[patch 3/3] x86/vdso: Sanitize vdso*_enabled handling

[Thomas Gleixner]

vdso*_enabled is conceptionally a boolean. Though there are leftovers from
the original implementation which required an int. That's just confusing
and error prone.

Convert evrything to boolean and correct stale comments.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Mathias Krause <minipli@xxxxxxxxxxxxxx>
---
 arch/x86/entry/vdso/vdso32-setup.c |   40 +++++++++++++++++++++----------------
 arch/x86/entry/vdso/vma.c          |   12 +++++++----
 arch/x86/include/asm/elf.h         |    4 +--
 arch/x86/um/vdso/vma.c             |    4 +--
 4 files changed, 35 insertions(+), 25 deletions(-)

--- a/arch/x86/entry/vdso/vdso32-setup.c
+++ b/arch/x86/entry/vdso/vdso32-setup.c
@@ -24,27 +24,19 @@
  * Should the kernel map a VDSO page into processes and pass its
  * address down to glibc upon exec()?
  */
-unsigned int __read_mostly vdso32_enabled = VDSO_DEFAULT;
+bool __read_mostly vdso32_enabled = VDSO_DEFAULT;
 
 static int __init vdso32_setup(char *s)
 {
-	vdso32_enabled = simple_strtoul(s, NULL, 0);
-
-	if (vdso32_enabled > 1) {
-		pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n");
-		vdso32_enabled = 0;
-	}
+	unsigned int ena = simple_strtoul(s, NULL, 0);
 
+	if (ena > 1)
+		pr_warn("vdso32=%u out of range [0-1], disabling vdso32\n", ena);
+	vdso32_enabled = ena == 1;
 	return 1;
 }
-
-/*
- * For consistency, the argument vdso32=[012] affects the 32-bit vDSO
- * behavior on both 64-bit and 32-bit kernels.
- * On 32-bit kernels, vdso=[012] means the same thing.
- */
+/* The vdso32 option is valid on 64bit and 32bit kernels */
 __setup("vdso32=", vdso32_setup);
-
 #ifdef CONFIG_X86_32
 __setup_param("vdso=", vdso_setup, vdso32_setup, 0);
 #endif
@@ -66,14 +58,27 @@ subsys_initcall(sysenter_setup);
 
 static const int zero;
 static const int one = 1;
+static int vdso32_sysctl;
+
+static int vdso_update_handler(struct ctl_table *table, int write,
+			       void __user *buffer, size_t *lenp,
+			       loff_t *ppos)
+{
+	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+
+	if (ret || !write)
+		return ret;
+	vdso32_enabled = !!vdso32_sysctl;
+	return 0;
+}
 
 static struct ctl_table abi_table2[] = {
 	{
 		.procname	= "vsyscall32",
-		.data		= &vdso32_enabled,
-		.maxlen		= sizeof(int),
+		.data		= &vdso32_sysctl,
+		.maxlen		= sizeof(bool),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
+		.proc_handler	= vdso_update_handler,
 		.extra1		= (int *)&zero,
 		.extra2		= (int *)&one,
 	},
@@ -91,6 +96,7 @@ static struct ctl_table abi_root_table2[
 
 static __init int ia32_binfmt_init(void)
 {
+	vdso32_sysctl = vdso32_enabled;
 	register_sysctl_table(abi_root_table2);
 	return 0;
 }
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -24,7 +24,7 @@
 #include <asm/cpufeature.h>
 
 #if defined(CONFIG_X86_64)
-unsigned int __read_mostly vdso64_enabled = 1;
+bool __read_mostly vdso64_enabled = true;
 #endif
 
 void __init init_vdso_image(const struct vdso_image *image)
@@ -279,7 +279,7 @@ int map_vdso_once(const struct vdso_imag
 #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
 static int load_vdso32(void)
 {
-	if (vdso32_enabled != 1)  /* Other values all mean "disabled" */
+	if (!vdso32_enabled)
 		return 0;
 
 	return map_vdso(&vdso_image_32, 0);
@@ -323,8 +323,12 @@ int arch_setup_additional_pages(struct l
 #ifdef CONFIG_X86_64
 static __init int vdso_setup(char *s)
 {
-	vdso64_enabled = simple_strtoul(s, NULL, 0);
-	return 0;
+	unsigned int ena = simple_strtoul(s, NULL, 0);
+
+	if (ena > 1)
+		pr_warn("vdso=%u out of range [0-1], disabling vdso\n",	ena);
+	vdso64_enabled = ena == 1;
+	return 1;
 }
 __setup("vdso=", vdso_setup);
 #endif
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -76,10 +76,10 @@ typedef struct user_fxsr_struct elf_fpxr
 #include <asm/vdso.h>
 
 #ifdef CONFIG_X86_64
-extern unsigned int vdso64_enabled;
+extern bool vdso64_enabled;
 #endif
 #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
-extern unsigned int vdso32_enabled;
+extern bool vdso32_enabled;
 #endif
 
 /*
--- a/arch/x86/um/vdso/vma.c
+++ b/arch/x86/um/vdso/vma.c
@@ -13,7 +13,7 @@
 #include <asm/elf.h>
 #include <linux/init.h>
 
-static unsigned int __read_mostly vdso_enabled = 1;
+static bool __read_mostly vdso_enabled = true;
 unsigned long um_vdso_addr;
 
 extern unsigned long task_size;
@@ -47,7 +47,7 @@ static int __init init_vdso(void)
 
 oom:
 	printk(KERN_ERR "Cannot allocate vdso\n");
-	vdso_enabled = 0;
+	vdso_enabled = false;
 
 	return -ENOMEM;
 }