ima: always return negative code for error

BugLink: https://bugs.launchpad.net/bugs/1849576
[ Upstream commit f5e1040196dbfe14c77ce3dfe3b7b08d2d961e88 ]

integrity_kernel_read() returns the number of bytes read. If this is
a short read then this positive value is returned from
ima_calc_file_hash_atfm(). Currently this is only indirectly called from
ima_calc_file_hash() and this function only tests for the return value
being zero or nonzero and also doesn't forward the return value.
Nevertheless there's no point in returning a positive value as an error,
so translate a short read into -EINVAL.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index 6b4771b73386aa573c2db5fab5c2de3c396ea7ee..ac1cf1dffc62434cc3799bf7ba6265737b4cc4de 100644 (file)
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -271,8 +271,11 @@ static int ima_calc_file_hash_atfm(struct file *file,
                rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
                rc = integrity_kernel_read(file, offset, rbuf[active],
                                           rbuf_len);
-               if (rc != rbuf_len)
+               if (rc != rbuf_len) {
+                       if (rc >= 0)
+                               rc = -EINVAL;
                        goto out3;
+               }
 
                if (rbuf[1] && offset) {
                        /* Using two buffers, and it is not the first