=X61BDpjdSnQ+6W3MiuKmSVuz9TUjaIzLAqYyHWtgzhX/wiXUcaPIaF9yzmzIwEK2jnc/9S5fC8/ghsJrD+zNQ65QO4uh+kdUfat3ENQZnOjEAQf4envcbbti0DqN95uyIxfD3mNDX7cp9Yo8cBdSMj8ozKtLz6z59WH8I4X2kvg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712563799; c=relaxed/simple; bh=JNFc4F167hpSFgsBvPrqtFJbZiF/Fqk7yk6nxtVXHRA=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=ly8FfUjglA/uTv2aCely/+Xebw/CHm26Rknl3aGCEOtCw3WjdD47neVpdpyXSFcinvbIj41YoTRTxkHFy9YVm5zNA8R7iX30yofhHTKqkMacTuCGwFS4BtOzMoCZNZK12TNZFmwxJYu7aEhPcszda26u4IcrazM34/cLs2xuWxI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZFJLfVAe; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZFJLfVAe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 64BADC43399; Mon, 8 Apr 2024 08:09:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1712563799; bh=JNFc4F167hpSFgsBvPrqtFJbZiF/Fqk7yk6nxtVXHRA=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=ZFJLfVAewQCa4CdnoSF20zK/+VJRD/0CYBVd+/ksicWGIwtsbojBOgZ9HUf5WHZ1f R/S/IZlWOvjQ8gtNqhfZ8Hjc2HrkNIPfzlm+OvFgOuqVNmQRCnCRZ/8nEvFFmAzbVO Xf9wCjzf6ilvfgTOOQE+YS2P9fgdDq01+qu/6HAhSlJgqPVaTrpa3O+X9+8hFqH5MP K/h6FgsY65quopECOF9tu2kNEhF1uA6jH7YUIUFb0behIdLeHVK6OKeH0Yef/6pGNh sgAfsdvQGMzo0gDoHsWdYo+6/DiiDExpN/4Pw4mxQn4vBzyjzyAqD7eQ8Eu/8H4ock ubetS8ez4BIWg== From: bentiss@kernel.org Date: Mon, 08 Apr 2024 10:09:27 +0200 Subject: [PATCH RFC bpf-next v6 2/6] bpf: Add support for KF_ARG_PTR_TO_TIMER Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240408-hid-bpf-sleepable-v6-2-0499ddd91b94@kernel.org> References: <20240408-hid-bpf-sleepable-v6-0-0499ddd91b94@kernel.org> In-Reply-To: <20240408-hid-bpf-sleepable-v6-0-0499ddd91b94@kernel.org> To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Mykola Lysenko , Shuah Khan Cc: Benjamin Tissoires , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Kumar Kartikeya Dwivedi X-Mailer: b4 0.12.4 X-Developer-Signature: v=1; a=ed25519-sha256; t=1712563787; l=4204; i=bentiss@kernel.org; s=20230215; h=from:subject:message-id; bh=s0w876z4WCZOEAGRxkVjR4XsfmFuFBrGvAiFCapdFjE=; b=/y+TNn3r9mE73W+o37r2GOBGpi5eXAv161C+UefqHJaSyeki0PLrwsYHsOpyYZ2stCWQdr5NX OtpVNxZ6sVBCFR+kpSwSuyKHUSShBibNb3V6krCnyoro0O5PIS2AvIH X-Developer-Key: i=bentiss@kernel.org; a=ed25519; pk=7D1DyAVh6ajCkuUTudt/chMuXWIJHlv2qCsRkIizvFw= X-Patchwork-Delegate: bpf@iogearbox.net X-Patchwork-State: RFC From: Kumar Kartikeya Dwivedi Introduce support for KF_ARG_PTR_TO_TIMER. The kfuncs will use bpf_timer as argument and that will be recognized as timer argument by verifier. bpf_timer_kern casting can happen inside kfunc, but using bpf_timer in argument makes life easier for users who work with non-kern type in BPF progs. Fix up process_timer_func's meta argument usage (ignore if NULL) so that we can share the same checks for helpers and kfuncs. meta argument is only needed to ensure bpf_timer_init's timer and map arguments are coming from the same map (map_uid logic is necessary for correct inner-map handling). No such concerns will be necessary for kfuncs as timer initialization happens using helpers, hence pass NULL to process_timer_func from kfunc argument handling code to ignore it. Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Benjamin Tissoires Acked-by: Eduard Zingerman --- changes in v6: - used Kumar's version of the patch - reverted `+BTF_ID(struct, bpf_timer_kern)` changes in v5: - also check for the reg offset changes in v4: - enforce KF_ARG_PTR_TO_TIMER to be of type PTR_TO_MAP_VALUE new in v3 (split from v2 02/10) --- kernel/bpf/verifier.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ca6cacf7b42f..ccfe9057d8dc 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7568,12 +7568,16 @@ static int process_timer_func(struct bpf_verifier_env *env, int regno, val + reg->off, map->record->timer_off); return -EINVAL; } + /* meta is only needed for bpf_timer_init to match timer and map */ + if (!meta) + goto out; if (meta->map_ptr) { verbose(env, "verifier bug. Two map pointers in a timer helper\n"); return -EFAULT; } meta->map_uid = reg->map_uid; meta->map_ptr = map; +out: return 0; } @@ -10826,6 +10830,7 @@ enum { KF_ARG_LIST_NODE_ID, KF_ARG_RB_ROOT_ID, KF_ARG_RB_NODE_ID, + KF_ARG_TIMER_ID, }; BTF_ID_LIST(kf_arg_btf_ids) @@ -10834,6 +10839,7 @@ BTF_ID(struct, bpf_list_head) BTF_ID(struct, bpf_list_node) BTF_ID(struct, bpf_rb_root) BTF_ID(struct, bpf_rb_node) +BTF_ID(struct, bpf_timer_kern) static bool __is_kfunc_ptr_arg_type(const struct btf *btf, const struct btf_param *arg, int type) @@ -10877,6 +10883,11 @@ static bool is_kfunc_arg_rbtree_node(const struct btf *btf, const struct btf_par return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_NODE_ID); } +static bool is_kfunc_arg_timer(const struct btf *btf, const struct btf_param *arg) +{ + return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_TIMER_ID); +} + static bool is_kfunc_arg_callback(struct bpf_verifier_env *env, const struct btf *btf, const struct btf_param *arg) { @@ -10946,6 +10957,7 @@ enum kfunc_ptr_arg_type { KF_ARG_PTR_TO_NULL, KF_ARG_PTR_TO_CONST_STR, KF_ARG_PTR_TO_MAP, + KF_ARG_PTR_TO_TIMER, }; enum special_kfunc_type { @@ -11102,6 +11114,9 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, if (is_kfunc_arg_map(meta->btf, &args[argno])) return KF_ARG_PTR_TO_MAP; + if (is_kfunc_arg_timer(meta->btf, &args[argno])) + return KF_ARG_PTR_TO_TIMER; + if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) { if (!btf_type_is_struct(ref_t)) { verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n", @@ -11735,6 +11750,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ case KF_ARG_PTR_TO_CALLBACK: case KF_ARG_PTR_TO_REFCOUNTED_KPTR: case KF_ARG_PTR_TO_CONST_STR: + case KF_ARG_PTR_TO_TIMER: /* Trusted by default */ break; default: @@ -12021,6 +12037,15 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ if (ret) return ret; break; + case KF_ARG_PTR_TO_TIMER: + if (reg->type != PTR_TO_MAP_VALUE) { + verbose(env, "arg#%d doesn't point to a map value\n", i); + return -EINVAL; + } + ret = process_timer_func(env, regno, NULL); + if (ret < 0) + return ret; + break; } }