From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-4.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_HI,T_RP_MATCHES_RCVD autolearn=unavailable autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 31F2D7E677 for ; Fri, 16 Mar 2018 18:18:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752209AbeCPSRd (ORCPT ); Fri, 16 Mar 2018 14:17:33 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:44542 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752914AbeCPSOf (ORCPT ); Fri, 16 Mar 2018 14:14:35 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4EAEED144C; Fri, 16 Mar 2018 18:14:34 +0000 (UTC) Received: from llong.com (dhcp-17-75.bos.redhat.com [10.18.17.75]) by smtp.corp.redhat.com (Postfix) with ESMTP id 06A25202322B; Fri, 16 Mar 2018 18:14:34 +0000 (UTC) From: Waiman Long To: "Luis R. Rodriguez" , Kees Cook Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, Jonathan Corbet , Andrew Morton , Al Viro , Matthew Wilcox , "Eric W. Biederman" , Waiman Long Subject: [PATCH v5 5/9] ipc: Clamp semmni to the real IPCMNI limit Date: Fri, 16 Mar 2018 14:13:46 -0400 Message-Id: <1521224030-2185-6-git-send-email-longman@redhat.com> In-Reply-To: <1521224030-2185-1-git-send-email-longman@redhat.com> References: <1521224030-2185-1-git-send-email-longman@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 16 Mar 2018 18:14:34 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 16 Mar 2018 18:14:34 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'longman@redhat.com' RCPT:'' Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org For SysV semaphores, the semmni value is the last part of the 4-element sem number array. To make semmni behave in a similar way to msgmni and shmmni, we can't directly use the _minmax handler. Instead, a special sem specific handler is added to check the last argument to make sure that it is clamped to the [0, IPCMNI] range and prints a warning message once when an out-of-range value is being written. This does require duplicating some of the code in the _minmax handlers. Signed-off-by: Waiman Long --- ipc/ipc_sysctl.c | 12 +++++++++++- ipc/sem.c | 25 +++++++++++++++++++++++++ ipc/util.h | 4 ++++ 3 files changed, 40 insertions(+), 1 deletion(-) diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c index 088721e..0ad7088 100644 --- a/ipc/ipc_sysctl.c +++ b/ipc/ipc_sysctl.c @@ -88,12 +88,22 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table, int write, return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos); } +static int proc_ipc_sem_dointvec(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, loff_t *ppos) +{ + int ret = proc_ipc_dointvec(table, write, buffer, lenp, ppos); + + sem_check_semmni(table, current->nsproxy->ipc_ns); + return ret; +} + #else #define proc_ipc_doulongvec_minmax NULL #define proc_ipc_dointvec NULL #define proc_ipc_dointvec_minmax NULL #define proc_ipc_dointvec_minmax_orphans NULL #define proc_ipc_auto_msgmni NULL +#define proc_ipc_sem_dointvec NULL #endif static int zero; @@ -177,7 +187,7 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table, int write, .data = &init_ipc_ns.sem_ctls, .maxlen = 4*sizeof(int), .mode = 0644, - .proc_handler = proc_ipc_dointvec, + .proc_handler = proc_ipc_sem_dointvec, }, #ifdef CONFIG_CHECKPOINT_RESTORE { diff --git a/ipc/sem.c b/ipc/sem.c index a4af049..faf2caa 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -2337,3 +2337,28 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it) return 0; } #endif + +#ifdef CONFIG_PROC_SYSCTL +/* + * Check to see if semmni is out of range and clamp it if necessary. + */ +void sem_check_semmni(struct ctl_table *table, struct ipc_namespace *ns) +{ + bool clamped = false; + + /* + * Clamp semmni to the range [0, IPCMNI]. + */ + if (ns->sc_semmni < 0) { + ns->sc_semmni = 0; + clamped = true; + } + if (ns->sc_semmni > IPCMNI) { + ns->sc_semmni = IPCMNI; + clamped = true; + } + if (clamped) + pr_warn_ratelimited("sysctl: \"sem[3]\" was set out of range [%d, %d], clamped to %d.\n", + 0, IPCMNI, ns->sc_semmni); +} +#endif diff --git a/ipc/util.h b/ipc/util.h index 89b8ec1..af57394 100644 --- a/ipc/util.h +++ b/ipc/util.h @@ -206,6 +206,10 @@ int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids, void (*free)(struct ipc_namespace *, struct kern_ipc_perm *)); +#ifdef CONFIG_PROC_SYSCTL +extern void sem_check_semmni(struct ctl_table *table, struct ipc_namespace *ns); +#endif + #ifdef CONFIG_COMPAT #include struct compat_ipc_perm { -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html