From patchwork Thu Apr 20 14:20:34 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adhemerval Zanella X-Patchwork-Id: 55707 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id B706D385703E for ; Thu, 20 Apr 2023 14:22:09 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B706D385703E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1682000529; bh=uNCnTOIWpO4MgAGq+jh5Qu5TWbhjXog98pInnVyNqF0=; h=To:Cc:Subject:Date:List-Id:List-Unsubscribe:List-Archive: List-Post:List-Help:List-Subscribe:From:Reply-To:From; b=tIfF8e4yaIT7MGnZEaMfONtu6mmEIVaLR65qi+0DHYbOQNdBkuAMQCWTmfiozpyPh x34vEhuJeBM0kZarpJ6oJBPeg5k1Ws+hcj3j6IF7s7kF3Snrh/CD6Njal/Alw2UwZM YQnrm8oLe6b0G3Adjsx0172bP204ogsG5uvOSrc4= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-oa1-x33.google.com (mail-oa1-x33.google.com [IPv6:2001:4860:4864:20::33]) by sourceware.org (Postfix) with ESMTPS id 6813C3858C83 for ; Thu, 20 Apr 2023 14:20:44 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 6813C3858C83 Received: by mail-oa1-x33.google.com with SMTP id 586e51a60fabf-18777914805so5025764fac.1 for ; Thu, 20 Apr 2023 07:20:44 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682000443; x=1684592443; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=uNCnTOIWpO4MgAGq+jh5Qu5TWbhjXog98pInnVyNqF0=; b=iMV9EejbaEa17og8NPlXjJvpOmBh1Yw4OycdS5nsPRrr08uugkMT6vF1wag+UTzHrM y73Xm0aU3sXWCPosolWJNnN8jjK5Ut7YR0YJu61DXXI4kw7wIi3wTHyK8P5TqokzB3Nv SM7MPMpJV7nnukQWpkIQ5YVfbrjeA6DFbX3BoUZnolBIuXSr9vxR97uCwJjhRGufJ3zb 3BMcGuOIqR+Yc+djnF+yky2M+xITVvhWntQTrFC+0GZYDAGy0Juk9fywiKFNfUuCHNaA rDEez7cvmmOP69FNzerSGBgNjoYfiw8toh66HmuHjKiQ/nVXFxeuO9Lnbcb0lqhk0Mhf N5WQ== X-Gm-Message-State: AAQBX9c3N9EJGROQEVXqVQLQRyOwpRMHeZHWgquDW24qCi5Ts2wfhM/K kcdTFfZ3ZaBQG+n8UlD4c95yLXswKMnkkpNzDe1ZBA== X-Google-Smtp-Source: AKy350bUauGejLyB9ja6kgqciAXn4xkSGMzy/XumnlhQn/z3XuMJz0RSAhYEFwvO3Pc5pvMgeuhbzw== X-Received: by 2002:aca:3dc6:0:b0:38e:2fba:990f with SMTP id k189-20020aca3dc6000000b0038e2fba990fmr3744042oia.29.1682000443074; Thu, 20 Apr 2023 07:20:43 -0700 (PDT) Received: from mandiga.. ([2804:1b3:a7c3:333:c0e2:699e:18c9:eb96]) by smtp.gmail.com with ESMTPSA id b35-20020a4a98e6000000b0051a6cb524b6sm668159ooj.2.2023.04.20.07.20.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Apr 2023 07:20:42 -0700 (PDT) To: libc-alpha@sourceware.org Cc: Luca Boccassi Subject: [PATCH v2 0/3] Add pidfd_spawn, pidfd_spawnp, pidfd_fork, and pidfd_getpid Date: Thu, 20 Apr 2023 11:20:34 -0300 Message-Id: <20230420142037.4063169-1-adhemerval.zanella@linaro.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Spam-Status: No, score=-6.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Adhemerval Zanella via Libc-alpha From: Adhemerval Zanella Reply-To: Adhemerval Zanella Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" The glibc 2.36 added wrappers for Linux syscall pidfd_open, pidfd_getfd, and pidfd_send_signal, and exported the P_PIDFD to use with waitid. However, although the pidfd is a race free interface, the pidfd_open is subject to TOCTOU if the file descriptor is not obtained directly from the clone or clone3 syscall (there is still a small window between the clone return and the pidfd_getfd where the process can be reaped and the process ID reused). A fully race free interface with posix_spawn interface is being discussed by GNOME [1] [2], and Qt already uses on its QtProcess implementation [3]. The Qt code has some pitfalls by not using a lib provided symbol: - It calls clone through the syscall symbol, which does not run the pthread_atfork handlers even though it really intends to use the clone semantic for fork (by only using CLONE_PIDFD | SIGCHLD). - It also does not reset any internal state, such as internal IO, malloc, loader, etc. locks. - It does not set the TCB tid field nor the robust list, used by pthread code. - It does not optimize process creation by using CLONE_VM and CLONE_VFORK. The pidfd_spawn and pidfd_spawnp handles all these cases by using the same internal implementation used by posix_spawn: int pidfd_spawn (int *restrict pidfd, const char *restrict file, const posix_spawn_file_actions_t *restrict facts, const posix_spawnattr_t *restrict attrp, char *const argv[restrict], char *const envp[restrict]) int pidfd_spawnp (int *restrict pidfd, const char *restrict path, const posix_spawn_file_actions_t *restrict facts, const posix_spawnattr_t *restrict attrp, char *const argv[restrict_arr], char *const envp[restrict_arr]); The implementation makes sure that kernel must support the complete pidfd interface, meaning that waitid (P_PIDFD) should be supported. It ensure that non racy workaround is required (such as reading procfs fdinfo pid to use along with old wait interfaces). If kernel does not have the required support the interface returns ENOSYS. A new symbol is used instead of a posix_spawn extension to avoid possible issue with language bindings that might track the argument lifetime. Both symbols reuse the posix_spawn posix_spawn_file_actions_t and posix_spawnattr_t, to either avoid rehash posix_spawn API or add a new one. It also mean that both interfaces support the same attribute and file actions, and a new flag or file actions on posix_spawn is also added automatically for pidfd_spawn. Along with the spawn interface, a fork like one is also provided: int pidfd_fork (unsigned int flags) The kernel already sets O_CLOEXEC as default and it follow fork/_Fork convention on returning a positive or negative value to the parent (with negative indicating an error) and zero to the child. Different than fork, pidfd_fork does not run the pthread_atfork handlers (similar to _Fork). It can be change by using PIDFD_FORK_RUNATFORK with flags. To have a way to interop between process IDs and process file descriptors, the pidfd_getpid is also provided. It just read the procps fdinfo entry from the file descriptor to get the process ID. --- Changes from v1: - Extended pidfd_getpid error codes to return EBADF if fdinfo does not have Pid entry or if the value is invalid, EREMOTE is pid is in a separate namespace, and ESRCH if is already terminated. - Extended tst-pidfd_getpid. - Rename PIDFD_FORK_RUNATFORK to PIDFDFORK_RUNATFORK to avoid clash with possible kernel extensions. [1] https://gitlab.gnome.org/GNOME/glib/-/issues/1866 [2] https://sourceware.org/bugzilla/show_bug.cgi?id=30349 [3] https://codebrowser.dev/qt6/qtbase/src/3rdparty/forkfd/forkfd_linux.c.html Adhemerval Zanella (3): posix: Add pidfd_spawn and pidfd_spawnp (BZ# 30349) posix: Add pidfd_fork linux: Add pidfd_getpid NEWS | 16 ++ bits/spawn_ext.h | 21 +++ include/clone_internal.h | 4 + manual/process.texi | 22 +-- posix/Makefile | 5 +- posix/fork-internal.c | 125 +++++++++++++ posix/fork-internal.h | 29 +++ posix/fork.c | 98 +--------- posix/spawn.h | 2 + posix/spawn_int.h | 3 +- posix/tst-posix_spawn-setsid.c | 168 +++++++++++++----- posix/tst-spawn-chdir.c | 15 +- posix/tst-spawn.c | 24 +-- posix/tst-spawn.h | 36 ++++ posix/tst-spawn2.c | 17 +- posix/tst-spawn3.c | 100 ++++++----- posix/tst-spawn4.c | 7 +- posix/tst-spawn5.c | 14 +- posix/tst-spawn6.c | 15 +- posix/tst-spawn7.c | 13 +- sysdeps/mach/hurd/bits/errno.h | 19 ++ sysdeps/nptl/_Fork.c | 2 +- sysdeps/unix/sysv/linux/Makefile | 25 +++ sysdeps/unix/sysv/linux/Versions | 6 + sysdeps/unix/sysv/linux/aarch64/libc.abilist | 4 + sysdeps/unix/sysv/linux/alpha/libc.abilist | 4 + sysdeps/unix/sysv/linux/arc/libc.abilist | 4 + sysdeps/unix/sysv/linux/arch-fork.h | 16 +- sysdeps/unix/sysv/linux/arm/be/libc.abilist | 4 + sysdeps/unix/sysv/linux/arm/le/libc.abilist | 4 + sysdeps/unix/sysv/linux/bits/spawn_ext.h | 45 +++++ sysdeps/unix/sysv/linux/clone-pidfd-support.c | 58 ++++++ sysdeps/unix/sysv/linux/csky/libc.abilist | 4 + sysdeps/unix/sysv/linux/hppa/libc.abilist | 4 + sysdeps/unix/sysv/linux/i386/libc.abilist | 4 + sysdeps/unix/sysv/linux/ia64/libc.abilist | 4 + .../sysv/linux/loongarch/lp64/libc.abilist | 4 + .../sysv/linux/m68k/coldfire/libc.abilist | 4 + .../unix/sysv/linux/m68k/m680x0/libc.abilist | 4 + .../sysv/linux/microblaze/be/libc.abilist | 4 + .../sysv/linux/microblaze/le/libc.abilist | 4 + .../sysv/linux/mips/mips32/fpu/libc.abilist | 4 + .../sysv/linux/mips/mips32/nofpu/libc.abilist | 4 + .../sysv/linux/mips/mips64/n32/libc.abilist | 4 + .../sysv/linux/mips/mips64/n64/libc.abilist | 4 + sysdeps/unix/sysv/linux/nios2/libc.abilist | 4 + sysdeps/unix/sysv/linux/or1k/libc.abilist | 4 + sysdeps/unix/sysv/linux/pidfd_fork.c | 76 ++++++++ sysdeps/unix/sysv/linux/pidfd_getpid.c | 94 ++++++++++ sysdeps/unix/sysv/linux/pidfd_spawn.c | 30 ++++ sysdeps/unix/sysv/linux/pidfd_spawnp.c | 30 ++++ .../linux/powerpc/powerpc32/fpu/libc.abilist | 4 + .../powerpc/powerpc32/nofpu/libc.abilist | 4 + .../linux/powerpc/powerpc64/be/libc.abilist | 4 + .../linux/powerpc/powerpc64/le/libc.abilist | 4 + sysdeps/unix/sysv/linux/procutils.c | 99 +++++++++++ sysdeps/unix/sysv/linux/procutils.h | 37 ++++ .../unix/sysv/linux/riscv/rv32/libc.abilist | 4 + .../unix/sysv/linux/riscv/rv64/libc.abilist | 4 + .../unix/sysv/linux/s390/s390-32/libc.abilist | 4 + .../unix/sysv/linux/s390/s390-64/libc.abilist | 4 + sysdeps/unix/sysv/linux/sh/be/libc.abilist | 4 + sysdeps/unix/sysv/linux/sh/le/libc.abilist | 4 + .../sysv/linux/sparc/sparc32/libc.abilist | 4 + .../sysv/linux/sparc/sparc64/libc.abilist | 4 + sysdeps/unix/sysv/linux/spawni.c | 20 ++- sysdeps/unix/sysv/linux/sys/pidfd.h | 17 ++ sysdeps/unix/sysv/linux/tst-pidfd.c | 45 +++++ sysdeps/unix/sysv/linux/tst-pidfd_fork.c | 150 ++++++++++++++++ .../sysv/linux/tst-posix_spawn-setsid-pidfd.c | 20 +++ .../unix/sysv/linux/tst-spawn-chdir-pidfd.c | 20 +++ sysdeps/unix/sysv/linux/tst-spawn-pidfd.c | 20 +++ sysdeps/unix/sysv/linux/tst-spawn-pidfd.h | 63 +++++++ sysdeps/unix/sysv/linux/tst-spawn2-pidfd.c | 20 +++ sysdeps/unix/sysv/linux/tst-spawn3-pidfd.c | 20 +++ sysdeps/unix/sysv/linux/tst-spawn4-pidfd.c | 20 +++ sysdeps/unix/sysv/linux/tst-spawn5-pidfd.c | 20 +++ sysdeps/unix/sysv/linux/tst-spawn6-pidfd.c | 20 +++ sysdeps/unix/sysv/linux/tst-spawn7-pidfd.c | 20 +++ .../unix/sysv/linux/x86_64/64/libc.abilist | 4 + .../unix/sysv/linux/x86_64/x32/libc.abilist | 4 + 81 files changed, 1623 insertions(+), 259 deletions(-) create mode 100644 bits/spawn_ext.h create mode 100644 posix/fork-internal.c create mode 100644 posix/fork-internal.h create mode 100644 posix/tst-spawn.h create mode 100644 sysdeps/unix/sysv/linux/bits/spawn_ext.h create mode 100644 sysdeps/unix/sysv/linux/clone-pidfd-support.c create mode 100644 sysdeps/unix/sysv/linux/pidfd_fork.c create mode 100644 sysdeps/unix/sysv/linux/pidfd_getpid.c create mode 100644 sysdeps/unix/sysv/linux/pidfd_spawn.c create mode 100644 sysdeps/unix/sysv/linux/pidfd_spawnp.c create mode 100644 sysdeps/unix/sysv/linux/procutils.c create mode 100644 sysdeps/unix/sysv/linux/procutils.h create mode 100644 sysdeps/unix/sysv/linux/tst-pidfd_fork.c create mode 100644 sysdeps/unix/sysv/linux/tst-posix_spawn-setsid-pidfd.c create mode 100644 sysdeps/unix/sysv/linux/tst-spawn-chdir-pidfd.c create mode 100644 sysdeps/unix/sysv/linux/tst-spawn-pidfd.c create mode 100644 sysdeps/unix/sysv/linux/tst-spawn-pidfd.h create mode 100644 sysdeps/unix/sysv/linux/tst-spawn2-pidfd.c create mode 100644 sysdeps/unix/sysv/linux/tst-spawn3-pidfd.c create mode 100644 sysdeps/unix/sysv/linux/tst-spawn4-pidfd.c create mode 100644 sysdeps/unix/sysv/linux/tst-spawn5-pidfd.c create mode 100644 sysdeps/unix/sysv/linux/tst-spawn6-pidfd.c create mode 100644 sysdeps/unix/sysv/linux/tst-spawn7-pidfd.c