[PATCH 3/3] selinux: expose policy SHA256 checksum via selinuxfs

[Sebastien Buisson]

Expose policy SHA256 checksum via selinuxfs.

Signed-off-by: Sebastien Buisson <sbuis...@ddn.com>
---
 security/selinux/selinuxfs.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index ce71718..b2d5deb 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -30,6 +30,7 @@
 #include <linux/uaccess.h>
 #include <linux/kobject.h>
 #include <linux/ctype.h>
+#include <crypto/sha.h>
 
 /* selinuxfs pseudo filesystem for exporting the security policy API.
    Based on the proc code and the fs/nfsd/nfsctl.c code. */
@@ -99,6 +100,7 @@ enum sel_inos {
        SEL_STATUS,     /* export current status using mmap() */
        SEL_POLICY,     /* allow userspace to read the in kernel policy */
        SEL_VALIDATE_TRANS, /* compute validatetrans decision */
+       SEL_POLICYCKSUM,/* return policy SHA256 checkum */
        SEL_INO_NEXT,   /* The next inode number to use */
 };
 
@@ -313,6 +315,22 @@ static ssize_t sel_read_policyvers(struct file *filp, char 
__user *buf,
        .llseek         = generic_file_llseek,
 };
 
+static ssize_t sel_read_policycksum(struct file *filp, char __user *buf,
+                                   size_t count, loff_t *ppos)
+{
+       size_t tmpbuflen = SHA256_DIGEST_SIZE*2 + 1;
+       char tmpbuf[tmpbuflen];
+       ssize_t length;
+
+       length = security_policydb_cksum(tmpbuf, tmpbuflen);
+       return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
+}
+
+static const struct file_operations sel_policycksum_ops = {
+       .read           = sel_read_policycksum,
+       .llseek         = generic_file_llseek,
+};
+
 /* declaration for sel_write_load */
 static int sel_make_bools(void);
 static int sel_make_classes(void);
@@ -1825,6 +1843,8 @@ static int sel_fill_super(struct super_block *sb, void 
*data, int silent)
                [SEL_POLICY] = {"policy", &sel_policy_ops, S_IRUGO},
                [SEL_VALIDATE_TRANS] = {"validatetrans", &sel_transition_ops,
                                        S_IWUGO},
+               [SEL_POLICYCKSUM] = {"policycksum", &sel_policycksum_ops,
+                                    S_IRUGO},
                /* last one */ {""}
        };
        ret = simple_fill_super(sb, SELINUX_MAGIC, selinux_files);
-- 
1.8.3.1