pstore: Honor dmesg_restrict sysctl on dmesg dumps
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 <yath@yath.de>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
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 <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
+#include <linux/syslog.h>
#include "internal.h"
@@ -120,6 +121,18 @@
.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 @@
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 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,
