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drivers/char: mark DMA buffers as reserved for the XHCI
The important part is to include those buffers in IOMMU page table relevant for the USB controller. Otherwise, DbC will stop working as soon as IOMMU is enabled, regardless of to which domain device assigned (be it xen or dom0). If the device is passed through to dom0 or other domain (see later patches), that domain will effectively have access to those buffers too. It does give such domain yet another way to DoS the system (as is the case when having PCI device assigned already), but also possibly steal the console ring content. Thus, such domain should be a trusted one. In any case, prevent anything else being placed on those pages by adding artificial padding. Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> Acked-by: Jan Beulich <jbeulich@suse.com>
This commit is contained in:
Marek Marczykowski-Górecki authored and Jan Beulich committed
1 parent
3fd9456f2d
commit
3a1a7b809f
1 file changed
+29
-14
+29
-14
@@ -20,6 +20,7 @@
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*/
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#include <xen/delay.h>
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#include <xen/iommu.h>
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#include <xen/mm.h>
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#include <xen/param.h>
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#include <xen/serial.h>
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@@ -1051,13 +1052,21 @@ static struct uart_driver dbc_uart_driver = {
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};
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/* Those are accessed via DMA. */
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static struct xhci_trb evt_trb[DBC_TRB_RING_CAP];
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static struct xhci_trb out_trb[DBC_TRB_RING_CAP];
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static struct xhci_trb in_trb[DBC_TRB_RING_CAP];
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static struct xhci_erst_segment erst __aligned(16);
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static struct xhci_dbc_ctx ctx __aligned(16);
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static uint8_t out_wrk_buf[DBC_WORK_RING_CAP];
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static struct xhci_string_descriptor str_buf[DBC_STRINGS_COUNT];
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struct dbc_dma_bufs {
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struct xhci_trb evt_trb[DBC_TRB_RING_CAP];
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struct xhci_trb out_trb[DBC_TRB_RING_CAP];
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struct xhci_trb in_trb[DBC_TRB_RING_CAP];
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uint8_t out_wrk_buf[DBC_WORK_RING_CAP];
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struct xhci_erst_segment erst __aligned(16);
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struct xhci_dbc_ctx ctx __aligned(16);
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struct xhci_string_descriptor str_buf[DBC_STRINGS_COUNT];
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/*
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* Don't place anything else on this page - it will be
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* DMA-reachable by the USB controller.
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*/
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};
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static struct dbc_dma_bufs __section(".bss.page_aligned") __aligned(PAGE_SIZE)
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dbc_dma_bufs;
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static int __init xhci_parse_dbgp(const char *opt_dbgp)
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{
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@@ -1104,17 +1113,23 @@ void __init xhci_dbc_uart_init(void)
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if ( !dbc->enable )
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return;
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dbc->dbc_ctx = &ctx;
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dbc->dbc_erst = &erst;
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dbc->dbc_ering.trb = evt_trb;
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dbc->dbc_oring.trb = out_trb;
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dbc->dbc_iring.trb = in_trb;
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dbc->dbc_owork.buf = out_wrk_buf;
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dbc->dbc_str = str_buf;
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dbc->dbc_ctx = &dbc_dma_bufs.ctx;
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dbc->dbc_erst = &dbc_dma_bufs.erst;
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dbc->dbc_ering.trb = dbc_dma_bufs.evt_trb;
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dbc->dbc_oring.trb = dbc_dma_bufs.out_trb;
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dbc->dbc_iring.trb = dbc_dma_bufs.in_trb;
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dbc->dbc_owork.buf = dbc_dma_bufs.out_wrk_buf;
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dbc->dbc_str = dbc_dma_bufs.str_buf;
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if ( dbc_open(dbc) )
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{
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iommu_add_extra_reserved_device_memory(
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PFN_DOWN(virt_to_maddr(&dbc_dma_bufs)),
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PFN_UP(sizeof(dbc_dma_bufs)),
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uart->dbc.sbdf);
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serial_register_uart(SERHND_XHCI, &dbc_uart_driver, &dbc_uart);
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}
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}
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#ifdef DBC_DEBUG
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static void dbc_dump(struct dbc *dbc)
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