Commit 1566f3dc authored by Stefan Richter's avatar Stefan Richter

firewire: cdev: restrict broadcast write requests to Units Space

We don't want random users write to Memory Space (e.g. PCs with physical
DMA filters down) or to core CSRs like Reset_Start.

This does not protect SBP-2 target CSRs.  But properly behaving SBP-2
targets ignore broadcast write requests to these registers, and the
maximum damage which can happen with laxer targets is DOS.  But there
are ways to create DOS situations anyway if there are devices with weak
device file permissions (like audio/video devices) present at the same
bus as an SBP-2 target.
Signed-off-by: default avatarStefan Richter <stefanr@s5r6.in-berlin.de>
parent acfe8333
...@@ -1245,6 +1245,10 @@ static int ioctl_send_broadcast_request(struct client *client, void *buffer) ...@@ -1245,6 +1245,10 @@ static int ioctl_send_broadcast_request(struct client *client, void *buffer)
return -EINVAL; return -EINVAL;
} }
/* Security policy: Only allow accesses to Units Space. */
if (request->offset < CSR_REGISTER_BASE + CSR_CONFIG_ROM_END)
return -EACCES;
return init_request(client, request, LOCAL_BUS | 0x3f, SCODE_100); return init_request(client, request, LOCAL_BUS | 0x3f, SCODE_100);
} }
......
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