xen/video: CFI hardening

Control Flow Integrity schemes use toolchain and optionally hardware support
to help protect against call/jump/return oriented programming attacks.

Use cf_check to annotate function pointer targets for the toolchain.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/drivers/video/lfb.c b/xen/drivers/video/lfb.c
index 9254b5e9022a8879a90a696bddfd99564830b889..a6fb837974f78457fa54257027b7fe6ece6d71cb 100644 (file)
--- a/xen/drivers/video/lfb.c
+++ b/xen/drivers/video/lfb.c
@@ -53,7 +53,7 @@ static void lfb_show_line(
 }
 
 /* Fast mode which redraws all modified parts of a 2D text buffer. */
-void lfb_redraw_puts(const char *s, size_t nr)
+void cf_check lfb_redraw_puts(const char *s, size_t nr)
 {
     unsigned int i, min_redraw_y = lfb.ypos;
 
@@ -98,7 +98,7 @@ void lfb_redraw_puts(const char *s, size_t nr)
 }
 
 /* Slower line-based scroll mode which interacts better with dom0. */
-void lfb_scroll_puts(const char *s, size_t nr)
+void cf_check lfb_scroll_puts(const char *s, size_t nr)
 {
     unsigned int i;
 

diff --git a/xen/drivers/video/lfb.h b/xen/drivers/video/lfb.h
index e743ccdd6b1199dd7a3b51fdbed789eb6161e75e..42161402d611b8cae502e3987de0293b116c02ef 100644 (file)
--- a/xen/drivers/video/lfb.h
+++ b/xen/drivers/video/lfb.h
@@ -35,8 +35,8 @@ struct lfb_prop {
     unsigned int text_rows;
 };
 
-void lfb_redraw_puts(const char *s, size_t nr);
-void lfb_scroll_puts(const char *s, size_t nr);
+void cf_check lfb_redraw_puts(const char *s, size_t nr);
+void cf_check lfb_scroll_puts(const char *s, size_t nr);
 void lfb_carriage_return(void);
 void lfb_free(void);
 

diff --git a/xen/drivers/video/vesa.c b/xen/drivers/video/vesa.c
index c8f81a5cc5fcbc0b87f7e636c94b366754b2ddfc..c41f6b8d40281e45e62264c8fc0e4e939f076631 100644 (file)
--- a/xen/drivers/video/vesa.c
+++ b/xen/drivers/video/vesa.c
@@ -17,7 +17,7 @@
 
 #define vlfb_info    vga_console_info.u.vesa_lfb
 
-static void lfb_flush(void);
+static void cf_check lfb_flush(void);
 
 static unsigned char *__read_mostly lfb;
 static const struct font_desc *__initdata font;
@@ -140,7 +140,7 @@ void __init vesa_init(void)
     video_puts = lfb_redraw_puts;
 }
 
-static void lfb_flush(void)
+static void cf_check lfb_flush(void)
 {
     __asm__ __volatile__ ("sfence" : : : "memory");
 }

diff --git a/xen/drivers/video/vga.c b/xen/drivers/video/vga.c
index 5e58f83c97ff175512008c102c884c103c5a7faa..e624ebff4f8c7096c03d080212846e9fc4ebbd6d 100644 (file)
--- a/xen/drivers/video/vga.c
+++ b/xen/drivers/video/vga.c
@@ -19,8 +19,8 @@ static int vgacon_keep;
 static unsigned int xpos, ypos;
 static unsigned char *video;
 
-static void vga_text_puts(const char *s, size_t nr);
-static void vga_noop_puts(const char *s, size_t nr) {}
+static void cf_check vga_text_puts(const char *s, size_t nr);
+static void cf_check vga_noop_puts(const char *s, size_t nr) {}
 void (*video_puts)(const char *, size_t nr) = vga_noop_puts;
 
 /*
@@ -179,7 +179,7 @@ void __init video_endboot(void)
     }
 }
 
-static void vga_text_puts(const char *s, size_t nr)
+static void cf_check vga_text_puts(const char *s, size_t nr)
 {
     for ( ; nr > 0; nr--, s++ )
     {