1 files changed, 49 insertions, 16 deletions

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index 84b938f86bea..0bd732843fe7 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -253,12 +253,12 @@ static int ima_calc_file_hash_atfm(struct file *file,
 				   struct crypto_ahash *tfm)
 {
 	loff_t i_size, offset;
-	char *rbuf;
-	int rc, read = 0, rbuf_len;
+	char *rbuf[2] = { NULL, };
+	int rc, read = 0, rbuf_len, active = 0, ahash_rc = 0;
 	struct ahash_request *req;
 	struct scatterlist sg[1];
 	struct ahash_completion res;
-	size_t rbuf_size;
+	size_t rbuf_size[2];
 
 	hash->length = crypto_ahash_digestsize(tfm);
 
@@ -284,36 +284,69 @@ static int ima_calc_file_hash_atfm(struct file *file,
 	 * Try to allocate maximum size of memory.
 	 * Fail if even a single page cannot be allocated.
 	 */
-	rbuf = ima_alloc_pages(i_size, &rbuf_size, 1);
-	if (!rbuf) {
+	rbuf[0] = ima_alloc_pages(i_size, &rbuf_size[0], 1);
+	if (!rbuf[0]) {
 		rc = -ENOMEM;
 		goto out1;
 	}
 
+	/* Only allocate one buffer if that is enough. */
+	if (i_size > rbuf_size[0]) {
+		/*
+		 * Try to allocate secondary buffer. If that fails fallback to
+		 * using single buffering. Use previous memory allocation size
+		 * as baseline for possible allocation size.
+		 */
+		rbuf[1] = ima_alloc_pages(i_size - rbuf_size[0],
+					  &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) {
-		rbuf_len = ima_kernel_read(file, offset, rbuf, PAGE_SIZE);
-		if (rbuf_len < 0) {
-			rc = rbuf_len;
-			break;
+		if (!rbuf[1] && offset) {
+			/* Not using two buffers, and it is not the first
+			 * read/request, wait for the completion of the
+			 * previous ahash_update() request.
+			 */
+			rc = ahash_wait(ahash_rc, &res);
+			if (rc)
+				goto out3;
+		}
+		/* read buffer */
+		rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
+		rc = ima_kernel_read(file, offset, rbuf[active], rbuf_len);
+		if (rc != rbuf_len)
+			goto out3;
+
+		if (rbuf[1] && offset) {
+			/* Using two buffers, and it is not the first
+			 * read/request, wait for the completion of the
+			 * previous ahash_update() request.
+			 */
+			rc = ahash_wait(ahash_rc, &res);
+			if (rc)
+				goto out3;
 		}
-		if (rbuf_len == 0)
-			break;
 
-		sg_init_one(&sg[0], rbuf, rbuf_len);
+		sg_init_one(&sg[0], rbuf[active], rbuf_len);
 		ahash_request_set_crypt(req, sg, NULL, rbuf_len);
 
-		rc = ahash_wait(crypto_ahash_update(req), &res);
-		if (rc)
-			break;
+		ahash_rc = crypto_ahash_update(req);
+
+		if (rbuf[1])
+			active = !active; /* swap buffers, if we use two */
 	}
+	/* 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, rbuf_size);
+	ima_free_pages(rbuf[0], rbuf_size[0]);
+	ima_free_pages(rbuf[1], rbuf_size[1]);
 out2:
 	if (!rc) {
 		ahash_request_set_crypt(req, NULL, hash->digest, 0);