From patchwork Sat Jun 8 09:01:27 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Benjamin Tissoires X-Patchwork-Id: 13690958 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 C431E14286; Sat, 8 Jun 2024 09:01:56 +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=1717837316; cv=none; b=I7F+4BVUZSqOUNkELOW8CA8c66QEIQG1SwZUEmB9AWgC+URvTsX+26tnpPctO2sQcG4frbcRBeb2tBemTdCXjdR1C7hVcMSJ4e4j9w+BurFOEEEcHZvZeTz7Euvhnu0591kDyDJeOhu8OH+yRxkrOaI1XqUBR6TVJC9j0Zld/Ww= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717837316; c=relaxed/simple; bh=HIrrmyaYgI3pACH+lmgDvM1+uBik3+a//vxGZcnQimg=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=KwD7ZuhRXLqKB8qjNFGxEBUrVEGjZ6R1FV8LjSwT96zccJie7sEy7ixPebi4kjoDAGa11qlZUukZh6njxaOa2Yl4DHaS4kguWqyi6+KbXifaoY0eHcxli/3uNf9jC+RN+siHkOHRd1hVswHal3l+TqPflBEx5lsFsxg7PiLf4AQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SxaO+UXD; 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="SxaO+UXD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CAB21C4AF07; Sat, 8 Jun 2024 09:01:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1717837316; bh=HIrrmyaYgI3pACH+lmgDvM1+uBik3+a//vxGZcnQimg=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=SxaO+UXDrTYRXcNH1lKaNZcThkDz/kaDxJZlwGVL/OGtNnTfgWxmkw41XdYdf0Ebb jsuRYuQfHXY/7SALbzLZhklF0rKo5fANbNUccxh07bX2n7l8Gb1VMHRNAnlMYmQ+B6 6hJHoGepPHc5tniZuodQi7lRriIIBp7d49T0+5OS1JHcO9HEnvVZOwyTLIxEPhchFo yZhjzR4Bryqky5W4ccCH9embWD+VVjwsfiSBxQxUAb8VVjiJdcUZ1z1EGLpox7weGY AU5LM5DzhkgE8uRcp/ppmupjBEnFFe/TSkDOq9pmORc/Vh17PVkfYnPzjPK91jPdly tsHv8j2HcieeA== From: Benjamin Tissoires Date: Sat, 08 Jun 2024 11:01:27 +0200 Subject: [PATCH HID v3 15/16] HID: bpf: rework hid_bpf_ops_btf_struct_access Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240608-hid_bpf_struct_ops-v3-15-6ac6ade58329@kernel.org> References: <20240608-hid_bpf_struct_ops-v3-0-6ac6ade58329@kernel.org> In-Reply-To: <20240608-hid_bpf_struct_ops-v3-0-6ac6ade58329@kernel.org> To: Shuah Khan , Jiri Kosina , Jonathan Corbet , Alexei Starovoitov Cc: linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-input@vger.kernel.org, linux-doc@vger.kernel.org, Benjamin Tissoires X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1717837279; l=4130; i=bentiss@kernel.org; s=20230215; h=from:subject:message-id; bh=HIrrmyaYgI3pACH+lmgDvM1+uBik3+a//vxGZcnQimg=; b=NMPE52ezcZipQcLjtnuDHX9D3HBCIFlM25VOGZTCC3fbQOZriKVwUTwVgtsbFvNMZYiLKLY/U cfBz6WfyaFIBxTLOrnghBmcCiq35Y4Ftrwyln8R0yVPHiTAT9UGA1ar X-Developer-Key: i=bentiss@kernel.org; a=ed25519; pk=7D1DyAVh6ajCkuUTudt/chMuXWIJHlv2qCsRkIizvFw= The idea is to provide a list of stucts and their editable fields. Currently no functional changes are introduced here, we will add some more writeable fields in the next patch. Signed-off-by: Benjamin Tissoires Acked-by: Alexei Starovoitov --- changes in v3: - rewrote WRITE_RANGE macro to not deal with offset from the caller side new in v2 --- drivers/hid/bpf/hid_bpf_struct_ops.c | 91 +++++++++++++++++++++++++++--------- 1 file changed, 69 insertions(+), 22 deletions(-) diff --git a/drivers/hid/bpf/hid_bpf_struct_ops.c b/drivers/hid/bpf/hid_bpf_struct_ops.c index 056d05d96962..b14eccb121e0 100644 --- a/drivers/hid/bpf/hid_bpf_struct_ops.c +++ b/drivers/hid/bpf/hid_bpf_struct_ops.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include "hid_bpf_dispatch.h" @@ -52,40 +53,86 @@ static int hid_bpf_ops_check_member(const struct btf_type *t, return 0; } +struct hid_bpf_offset_write_range { + const char *struct_name; + u32 struct_length; + u32 start; + u32 end; +}; + static int hid_bpf_ops_btf_struct_access(struct bpf_verifier_log *log, const struct bpf_reg_state *reg, int off, int size) { - const struct btf_type *state; - const struct btf_type *t; - s32 type_id; +#define WRITE_RANGE(_name, _field, _is_string) \ + { \ + .struct_name = #_name, \ + .struct_length = sizeof(struct _name), \ + .start = offsetof(struct _name, _field), \ + .end = offsetofend(struct _name, _field) - !!(_is_string), \ + } - type_id = btf_find_by_name_kind(reg->btf, "hid_bpf_ctx", - BTF_KIND_STRUCT); - if (type_id < 0) - return -EINVAL; + const struct hid_bpf_offset_write_range write_ranges[] = { + WRITE_RANGE(hid_bpf_ctx, retval, false), + }; +#undef WRITE_RANGE + const struct btf_type *state = NULL; + const struct btf_type *t; + const char *cur = NULL; + int i; t = btf_type_by_id(reg->btf, reg->btf_id); - state = btf_type_by_id(reg->btf, type_id); - if (t != state) { - bpf_log(log, "only access to hid_bpf_ctx is supported\n"); - return -EACCES; - } - /* out-of-bound access in hid_bpf_ctx */ - if (off + size > sizeof(struct hid_bpf_ctx)) { - bpf_log(log, "write access at off %d with size %d\n", off, size); - return -EACCES; + for (i = 0; i < ARRAY_SIZE(write_ranges); i++) { + const struct hid_bpf_offset_write_range *write_range = &write_ranges[i]; + s32 type_id; + + /* we already found a writeable struct, but there is a + * new one, let's break the loop. + */ + if (t == state && write_range->struct_name != cur) + break; + + /* new struct to look for */ + if (write_range->struct_name != cur) { + type_id = btf_find_by_name_kind(reg->btf, write_range->struct_name, + BTF_KIND_STRUCT); + if (type_id < 0) + return -EINVAL; + + state = btf_type_by_id(reg->btf, type_id); + } + + /* this is not the struct we are looking for */ + if (t != state) { + cur = write_range->struct_name; + continue; + } + + /* first time we see this struct, check for out of bounds */ + if (cur != write_range->struct_name && + off + size > write_range->struct_length) { + bpf_log(log, "write access for struct %s at off %d with size %d\n", + write_range->struct_name, off, size); + return -EACCES; + } + + /* now check if we are in our boundaries */ + if (off >= write_range->start && off + size <= write_range->end) + return NOT_INIT; + + cur = write_range->struct_name; } - if (off < offsetof(struct hid_bpf_ctx, retval)) { + + if (t != state) + bpf_log(log, "write access to this struct is not supported\n"); + else bpf_log(log, - "write access at off %d with size %d on read-only part of hid_bpf_ctx\n", - off, size); - return -EACCES; - } + "write access at off %d with size %d on read-only part of %s\n", + off, size, cur); - return NOT_INIT; + return -EACCES; } static const struct bpf_verifier_ops hid_bpf_verifier_ops = {