[PATCH] Smack: SMACK_IOCLOADACCESS

Jarkko Sakkinen
2011-08-26T05:52:38Z

IOCTL call for /smack/load that takes access rule in
the same format as they are written into /smack/load.
Sets errno to zero if access is allowed and to EACCES
if not.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
---
include/linux/smack.h | 29 ++++++++
security/smack/smack.h | 1 +
security/smack/smackfs.c | 173 +++++++++++++++++++++++++++++-----------------
3 files changed, 140 insertions(+), 63 deletions(-)
create mode 100644 include/linux/smack.h

diff --git a/include/linux/smack.h b/include/linux/smack.h
new file mode 100644
index 0000000..c574713
--- /dev/null
+++ b/include/linux/smack.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2011, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Author:
+ * Jarkko Sakkinen <jarkko.sakkinen@intel.com>
+ *
+ */
+
+#ifndef _SMACK_H
+#define _SMACK_H
+
+#define SMACK_IOC_BASE 'S'
+#define SMACK_IOC_LOAD_ACCESS _IOR(SMACK_IOC_BASE, 0, const char *)
+
+#endif /* _SMACK_H */
diff --git a/security/smack/smack.h b/security/smack/smack.h
index 2b6c6a5..82c5a30 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -189,6 +189,7 @@ struct smk_audit_info {
struct common_audit_data a;
#endif
};
+
/*
* These functions are in smack_lsm.c
*/
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index f934601..68168d0 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -27,6 +27,7 @@
#include <linux/seq_file.h>
#include <linux/ctype.h>
#include <linux/audit.h>
+#include <linux/smack.h>
#include "smack.h"

/*
@@ -176,71 +177,19 @@ static int smk_set_access(struct smack_rule *srp, struct list_head *rule_list,
}

/**
- * smk_write_load_list - write() for any /smack/load
- * @file: file pointer, not actually used
- * @buf: where to get the data from
- * @count: bytes sent
- * @ppos: where to start - must be 0
- * @rule_list: the list of rules to write to
- * @rule_lock: lock for the rule list
- *
- * Get one smack access rule from above.
- * The format is exactly:
- * char subject[SMK_LABELLEN]
- * char object[SMK_LABELLEN]
- * char access[SMK_ACCESSLEN]
- *
- * writes must be SMK_LABELLEN+SMK_LABELLEN+SMK_ACCESSLEN bytes.
+ * smk_parse_rule - parse subject, object and access type
+ * @data: string to be parsed whose size is SMK_LOADLEN
+ * @rule: parsed entities are stored in here
*/
-static ssize_t smk_write_load_list(struct file *file, const char __user *buf,
- size_t count, loff_t *ppos,
- struct list_head *rule_list,
- struct mutex *rule_lock)
+static int smk_parse_rule(const char *data, struct smack_rule *rule)
{
- struct smack_rule *rule;
- char *data;
- int rc = -EINVAL;
-
- /*
- * No partial writes.
- * Enough data must be present.
- */
- if (*ppos != 0)
- return -EINVAL;
- /*
- * Minor hack for backward compatibility
- */
- if (count < (SMK_OLOADLEN) || count > SMK_LOADLEN)
- return -EINVAL;
-
- data = kzalloc(SMK_LOADLEN, GFP_KERNEL);
- if (data == NULL)
- return -ENOMEM;
-
- if (copy_from_user(data, buf, count) != 0) {
- rc = -EFAULT;
- goto out;
- }
-
- /*
- * More on the minor hack for backward compatibility
- */
- if (count == (SMK_OLOADLEN))
- data[SMK_OLOADLEN] = '-';
-
- rule = kzalloc(sizeof(*rule), GFP_KERNEL);
- if (rule == NULL) {
- rc = -ENOMEM;
- goto out;
- }
-
rule->smk_subject = smk_import(data, 0);
if (rule->smk_subject == NULL)
- goto out_free_rule;
+ return -1;

rule->smk_object = smk_import(data + SMK_LABELLEN, 0);
if (rule->smk_object == NULL)
- goto out_free_rule;
+ return -1;

rule->smk_access = 0;

@@ -252,7 +201,7 @@ static ssize_t smk_write_load_list(struct file *file, const char __user *buf,
rule->smk_access |= MAY_READ;
break;
default:
- goto out_free_rule;
+ return -1;
}

switch (data[SMK_LABELLEN + SMK_LABELLEN + 1]) {
@@ -263,7 +212,7 @@ static ssize_t smk_write_load_list(struct file *file, const char __user *buf,
rule->smk_access |= MAY_WRITE;
break;
default:
- goto out_free_rule;
+ return -1;
}

switch (data[SMK_LABELLEN + SMK_LABELLEN + 2]) {
@@ -274,7 +223,7 @@ static ssize_t smk_write_load_list(struct file *file, const char __user *buf,
rule->smk_access |= MAY_EXEC;
break;
default:
- goto out_free_rule;
+ return -1;
}

switch (data[SMK_LABELLEN + SMK_LABELLEN + 3]) {
@@ -285,7 +234,7 @@ static ssize_t smk_write_load_list(struct file *file, const char __user *buf,
rule->smk_access |= MAY_APPEND;
break;
default:
- goto out_free_rule;
+ return -1;
}

switch (data[SMK_LABELLEN + SMK_LABELLEN + 4]) {
@@ -296,9 +245,74 @@ static ssize_t smk_write_load_list(struct file *file, const char __user *buf,
rule->smk_access |= MAY_TRANSMUTE;
break;
default:
- goto out_free_rule;
+ return -1;
+ }
+
+ return 0;
+}
+
+/**
+ * smk_write_load_list - write() for any /smack/load
+ * @file: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start - must be 0
+ * @rule_list: the list of rules to write to
+ * @rule_lock: lock for the rule list
+ *
+ * Get one smack access rule from above.
+ * The format is exactly:
+ * char subject[SMK_LABELLEN]
+ * char object[SMK_LABELLEN]
+ * char access[SMK_ACCESSLEN]
+ *
+ * writes must be SMK_LABELLEN+SMK_LABELLEN+SMK_ACCESSLEN bytes.
+ */
+static ssize_t smk_write_load_list(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos,
+ struct list_head *rule_list,
+ struct mutex *rule_lock)
+{
+ struct smack_rule *rule;
+ char *data;
+ int rc = -EINVAL;
+
+ /*
+ * No partial writes.
+ * Enough data must be present.
+ */
+ if (*ppos != 0)
+ return -EINVAL;
+ /*
+ * Minor hack for backward compatibility
+ */
+ if (count < (SMK_OLOADLEN) || count > SMK_LOADLEN)
+ return -EINVAL;
+
+ data = kzalloc(SMK_LOADLEN, GFP_KERNEL);
+ if (data == NULL)
+ return -ENOMEM;
+
+ if (copy_from_user(data, buf, count) != 0) {
+ rc = -EFAULT;
+ goto out;
+ }
+
+ /*
+ * More on the minor hack for backward compatibility
+ */
+ if (count == (SMK_OLOADLEN))
+ data[SMK_OLOADLEN] = '-';
+
+ rule = kzalloc(sizeof(*rule), GFP_KERNEL);
+ if (rule == NULL) {
+ rc = -ENOMEM;
+ goto out;
}

+ if (smk_parse_rule(data, rule))
+ goto out_free_rule;
+
rc = count;
/*
* smk_set_access returns true if there was already a rule
@@ -416,12 +430,45 @@ static ssize_t smk_write_load(struct file *file, const char __user *buf,
&smack_list_lock);
}

+/**
+ * smk_ioctl_load - ioctl() for /smack/load
+ * @file: file pointer, not actually used
+ * @cmd: IOCTL command
+ * @arg: IOCTL command argument
+ */
+static long smk_ioctl_load(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ char data[SMK_LOADLEN];
+ struct smack_rule rule;
+
+ /* Currently we have only single IOCTL command supported */
+ if (cmd != SMACK_IOC_LOAD_ACCESS)
+ return -ENOTTY;
+
+ if (!capable(CAP_MAC_ADMIN))
+ return -EPERM;
+
+ if (copy_from_user(data, (const char __user *)arg, SMK_LOADLEN))
+ return -EFAULT;
+
+ if (smk_parse_rule(data, &rule))
+ return -EINVAL;
+
+ if (smk_access(rule.smk_subject, rule.smk_object,
+ rule.smk_access, NULL) != 0)
+ return -EACCES;
+
+ return 0;
+}
+
static const struct file_operations smk_load_ops = {
.open = smk_open_load,
.read = seq_read,
.llseek = seq_lseek,
.write = smk_write_load,
.release = seq_release,
+ .unlocked_ioctl = smk_ioctl_load,
};

/**
--
1.7.4.1