From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:48160 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1759291AbeD0VAy (ORCPT ); Fri, 27 Apr 2018 17:00:54 -0400 From: Waiman Long To: "Luis R. Rodriguez" , Kees Cook , Andrew Morton , Jonathan Corbet Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, Al Viro , Matthew Wilcox , "Eric W. Biederman" , Waiman Long Subject: [PATCH v6 5/8] ipc: Clamp semmni to the real IPCMNI limit Date: Fri, 27 Apr 2018 17:00:35 -0400 Message-Id: <1524862838-8247-6-git-send-email-longman@redhat.com> In-Reply-To: <1524862838-8247-1-git-send-email-longman@redhat.com> References: <1524862838-8247-1-git-send-email-longman@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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 d71f949..478e634 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 06be75d..96bdec6 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -2397,3 +2397,28 @@ 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 acc5159..7c20871 100644 --- a/ipc/util.h +++ b/ipc/util.h @@ -218,6 +218,10 @@ 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