1 files changed, 34 insertions, 20 deletions

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index cb041af9eddb..af680b5b678a 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -232,7 +232,7 @@ static int ima_calc_file_hash_atfm(struct file *file,
 {
 	loff_t i_size, offset;
 	char *rbuf[2] = { NULL, };
-	int rc, read = 0, rbuf_len, active = 0, ahash_rc = 0;
+	int rc, rbuf_len, active = 0, ahash_rc = 0;
 	struct ahash_request *req;
 	struct scatterlist sg[1];
 	struct ahash_completion res;
@@ -279,11 +279,6 @@ static int ima_calc_file_hash_atfm(struct file *file,
 					  &rbuf_size[1], 0);
 	}
 
-	if (!(file->f_mode & FMODE_READ)) {
-		file->f_mode |= FMODE_READ;
-		read = 1;
-	}
-
 	for (offset = 0; offset < i_size; offset += rbuf_len) {
 		if (!rbuf[1] && offset) {
 			/* Not using two buffers, and it is not the first
@@ -322,8 +317,6 @@ static int ima_calc_file_hash_atfm(struct file *file,
 	/* wait for the last update request to complete */
 	rc = ahash_wait(ahash_rc, &res);
 out3:
-	if (read)
-		file->f_mode &= ~FMODE_READ;
 	ima_free_pages(rbuf[0], rbuf_size[0]);
 	ima_free_pages(rbuf[1], rbuf_size[1]);
 out2:
@@ -358,7 +351,7 @@ static int ima_calc_file_hash_tfm(struct file *file,
 {
 	loff_t i_size, offset = 0;
 	char *rbuf;
-	int rc, read = 0;
+	int rc;
 	SHASH_DESC_ON_STACK(shash, tfm);
 
 	shash->tfm = tfm;
@@ -379,11 +372,6 @@ static int ima_calc_file_hash_tfm(struct file *file,
 	if (!rbuf)
 		return -ENOMEM;
 
-	if (!(file->f_mode & FMODE_READ)) {
-		file->f_mode |= FMODE_READ;
-		read = 1;
-	}
-
 	while (offset < i_size) {
 		int rbuf_len;
 
@@ -400,8 +388,6 @@ static int ima_calc_file_hash_tfm(struct file *file,
 		if (rc)
 			break;
 	}
-	if (read)
-		file->f_mode &= ~FMODE_READ;
 	kfree(rbuf);
 out:
 	if (!rc)
@@ -442,6 +428,8 @@ int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
 {
 	loff_t i_size;
 	int rc;
+	struct file *f = file;
+	bool new_file_instance = false, modified_flags = false;
 
 	/*
 	 * For consistency, fail file's opened with the O_DIRECT flag on
@@ -453,15 +441,41 @@ int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
 		return -EINVAL;
 	}
 
-	i_size = i_size_read(file_inode(file));
+	/* Open a new file instance in O_RDONLY if we cannot read */
+	if (!(file->f_mode & FMODE_READ)) {
+		int flags = file->f_flags & ~(O_WRONLY | O_APPEND |
+				O_TRUNC | O_CREAT | O_NOCTTY | O_EXCL);
+		flags |= O_RDONLY;
+		f = dentry_open(&file->f_path, flags, file->f_cred);
+		if (IS_ERR(f)) {
+			/*
+			 * Cannot open the file again, lets modify f_flags
+			 * of original and continue
+			 */
+			pr_info_ratelimited("Unable to reopen file for reading.\n");
+			f = file;
+			f->f_flags |= FMODE_READ;
+			modified_flags = true;
+		} else {
+			new_file_instance = true;
+		}
+	}
+
+	i_size = i_size_read(file_inode(f));
 
 	if (ima_ahash_minsize && i_size >= ima_ahash_minsize) {
-		rc = ima_calc_file_ahash(file, hash);
+		rc = ima_calc_file_ahash(f, hash);
 		if (!rc)
-			return 0;
+			goto out;
 	}
 
-	return ima_calc_file_shash(file, hash);
+	rc = ima_calc_file_shash(f, hash);
+out:
+	if (new_file_instance)
+		fput(f);
+	else if (modified_flags)
+		f->f_flags &= ~FMODE_READ;
+	return rc;
 }
 
 /*