Update dmesg_restrict patch to v2
This commit is contained in:
Josh Boyer
parent
967548beda
commit
078da2408e
@ -1,46 +1,162 @@
|
|||||||
From feaf4959c30d0640093a607c577940d3e9351076 Mon Sep 17 00:00:00 2001
|
From ce10d1b72b4da3c98bbbcb1b945687d964c31923 Mon Sep 17 00:00:00 2001
|
||||||
From: Josh Boyer <jwboyer@redhat.com>
|
From: Josh Boyer <jwboyer@redhat.com>
|
||||||
Date: Fri, 22 Feb 2013 11:47:37 -0500
|
Date: Tue, 9 Apr 2013 11:08:13 -0400
|
||||||
Subject: [PATCH] kmsg: Honor dmesg_restrict sysctl on /dev/kmsg
|
Subject: [PATCH] kmsg: Honor dmesg_restrict sysctl on /dev/kmsg
|
||||||
|
|
||||||
Originally, the addition of the dmesg_restrict covered both the syslog
|
The dmesg_restrict sysctl currently covers the syslog method for access
|
||||||
method of accessing dmesg, as well as /dev/kmsg itself. This was done
|
dmesg, however /dev/kmsg isn't covered by the same protections. Most
|
||||||
indirectly by security_syslog calling cap_syslog before doing any LSM
|
people haven't noticed because util-linux dmesg(1) defaults to using the
|
||||||
checks.
|
syslog method for access in older versions. With util-linux dmesg(1)
|
||||||
|
defaults to reading directly from /dev/kmsg.
|
||||||
|
|
||||||
However, commit 12b3052c3ee (capabilities/syslog: open code cap_syslog
|
Fix this by reworking all of the access methods to use the
|
||||||
logic to fix build failure) moved the code around and pushed the checks
|
check_syslog_permissions function and adding checks to devkmsg_open and
|
||||||
into the caller itself. That seems to have inadvertently dropped the
|
devkmsg_read.
|
||||||
checks for dmesg_restrict on /dev/kmsg. Most people haven't noticed
|
|
||||||
because util-linux dmesg(1) defaults to using the syslog method for
|
|
||||||
access in older versions. With util-linux 2.22 and a kernel newer than
|
|
||||||
3.5, dmesg(1) defaults to reading directly from /dev/kmsg.
|
|
||||||
|
|
||||||
Fix this by making an explicit check in the devkmsg_open function.
|
|
||||||
|
|
||||||
This fixes https://bugzilla.redhat.com/show_bug.cgi?id=903192
|
This fixes https://bugzilla.redhat.com/show_bug.cgi?id=903192
|
||||||
|
|
||||||
Reported-by: Christian Kujau <lists@nerdbynature.de>
|
Reported-by: Christian Kujau <lists@nerdbynature.de>
|
||||||
CC: stable@vger.kernel.org
|
CC: stable@vger.kernel.org
|
||||||
|
Signed-off-by: Eric Paris <eparis@redhat.com>
|
||||||
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
|
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
|
||||||
---
|
---
|
||||||
kernel/printk.c | 3 +++
|
kernel/printk.c | 91 +++++++++++++++++++++++++++++----------------------------
|
||||||
1 file changed, 3 insertions(+)
|
1 file changed, 47 insertions(+), 44 deletions(-)
|
||||||
|
|
||||||
diff --git a/kernel/printk.c b/kernel/printk.c
|
diff --git a/kernel/printk.c b/kernel/printk.c
|
||||||
index f24633a..398ef9a 100644
|
index abbdd9e..5541095 100644
|
||||||
--- a/kernel/printk.c
|
--- a/kernel/printk.c
|
||||||
+++ b/kernel/printk.c
|
+++ b/kernel/printk.c
|
||||||
@@ -615,6 +615,9 @@ static int devkmsg_open(struct inode *inode, struct file *file)
|
@@ -368,6 +368,46 @@ static void log_store(int facility, int level,
|
||||||
struct devkmsg_user *user;
|
log_next_seq++;
|
||||||
int err;
|
}
|
||||||
|
|
||||||
+ if (dmesg_restrict && !capable(CAP_SYSLOG))
|
+#ifdef CONFIG_SECURITY_DMESG_RESTRICT
|
||||||
+ return -EACCES;
|
+int dmesg_restrict = 1;
|
||||||
|
+#else
|
||||||
|
+int dmesg_restrict;
|
||||||
|
+#endif
|
||||||
+
|
+
|
||||||
/* write-only does not need any file context */
|
+static int syslog_action_restricted(int type)
|
||||||
|
+{
|
||||||
|
+ if (dmesg_restrict)
|
||||||
|
+ return 1;
|
||||||
|
+ /* Unless restricted, we allow "read all" and "get buffer size" for everybody */
|
||||||
|
+ return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER;
|
||||||
|
+}
|
||||||
|
+
|
||||||
|
+static int check_syslog_permissions(int type, bool from_file)
|
||||||
|
+{
|
||||||
|
+ /*
|
||||||
|
+ * If this is from /proc/kmsg and we've already opened it, then we've
|
||||||
|
+ * already done the capabilities checks at open time.
|
||||||
|
+ */
|
||||||
|
+ if (from_file && type != SYSLOG_ACTION_OPEN)
|
||||||
|
+ goto ok;
|
||||||
|
+
|
||||||
|
+ if (syslog_action_restricted(type)) {
|
||||||
|
+ if (capable(CAP_SYSLOG))
|
||||||
|
+ goto ok;
|
||||||
|
+ /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */
|
||||||
|
+ if (capable(CAP_SYS_ADMIN)) {
|
||||||
|
+ printk_once(KERN_WARNING "%s (%d): "
|
||||||
|
+ "Attempt to access syslog with CAP_SYS_ADMIN "
|
||||||
|
+ "but no CAP_SYSLOG (deprecated).\n",
|
||||||
|
+ current->comm, task_pid_nr(current));
|
||||||
|
+ goto ok;
|
||||||
|
+ }
|
||||||
|
+ return -EPERM;
|
||||||
|
+ }
|
||||||
|
+ok:
|
||||||
|
+ return security_syslog(type);
|
||||||
|
+}
|
||||||
|
+
|
||||||
|
/* /dev/kmsg - userspace message inject/listen interface */
|
||||||
|
struct devkmsg_user {
|
||||||
|
u64 seq;
|
||||||
|
@@ -443,10 +483,16 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
|
||||||
|
char cont = '-';
|
||||||
|
size_t len;
|
||||||
|
ssize_t ret;
|
||||||
|
+ int err;
|
||||||
|
|
||||||
|
if (!user)
|
||||||
|
return -EBADF;
|
||||||
|
|
||||||
|
+ err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
|
||||||
|
+ SYSLOG_FROM_FILE);
|
||||||
|
+ if (err)
|
||||||
|
+ return err;
|
||||||
|
+
|
||||||
|
ret = mutex_lock_interruptible(&user->lock);
|
||||||
|
if (ret)
|
||||||
|
return ret;
|
||||||
|
@@ -624,7 +670,7 @@ static int devkmsg_open(struct inode *inode, struct file *file)
|
||||||
if ((file->f_flags & O_ACCMODE) == O_WRONLY)
|
if ((file->f_flags & O_ACCMODE) == O_WRONLY)
|
||||||
return 0;
|
return 0;
|
||||||
--
|
|
||||||
1.8.1.2
|
- err = security_syslog(SYSLOG_ACTION_READ_ALL);
|
||||||
|
+ err = check_syslog_permissions(SYSLOG_ACTION_OPEN, SYSLOG_FROM_FILE);
|
||||||
|
if (err)
|
||||||
|
return err;
|
||||||
|
|
||||||
|
@@ -817,45 +863,6 @@ static inline void boot_delay_msec(int level)
|
||||||
|
}
|
||||||
|
#endif
|
||||||
|
|
||||||
|
-#ifdef CONFIG_SECURITY_DMESG_RESTRICT
|
||||||
|
-int dmesg_restrict = 1;
|
||||||
|
-#else
|
||||||
|
-int dmesg_restrict;
|
||||||
|
-#endif
|
||||||
|
-
|
||||||
|
-static int syslog_action_restricted(int type)
|
||||||
|
-{
|
||||||
|
- if (dmesg_restrict)
|
||||||
|
- return 1;
|
||||||
|
- /* Unless restricted, we allow "read all" and "get buffer size" for everybody */
|
||||||
|
- return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER;
|
||||||
|
-}
|
||||||
|
-
|
||||||
|
-static int check_syslog_permissions(int type, bool from_file)
|
||||||
|
-{
|
||||||
|
- /*
|
||||||
|
- * If this is from /proc/kmsg and we've already opened it, then we've
|
||||||
|
- * already done the capabilities checks at open time.
|
||||||
|
- */
|
||||||
|
- if (from_file && type != SYSLOG_ACTION_OPEN)
|
||||||
|
- return 0;
|
||||||
|
-
|
||||||
|
- if (syslog_action_restricted(type)) {
|
||||||
|
- if (capable(CAP_SYSLOG))
|
||||||
|
- return 0;
|
||||||
|
- /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */
|
||||||
|
- if (capable(CAP_SYS_ADMIN)) {
|
||||||
|
- printk_once(KERN_WARNING "%s (%d): "
|
||||||
|
- "Attempt to access syslog with CAP_SYS_ADMIN "
|
||||||
|
- "but no CAP_SYSLOG (deprecated).\n",
|
||||||
|
- current->comm, task_pid_nr(current));
|
||||||
|
- return 0;
|
||||||
|
- }
|
||||||
|
- return -EPERM;
|
||||||
|
- }
|
||||||
|
- return 0;
|
||||||
|
-}
|
||||||
|
-
|
||||||
|
#if defined(CONFIG_PRINTK_TIME)
|
||||||
|
static bool printk_time = 1;
|
||||||
|
#else
|
||||||
|
@@ -1131,10 +1138,6 @@ int do_syslog(int type, char __user *buf, int len, bool from_file)
|
||||||
|
if (error)
|
||||||
|
goto out;
|
||||||
|
|
||||||
|
- error = security_syslog(type);
|
||||||
|
- if (error)
|
||||||
|
- return error;
|
||||||
|
-
|
||||||
|
switch (type) {
|
||||||
|
case SYSLOG_ACTION_CLOSE: /* Close log */
|
||||||
|
break;
|
||||||
|
--
|
||||||
|
1.8.1.4
|
||||||
|
|
||||||
|
|||||||
Loading…
Reference in New Issue
Block a user