From b3883a9a1f09e7b41f4dcb1bbd7262216a62d253 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Sun, 23 Oct 2022 22:06:00 +0200
Subject: [PATCH] stackprotector: move get_random_canary() into
 stackprotector.h

This has nothing to do with random.c and everything to do with stack
protectors. Yes, it uses randomness. But many things use randomness.
random.h and random.c are concerned with the generation of randomness,
not with each and every use. So move this function into the more
specific stackprotector.h file where it belongs.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/x86/kernel/cpu/common.c   |  2 +-
 arch/x86/kernel/setup_percpu.c |  2 +-
 arch/x86/kernel/smpboot.c      |  1 +
 arch/x86/xen/enlighten_pv.c    |  2 +-
 include/linux/random.h         | 19 -------------------
 include/linux/stackprotector.h | 19 +++++++++++++++++++
 kernel/fork.c                  |  2 +-
 7 files changed, 24 insertions(+), 23 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 3e508f2390983..3f66dd03c0919 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -22,9 +22,9 @@
 #include <linux/io.h>
 #include <linux/syscore_ops.h>
 #include <linux/pgtable.h>
+#include <linux/stackprotector.h>
 
 #include <asm/cmdline.h>
-#include <asm/stackprotector.h>
 #include <asm/perf_event.h>
 #include <asm/mmu_context.h>
 #include <asm/doublefault.h>
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 49325caa7307d..b26123c90b4fd 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -11,6 +11,7 @@
 #include <linux/smp.h>
 #include <linux/topology.h>
 #include <linux/pfn.h>
+#include <linux/stackprotector.h>
 #include <asm/sections.h>
 #include <asm/processor.h>
 #include <asm/desc.h>
@@ -21,7 +22,6 @@
 #include <asm/proto.h>
 #include <asm/cpumask.h>
 #include <asm/cpu.h>
-#include <asm/stackprotector.h>
 
 DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
 EXPORT_PER_CPU_SYMBOL(cpu_number);
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3f3ea0287f694..5a742b6ec46d0 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -56,6 +56,7 @@
 #include <linux/numa.h>
 #include <linux/pgtable.h>
 #include <linux/overflow.h>
+#include <linux/stackprotector.h>
 
 #include <asm/acpi.h>
 #include <asm/desc.h>
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index f82857e488152..745420853a7cb 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -32,6 +32,7 @@
 #include <linux/edd.h>
 #include <linux/reboot.h>
 #include <linux/virtio_anchor.h>
+#include <linux/stackprotector.h>
 
 #include <xen/xen.h>
 #include <xen/events.h>
@@ -64,7 +65,6 @@
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
 #include <asm/reboot.h>
-#include <asm/stackprotector.h>
 #include <asm/hypervisor.h>
 #include <asm/mach_traps.h>
 #include <asm/mwait.h>
diff --git a/include/linux/random.h b/include/linux/random.h
index bd954ecbef901..d1d680b9701d2 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -116,25 +116,6 @@ static inline u32 get_random_u32_inclusive(u32 floor, u32 ceil)
 	return floor + get_random_u32_below(ceil - floor + 1);
 }
 
-/*
- * On 64-bit architectures, protect against non-terminated C string overflows
- * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
- */
-#ifdef CONFIG_64BIT
-# ifdef __LITTLE_ENDIAN
-#  define CANARY_MASK 0xffffffffffffff00UL
-# else /* big endian, 64 bits: */
-#  define CANARY_MASK 0x00ffffffffffffffUL
-# endif
-#else /* 32 bits: */
-# define CANARY_MASK 0xffffffffUL
-#endif
-
-static inline unsigned long get_random_canary(void)
-{
-	return get_random_long() & CANARY_MASK;
-}
-
 void __init random_init_early(const char *command_line);
 void __init random_init(void);
 bool rng_is_initialized(void);
diff --git a/include/linux/stackprotector.h b/include/linux/stackprotector.h
index 4c678c4fec58e..9c88707d9a0f5 100644
--- a/include/linux/stackprotector.h
+++ b/include/linux/stackprotector.h
@@ -6,6 +6,25 @@
 #include <linux/sched.h>
 #include <linux/random.h>
 
+/*
+ * On 64-bit architectures, protect against non-terminated C string overflows
+ * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
+ */
+#ifdef CONFIG_64BIT
+# ifdef __LITTLE_ENDIAN
+#  define CANARY_MASK 0xffffffffffffff00UL
+# else /* big endian, 64 bits: */
+#  define CANARY_MASK 0x00ffffffffffffffUL
+# endif
+#else /* 32 bits: */
+# define CANARY_MASK 0xffffffffUL
+#endif
+
+static inline unsigned long get_random_canary(void)
+{
+	return get_random_long() & CANARY_MASK;
+}
+
 #if defined(CONFIG_STACKPROTECTOR) || defined(CONFIG_ARM64_PTR_AUTH)
 # include <asm/stackprotector.h>
 #else
diff --git a/kernel/fork.c b/kernel/fork.c
index 08969f5aa38d5..ec57cae58ff18 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -75,7 +75,6 @@
 #include <linux/freezer.h>
 #include <linux/delayacct.h>
 #include <linux/taskstats_kern.h>
-#include <linux/random.h>
 #include <linux/tty.h>
 #include <linux/fs_struct.h>
 #include <linux/magic.h>
@@ -97,6 +96,7 @@
 #include <linux/scs.h>
 #include <linux/io_uring.h>
 #include <linux/bpf.h>
+#include <linux/stackprotector.h>
 
 #include <asm/pgalloc.h>
 #include <linux/uaccess.h>
-- 
2.30.2