From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-vk1-f177.google.com (mail-vk1-f177.google.com [209.85.221.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2F86A43CEEE for ; Thu, 30 Apr 2026 15:50:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777564248; cv=none; b=OBCYrrRmoBairZjX787LTBCmUeqMG/564balptpjeiG8dkLXchI0+tRHbmnI80pVE1HNr5nFi/oHztc/PjCMLaDnZWJh3HjHqZXjJwY05JzeG4V2FYpRvbkQj1a1P1yS4ZtcMzwcXAzYLvDenoUWripKgQVtrto6rfwfEDmWeRc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777564248; c=relaxed/simple; bh=l9W2wL9n1BnbNB9e+Pd9HayxGawVzMrl1//pFSzsERs=; h=From:To:Subject:Date:Message-ID:MIME-Version; b=XvBYT7dwdDkHvRKYqXNLaRogPX4rQuQqwgAY5ouYTH5x2hp5yyJ3hD6vVUxAN9pxCBXk4FI/9rpV9sHEq6U5hCKWJNdzGS75tEbN8KgSWIuM80nXWmMFNmkoA4b1JaO1QdhJ44OIQ0TUg9aT/T747M5uFrxglSL6C92ZJaMJwKs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=P0EAv0Er; arc=none smtp.client-ip=209.85.221.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="P0EAv0Er" Received: by mail-vk1-f177.google.com with SMTP id 71dfb90a1353d-56f3e6bbecdso396144e0c.2 for ; Thu, 30 Apr 2026 08:50:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1777564246; x=1778169046; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:to :from:from:to:cc:subject:date:message-id:reply-to; bh=qOCTQsLc7aZtkFgQC+bhYtKzA1I1EcWEyXZ/7l19w+U=; b=P0EAv0ErkSxy4CHv/BSsQrVMGdrMJhWVB4QAzaXyAveu2hBn6mCA4ffdK5ycgguUVP RiiUsoCWq46gsDA8NDIEDxZNQjK8sQxb3CIBEjKhg2OC5EHZlRtB7VoAEMdn/mLRTV0p 7tySDO8iIfdagFuVx3aUFFcNtqm9BaOtIYct6kL8EedaJelobNDo6IQH/16Q9juFWz3y tkUOGE9ny6J8rBM6fn+Ra0A2T9mZGhCK+PuJPGyAQ7mEVRVoCKaOPEypl88Rm6gc+3Tw 2T886R0IQDC6WaFwLeJDNuV7ymJ45UE2nbeuAS1Flzx+ilHKxw5FWpLc7jYFM0/a2UED CN3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777564246; x=1778169046; h=content-transfer-encoding:mime-version:message-id:date:subject:to :from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=qOCTQsLc7aZtkFgQC+bhYtKzA1I1EcWEyXZ/7l19w+U=; b=UU3TQIgtTD8c5W4YZN9tJCZ7xKjO2xer2P2C4horcmKzwzSixDWLN90MtO6hkb6J+g GHKizTaVONkr1aSny6y3bX5WEjrqN1IXFIqvyBXYUJG4Vl0mHQoUflRuEcrd7RPdKy1a h4S4ICmAN4ZKRPsO42MHhfUrWKIQOiKGRf5DdaExpxukN81TKZ6xy5tZwX/2LYVFp2Me wdd+WPBwyvDr16fHN1guFEw7IdHlLPgEvsbhtxmpv8QqCB2m97HDO1WlsMVyhubK2QLl GUKo8HqIAMG2h1JKp08ic5qB4pAuRUeutY7f5HmMEdlzR9SdbnnIhP4AdeF26G7MXdkF rcog== X-Gm-Message-State: AOJu0YxEwnJ+FIPubump6Jf9G8alkKHNhUnFrlfxsZtSxOXGPU+q6PKg kHuF20c0ovlhPfeTijdUX0uLpn+tE/zMJvcjVVaP/y60M8m5NXY1/jityiVi2w== X-Gm-Gg: AeBDiet/2T5NTTuDGe3N0osWPAhoQUXbNxLsFQ7udxK7xJLphCyuv1Z6aKpF+WnSqNu DzndlVPrZyV5bc8xM1r50hfEQR00fy3VLbH1Rp1Oef5lNQ/uKbsuOU/cdYrwGby4SOzxUB+chCu o/SWwKHR1klt1SCTYdHNtoSbucgw1QDkXGjR7dE8Dd5UW+x1SqTHCkgmfIHGFfdMC6KE4EofdCs z1Yq+ojHrjedx0lZGSUqipZl1EjF2Kh7gPYzOHGpA3In0z3ejwCW+DEjxqjWa9j7zFf1KBNGy01 oSLadzNzSrIGZraI62R619EdLurIIEJH0bZCZ7OrZ/V0pC4/GEJGVnqVQE9NiwmXKuLdyQgw44M 9qSPYn4G3X4A7sq+sXXaTKdhOPcQh5FS5vA8GEJ0BsnEOnGOn4iu4C2CmK+phEpRt3k3XYLHgrA d0tZqw/vvS2bpcX20RcqHMFGwAm6OGppb547J2x3wa5nCCWgwWz9hq8EGQQi0FXZGvYkDbjFmdB N3Ir/Ze9t0kYpKtq465UktSloU3 X-Received: by 2002:a05:6122:4f8a:b0:56e:ded3:98eb with SMTP id 71dfb90a1353d-573c95d7b93mr1599452e0c.6.1777564245779; Thu, 30 Apr 2026 08:50:45 -0700 (PDT) Received: from lvondent-mobl5 ([72.188.211.115]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-573b6dfa5b4sm3199545e0c.16.2026.04.30.08.50.44 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Apr 2026 08:50:45 -0700 (PDT) From: Luiz Augusto von Dentz To: linux-bluetooth@vger.kernel.org Subject: [RFC PATCH BlueZ 1/3] shared/hci: Add BPF filter for registered events Date: Thu, 30 Apr 2026 11:50:36 -0400 Message-ID: <20260430155038.426968-1-luiz.dentz@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-bluetooth@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Luiz Augusto von Dentz Implement a BPF socket filter in bt_hci_register/bt_hci_unregister that uses setsockopt(SO_ATTACH_FILTER) to only accept HCI events that have been registered, plus BT_HCI_EVT_CMD_COMPLETE and BT_HCI_EVT_CMD_STATUS which are always needed for command response processing. The filter is rebuilt each time an event is registered or unregistered, and only applies to non-stream (raw socket) connections. Assisted-by: Claude:claude-opus-4.6 --- src/shared/hci.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 84 insertions(+) diff --git a/src/shared/hci.c b/src/shared/hci.c index 0faa6dea555d..5105b0b2f320 100644 --- a/src/shared/hci.c +++ b/src/shared/hci.c @@ -23,6 +23,7 @@ #include #include #include +#include #include "bluetooth/hci.h" #include "monitor/bt.h" @@ -565,6 +566,85 @@ bool bt_hci_flush(struct bt_hci *hci) return true; } +static void update_evt_filter(struct bt_hci *hci) +{ + const struct queue_entry *entry; + struct sock_filter *filters; + struct sock_fprog fprog; + unsigned int count, i; + int fd; + + fd = io_get_fd(hci->io); + if (fd < 0) + return; + + /* If stream-based (not a raw socket), no BPF filtering needed */ + if (hci->is_stream) + return; + + count = queue_length(hci->evt_list); + + /* Build filter: load event code, check defaults + registered events. + * Packet layout for HCI_CHANNEL_RAW: [H4 type (1 byte)][evt code (1)] + * So event code is at offset 1. + * + * Filter structure: + * [0] Load byte at offset 1 (event code) + * [1] JEQ BT_HCI_EVT_CMD_COMPLETE -> accept + * [2] JEQ BT_HCI_EVT_CMD_STATUS -> accept + * [3..3+count-1] JEQ registered_event -> accept + * [3+count] reject + * [4+count] accept + */ + filters = malloc(sizeof(*filters) * (count + 5)); + if (!filters) + return; + + i = 0; + + /* Load event code byte */ + filters[i++] = (struct sock_filter) + BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 1); + + /* Check BT_HCI_EVT_CMD_COMPLETE (0x0e) */ + filters[i++] = (struct sock_filter) + BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, BT_HCI_EVT_CMD_COMPLETE, + count + 2, 0); + + /* Check BT_HCI_EVT_CMD_STATUS (0x0f) */ + filters[i++] = (struct sock_filter) + BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, BT_HCI_EVT_CMD_STATUS, + count + 1, 0); + + /* Check each registered event */ + entry = queue_get_entries(hci->evt_list); + while (entry) { + const struct evt *evt = entry->data; + unsigned int jump = count - (i - 3); + + filters[i] = (struct sock_filter) + BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, evt->event, + jump, 0); + i++; + entry = entry->next; + } + + /* Reject */ + filters[i++] = (struct sock_filter) + BPF_STMT(BPF_RET | BPF_K, 0); + + /* Accept */ + filters[i++] = (struct sock_filter) + BPF_STMT(BPF_RET | BPF_K, 0x0fffffff); + + fprog.len = i; + fprog.filter = filters; + + setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog)); + + free(filters); +} + unsigned int bt_hci_register(struct bt_hci *hci, uint8_t event, bt_hci_callback_func_t callback, void *user_data, bt_hci_destroy_func_t destroy) @@ -591,6 +671,8 @@ unsigned int bt_hci_register(struct bt_hci *hci, uint8_t event, return 0; } + update_evt_filter(hci); + return evt->id; } @@ -657,6 +739,8 @@ bool bt_hci_unregister(struct bt_hci *hci, unsigned int id) evt_free(evt); + update_evt_filter(hci); + return true; } -- 2.53.0