x86/sev: Check IOBM for IOIO exceptions from user-space
[ upstream commit b9cb9c45583b911e0db71d09caa6b56469eb2bdf ]
Check the IO permission bitmap (if present) before emulating IOIO #VC
exceptions for user-space. These permissions are checked by hardware
already before the #VC is raised, but due to the VC-handler decoding
race it needs to be checked again in software.
BUG=b/309804303
TEST=presubmit
RELEASE_NOTE=Fixes CVE-2023-46813.
SOURCE=UPSTREAM(b9cb9c45583b)
Fixes: 25189d08e516 ("x86/sev-es: Add support for handling IOIO exceptions")
Reported-by: Tom Dohrmann <erbse.13@gmx.de>
Change-Id: I2706d20137e1d96d095cfd9f8e86aa6db2469603
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Tom Dohrmann <erbse.13@gmx.de>
Cc: <stable@kernel.org>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/61354
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Oleksandr Tymoshenko <ovt@google.com>
diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
index 52f989f..c9314f4 100644
--- a/arch/x86/boot/compressed/sev.c
+++ b/arch/x86/boot/compressed/sev.c
@@ -103,6 +103,11 @@
return ES_OK;
}
+static enum es_result vc_ioio_check(struct es_em_ctxt *ctxt, u16 port, size_t size)
+{
+ return ES_OK;
+}
+
#undef __init
#undef __pa
#define __init
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
index e844b18..eada677 100644
--- a/arch/x86/kernel/sev-shared.c
+++ b/arch/x86/kernel/sev-shared.c
@@ -684,6 +684,9 @@
static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
{
struct insn *insn = &ctxt->insn;
+ size_t size;
+ u64 port;
+
*exitinfo = 0;
switch (insn->opcode.bytes[0]) {
@@ -692,7 +695,7 @@
case 0x6d:
*exitinfo |= IOIO_TYPE_INS;
*exitinfo |= IOIO_SEG_ES;
- *exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
+ port = ctxt->regs->dx & 0xffff;
break;
/* OUTS opcodes */
@@ -700,41 +703,43 @@
case 0x6f:
*exitinfo |= IOIO_TYPE_OUTS;
*exitinfo |= IOIO_SEG_DS;
- *exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
+ port = ctxt->regs->dx & 0xffff;
break;
/* IN immediate opcodes */
case 0xe4:
case 0xe5:
*exitinfo |= IOIO_TYPE_IN;
- *exitinfo |= (u8)insn->immediate.value << 16;
+ port = (u8)insn->immediate.value & 0xffff;
break;
/* OUT immediate opcodes */
case 0xe6:
case 0xe7:
*exitinfo |= IOIO_TYPE_OUT;
- *exitinfo |= (u8)insn->immediate.value << 16;
+ port = (u8)insn->immediate.value & 0xffff;
break;
/* IN register opcodes */
case 0xec:
case 0xed:
*exitinfo |= IOIO_TYPE_IN;
- *exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
+ port = ctxt->regs->dx & 0xffff;
break;
/* OUT register opcodes */
case 0xee:
case 0xef:
*exitinfo |= IOIO_TYPE_OUT;
- *exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
+ port = ctxt->regs->dx & 0xffff;
break;
default:
return ES_DECODE_FAILED;
}
+ *exitinfo |= port << 16;
+
switch (insn->opcode.bytes[0]) {
case 0x6c:
case 0x6e:
@@ -744,12 +749,15 @@
case 0xee:
/* Single byte opcodes */
*exitinfo |= IOIO_DATA_8;
+ size = 1;
break;
default:
/* Length determined by instruction parsing */
*exitinfo |= (insn->opnd_bytes == 2) ? IOIO_DATA_16
: IOIO_DATA_32;
+ size = (insn->opnd_bytes == 2) ? 2 : 4;
}
+
switch (insn->addr_bytes) {
case 2:
*exitinfo |= IOIO_ADDR_16;
@@ -765,7 +773,7 @@
if (insn_has_rep_prefix(insn))
*exitinfo |= IOIO_REP;
- return ES_OK;
+ return vc_ioio_check(ctxt, (u16)port, size);
}
static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 4066bcd..dfcbe0d 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -512,6 +512,33 @@
return ES_OK;
}
+static enum es_result vc_ioio_check(struct es_em_ctxt *ctxt, u16 port, size_t size)
+{
+ BUG_ON(size > 4);
+
+ if (user_mode(ctxt->regs)) {
+ struct thread_struct *t = ¤t->thread;
+ struct io_bitmap *iobm = t->io_bitmap;
+ size_t idx;
+
+ if (!iobm)
+ goto fault;
+
+ for (idx = port; idx < port + size; ++idx) {
+ if (test_bit(idx, iobm->bitmap))
+ goto fault;
+ }
+ }
+
+ return ES_OK;
+
+fault:
+ ctxt->fi.vector = X86_TRAP_GP;
+ ctxt->fi.error_code = 0;
+
+ return ES_EXCEPTION;
+}
+
/* Include code shared with pre-decompression boot stage */
#include "sev-shared.c"
