IB/ipath: Prevent random program use of diags interface

To prevent random utility reads and writes of the diag interface to the
chip, we first require a handshake of reading from offset 0 and writing
to offset 0 before any other reads or writes can be done through the
diags device.   Otherwise chip errors can be triggered.

Signed-off-by: Dave Olson <dave.olson@qlogic.com>
Signed-off-by: Bryan O'Sullivan <bryan.osullivan@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_diag.c b/drivers/infiniband/hw/ipath/ipath_diag.c
index 0f13a2182cc7..63e8368b0e95 100644
--- a/drivers/infiniband/hw/ipath/ipath_diag.c
+++ b/drivers/infiniband/hw/ipath/ipath_diag.c
@@ -296,7 +296,7 @@ static int ipath_diag_open(struct inode *in, struct file *fp)
         }
 
         fp->private_data = dd;
-        ipath_diag_inuse = 1;
+        ipath_diag_inuse = -2;
         diag_set_link = 0;
         ret = 0;
 
@@ -461,6 +461,8 @@ static ssize_t ipath_diag_read(struct file *fp, char __user *data,
         else if ((count % 4) || (*off % 4))
                 /* address or length is not 32-bit aligned, hence invalid */
                 ret = -EINVAL;
+        else if (ipath_diag_inuse < 1 && (*off || count != 8))
+                ret = -EINVAL;  /* prevent cat /dev/ipath_diag* */
         else if ((count % 8) || (*off % 8))
                 /* address or length not 64-bit aligned; do 32-bit reads */
                 ret = ipath_read_umem32(dd, data, kreg_base + *off, count);
@@ -470,6 +472,8 @@ static ssize_t ipath_diag_read(struct file *fp, char __user *data,
         if (ret >= 0) {
                 *off += count;
                 ret = count;
+                if (ipath_diag_inuse == -2)
+                        ipath_diag_inuse++;
         }
 
         return ret;
@@ -489,6 +493,9 @@ static ssize_t ipath_diag_write(struct file *fp, const char __user *data,
         else if ((count % 4) || (*off % 4))
                 /* address or length is not 32-bit aligned, hence invalid */
                 ret = -EINVAL;
+        else if ((ipath_diag_inuse == -1 && (*off || count != 8)) ||
+                 ipath_diag_inuse == -2)  /* read qw off 0, write qw off 0 */
+                ret = -EINVAL;  /* before any other write allowed */
         else if ((count % 8) || (*off % 8))
                 /* address or length not 64-bit aligned; do 32-bit writes */
                 ret = ipath_write_umem32(dd, kreg_base + *off, data, count);
@@ -498,6 +505,8 @@ static ssize_t ipath_diag_write(struct file *fp, const char __user *data,
         if (ret >= 0) {
                 *off += count;
                 ret = count;
+                if (ipath_diag_inuse == -1)
+                        ipath_diag_inuse = 1; /* all read/write OK now */
         }
 
         return ret;