[PATCH v1 2/4] integrity: provide file reading API

[Dmitry Kasatkin]

Signed-off-by: Dmitry Kasatkin <d.kasatkin@xxxxxxxxxxx>
---
 security/integrity/Kconfig     |  3 +++
 security/integrity/digsig.c    | 41 +++++++++++++++++++++++++++++++++++++++++
 security/integrity/integrity.h |  2 +-
 3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig
index 463219b..1f000c4 100644
--- a/security/integrity/Kconfig
+++ b/security/integrity/Kconfig
@@ -50,6 +50,9 @@ config INTEGRITY_AUDIT
 	  be enabled by specifying 'integrity_audit=1' on the kernel
 	  command line.
 
+config INTEGRITY_FILE_READ
+	def_bool n
+
 source security/integrity/ima/Kconfig
 source security/integrity/evm/Kconfig
 
diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index 8d4fbff..85d6662 100644
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -18,6 +18,8 @@
 #include <linux/cred.h>
 #include <linux/key-type.h>
 #include <linux/digsig.h>
+#include <linux/slab.h>
+#include <linux/file.h>
 
 #include "integrity.h"
 
@@ -63,6 +65,45 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
 	return -EOPNOTSUPP;
 }
 
+#ifdef CONFIG_INTEGRITY_FILE_READ
+int 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;
+	}
+
+	/* should be ima_kernel_read */
+	rc = 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;
+}
+#endif
+
 int integrity_init_keyring(const unsigned int id)
 {
 	const struct cred *cred = current_cred();
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index 7656d47..f77de68 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -130,7 +130,7 @@ struct integrity_iint_cache *integrity_iint_find(struct inode *inode);
 
 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
 			    const char *digest, int digestlen);
-
+int integrity_read_file(const char *path, char **data);
 int integrity_init_keyring(const unsigned int id);
 #else
 
-- 
1.9.1

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