integrity: define a new function integrity_read_file()

This patch defines a new function called integrity_read_file()
to read file from the kernel into a buffer. Subsequent patches
will read a file containing the public keys and load them onto
the IMA keyring.

This patch moves and renames ima_kernel_read(), the non-security
checking version of kernel_read(), to integrity_kernel_read().

Changes in v3:
* Patch descriptions improved (Mimi)
* Add missing cast (kbuild test robot)

Changes in v2:
* configuration option removed
* function declared as '__init'

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

diff --git a/security/integrity/iint.c b/security/integrity/iint.c
index cc3eb4de18a1c14787dd44d2a3a5d9f98b225271..dbee618526b673e3e828ea452de4ad9ba82e2a12 100644 (file)
--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c
@@ -19,6 +19,8 @@
 #include <linux/module.h>
 #include <linux/spinlock.h>
 #include <linux/rbtree.h>
+#include <linux/file.h>
+#include <linux/uaccess.h>
 #include "integrity.h"
 
 static struct rb_root integrity_iint_tree = RB_ROOT;
@@ -167,3 +169,79 @@ static int __init integrity_iintcache_init(void)
        return 0;
 }
 security_initcall(integrity_iintcache_init);
+
+
+/*
+ * integrity_kernel_read - read data from the file
+ *
+ * This is a function for reading file content instead of kernel_read().
+ * It does not perform locking checks to ensure it cannot be blocked.
+ * It does not perform security checks because it is irrelevant for IMA.
+ *
+ */
+int integrity_kernel_read(struct file *file, loff_t offset,
+                         char *addr, unsigned long count)
+{
+       mm_segment_t old_fs;
+       char __user *buf = (char __user *)addr;
+       ssize_t ret = -EINVAL;
+
+       if (!(file->f_mode & FMODE_READ))
+               return -EBADF;
+
+       old_fs = get_fs();
+       set_fs(get_ds());
+       if (file->f_op->read)
+               ret = file->f_op->read(file, buf, count, &offset);
+       else if (file->f_op->aio_read)
+               ret = do_sync_read(file, buf, count, &offset);
+       else if (file->f_op->read_iter)
+               ret = new_sync_read(file, buf, count, &offset);
+       set_fs(old_fs);
+       return ret;
+}
+
+/*
+ * integrity_read_file - read entire file content into the buffer
+ *
+ * This is function opens a file, allocates the buffer of required
+ * size, read entire file content to the buffer and closes the file
+ *
+ * It is used only by init code.
+ *
+ */
+int __init integrity_read_file(const char *path, char **data)
+{
+       struct file *file;
+       loff_t size;
+       char *buf;
+       int rc = -EINVAL;
+
+       file = filp_open(path, O_RDONLY, 0);
+       if (IS_ERR(file)) {
+               rc = PTR_ERR(file);
+               pr_err("Unable to open file: %s (%d)", path, rc);
+               return rc;
+       }
+
+       size = i_size_read(file_inode(file));
+       if (size <= 0)
+               goto out;
+
+       buf = kmalloc(size, GFP_KERNEL);
+       if (!buf) {
+               rc = -ENOMEM;
+               goto out;
+       }
+
+       rc = integrity_kernel_read(file, 0, buf, size);
+       if (rc < 0)
+               kfree(buf);
+       else if (rc != size)
+               rc = -EIO;
+       else
+               *data = buf;
+out:
+       fput(file);
+       return rc;
+}

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index d34e7dfc1118070a5888fd12629e388ee9aeae65..5df4d960d4dcfbc26b1bcbbf66dc8c03ece77f34 100644 (file)
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -67,36 +67,6 @@ MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size");
 static struct crypto_shash *ima_shash_tfm;
 static struct crypto_ahash *ima_ahash_tfm;
 
-/**
- * ima_kernel_read - read file content
- *
- * This is a function for reading file content instead of kernel_read().
- * It does not perform locking checks to ensure it cannot be blocked.
- * It does not perform security checks because it is irrelevant for IMA.
- *
- */
-static int ima_kernel_read(struct file *file, loff_t offset,
-                          char *addr, unsigned long count)
-{
-       mm_segment_t old_fs;
-       char __user *buf = addr;
-       ssize_t ret = -EINVAL;
-
-       if (!(file->f_mode & FMODE_READ))
-               return -EBADF;
-
-       old_fs = get_fs();
-       set_fs(get_ds());
-       if (file->f_op->read)
-               ret = file->f_op->read(file, buf, count, &offset);
-       else if (file->f_op->aio_read)
-               ret = do_sync_read(file, buf, count, &offset);
-       else if (file->f_op->read_iter)
-               ret = new_sync_read(file, buf, count, &offset);
-       set_fs(old_fs);
-       return ret;
-}
-
 int __init ima_init_crypto(void)
 {
        long rc;
@@ -324,7 +294,8 @@ static int ima_calc_file_hash_atfm(struct file *file,
                }
                /* read buffer */
                rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
-               rc = ima_kernel_read(file, offset, rbuf[active], rbuf_len);
+               rc = integrity_kernel_read(file, offset, rbuf[active],
+                                          rbuf_len);
                if (rc != rbuf_len)
                        goto out3;
 
@@ -417,7 +388,7 @@ static int ima_calc_file_hash_tfm(struct file *file,
        while (offset < i_size) {
                int rbuf_len;
 
-               rbuf_len = ima_kernel_read(file, offset, rbuf, PAGE_SIZE);
+               rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE);
                if (rbuf_len < 0) {
                        rc = rbuf_len;
                        break;

diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index f51ad65c894d021db00f7d71f1f344d045464ba6..20d220481025a4e8e229891222331c9cf88a077b 100644 (file)
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -119,6 +119,10 @@ struct integrity_iint_cache {
  */
 struct integrity_iint_cache *integrity_iint_find(struct inode *inode);
 
+int integrity_kernel_read(struct file *file, loff_t offset,
+                         char *addr, unsigned long count);
+int __init integrity_read_file(const char *path, char **data);
+
 #define INTEGRITY_KEYRING_EVM          0
 #define INTEGRITY_KEYRING_MODULE       1
 #define INTEGRITY_KEYRING_IMA          2