From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7CF94C43381 for ; Thu, 14 Mar 2019 21:49:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 453C92087C for ; Thu, 14 Mar 2019 21:49:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="M0OtEsjL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728040AbfCNVtI (ORCPT ); Thu, 14 Mar 2019 17:49:08 -0400 Received: from mail-qk1-f196.google.com ([209.85.222.196]:35435 "EHLO mail-qk1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727994AbfCNVtB (ORCPT ); Thu, 14 Mar 2019 17:49:01 -0400 Received: by mail-qk1-f196.google.com with SMTP id z13so4340282qki.2 for ; Thu, 14 Mar 2019 14:49:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=c4IczZcemQJBUyUO4U++jGJlzY5GklZ2NZ3zCflWwn8=; b=M0OtEsjLT3o1G8Q3cafkdUpSCoPUJkTZfiitOqIY/qB0DzM1YqY3uqhLBbfA9+V0Oa EN/oUeiAwOzo95ZkqAk9F9sAPhvGCeZSf2mLcS/e3Ycm7ncrL5R/vin/2ADy6Dd53hCM xxmbtuIFYjnvYBEdGJrtGL6CVVbx1a/UH0lXc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=c4IczZcemQJBUyUO4U++jGJlzY5GklZ2NZ3zCflWwn8=; b=GDvYo13C06SX4GrwoJw7CBLHfbxiLvG0ggPxXR9bOnjSitaisLKl1CadiJYcU4gdWk 7P7VUO4CI+4uRriqmtYDVV2zpat2rxqX0uQpn0S5l8iCbYN7HBBAdvAaOJT362VVoWQT eT6NqrsdLW9d1f8dF8uwd+N6z/HU+U3PNxzkGY+zEUvlKF6nM6PKL7EQB9XGZ4Jv0sEL P6DVyIWA3BsuW+C2SZ1mumCEQVW7LhjbezhzzR/YGGExdxYvUJGumJkc/DYxDWQdeO88 5mFQiBi9oEK9nXgdo8OAjsEOKOQZubhznv52NT2+i/TxM4t6ClryyBIMhSOOQCKrOPex Q3aQ== X-Gm-Message-State: APjAAAX+FHvvahjAoGLqy6uabHxx/woaGfZQJjgveYTtSm9FAmVcT+EM SaaE7Yg63RFuqv8r5mZ+PG34Ai1lwLc= X-Google-Smtp-Source: APXvYqxzcuUnWSzeDwWPdHSSmi1kpNflcGQvZsrcJZqSXfwdL86aFq6BWRW0Kgb3udVE8q2hNgpkyQ== X-Received: by 2002:ae9:f101:: with SMTP id k1mr387571qkg.111.1552600139578; Thu, 14 Mar 2019 14:48:59 -0700 (PDT) Received: from joelaf.cam.corp.google.com ([2620:0:1004:1100:cca9:fccc:8667:9bdc]) by smtp.gmail.com with ESMTPSA id o19sm96827qkl.65.2019.03.14.14.48.58 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 14 Mar 2019 14:48:58 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org, mtk.manpages@gmail.com Cc: "Joel Fernandes (Google)" , Andrew Morton , Andy Lutomirski , dancol@google.com, Jann Horn , John Stultz , kernel-team@android.com, linux-api@vger.kernel.org, linux-man@vger.kernel.org, linux-mm@kvack.org, Matthew Wilcox , Mike Kravetz , Shuah Khan , Stephen Rothwell Subject: [PATCH -manpage 2/2] memfd_create.2: Update manpage with new memfd F_SEAL_FUTURE_WRITE seal Date: Thu, 14 Mar 2019 17:48:44 -0400 Message-Id: <20190314214844.207430-3-joel@joelfernandes.org> X-Mailer: git-send-email 2.21.0.360.g471c308f928-goog In-Reply-To: <20190314214844.207430-1-joel@joelfernandes.org> References: <20190314214844.207430-1-joel@joelfernandes.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org More details of the seal can be found in the LKML patch: https://lore.kernel.org/lkml/20181120052137.74317-1-joel@joelfernandes.org/T/#t Signed-off-by: Joel Fernandes (Google) --- man2/memfd_create.2 | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/man2/memfd_create.2 b/man2/memfd_create.2 index 15b1362f5525..3b7f032407ed 100644 --- a/man2/memfd_create.2 +++ b/man2/memfd_create.2 @@ -280,7 +280,15 @@ in order to restrict further modifications on the file. (If placing the seal .BR F_SEAL_WRITE , then it will be necessary to first unmap the shared writable mapping -created in the previous step.) +created in the previous step. Otherwise, behavior similar to +.BR F_SEAL_WRITE +can be achieved, by using +.BR F_SEAL_FUTURE_WRITE +which will prevent future writes via +.BR mmap (2) +and +.BR write (2) +from succeeding, while keeping existing shared writable mappings). .IP 4. A second process obtains a file descriptor for the .BR tmpfs (5) @@ -425,6 +433,7 @@ main(int argc, char *argv[]) fprintf(stderr, "\et\etg \- F_SEAL_GROW\en"); fprintf(stderr, "\et\ets \- F_SEAL_SHRINK\en"); fprintf(stderr, "\et\etw \- F_SEAL_WRITE\en"); + fprintf(stderr, "\et\etW \- F_SEAL_FUTURE_WRITE\en"); fprintf(stderr, "\et\etS \- F_SEAL_SEAL\en"); exit(EXIT_FAILURE); } @@ -463,6 +472,8 @@ main(int argc, char *argv[]) seals |= F_SEAL_SHRINK; if (strchr(seals_arg, \(aqw\(aq) != NULL) seals |= F_SEAL_WRITE; + if (strchr(seals_arg, \(aqW\(aq) != NULL) + seals |= F_SEAL_FUTURE_WRITE; if (strchr(seals_arg, \(aqS\(aq) != NULL) seals |= F_SEAL_SEAL; @@ -518,6 +529,8 @@ main(int argc, char *argv[]) printf(" GROW"); if (seals & F_SEAL_WRITE) printf(" WRITE"); + if (seals & F_SEAL_FUTURE_WRITE) + printf(" FUTURE_WRITE"); if (seals & F_SEAL_SHRINK) printf(" SHRINK"); printf("\en"); -- 2.21.0.360.g471c308f928-goog