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selinux: fix case of names with whitespace/multibytes on /selinux/create

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I submit the patch again, according to patch submission convension.

This patch enables to accept percent-encoded object names as forth
argument of /selinux/create interface to avoid possible bugs when we
give an object name including whitespace or multibutes.

E.g) if and when a userspace object manager tries to create a new object
 named as "resolve.conf but fake", it shall give this name as the forth
 argument of the /selinux/create. But sscanf() logic in kernel space
 fetches only the part earlier than the first whitespace.
 In this case, selinux may unexpectedly answer a default security context
 configured to "resolve.conf", but it is bug.

Although I could not test this patch on named TYPE_TRANSITION rules
actually, But debug printk() message seems to me the logic works
correctly.
I assume the libselinux provides an interface to apply this logic
transparently, so nothing shall not be changed from the viewpoint of
application.

Signed-off-by: KaiGai Kohei <kohei.kaigai@emea.nec.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
This commit is contained in:
Kohei Kaigai 2011-05-26 14:59:25 -04:00 committed by Eric Paris
parent ea77f7a2e8
commit 0f7e4c33eb
1 changed files with 36 additions and 1 deletions
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37
security/selinux/selinuxfs.c
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@ -29,6 +29,7 @@
#include <linux/audit.h>
#include <linux/uaccess.h>
#include <linux/kobject.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. */
@ -751,6 +752,14 @@ 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;
@ -785,8 +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)