From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752102AbaJSSKw (ORCPT ); Sun, 19 Oct 2014 14:10:52 -0400 Received: from karr.yath.de ([144.76.4.50]:44567 "EHLO karr.yath.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751902AbaJSSKu (ORCPT ); Sun, 19 Oct 2014 14:10:50 -0400 X-Greylist: delayed 321 seconds by postgrey-1.27 at vger.kernel.org; Sun, 19 Oct 2014 14:10:49 EDT Date: Sun, 19 Oct 2014 20:05:15 +0200 From: Sebastian Schmidt To: Anton Vorontsov , Colin Cross , Kees Cook , Tony Luck Cc: linux-kernel@vger.kernel.org Subject: [PATCH] pstore: honor dmesg_restrict sysctl on dmesg dumps Message-ID: <20141019180515.GA14661@moniac.lan.yath.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When the kernel.dmesg_restrict restriction is in place, only users with CAP_SYSLOG should be able to access crash dumps (like: attacker is trying to exploit a bug, watchdog reboots, attacker can happily read crash dumps and logs). This puts the restriction on console-* types as well as sensitive information could have been leaked there. Other log types are unaffected. Signed-off-by: Sebastian Schmidt --- fs/pstore/inode.c | 22 ++++++++++++++++++++++ include/linux/syslog.h | 1 + kernel/printk/printk.c | 2 +- 3 files changed, 24 insertions(+), 1 deletion(-) diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c index fafb7a0..5041660 100644 --- a/fs/pstore/inode.c +++ b/fs/pstore/inode.c @@ -36,6 +36,7 @@ #include #include #include +#include #include "internal.h" @@ -120,6 +121,18 @@ static const struct seq_operations pstore_ftrace_seq_ops = { .show = pstore_ftrace_seq_show, }; +static int pstore_check_syslog_permissions(struct pstore_private *ps) +{ + switch (ps->type) { + case PSTORE_TYPE_DMESG: + case PSTORE_TYPE_CONSOLE: + return check_syslog_permissions(SYSLOG_ACTION_READ_ALL, + SYSLOG_FROM_READER); + default: + return 0; + } +} + static ssize_t pstore_file_read(struct file *file, char __user *userbuf, size_t count, loff_t *ppos) { @@ -138,6 +151,10 @@ static int pstore_file_open(struct inode *inode, struct file *file) int err; const struct seq_operations *sops = NULL; + err = pstore_check_syslog_permissions(ps); + if (err) + return err; + if (ps->type == PSTORE_TYPE_FTRACE) sops = &pstore_ftrace_seq_ops; @@ -174,6 +191,11 @@ static const struct file_operations pstore_file_operations = { static int pstore_unlink(struct inode *dir, struct dentry *dentry) { struct pstore_private *p = dentry->d_inode->i_private; + int err; + + err = pstore_check_syslog_permissions(p); + if (err) + return err; if (p->psi->erase) p->psi->erase(p->type, p->id, p->count, diff --git a/include/linux/syslog.h b/include/linux/syslog.h index 98a3153..9def529 100644 --- a/include/linux/syslog.h +++ b/include/linux/syslog.h @@ -48,5 +48,6 @@ #define SYSLOG_FROM_PROC 1 int do_syslog(int type, char __user *buf, int count, bool from_file); +int check_syslog_permissions(int type, bool from_file); #endif /* _LINUX_SYSLOG_H */ diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index ced2b84..c8755e7 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -480,7 +480,7 @@ static int syslog_action_restricted(int type) type != SYSLOG_ACTION_SIZE_BUFFER; } -static int check_syslog_permissions(int type, bool from_file) +int check_syslog_permissions(int type, bool from_file) { /* * If this is from /proc/kmsg and we've already opened it, then we've -- 2.1.1