[PATCH 07/14] uaccess: generalize access_ok()

Arnd Bergmann
2022-02-14T16:37:38Z

From: Arnd Bergmann <arnd@arndb.de>

There are many different ways that access_ok() is defined across
architectures, but in the end, they all just compare against the
user_addr_max() value or they accept anything.

Provide one definition that works for most architectures, checking
against TASK_SIZE_MAX for user processes or skipping the check inside
of uaccess_kernel() sections.

For architectures without CONFIG_SET_FS(), this should be the fastest
check, as it comes down to a single comparison of a pointer against a
compile-time constant, while the architecture specific versions tend to
do something more complex for historic reasons or get something wrong.

Type checking for __user annotations is handled inconsistently across
architectures, but this is easily simplified as well by using an inline
function that takes a 'const void __user *' argument. A handful of
callers need an extra __user annotation for this.

Some architectures had trick to use 33-bit or 65-bit arithmetic on the
addresses to calculate the overflow, however this simpler version uses
fewer registers, which means it can produce better object code in the
end despite needing a second (statically predicted) branch.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
arch/alpha/include/asm/uaccess.h | 34 +++------------
arch/arc/include/asm/uaccess.h | 29 -------------
arch/arm/include/asm/uaccess.h | 20 +--------
arch/arm/kernel/swp_emulate.c | 2 +-
arch/arm/kernel/traps.c | 2 +-
arch/arm64/include/asm/uaccess.h | 5 ++-
arch/csky/include/asm/uaccess.h | 8 ----
arch/csky/kernel/signal.c | 2 +-
arch/hexagon/include/asm/uaccess.h | 25 ------------
arch/ia64/include/asm/uaccess.h | 5 +--
arch/m68k/include/asm/uaccess.h | 5 ++-
arch/microblaze/include/asm/uaccess.h | 8 +---
arch/mips/include/asm/uaccess.h | 29 +------------
arch/nds32/include/asm/uaccess.h | 7 +---
arch/nios2/include/asm/uaccess.h | 11 +----
arch/nios2/kernel/signal.c | 20 +++++----
arch/openrisc/include/asm/uaccess.h | 19 +--------
arch/parisc/include/asm/uaccess.h | 10 +++--
arch/powerpc/include/asm/uaccess.h | 11 +----
arch/powerpc/lib/sstep.c | 4 +-
arch/riscv/include/asm/uaccess.h | 31 +-------------
arch/riscv/kernel/perf_callchain.c | 2 +-
arch/s390/include/asm/uaccess.h | 11 ++---
arch/sh/include/asm/uaccess.h | 22 +---------
arch/sparc/include/asm/uaccess.h | 3 --
arch/sparc/include/asm/uaccess_32.h | 18 ++------
arch/sparc/include/asm/uaccess_64.h | 35 ++++------------
arch/sparc/kernel/signal_32.c | 2 +-
arch/um/include/asm/uaccess.h | 5 ++-
arch/x86/include/asm/uaccess.h | 14 +------
arch/xtensa/include/asm/uaccess.h | 10 +----
include/asm-generic/access_ok.h | 59 +++++++++++++++++++++++++++
include/asm-generic/uaccess.h | 21 +---------
include/linux/uaccess.h | 7 ----
34 files changed, 130 insertions(+), 366 deletions(-)
create mode 100644 include/asm-generic/access_ok.h

diff --git a/arch/alpha/include/asm/uaccess.h b/arch/alpha/include/asm/uaccess.h
index 1b6f25efa247..82c5743fc9cd 100644
--- a/arch/alpha/include/asm/uaccess.h
+++ b/arch/alpha/include/asm/uaccess.h
@@ -20,28 +20,7 @@
#define get_fs() (current_thread_info()->addr_limit)
#define set_fs(x) (current_thread_info()->addr_limit = (x))

-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-
-/*
- * Is a address valid? This does a straightforward calculation rather
- * than tests.
- *
- * Address valid if:
- * - "addr" doesn't have any high-bits set
- * - AND "size" doesn't have any high-bits set
- * - AND "addr+size-(size != 0)" doesn't have any high-bits set
- * - OR we are in kernel mode.
- */
-#define __access_ok(addr, size) ({ \
- unsigned long __ao_a = (addr), __ao_b = (size); \
- unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b; \
- (get_fs().seg & (__ao_a | __ao_b | __ao_end)) == 0; })
-
-#define access_ok(addr, size) \
-({ \
- __chk_user_ptr(addr); \
- __access_ok(((unsigned long)(addr)), (size)); \
-})
+#include <asm-generic/access_ok.h>

/*
* These are the main single-value transfer routines. They automatically
@@ -105,7 +84,7 @@ extern void __get_user_unknown(void);
long __gu_err = -EFAULT; \
unsigned long __gu_val = 0; \
const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
- if (__access_ok((unsigned long)__gu_addr, size)) { \
+ if (__access_ok(__gu_addr, size)) { \
__gu_err = 0; \
switch (size) { \
case 1: __get_user_8(__gu_addr); break; \
@@ -200,7 +179,7 @@ extern void __put_user_unknown(void);
({ \
long __pu_err = -EFAULT; \
__typeof__(*(ptr)) __user *__pu_addr = (ptr); \
- if (__access_ok((unsigned long)__pu_addr, size)) { \
+ if (__access_ok(__pu_addr, size)) { \
__pu_err = 0; \
switch (size) { \
case 1: __put_user_8(x, __pu_addr); break; \
@@ -316,17 +295,14 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long len)

extern long __clear_user(void __user *to, long len);

-extern inline long
+static inline long
clear_user(void __user *to, long len)
{
- if (__access_ok((unsigned long)to, len))
+ if (__access_ok(to, len))
len = __clear_user(to, len);
return len;
}

-#define user_addr_max() \
- (uaccess_kernel() ? ~0UL : TASK_SIZE)
-
extern long strncpy_from_user(char *dest, const char __user *src, long count);
extern __must_check long strnlen_user(const char __user *str, long n);

diff --git a/arch/arc/include/asm/uaccess.h b/arch/arc/include/asm/uaccess.h
index 783bfdb3bfa3..30f80b4be2ab 100644
--- a/arch/arc/include/asm/uaccess.h
+++ b/arch/arc/include/asm/uaccess.h
@@ -23,35 +23,6 @@

#include <linux/string.h> /* for generic string functions */

-
-#define __kernel_ok (uaccess_kernel())
-
-/*
- * Algorithmically, for __user_ok() we want do:
- * (start < TASK_SIZE) && (start+len < TASK_SIZE)
- * where TASK_SIZE could either be retrieved from thread_info->addr_limit or
- * emitted directly in code.
- *
- * This can however be rewritten as follows:
- * (len <= TASK_SIZE) && (start+len < TASK_SIZE)
- *
- * Because it essentially checks if buffer end is within limit and @len is
- * non-ngeative, which implies that buffer start will be within limit too.
- *
- * The reason for rewriting being, for majority of cases, @len is generally
- * compile time constant, causing first sub-expression to be compile time
- * subsumed.
- *
- * The second part would generate weird large LIMMs e.g. (0x6000_0000 - 0x10),
- * so we check for TASK_SIZE using get_fs() since the addr_limit load from mem
- * would already have been done at this call site for __kernel_ok()
- *
- */
-#define __user_ok(addr, sz) (((sz) <= TASK_SIZE) && \
- ((addr) <= (get_fs() - (sz))))
-#define __access_ok(addr, sz) (unlikely(__kernel_ok) || \
- likely(__user_ok((addr), (sz))))
-
/*********** Single byte/hword/word copies ******************/

#define __get_user_fn(sz, u, k) \
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index d20d78c34b94..2fcbec9c306c 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -55,21 +55,6 @@ extern int __put_user_bad(void);

#ifdef CONFIG_MMU

-/*
- * We use 33-bit arithmetic here. Success returns zero, failure returns
- * addr_limit. We take advantage that addr_limit will be zero for KERNEL_DS,
- * so this will always return success in that case.
- */
-#define __range_ok(addr, size) ({ \
- unsigned long flag, roksum; \
- __chk_user_ptr(addr); \
- __asm__(".syntax unified\n" \
- "adds %1, %2, %3; sbcscc %1, %1, %0; movcc %0, #0" \
- : "=&r" (flag), "=&r" (roksum) \
- : "r" (addr), "Ir" (size), "0" (TASK_SIZE) \
- : "cc"); \
- flag; })
-
/*
* This is a type: either unsigned long, if the argument fits into
* that type, or otherwise unsigned long long.
@@ -241,15 +226,12 @@ extern int __put_user_8(void *, unsigned long long);

#else /* CONFIG_MMU */

-#define __addr_ok(addr) ((void)(addr), 1)
-#define __range_ok(addr, size) ((void)(addr), 0)
-
#define get_user(x, p) __get_user(x, p)
#define __put_user_check __put_user_nocheck

#endif /* CONFIG_MMU */

-#define access_ok(addr, size) (__range_ok(addr, size) == 0)
+#include <asm-generic/access_ok.h>

#ifdef CONFIG_CPU_SPECTRE
/*
diff --git a/arch/arm/kernel/swp_emulate.c b/arch/arm/kernel/swp_emulate.c
index 6166ba38bf99..b74bfcf94fb1 100644
--- a/arch/arm/kernel/swp_emulate.c
+++ b/arch/arm/kernel/swp_emulate.c
@@ -195,7 +195,7 @@ static int swp_handler(struct pt_regs *regs, unsigned int instr)
destreg, EXTRACT_REG_NUM(instr, RT2_OFFSET), data);

/* Check access in reasonable access range for both SWP and SWPB */
- if (!access_ok((address & ~3), 4)) {
+ if (!access_ok((void __user *)(address & ~3), 4)) {
pr_debug("SWP{B} emulation: access to %p not allowed!\n",
(void *)address);
res = -EFAULT;
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index da04ed85855a..26c8c8276297 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -576,7 +576,7 @@ do_cache_op(unsigned long start, unsigned long end, int flags)
if (end < start || flags)
return -EINVAL;

- if (!access_ok(start, end - start))
+ if (!access_ok((void __user *)start, end - start))
return -EFAULT;

return __do_cache_op(start, end);
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 2e20879fe3cf..357f7bd9c981 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -33,7 +33,7 @@
* This is equivalent to the following test:
* (u65)addr + (u65)size <= (u65)TASK_SIZE_MAX
*/
-static inline unsigned long __range_ok(const void __user *addr, unsigned long size)
+static inline unsigned long __access_ok(const void __user *addr, unsigned long size)
{
unsigned long ret, limit = TASK_SIZE_MAX - 1;

@@ -66,8 +66,9 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si

return ret;
}
+#define __access_ok __access_ok

-#define access_ok(addr, size) __range_ok(addr, size)
+#include <asm-generic/access_ok.h>

/*
* User access enabling/disabling.
diff --git a/arch/csky/include/asm/uaccess.h b/arch/csky/include/asm/uaccess.h
index ac5a54f57d40..fec8f77ffc99 100644
--- a/arch/csky/include/asm/uaccess.h
+++ b/arch/csky/include/asm/uaccess.h
@@ -5,14 +5,6 @@

#define user_addr_max() (current_thread_info()->addr_limit.seg)

-static inline int __access_ok(unsigned long addr, unsigned long size)
-{
- unsigned long limit = user_addr_max();
-
- return (size <= limit) && (addr <= (limit - size));
-}
-#define __access_ok __access_ok
-
/*
* __put_user_fn
*/
diff --git a/arch/csky/kernel/signal.c b/arch/csky/kernel/signal.c
index c7b763d2f526..8867ddf3e6c7 100644
--- a/arch/csky/kernel/signal.c
+++ b/arch/csky/kernel/signal.c
@@ -136,7 +136,7 @@ static inline void __user *get_sigframe(struct ksignal *ksig,
static int
setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
{
- struct rt_sigframe *frame;
+ struct rt_sigframe __user *frame;
int err = 0;

frame = get_sigframe(ksig, regs, sizeof(*frame));
diff --git a/arch/hexagon/include/asm/uaccess.h b/arch/hexagon/include/asm/uaccess.h
index 719ba3f3c45c..bff77efc0d9a 100644
--- a/arch/hexagon/include/asm/uaccess.h
+++ b/arch/hexagon/include/asm/uaccess.h
@@ -12,31 +12,6 @@
*/
#include <asm/sections.h>

-/*
- * access_ok: - Checks if a user space pointer is valid
- * @addr: User space pointer to start of block to check
- * @size: Size of block to check
- *
- * Context: User context only. This function may sleep if pagefaults are
- * enabled.
- *
- * Checks if a pointer to a block of memory in user space is valid.
- *
- * Returns true (nonzero) if the memory block *may* be valid, false (zero)
- * if it is definitely invalid.
- *
- */
-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
-
-static inline int __access_ok(unsigned long addr, unsigned long size)
-{
- unsigned long limit = TASK_SIZE;
-
- return (size <= limit) && (addr <= (limit - size));
-}
-#define __access_ok __access_ok
-
/*
* When a kernel-mode page fault is taken, the faulting instruction
* address is checked against a table of exception_table_entries.
diff --git a/arch/ia64/include/asm/uaccess.h b/arch/ia64/include/asm/uaccess.h
index e19d2dcc0ced..e242a3cc1330 100644
--- a/arch/ia64/include/asm/uaccess.h
+++ b/arch/ia64/include/asm/uaccess.h
@@ -50,8 +50,6 @@
#define get_fs() (current_thread_info()->addr_limit)
#define set_fs(x) (current_thread_info()->addr_limit = (x))

-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-
/*
* When accessing user memory, we need to make sure the entire area really is in
* user-level space. In order to do this efficiently, we make sure that the page at
@@ -65,7 +63,8 @@ static inline int __access_ok(const void __user *p, unsigned long size)
return likely(addr <= seg) &&
(seg == KERNEL_DS.seg || likely(REGION_OFFSET(addr) < RGN_MAP_LIMIT));
}
-#define access_ok(addr, size) __access_ok((addr), (size))
+#define __access_ok __access_ok
+#include <asm-generic/access_ok.h>

/*
* These are the main single-value transfer routines. They automatically
diff --git a/arch/m68k/include/asm/uaccess.h b/arch/m68k/include/asm/uaccess.h
index 79617c0b2f91..d6bb5720365a 100644
--- a/arch/m68k/include/asm/uaccess.h
+++ b/arch/m68k/include/asm/uaccess.h
@@ -12,15 +12,18 @@
#include <asm/extable.h>

/* We let the MMU do all checking */
-static inline int access_ok(const void __user *addr,
+static inline int __access_ok(const void __user *addr,
unsigned long size)
{
/*
* XXX: for !CONFIG_CPU_HAS_ADDRESS_SPACES this really needs to check
* for TASK_SIZE!
+ * Removing this helper is probably sufficient.
*/
return 1;
}
+#define __access_ok __access_ok
+#include <asm-generic/access_ok.h>

/*
* Not all varients of the 68k family support the notion of address spaces.
diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
index 5b6e0e7788f4..dd82e90adb52 100644
--- a/arch/microblaze/include/asm/uaccess.h
+++ b/arch/microblaze/include/asm/uaccess.h
@@ -39,13 +39,7 @@

# define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)

-static inline int __access_ok(unsigned long addr, unsigned long size)
-{
- unsigned long limit = user_addr_max();
-
- return (size <= limit) && (addr <= (limit - size));
-}
-#define access_ok(addr, size) __access_ok((unsigned long)addr, size)
+#include <asm-generic/access_ok.h>

# define __FIXUP_SECTION ".section .fixup,\"ax\"\n"
# define __EX_TABLE_SECTION ".section __ex_table,\"a\"\n"
diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
index d7c89dc3426c..436248652b28 100644
--- a/arch/mips/include/asm/uaccess.h
+++ b/arch/mips/include/asm/uaccess.h
@@ -44,34 +44,7 @@ extern u64 __ua_limit;

#endif /* CONFIG_64BIT */

-/*
- * access_ok: - Checks if a user space pointer is valid
- * @addr: User space pointer to start of block to check
- * @size: Size of block to check
- *
- * Context: User context only. This function may sleep if pagefaults are
- * enabled.
- *
- * Checks if a pointer to a block of memory in user space is valid.
- *
- * Returns true (nonzero) if the memory block may be valid, false (zero)
- * if it is definitely invalid.
- *
- * Note that, depending on architecture, this function probably just
- * checks that the pointer is in the user space range - after calling
- * this function, memory access functions may still return -EFAULT.
- */
-
-static inline int __access_ok(const void __user *p, unsigned long size)
-{
- unsigned long addr = (unsigned long)p;
- unsigned long limit = TASK_SIZE_MAX;
-
- return (size <= limit) && (addr <= (limit - size));
-}
-
-#define access_ok(addr, size) \
- likely(__access_ok((addr), (size)))
+#include <asm-generic/access_ok.h>

/*
* put_user: - Write a simple value into user space.
diff --git a/arch/nds32/include/asm/uaccess.h b/arch/nds32/include/asm/uaccess.h
index 37a40981deb3..832d642a4068 100644
--- a/arch/nds32/include/asm/uaccess.h
+++ b/arch/nds32/include/asm/uaccess.h
@@ -38,18 +38,15 @@ extern int fixup_exception(struct pt_regs *regs);

#define get_fs() (current_thread_info()->addr_limit)
#define user_addr_max get_fs
+#define uaccess_kernel() (get_fs() == KERNEL_DS)

static inline void set_fs(mm_segment_t fs)
{
current_thread_info()->addr_limit = fs;
}

-#define uaccess_kernel() (get_fs() == KERNEL_DS)
+#include <asm-generic/access_ok.h>

-#define __range_ok(addr, size) (size <= get_fs() && addr <= (get_fs() -size))
-
-#define access_ok(addr, size) \
- __range_ok((unsigned long)addr, (unsigned long)size)
/*
* Single-value transfer routines. They automatically use the right
* size if we just have the right pointer type. Note that the functions
diff --git a/arch/nios2/include/asm/uaccess.h b/arch/nios2/include/asm/uaccess.h
index ba9340e96fd4..9a7658df7f8d 100644
--- a/arch/nios2/include/asm/uaccess.h
+++ b/arch/nios2/include/asm/uaccess.h
@@ -30,19 +30,10 @@
#define get_fs() (current_thread_info()->addr_limit)
#define set_fs(seg) (current_thread_info()->addr_limit = (seg))

-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-
-#define __access_ok(addr, len) \
- (((signed long)(((long)get_fs().seg) & \
- ((long)(addr) | (((long)(addr)) + (len)) | (len)))) == 0)
-
-#define access_ok(addr, len) \
- likely(__access_ok((unsigned long)(addr), (unsigned long)(len)))
+#include <asm-generic/access_ok.h>

# define __EX_TABLE_SECTION ".section __ex_table,\"a\"\n"

-#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
-
/*
* Zero Userspace
*/
diff --git a/arch/nios2/kernel/signal.c b/arch/nios2/kernel/signal.c
index 2009ae2d3c3b..386e46443b60 100644
--- a/arch/nios2/kernel/signal.c
+++ b/arch/nios2/kernel/signal.c
@@ -36,10 +36,10 @@ struct rt_sigframe {

static inline int rt_restore_ucontext(struct pt_regs *regs,
struct switch_stack *sw,
- struct ucontext *uc, int *pr2)
+ struct ucontext __user *uc, int *pr2)
{
int temp;
- unsigned long *gregs = uc->uc_mcontext.gregs;
+ unsigned long __user *gregs = uc->uc_mcontext.gregs;
int err;

/* Always make any pending restarted system calls return -EINTR */
@@ -102,10 +102,11 @@ asmlinkage int do_rt_sigreturn(struct switch_stack *sw)
{
struct pt_regs *regs = (struct pt_regs *)(sw + 1);
/* Verify, can we follow the stack back */
- struct rt_sigframe *frame = (struct rt_sigframe *) regs->sp;
+ struct rt_sigframe __user *frame;
sigset_t set;
int rval;

+ frame = (struct rt_sigframe __user *) regs->sp;
if (!access_ok(frame, sizeof(*frame)))
goto badframe;

@@ -124,10 +125,10 @@ asmlinkage int do_rt_sigreturn(struct switch_stack *sw)
return 0;
}

-static inline int rt_setup_ucontext(struct ucontext *uc, struct pt_regs *regs)
+static inline int rt_setup_ucontext(struct ucontext __user *uc, struct pt_regs *regs)
{
struct switch_stack *sw = (struct switch_stack *)regs - 1;
- unsigned long *gregs = uc->uc_mcontext.gregs;
+ unsigned long __user *gregs = uc->uc_mcontext.gregs;
int err = 0;

err |= __put_user(MCONTEXT_VERSION, &uc->uc_mcontext.version);
@@ -162,8 +163,9 @@ static inline int rt_setup_ucontext(struct ucontext *uc, struct pt_regs *regs)
return err;
}

-static inline void *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
- size_t frame_size)
+static inline void __user *get_sigframe(struct ksignal *ksig,
+ struct pt_regs *regs,
+ size_t frame_size)
{
unsigned long usp;

@@ -174,13 +176,13 @@ static inline void *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
usp = sigsp(usp, ksig);

/* Verify, is it 32 or 64 bit aligned */
- return (void *)((usp - frame_size) & -8UL);
+ return (void __user *)((usp - frame_size) & -8UL);
}

static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
struct pt_regs *regs)
{
- struct rt_sigframe *frame;
+ struct rt_sigframe __user *frame;
int err = 0;

frame = get_sigframe(ksig, regs, sizeof(*frame));
diff --git a/arch/openrisc/include/asm/uaccess.h b/arch/openrisc/include/asm/uaccess.h
index 120f5005461b..8f049ec99b3e 100644
--- a/arch/openrisc/include/asm/uaccess.h
+++ b/arch/openrisc/include/asm/uaccess.h
@@ -45,21 +45,7 @@

#define uaccess_kernel() (get_fs() == KERNEL_DS)

-/* Ensure that the range from addr to addr+size is all within the process'
- * address space
- */
-static inline int __range_ok(unsigned long addr, unsigned long size)
-{
- const mm_segment_t fs = get_fs();
-
- return size <= fs && addr <= (fs - size);
-}
-
-#define access_ok(addr, size) \
-({ \
- __chk_user_ptr(addr); \
- __range_ok((unsigned long)(addr), (size)); \
-})
+#include <asm-generic/access_ok.h>

/*
* These are the main single-value transfer routines. They automatically
@@ -268,9 +254,6 @@ clear_user(void __user *addr, unsigned long size)
return size;
}

-#define user_addr_max() \
- (uaccess_kernel() ? ~0UL : TASK_SIZE)
-
extern long strncpy_from_user(char *dest, const char __user *src, long count);

extern __must_check long strnlen_user(const char __user *str, long n);
diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h
index 0925bbd6db67..b68f19e11361 100644
--- a/arch/parisc/include/asm/uaccess.h
+++ b/arch/parisc/include/asm/uaccess.h
@@ -17,9 +17,13 @@
* We just let the page fault handler do the right thing. This also means
* that put_user is the same as __put_user, etc.
*/
-
-#define access_ok(uaddr, size) \
- ( (uaddr) == (uaddr) )
+static inline int __access_ok(const void __user *addr, unsigned long size)
+{
+ return 1;
+}
+#define __access_ok __access_ok
+#define TASK_SIZE_MAX DEFAULT_TASK_SIZE
+#include <asm-generic/access_ok.h>

#define put_user __put_user
#define get_user __get_user
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index a0032c2e7550..2e83217f52de 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -11,18 +11,9 @@
#ifdef __powerpc64__
/* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
#define TASK_SIZE_MAX TASK_SIZE_USER64
-#else
-#define TASK_SIZE_MAX TASK_SIZE
#endif

-static inline bool __access_ok(unsigned long addr, unsigned long size)
-{
- return addr < TASK_SIZE_MAX && size <= TASK_SIZE_MAX - addr;
-}
-
-#define access_ok(addr, size) \
- (__chk_user_ptr(addr), \
- __access_ok((unsigned long)(addr), (size)))
+#include <asm-generic/access_ok.h>

/*
* These are the main single-value transfer routines. They automatically
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index a94b0cd0bdc5..022d23ae300b 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -112,9 +112,9 @@ static nokprobe_inline long address_ok(struct pt_regs *regs,
{
if (!user_mode(regs))
return 1;
- if (__access_ok(ea, nb))
+ if (access_ok((void __user *)ea, nb))
return 1;
- if (__access_ok(ea, 1))
+ if (access_ok((void __user *)ea, 1))
/* Access overlaps the end of the user region */
regs->dar = TASK_SIZE_MAX - 1;
else
diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
index 4407b9e48d2c..855450bed9f5 100644
--- a/arch/riscv/include/asm/uaccess.h
+++ b/arch/riscv/include/asm/uaccess.h
@@ -21,42 +21,13 @@
#include <asm/byteorder.h>
#include <asm/extable.h>
#include <asm/asm.h>
+#include <asm-generic/access_ok.h>

#define __enable_user_access() \
__asm__ __volatile__ ("csrs sstatus, %0" : : "r" (SR_SUM) : "memory")
#define __disable_user_access() \
__asm__ __volatile__ ("csrc sstatus, %0" : : "r" (SR_SUM) : "memory")

-/**
- * access_ok: - Checks if a user space pointer is valid
- * @addr: User space pointer to start of block to check
- * @size: Size of block to check
- *
- * Context: User context only. This function may sleep.
- *
- * Checks if a pointer to a block of memory in user space is valid.
- *
- * Returns true (nonzero) if the memory block may be valid, false (zero)
- * if it is definitely invalid.
- *
- * Note that, depending on architecture, this function probably just
- * checks that the pointer is in the user space range - after calling
- * this function, memory access functions may still return -EFAULT.
- */
-#define access_ok(addr, size) ({ \
- __chk_user_ptr(addr); \
- likely(__access_ok((unsigned long __force)(addr), (size))); \
-})
-
-/*
- * Ensure that the range [addr, addr+size) is within the process's
- * address space
- */
-static inline int __access_ok(unsigned long addr, unsigned long size)
-{
- return size <= TASK_SIZE && addr <= TASK_SIZE - size;
-}
-
/*
* The exception table consists of pairs of addresses: the first is the
* address of an instruction that is allowed to fault, and the second is
diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
index 1fc075b8f764..f0c7bb98119a 100644
--- a/arch/riscv/kernel/perf_callchain.c
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -15,7 +15,7 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
{
struct stackframe buftail;
unsigned long ra = 0;
- unsigned long *user_frame_tail =
+ unsigned long __user *user_frame_tail =
(unsigned long *)(fp - sizeof(struct stackframe));

/* Check accessibility of one struct frame_tail beyond */
diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index 29332edf46f0..f84d70c8e188 100644
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -20,18 +20,13 @@

void debug_user_asce(int exit);

-static inline int __range_ok(unsigned long addr, unsigned long size)
+static inline int __access_ok(const void __user *addr, unsigned long size)
{
return 1;
}
+#define __access_ok __access_ok

-#define __access_ok(addr, size) \
-({ \
- __chk_user_ptr(addr); \
- __range_ok((unsigned long)(addr), (size)); \
-})
-
-#define access_ok(addr, size) __access_ok(addr, size)
+#include <asm-generic/access_ok.h>

unsigned long __must_check
raw_copy_from_user(void *to, const void __user *from, unsigned long n);
diff --git a/arch/sh/include/asm/uaccess.h b/arch/sh/include/asm/uaccess.h
index 8867bb04b00e..ccd219d74851 100644
--- a/arch/sh/include/asm/uaccess.h
+++ b/arch/sh/include/asm/uaccess.h
@@ -5,28 +5,10 @@
#include <asm/segment.h>
#include <asm/extable.h>

-#define __addr_ok(addr) \
- ((unsigned long __force)(addr) < current_thread_info()->addr_limit.seg)
-
-/*
- * __access_ok: Check if address with size is OK or not.
- *
- * Uhhuh, this needs 33-bit arithmetic. We have a carry..
- *
- * sum := addr + size; carry? --> flag = true;
- * if (sum >= addr_limit) flag = true;
- */
-#define __access_ok(addr, size) ({ \
- unsigned long __ao_a = (addr), __ao_b = (size); \
- unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b; \
- __ao_end >= __ao_a && __addr_ok(__ao_end); })
-
-#define access_ok(addr, size) \
- (__chk_user_ptr(addr), \
- __access_ok((unsigned long __force)(addr), (size)))
-
#define user_addr_max() (current_thread_info()->addr_limit.seg)

+#include <asm-generic/access_ok.h>
+
/*
* Uh, these should become the main single-value transfer routines ...
* They automatically use the right size if we just have the right
diff --git a/arch/sparc/include/asm/uaccess.h b/arch/sparc/include/asm/uaccess.h
index 390094200fc4..ee75f69e3fcd 100644
--- a/arch/sparc/include/asm/uaccess.h
+++ b/arch/sparc/include/asm/uaccess.h
@@ -10,9 +10,6 @@
#include <asm/uaccess_32.h>
#endif

-#define user_addr_max() \
- (uaccess_kernel() ? ~0UL : TASK_SIZE)
-
long strncpy_from_user(char *dest, const char __user *src, long count);

#endif
diff --git a/arch/sparc/include/asm/uaccess_32.h b/arch/sparc/include/asm/uaccess_32.h
index 4a12346bb69c..367747116260 100644
--- a/arch/sparc/include/asm/uaccess_32.h
+++ b/arch/sparc/include/asm/uaccess_32.h
@@ -25,17 +25,7 @@
#define get_fs() (current->thread.current_ds)
#define set_fs(val) ((current->thread.current_ds) = (val))

-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-
-/* We have there a nice not-mapped page at PAGE_OFFSET - PAGE_SIZE, so that this test
- * can be fairly lightweight.
- * No one can read/write anything from userland in the kernel space by setting
- * large size and address near to PAGE_OFFSET - a fault will break his intentions.
- */
-#define __user_ok(addr, size) ({ (void)(size); (addr) < STACK_TOP; })
-#define __kernel_ok (uaccess_kernel())
-#define __access_ok(addr, size) (__user_ok((addr) & get_fs().seg, (size)))
-#define access_ok(addr, size) __access_ok((unsigned long)(addr), size)
+#include <asm-generic/access_ok.h>

/* Uh, these should become the main single-value transfer routines..
* They automatically use the right size if we just have the right
@@ -47,13 +37,13 @@
* and hide all the ugliness from the user.
*/
#define put_user(x, ptr) ({ \
- unsigned long __pu_addr = (unsigned long)(ptr); \
+ void __user *__pu_addr = (ptr); \
__chk_user_ptr(ptr); \
__put_user_check((__typeof__(*(ptr)))(x), __pu_addr, sizeof(*(ptr))); \
})

#define get_user(x, ptr) ({ \
- unsigned long __gu_addr = (unsigned long)(ptr); \
+ const void __user *__gu_addr = (ptr); \
__chk_user_ptr(ptr); \
__get_user_check((x), __gu_addr, sizeof(*(ptr)), __typeof__(*(ptr))); \
})
@@ -232,7 +222,7 @@ static inline unsigned long __clear_user(void __user *addr, unsigned long size)

static inline unsigned long clear_user(void __user *addr, unsigned long n)
{
- if (n && __access_ok((unsigned long) addr, n))
+ if (n && __access_ok(addr, n))
return __clear_user(addr, n);
else
return n;
diff --git a/arch/sparc/include/asm/uaccess_64.h b/arch/sparc/include/asm/uaccess_64.h
index 5c12fb46bc61..000bac67cf31 100644
--- a/arch/sparc/include/asm/uaccess_64.h
+++ b/arch/sparc/include/asm/uaccess_64.h
@@ -31,7 +31,12 @@

#define get_fs() ((mm_segment_t){(current_thread_info()->current_ds)})

-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
+static inline int __access_ok(const void __user *addr, unsigned long size)
+{
+ return 1;
+}
+#define __access_ok __access_ok
+#include <asm-generic/access_ok.h>

#define set_fs(val) \
do { \
@@ -43,33 +48,7 @@ do { \
* Test whether a block of memory is a valid user space address.
* Returns 0 if the range is valid, nonzero otherwise.
*/
-static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
-{
- if (__builtin_constant_p(size))
- return addr > limit - size;
-
- addr += size;
- if (addr < size)
- return true;
-
- return addr > limit;
-}
-
-#define __range_not_ok(addr, size, limit) \
-({ \
- __chk_user_ptr(addr); \
- __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
-})
-
-static inline int __access_ok(const void __user * addr, unsigned long size)
-{
- return 1;
-}
-
-static inline int access_ok(const void __user * addr, unsigned long size)
-{
- return 1;
-}
+#define __range_not_ok(addr, size, limit) (!__access_ok(addr, size))

void __retl_efault(void);

diff --git a/arch/sparc/kernel/signal_32.c b/arch/sparc/kernel/signal_32.c
index ffab16369bea..74f80443b195 100644
--- a/arch/sparc/kernel/signal_32.c
+++ b/arch/sparc/kernel/signal_32.c
@@ -65,7 +65,7 @@ struct rt_signal_frame {
*/
static inline bool invalid_frame_pointer(void __user *fp, int fplen)
{
- if ((((unsigned long) fp) & 15) || !__access_ok((unsigned long)fp, fplen))
+ if ((((unsigned long) fp) & 15) || !access_ok(fp, fplen))
return true;

return false;
diff --git a/arch/um/include/asm/uaccess.h b/arch/um/include/asm/uaccess.h
index 1ecfc96bcc50..7d9d60e41e4e 100644
--- a/arch/um/include/asm/uaccess.h
+++ b/arch/um/include/asm/uaccess.h
@@ -25,7 +25,7 @@
extern unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n);
extern unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n);
extern unsigned long __clear_user(void __user *mem, unsigned long len);
-static inline int __access_ok(unsigned long addr, unsigned long size);
+static inline int __access_ok(const void __user *ptr, unsigned long size);

/* Teach asm-generic/uaccess.h that we have C functions for these. */
#define __access_ok __access_ok
@@ -36,8 +36,9 @@ static inline int __access_ok(unsigned long addr, unsigned long size);

#include <asm-generic/uaccess.h>

-static inline int __access_ok(unsigned long addr, unsigned long size)
+static inline int __access_ok(const void __user *ptr, unsigned long size)
{
+ unsigned long addr = (unsigned long)ptr;
return __addr_range_nowrap(addr, size) &&
(__under_task_size(addr, size) ||
__access_ok_vsyscall(addr, size));
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index c6d9dc42724d..c5e4bb7161bc 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -12,18 +12,6 @@
#include <asm/smap.h>
#include <asm/extable.h>

-/*
- * Test whether a block of memory is a valid user space address.
- * Returns 0 if the range is valid, nonzero otherwise.
- */
-static inline bool __access_ok(void __user *ptr, unsigned long size)
-{
- unsigned long limit = TASK_SIZE_MAX;
- unsigned long addr = ptr;
-
- return (size <= limit) && (addr <= (limit - size));
-}
-
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
static inline bool pagefault_disabled(void);
# define WARN_ON_IN_IRQ() \
@@ -55,6 +43,8 @@ static inline bool pagefault_disabled(void);
likely(__access_ok(addr, size));\
})

+#include <asm-generic/access_ok.h>
+
#define __range_not_ok(addr, size, limit) (!__access_ok(addr, size))
#define __chk_range_not_ok(addr, size, limit) (!__access_ok((void __user *)addr, size))

diff --git a/arch/xtensa/include/asm/uaccess.h b/arch/xtensa/include/asm/uaccess.h
index 75bd8fbf52ba..0edd9e4b23d0 100644
--- a/arch/xtensa/include/asm/uaccess.h
+++ b/arch/xtensa/include/asm/uaccess.h
@@ -35,15 +35,7 @@
#define get_fs() (current->thread.current_ds)
#define set_fs(val) (current->thread.current_ds = (val))

-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-
-#define __kernel_ok (uaccess_kernel())
-#define __user_ok(addr, size) \
- (((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size)))
-#define __access_ok(addr, size) (__kernel_ok || __user_ok((addr), (size)))
-#define access_ok(addr, size) __access_ok((unsigned long)(addr), (size))
-
-#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
+#include <asm-generic/access_ok.h>

/*
* These are the main single-value transfer routines. They
diff --git a/include/asm-generic/access_ok.h b/include/asm-generic/access_ok.h
new file mode 100644
index 000000000000..883b573af5fe
--- /dev/null
+++ b/include/asm-generic/access_ok.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_GENERIC_ACCESS_OK_H__
+#define __ASM_GENERIC_ACCESS_OK_H__
+
+/*
+ * Checking whether a pointer is valid for user space access.
+ * These definitions work on most architectures, but overrides can
+ * be used where necessary.
+ */
+
+/*
+ * architectures with compat tasks have a variable TASK_SIZE and should
+ * override this to a constant.
+ */
+#ifndef TASK_SIZE_MAX
+#define TASK_SIZE_MAX TASK_SIZE
+#endif
+
+#ifndef uaccess_kernel
+#ifdef CONFIG_SET_FS
+#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
+#else
+#define uaccess_kernel() (0)
+#endif
+#endif
+
+#ifndef user_addr_max
+#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE_MAX)
+#endif
+
+#ifndef __access_ok
+/*
+ * 'size' is a compile-time constant for most callers, so optimize for
+ * this case to turn the check into a single comparison against a constant
+ * limit and catch all possible overflows.
+ * On architectures with separate user address space (m68k, s390, parisc,
+ * sparc64) or those without an MMU, this should always return true.
+ *
+ * This version was originally contributed by Jonas Bonn for the
+ * OpenRISC architecture, and was found to be the most efficient
+ * for constant 'size' and 'limit' values.
+ */
+static inline int __access_ok(const void __user *ptr, unsigned long size)
+{
+ unsigned long limit = user_addr_max();
+ unsigned long addr = (unsigned long)ptr;
+
+ if (limit == ULONG_MAX)
+ return true;
+
+ return (size <= limit) && (addr <= (limit - size));
+}
+#endif
+
+#ifndef access_ok
+#define access_ok(addr, size) likely(__access_ok(addr, size))
+#endif
+
+#endif
diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
index 0870fa11a7c5..ebc685dc8d74 100644
--- a/include/asm-generic/uaccess.h
+++ b/include/asm-generic/uaccess.h
@@ -114,28 +114,9 @@ static inline void set_fs(mm_segment_t fs)
}
#endif

-#ifndef uaccess_kernel
-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-#endif
-
-#ifndef user_addr_max
-#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
-#endif
-
#endif /* CONFIG_SET_FS */

-#define access_ok(addr, size) __access_ok((unsigned long)(addr),(size))
-
-/*
- * The architecture should really override this if possible, at least
- * doing a check on the get_fs()
- */
-#ifndef __access_ok
-static inline int __access_ok(unsigned long addr, unsigned long size)
-{
- return 1;
-}
-#endif
+#include <asm-generic/access_ok.h>

/*
* These are the main single-value transfer routines. They automatically
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 67e9bc94dc40..2c31667e62e0 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -33,13 +33,6 @@ typedef struct {
/* empty dummy */
} mm_segment_t;

-#ifndef TASK_SIZE_MAX
-#define TASK_SIZE_MAX TASK_SIZE
-#endif
-
-#define uaccess_kernel() (false)
-#define user_addr_max() (TASK_SIZE_MAX)
-
static inline mm_segment_t force_uaccess_begin(void)
{
return (mm_segment_t) { };
--
2.29.2