Kohei KaiGai wrote:
This patch allows to accept percent-encoded object name as the forth
argument of /selinux/create interface to avoid possible bugs when we
supply an object name that includes whitespace or multibytes.
Why not use standard bash escaping instead of html entities?
Although I could not test this patch on named TYPE_TRANSITION rules,
but printk() messages for debugging seems to me the logic works correctly.
I assume the libselinux provide the logic to encode object name, so it shall
be applied transparently for the viewpoint of application.
Signed-off-by: KaiGai Kohei<kohei.kaigai@xxxxxxxxxx>
---
security/selinux/selinuxfs.c | 38 +++++++++++++++++++++++++++++++++++++-
1 files changed, 37 insertions(+), 1 deletions(-)
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index 973f5a4..4fde279 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -28,6 +28,7 @@
#include<linux/percpu.h>
#include<linux/audit.h>
#include<linux/uaccess.h>
+#include<linux/ctype.h>
/* selinuxfs pseudo filesystem for exporting the security policy API.
Based on the proc code and the fs/nfsd/nfsctl.c code. */
@@ -750,6 +751,15 @@ out:
return length;
}
+static inline int hexcode_to_int(int code)
+{
+ if (code == '\0' || !isxdigit(code))
+ return -1;
+ if (isdigit(code))
+ return code - '0';
+ return tolower(code) - 'a' + 10;
+}
+
static ssize_t sel_write_create(struct file *file, char *buf, size_t size)
{
char *scon = NULL, *tcon = NULL;
@@ -784,8 +794,34 @@ static ssize_t sel_write_create(struct file
*file, char *buf, size_t size)
nargs = sscanf(buf, "%s %s %hu %s", scon, tcon,&tclass, namebuf);
if (nargs< 3 || nargs> 4)
goto out;
- if (nargs == 4)
+ if (nargs == 4) {
+ /*
+ * If and when the name of new object to be queried contains
+ * either whitespace or multibyte characters, they shall be
+ * encoded based on the percentage-encoding rule.
+ * If not encoded, the sscanf logic picks up only left-half
+ * of the supplied name; splitted by a whitespace unexpectedly.
+ */
+ char *r, *w;
+ int c1, c2;
+
+ r = w = namebuf;
+ do {
+ c1 = *r++;
+ if (c1 == '+')
+ c1 = ' ';
+ else if (c1 == '%') {
+ if ((c1 = hexcode_to_int(*r++))< 0)
+ goto out;
+ if ((c2 = hexcode_to_int(*r++))< 0)
+ goto out;
+ c1 = (c1<< 4) | c2;
+ }
+ *w++ = c1;
+ } while (c1 != '\0');
+
objname = namebuf;
+ }
length = security_context_to_sid(scon, strlen(scon) + 1,&ssid);
if (length)
--
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