Smack: Make the syslog control configurable
The syslog control requires that the calling proccess
have the floor ("_") Smack label. Tizen does not run any
processes except for kernel helpers with the floor label.
This changes allows the admin to configure a specific
label for syslog. The default value is the star ("*")
label, effectively removing the restriction. The value
can be set using smackfs/syslog for anyone who wants
a more restrictive behavior.
Targeted for git://git.gitorious.org/smack-next/kernel.git
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 1c89ade..f5a6bb8 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -52,6 +52,7 @@
SMK_CIPSO2 = 17, /* load long label -> CIPSO mapping */
SMK_REVOKE_SUBJ = 18, /* set rules with subject label to '-' */
SMK_CHANGE_RULE = 19, /* change or add rules (long labels) */
+ SMK_SYSLOG = 20, /* change syslog label) */
};
/*
@@ -59,6 +60,7 @@
*/
static DEFINE_MUTEX(smack_cipso_lock);
static DEFINE_MUTEX(smack_ambient_lock);
+static DEFINE_MUTEX(smack_syslog_lock);
static DEFINE_MUTEX(smk_netlbladdr_lock);
/*
@@ -90,7 +92,13 @@
* everyone. It is expected that the hat (^) label
* will be used if any label is used.
*/
-char *smack_onlycap;
+struct smack_known *smack_onlycap;
+
+/*
+ * If this value is set restrict syslog use to the label specified.
+ * It can be reset via smackfs/syslog
+ */
+struct smack_known *smack_syslog_label;
/*
* Certain IP addresses may be designated as single label hosts.
@@ -1603,7 +1611,7 @@
};
/**
- * smk_read_onlycap - read() for /smack/onlycap
+ * smk_read_onlycap - read() for smackfs/onlycap
* @filp: file pointer, not actually used
* @buf: where to put the result
* @cn: maximum to send along
@@ -1622,7 +1630,7 @@
return 0;
if (smack_onlycap != NULL)
- smack = smack_onlycap;
+ smack = smack_onlycap->smk_known;
asize = strlen(smack) + 1;
@@ -1633,7 +1641,7 @@
}
/**
- * smk_write_onlycap - write() for /smack/onlycap
+ * smk_write_onlycap - write() for smackfs/onlycap
* @file: file pointer, not actually used
* @buf: where to get the data from
* @count: bytes sent
@@ -1656,7 +1664,7 @@
* explicitly for clarity. The smk_access() implementation
* would use smk_access(smack_onlycap, MAY_WRITE)
*/
- if (smack_onlycap != NULL && smack_onlycap != skp->smk_known)
+ if (smack_onlycap != NULL && smack_onlycap != skp)
return -EPERM;
data = kzalloc(count, GFP_KERNEL);
@@ -1676,7 +1684,7 @@
if (copy_from_user(data, buf, count) != 0)
rc = -EFAULT;
else
- smack_onlycap = smk_import(data, count);
+ smack_onlycap = smk_import_entry(data, count);
kfree(data);
return rc;
@@ -2159,12 +2167,89 @@
};
/**
- * smk_fill_super - fill the /smackfs superblock
+ * smk_read_syslog - read() for smackfs/syslog
+ * @filp: file pointer, not actually used
+ * @buf: where to put the result
+ * @cn: maximum to send along
+ * @ppos: where to start
+ *
+ * Returns number of bytes read or error code, as appropriate
+ */
+static ssize_t smk_read_syslog(struct file *filp, char __user *buf,
+ size_t cn, loff_t *ppos)
+{
+ struct smack_known *skp;
+ ssize_t rc = -EINVAL;
+ int asize;
+
+ if (*ppos != 0)
+ return 0;
+
+ if (smack_syslog_label == NULL)
+ skp = &smack_known_star;
+ else
+ skp = smack_syslog_label;
+
+ asize = strlen(skp->smk_known) + 1;
+
+ if (cn >= asize)
+ rc = simple_read_from_buffer(buf, cn, ppos, skp->smk_known,
+ asize);
+
+ return rc;
+}
+
+/**
+ * smk_write_syslog - write() for smackfs/syslog
+ * @file: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start
+ *
+ * Returns number of bytes written or error code, as appropriate
+ */
+static ssize_t smk_write_syslog(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ char *data;
+ struct smack_known *skp;
+ int rc = count;
+
+ if (!smack_privileged(CAP_MAC_ADMIN))
+ return -EPERM;
+
+ data = kzalloc(count, GFP_KERNEL);
+ if (data == NULL)
+ return -ENOMEM;
+
+ if (copy_from_user(data, buf, count) != 0)
+ rc = -EFAULT;
+ else {
+ skp = smk_import_entry(data, count);
+ if (skp == NULL)
+ rc = -EINVAL;
+ else
+ smack_syslog_label = smk_import_entry(data, count);
+ }
+
+ kfree(data);
+ return rc;
+}
+
+static const struct file_operations smk_syslog_ops = {
+ .read = smk_read_syslog,
+ .write = smk_write_syslog,
+ .llseek = default_llseek,
+};
+
+
+/**
+ * smk_fill_super - fill the smackfs superblock
* @sb: the empty superblock
* @data: unused
* @silent: unused
*
- * Fill in the well known entries for /smack
+ * Fill in the well known entries for the smack filesystem
*
* Returns 0 on success, an error code on failure
*/
@@ -2209,6 +2294,8 @@
S_IRUGO|S_IWUSR},
[SMK_CHANGE_RULE] = {
"change-rule", &smk_change_rule_ops, S_IRUGO|S_IWUSR},
+ [SMK_SYSLOG] = {
+ "syslog", &smk_syslog_ops, S_IRUGO|S_IWUSR},
/* last one */
{""}
};