From b1eae36683cdfe63af5749b5fe86b1c08fc0f63e Mon Sep 17 00:00:00 2001 From: Jon Maloy Date: Wed, 13 Apr 2022 14:51:06 -0400 Subject: [PATCH 04/11] softmmu/physmem: Introduce MemTxAttrs::memory field and MEMTX_ACCESS_ERROR MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Jon Maloy RH-MergeRequest: 158: hw/intc/arm_gicv3: Check for !MEMTX_OK instead of MEMTX_ERROR RH-Commit: [3/3] 84d64fe85a106f8faf579e43266d4349fc8e65b4 (jmaloy/qemu-kvm) RH-Bugzilla: 2075686 RH-Acked-by: Miroslav Rezanina RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Peter Xu Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2075686 Upstream: Merged CVE: CVE-2021-3750 Conflicts: memalign.h has not been introduced in this version. Instead, we include osdep.h where the function prototypes are to be found. commit 3ab6fdc91b72e156da22848f0003ff4225690ced Author: Philippe Mathieu-Daudé Date: Wed Dec 15 19:24:21 2021 +0100 softmmu/physmem: Introduce MemTxAttrs::memory field and MEMTX_ACCESS_ERROR Add the 'memory' bit to the memory attributes to restrict bus controller accesses to memories. Introduce flatview_access_allowed() to check bus permission before running any bus transaction. Have read/write accessors return MEMTX_ACCESS_ERROR if an access is restricted. There is no change for the default case where 'memory' is not set. Signed-off-by: Philippe Mathieu-Daudé Message-Id: <20211215182421.418374-4-philmd@redhat.com> Reviewed-by: Richard Henderson Reviewed-by: Stefan Hajnoczi [thuth: Replaced MEMTX_BUS_ERROR with MEMTX_ACCESS_ERROR, remove "inline"] Signed-off-by: Thomas Huth (cherry picked from commit 3ab6fdc91b72e156da22848f0003ff4225690ced) Signed-off-by: Jon Maloy --- include/exec/memattrs.h | 9 +++++++++ softmmu/physmem.c | 45 +++++++++++++++++++++++++++++++++++++++-- 2 files changed, 52 insertions(+), 2 deletions(-) diff --git a/include/exec/memattrs.h b/include/exec/memattrs.h index 95f2d20d55..9fb98bc1ef 100644 --- a/include/exec/memattrs.h +++ b/include/exec/memattrs.h @@ -35,6 +35,14 @@ typedef struct MemTxAttrs { unsigned int secure:1; /* Memory access is usermode (unprivileged) */ unsigned int user:1; + /* + * Bus interconnect and peripherals can access anything (memories, + * devices) by default. By setting the 'memory' bit, bus transaction + * are restricted to "normal" memories (per the AMBA documentation) + * versus devices. Access to devices will be logged and rejected + * (see MEMTX_ACCESS_ERROR). + */ + unsigned int memory:1; /* Requester ID (for MSI for example) */ unsigned int requester_id:16; /* Invert endianness for this page */ @@ -66,6 +74,7 @@ typedef struct MemTxAttrs { #define MEMTX_OK 0 #define MEMTX_ERROR (1U << 0) /* device returned an error */ #define MEMTX_DECODE_ERROR (1U << 1) /* nothing at that address */ +#define MEMTX_ACCESS_ERROR (1U << 2) /* access denied */ typedef uint32_t MemTxResult; #endif diff --git a/softmmu/physmem.c b/softmmu/physmem.c index 483a31be81..4d0ef5f92f 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -41,6 +41,8 @@ #include "qemu/config-file.h" #include "qemu/error-report.h" #include "qemu/qemu-print.h" +#include "qemu/log.h" +#include "qemu/osdep.h" #include "exec/memory.h" #include "exec/ioport.h" #include "sysemu/dma.h" @@ -2759,6 +2761,33 @@ static bool prepare_mmio_access(MemoryRegion *mr) return release_lock; } +/** + * flatview_access_allowed + * @mr: #MemoryRegion to be accessed + * @attrs: memory transaction attributes + * @addr: address within that memory region + * @len: the number of bytes to access + * + * Check if a memory transaction is allowed. + * + * Returns: true if transaction is allowed, false if denied. + */ +static bool flatview_access_allowed(MemoryRegion *mr, MemTxAttrs attrs, + hwaddr addr, hwaddr len) +{ + if (likely(!attrs.memory)) { + return true; + } + if (memory_region_is_ram(mr)) { + return true; + } + qemu_log_mask(LOG_GUEST_ERROR, + "Invalid access to non-RAM device at " + "addr 0x%" HWADDR_PRIX ", size %" HWADDR_PRIu ", " + "region '%s'\n", addr, len, memory_region_name(mr)); + return false; +} + /* Called within RCU critical section. */ static MemTxResult flatview_write_continue(FlatView *fv, hwaddr addr, MemTxAttrs attrs, @@ -2773,7 +2802,10 @@ static MemTxResult flatview_write_continue(FlatView *fv, hwaddr addr, const uint8_t *buf = ptr; for (;;) { - if (!memory_access_is_direct(mr, true)) { + if (!flatview_access_allowed(mr, attrs, addr1, l)) { + result |= MEMTX_ACCESS_ERROR; + /* Keep going. */ + } else if (!memory_access_is_direct(mr, true)) { release_lock |= prepare_mmio_access(mr); l = memory_access_size(mr, l, addr1); /* XXX: could force current_cpu to NULL to avoid @@ -2818,6 +2850,9 @@ static MemTxResult flatview_write(FlatView *fv, hwaddr addr, MemTxAttrs attrs, l = len; mr = flatview_translate(fv, addr, &addr1, &l, true, attrs); + if (!flatview_access_allowed(mr, attrs, addr, len)) { + return MEMTX_ACCESS_ERROR; + } return flatview_write_continue(fv, addr, attrs, buf, len, addr1, l, mr); } @@ -2836,7 +2871,10 @@ MemTxResult flatview_read_continue(FlatView *fv, hwaddr addr, fuzz_dma_read_cb(addr, len, mr); for (;;) { - if (!memory_access_is_direct(mr, false)) { + if (!flatview_access_allowed(mr, attrs, addr1, l)) { + result |= MEMTX_ACCESS_ERROR; + /* Keep going. */ + } else if (!memory_access_is_direct(mr, false)) { /* I/O case */ release_lock |= prepare_mmio_access(mr); l = memory_access_size(mr, l, addr1); @@ -2879,6 +2917,9 @@ static MemTxResult flatview_read(FlatView *fv, hwaddr addr, l = len; mr = flatview_translate(fv, addr, &addr1, &l, false, attrs); + if (!flatview_access_allowed(mr, attrs, addr, len)) { + return MEMTX_ACCESS_ERROR; + } return flatview_read_continue(fv, addr, attrs, buf, len, addr1, l, mr); } -- 2.27.0