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-rw-r--r--arch/x86/entry/vsyscall/Makefile3
-rw-r--r--arch/x86/entry/vsyscall/vsyscall_64.c37
-rw-r--r--arch/x86/entry/vsyscall/vsyscall_emu_64.S3
-rw-r--r--arch/x86/entry/vsyscall/vsyscall_gtod.c83
4 files changed, 35 insertions, 91 deletions
diff --git a/arch/x86/entry/vsyscall/Makefile b/arch/x86/entry/vsyscall/Makefile
index a9f4856f622a..93c1b3e949a7 100644
--- a/arch/x86/entry/vsyscall/Makefile
+++ b/arch/x86/entry/vsyscall/Makefile
@@ -1,7 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0-only
#
# Makefile for the x86 low level vsyscall code
#
-obj-y := vsyscall_gtod.o
-
obj-$(CONFIG_X86_VSYSCALL_EMULATION) += vsyscall_64.o vsyscall_emu_64.o
diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c
index 2f31faf339d5..e7c596dea947 100644
--- a/arch/x86/entry/vsyscall/vsyscall_64.c
+++ b/arch/x86/entry/vsyscall/vsyscall_64.c
@@ -42,9 +42,11 @@
#define CREATE_TRACE_POINTS
#include "vsyscall_trace.h"
-static enum { EMULATE, NONE } vsyscall_mode =
+static enum { EMULATE, XONLY, NONE } vsyscall_mode __ro_after_init =
#ifdef CONFIG_LEGACY_VSYSCALL_NONE
NONE;
+#elif defined(CONFIG_LEGACY_VSYSCALL_XONLY)
+ XONLY;
#else
EMULATE;
#endif
@@ -54,6 +56,8 @@ static int __init vsyscall_setup(char *str)
if (str) {
if (!strcmp("emulate", str))
vsyscall_mode = EMULATE;
+ else if (!strcmp("xonly", str))
+ vsyscall_mode = XONLY;
else if (!strcmp("none", str))
vsyscall_mode = NONE;
else
@@ -113,7 +117,8 @@ static bool write_ok_or_segv(unsigned long ptr, size_t size)
}
}
-bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
+bool emulate_vsyscall(unsigned long error_code,
+ struct pt_regs *regs, unsigned long address)
{
struct task_struct *tsk;
unsigned long caller;
@@ -122,6 +127,22 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
long ret;
unsigned long orig_dx;
+ /* Write faults or kernel-privilege faults never get fixed up. */
+ if ((error_code & (X86_PF_WRITE | X86_PF_USER)) != X86_PF_USER)
+ return false;
+
+ if (!(error_code & X86_PF_INSTR)) {
+ /* Failed vsyscall read */
+ if (vsyscall_mode == EMULATE)
+ return false;
+
+ /*
+ * User code tried and failed to read the vsyscall page.
+ */
+ warn_bad_vsyscall(KERN_INFO, regs, "vsyscall read attempt denied -- look up the vsyscall kernel parameter if you need a workaround");
+ return false;
+ }
+
/*
* No point in checking CS -- the only way to get here is a user mode
* trap to a high address, which means that we're in 64-bit user code.
@@ -284,7 +305,7 @@ static const char *gate_vma_name(struct vm_area_struct *vma)
static const struct vm_operations_struct gate_vma_ops = {
.name = gate_vma_name,
};
-static struct vm_area_struct gate_vma = {
+static struct vm_area_struct gate_vma __ro_after_init = {
.vm_start = VSYSCALL_ADDR,
.vm_end = VSYSCALL_ADDR + PAGE_SIZE,
.vm_page_prot = PAGE_READONLY_EXEC,
@@ -357,12 +378,20 @@ void __init map_vsyscall(void)
extern char __vsyscall_page;
unsigned long physaddr_vsyscall = __pa_symbol(&__vsyscall_page);
- if (vsyscall_mode != NONE) {
+ /*
+ * For full emulation, the page needs to exist for real. In
+ * execute-only mode, there is no PTE at all backing the vsyscall
+ * page.
+ */
+ if (vsyscall_mode == EMULATE) {
__set_fixmap(VSYSCALL_PAGE, physaddr_vsyscall,
PAGE_KERNEL_VVAR);
set_vsyscall_pgtable_user_bits(swapper_pg_dir);
}
+ if (vsyscall_mode == XONLY)
+ gate_vma.vm_flags = VM_EXEC;
+
BUILD_BUG_ON((unsigned long)__fix_to_virt(VSYSCALL_PAGE) !=
(unsigned long)VSYSCALL_ADDR);
}
diff --git a/arch/x86/entry/vsyscall/vsyscall_emu_64.S b/arch/x86/entry/vsyscall/vsyscall_emu_64.S
index c9596a9af159..2e203f3a25a7 100644
--- a/arch/x86/entry/vsyscall/vsyscall_emu_64.S
+++ b/arch/x86/entry/vsyscall/vsyscall_emu_64.S
@@ -1,9 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
/*
* vsyscall_emu_64.S: Vsyscall emulation page
*
* Copyright (c) 2011 Andy Lutomirski
- *
- * Subject to the GNU General Public License, version 2
*/
#include <linux/linkage.h>
diff --git a/arch/x86/entry/vsyscall/vsyscall_gtod.c b/arch/x86/entry/vsyscall/vsyscall_gtod.c
deleted file mode 100644
index cfcdba082feb..000000000000
--- a/arch/x86/entry/vsyscall/vsyscall_gtod.c
+++ /dev/null
@@ -1,83 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
- * Copyright 2003 Andi Kleen, SuSE Labs.
- *
- * Modified for x86 32 bit architecture by
- * Stefani Seibold <stefani@seibold.net>
- * sponsored by Rohde & Schwarz GmbH & Co. KG Munich/Germany
- *
- * Thanks to hpa@transmeta.com for some useful hint.
- * Special thanks to Ingo Molnar for his early experience with
- * a different vsyscall implementation for Linux/IA32 and for the name.
- *
- */
-
-#include <linux/timekeeper_internal.h>
-#include <asm/vgtod.h>
-#include <asm/vvar.h>
-
-int vclocks_used __read_mostly;
-
-DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data);
-
-void update_vsyscall_tz(void)
-{
- vsyscall_gtod_data.tz_minuteswest = sys_tz.tz_minuteswest;
- vsyscall_gtod_data.tz_dsttime = sys_tz.tz_dsttime;
-}
-
-void update_vsyscall(struct timekeeper *tk)
-{
- int vclock_mode = tk->tkr_mono.clock->archdata.vclock_mode;
- struct vsyscall_gtod_data *vdata = &vsyscall_gtod_data;
- struct vgtod_ts *base;
- u64 nsec;
-
- /* Mark the new vclock used. */
- BUILD_BUG_ON(VCLOCK_MAX >= 32);
- WRITE_ONCE(vclocks_used, READ_ONCE(vclocks_used) | (1 << vclock_mode));
-
- gtod_write_begin(vdata);
-
- /* copy vsyscall data */
- vdata->vclock_mode = vclock_mode;
- vdata->cycle_last = tk->tkr_mono.cycle_last;
- vdata->mask = tk->tkr_mono.mask;
- vdata->mult = tk->tkr_mono.mult;
- vdata->shift = tk->tkr_mono.shift;
-
- base = &vdata->basetime[CLOCK_REALTIME];
- base->sec = tk->xtime_sec;
- base->nsec = tk->tkr_mono.xtime_nsec;
-
- base = &vdata->basetime[CLOCK_TAI];
- base->sec = tk->xtime_sec + (s64)tk->tai_offset;
- base->nsec = tk->tkr_mono.xtime_nsec;
-
- base = &vdata->basetime[CLOCK_MONOTONIC];
- base->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
- nsec = tk->tkr_mono.xtime_nsec;
- nsec += ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift);
- while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
- nsec -= ((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
- base->sec++;
- }
- base->nsec = nsec;
-
- base = &vdata->basetime[CLOCK_REALTIME_COARSE];
- base->sec = tk->xtime_sec;
- base->nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
-
- base = &vdata->basetime[CLOCK_MONOTONIC_COARSE];
- base->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
- nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
- nsec += tk->wall_to_monotonic.tv_nsec;
- while (nsec >= NSEC_PER_SEC) {
- nsec -= NSEC_PER_SEC;
- base->sec++;
- }
- base->nsec = nsec;
-
- gtod_write_end(vdata);
-}
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