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=-16.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 876D4C10F14 for ; Thu, 11 Apr 2019 01:44:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 48BC920850 for ; Thu, 11 Apr 2019 01:44:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="FsQW3DxU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726786AbfDKBoI (ORCPT ); Wed, 10 Apr 2019 21:44:08 -0400 Received: from mail-yb1-f201.google.com ([209.85.219.201]:48352 "EHLO mail-yb1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726709AbfDKBoF (ORCPT ); Wed, 10 Apr 2019 21:44:05 -0400 Received: by mail-yb1-f201.google.com with SMTP id u125so3214202ybb.15 for ; Wed, 10 Apr 2019 18:44:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=PyLdI7PZk1GSB43N13T7W74jY1CSZ1+A35vi7emlRBQ=; b=FsQW3DxUQfr3UEIOZaRtKQ14YG36rNMZAoP4RXuDnHZhTnzx8vfU+n++RB/3o0dp0u SH9s3G7Hv6ADWQtomsgGHp312SSsN6EYFO/ZI8x3zaQMzGdV60aG2if6ijB0CU2Xj/5p Wr+u7Wyb361ndUXGOOmlpRDdcHAAPNwaAxiqvx8CH06ziaPdVT7gmlngsPDr1J560YOg I5i/EcCf6HzZpeddrmKyHhq3l9q6cka24b266kjFb1tp+leUWTHkX9an5xjDZPYer8TK J/UNaD9DJCmOSB51Myj5q3PE83dNf3d9ehU/VPU0ePxzOZUM8hhQHSuA7EePSmvIH3LA aFig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=PyLdI7PZk1GSB43N13T7W74jY1CSZ1+A35vi7emlRBQ=; b=TQ8UDMv7MaV/Z+H8EaKA3U72CySp1UDnV9V9ya5gd3MU4SOuDOIN84He25tRPcecdH RMhSy2TB0/1RLgqM7uYdcgweXhbtn9z6u5RC5PCVAIfaIy8Og8I++nge/aAraHqU6V8g WMauJ+x8U7rIX8jW46xMhgsq4brvCJGWzh9c4BRNdHKm72jO3Wfl6T7KpzmiBkHo3CMX oHddXV0mkgb4ijgKTOZSh3xHnQMPrjNKH+4yLPDrqx6XMgFtegzHq5oXxa/YWghExMWC Z2dkGaILWSgs2mQFG7ftxxVgfCTb1VNye8pZ2nP5m5O3pFFNkFWnIKAJNKx6ErXbeMHK wsiQ== X-Gm-Message-State: APjAAAXXwYa7lDfU20uY98UuLpRK8xT6NCe31EjhftWaoYciTw7u+KQE TjXTBs00MES/uBsAQq0SeXN8uN9Din4= X-Google-Smtp-Source: APXvYqzoYtryft6snCAH2tsCLNm6pZ/FkqZ/mICxzIwSzE/D420FbpbEJQwThBXlAukM5+6xtF5vw2sOQK0= X-Received: by 2002:a25:5:: with SMTP id 5mr10518104yba.52.1554947044969; Wed, 10 Apr 2019 18:44:04 -0700 (PDT) Date: Wed, 10 Apr 2019 18:43:53 -0700 In-Reply-To: <20190411014353.113252-1-surenb@google.com> Message-Id: <20190411014353.113252-3-surenb@google.com> Mime-Version: 1.0 References: <20190411014353.113252-1-surenb@google.com> X-Mailer: git-send-email 2.21.0.392.gf8f6787159e-goog Subject: [RFC 2/2] signal: extend pidfd_send_signal() to allow expedited process killing From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: mhocko@suse.com, rientjes@google.com, willy@infradead.org, yuzhoujian@didichuxing.com, jrdr.linux@gmail.com, guro@fb.com, hannes@cmpxchg.org, penguin-kernel@I-love.SAKURA.ne.jp, ebiederm@xmission.com, shakeelb@google.com, christian@brauner.io, minchan@kernel.org, timmurray@google.com, dancol@google.com, joel@joelfernandes.org, jannh@google.com, surenb@google.com, linux-mm@kvack.org, lsf-pc@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add new SS_EXPEDITE flag to be used when sending SIGKILL via pidfd_send_signal() syscall to allow expedited memory reclaim of the victim process. The usage of this flag is currently limited to SIGKILL signal and only to privileged users. Signed-off-by: Suren Baghdasaryan --- include/linux/sched/signal.h | 3 ++- include/linux/signal.h | 11 ++++++++++- ipc/mqueue.c | 2 +- kernel/signal.c | 37 ++++++++++++++++++++++++++++-------- kernel/time/itimer.c | 2 +- 5 files changed, 43 insertions(+), 12 deletions(-) diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index e412c092c1e8..8a227633a058 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -327,7 +327,8 @@ extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *); extern void force_sigsegv(int sig, struct task_struct *p); extern int force_sig_info(int, struct kernel_siginfo *, struct task_struct *); extern int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp); -extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid); +extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid, + bool expedite); extern int kill_pid_info_as_cred(int, struct kernel_siginfo *, struct pid *, const struct cred *); extern int kill_pgrp(struct pid *pid, int sig, int priv); diff --git a/include/linux/signal.h b/include/linux/signal.h index 9702016734b1..34b7852aa4a0 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -446,8 +446,17 @@ int __save_altstack(stack_t __user *, unsigned long); } while (0); #ifdef CONFIG_PROC_FS + +/* + * SS_FLAGS values used in pidfd_send_signal: + * + * SS_EXPEDITE indicates desire to expedite the operation. + */ +#define SS_EXPEDITE 0x00000001 + struct seq_file; extern void render_sigset_t(struct seq_file *, const char *, sigset_t *); -#endif + +#endif /* CONFIG_PROC_FS */ #endif /* _LINUX_SIGNAL_H */ diff --git a/ipc/mqueue.c b/ipc/mqueue.c index aea30530c472..27c66296e08e 100644 --- a/ipc/mqueue.c +++ b/ipc/mqueue.c @@ -720,7 +720,7 @@ static void __do_notify(struct mqueue_inode_info *info) rcu_read_unlock(); kill_pid_info(info->notify.sigev_signo, - &sig_i, info->notify_owner); + &sig_i, info->notify_owner, false); break; case SIGEV_THREAD: set_cookie(info->notify_cookie, NOTIFY_WOKENUP); diff --git a/kernel/signal.c b/kernel/signal.c index f98448cf2def..02ed4332d17c 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -43,6 +43,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -1394,7 +1395,8 @@ int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp) return success ? 0 : retval; } -int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid) +int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid, + bool expedite) { int error = -ESRCH; struct task_struct *p; @@ -1402,8 +1404,17 @@ int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid) for (;;) { rcu_read_lock(); p = pid_task(pid, PIDTYPE_PID); - if (p) + if (p) { error = group_send_sig_info(sig, info, p, PIDTYPE_TGID); + + /* + * Ignore expedite_reclaim return value, it is best + * effort only. + */ + if (!error && expedite) + expedite_reclaim(p); + } + rcu_read_unlock(); if (likely(!p || error != -ESRCH)) return error; @@ -1420,7 +1431,7 @@ static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid) { int error; rcu_read_lock(); - error = kill_pid_info(sig, info, find_vpid(pid)); + error = kill_pid_info(sig, info, find_vpid(pid), false); rcu_read_unlock(); return error; } @@ -1487,7 +1498,7 @@ static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid) if (pid > 0) { rcu_read_lock(); - ret = kill_pid_info(sig, info, find_vpid(pid)); + ret = kill_pid_info(sig, info, find_vpid(pid), false); rcu_read_unlock(); return ret; } @@ -1704,7 +1715,7 @@ EXPORT_SYMBOL(kill_pgrp); int kill_pid(struct pid *pid, int sig, int priv) { - return kill_pid_info(sig, __si_special(priv), pid); + return kill_pid_info(sig, __si_special(priv), pid, false); } EXPORT_SYMBOL(kill_pid); @@ -3577,10 +3588,20 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, struct pid *pid; kernel_siginfo_t kinfo; - /* Enforce flags be set to 0 until we add an extension. */ - if (flags) + /* Enforce no unknown flags. */ + if (flags & ~SS_EXPEDITE) return -EINVAL; + if (flags & SS_EXPEDITE) { + /* Enforce SS_EXPEDITE to be used with SIGKILL only. */ + if (sig != SIGKILL) + return -EINVAL; + + /* Limit expedited killing to privileged users only. */ + if (!capable(CAP_SYS_NICE)) + return -EPERM; + } + f = fdget_raw(pidfd); if (!f.file) return -EBADF; @@ -3614,7 +3635,7 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, prepare_kill_siginfo(sig, &kinfo); } - ret = kill_pid_info(sig, &kinfo, pid); + ret = kill_pid_info(sig, &kinfo, pid, (flags & SS_EXPEDITE) != 0); err: fdput(f); diff --git a/kernel/time/itimer.c b/kernel/time/itimer.c index 02068b2d5862..c926483cdb53 100644 --- a/kernel/time/itimer.c +++ b/kernel/time/itimer.c @@ -140,7 +140,7 @@ enum hrtimer_restart it_real_fn(struct hrtimer *timer) struct pid *leader_pid = sig->pids[PIDTYPE_TGID]; trace_itimer_expire(ITIMER_REAL, leader_pid, 0); - kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid); + kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid, false); return HRTIMER_NORESTART; } -- 2.21.0.392.gf8f6787159e-goog