From: Christoph Hellwig <hch@lst.de>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Michael Ellerman <mpe@ellerman.id.au>,
x86@kernel.org
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 12/14] x86: remove address space overrides using set_fs()
Date: Thu, 3 Sep 2020 16:22:40 +0200 [thread overview]
Message-ID: <20200903142242.925828-13-hch@lst.de> (raw)
In-Reply-To: <20200903142242.925828-1-hch@lst.de>
Stop providing the possibility to override the address space using
set_fs() now that there is no need for that any more. To properly
handle the TASK_SIZE_MAX checking for 4 vs 5-level page tables on
x86 a new alternative is introduced, which just like the one in
entry_64.S has to use the hardcoded virtual address bits to escape
the fact that TASK_SIZE_MAX isn't actually a constant when 5-level
page tables are enabled.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
arch/x86/Kconfig | 1 -
arch/x86/ia32/ia32_aout.c | 1 -
arch/x86/include/asm/processor.h | 11 +------
arch/x86/include/asm/thread_info.h | 2 --
arch/x86/include/asm/uaccess.h | 26 +----------------
arch/x86/kernel/asm-offsets.c | 3 --
arch/x86/lib/getuser.S | 47 +++++++++++++++---------------
arch/x86/lib/putuser.S | 25 ++++++++--------
8 files changed, 39 insertions(+), 77 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f85c13355732fe..7101ac64bb209d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -237,7 +237,6 @@ config X86
select HAVE_ARCH_KCSAN if X86_64
select X86_FEATURE_NAMES if PROC_FS
select PROC_PID_ARCH_STATUS if PROC_FS
- select SET_FS
imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
config INSTRUCTION_DECODER
diff --git a/arch/x86/ia32/ia32_aout.c b/arch/x86/ia32/ia32_aout.c
index ca8a657edf5977..a09fc37ead9d47 100644
--- a/arch/x86/ia32/ia32_aout.c
+++ b/arch/x86/ia32/ia32_aout.c
@@ -239,7 +239,6 @@ static int load_aout_binary(struct linux_binprm *bprm)
(regs)->ss = __USER32_DS;
regs->r8 = regs->r9 = regs->r10 = regs->r11 =
regs->r12 = regs->r13 = regs->r14 = regs->r15 = 0;
- set_fs(USER_DS);
return 0;
}
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 1618eeb08361a9..189573d95c3af6 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -482,10 +482,6 @@ extern unsigned int fpu_user_xstate_size;
struct perf_event;
-typedef struct {
- unsigned long seg;
-} mm_segment_t;
-
struct thread_struct {
/* Cached TLS descriptors: */
struct desc_struct tls_array[GDT_ENTRY_TLS_ENTRIES];
@@ -538,8 +534,6 @@ struct thread_struct {
*/
unsigned long iopl_emul;
- mm_segment_t addr_limit;
-
unsigned int sig_on_uaccess_err:1;
/* Floating point and extended processor state */
@@ -785,15 +779,12 @@ static inline void spin_lock_prefetch(const void *x)
#define INIT_THREAD { \
.sp0 = TOP_OF_INIT_STACK, \
.sysenter_cs = __KERNEL_CS, \
- .addr_limit = KERNEL_DS, \
}
#define KSTK_ESP(task) (task_pt_regs(task)->sp)
#else
-#define INIT_THREAD { \
- .addr_limit = KERNEL_DS, \
-}
+#define INIT_THREAD { }
extern unsigned long KSTK_ESP(struct task_struct *task);
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 267701ae3d86dd..44733a4bfc4294 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -102,7 +102,6 @@ struct thread_info {
#define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
#define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
#define TIF_X32 30 /* 32-bit native x86-64 binary */
-#define TIF_FSCHECK 31 /* Check FS is USER_DS on return */
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
@@ -131,7 +130,6 @@ struct thread_info {
#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
#define _TIF_ADDR32 (1 << TIF_ADDR32)
#define _TIF_X32 (1 << TIF_X32)
-#define _TIF_FSCHECK (1 << TIF_FSCHECK)
/* flags to check in __switch_to() */
#define _TIF_WORK_CTXSW_BASE \
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index ecefaffd15d4c8..a4ceda0510ea87 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -12,30 +12,6 @@
#include <asm/smap.h>
#include <asm/extable.h>
-/*
- * The fs value determines whether argument validity checking should be
- * performed or not. If get_fs() == USER_DS, checking is performed, with
- * get_fs() == KERNEL_DS, checking is bypassed.
- *
- * For historical reasons, these macros are grossly misnamed.
- */
-
-#define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
-
-#define KERNEL_DS MAKE_MM_SEG(-1UL)
-#define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX)
-
-#define get_fs() (current->thread.addr_limit)
-static inline void set_fs(mm_segment_t fs)
-{
- current->thread.addr_limit = fs;
- /* On user-mode return, check fs is correct */
- set_thread_flag(TIF_FSCHECK);
-}
-
-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-#define user_addr_max() (current->thread.addr_limit.seg)
-
/*
* Test whether a block of memory is a valid user space address.
* Returns 0 if the range is valid, nonzero otherwise.
@@ -93,7 +69,7 @@ static inline bool pagefault_disabled(void);
#define access_ok(addr, size) \
({ \
WARN_ON_IN_IRQ(); \
- likely(!__range_not_ok(addr, size, user_addr_max())); \
+ likely(!__range_not_ok(addr, size, TASK_SIZE_MAX)); \
})
/*
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 3ca07ad552ae0c..70b7154f4bdd62 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -37,9 +37,6 @@ static void __used common(void)
OFFSET(TASK_stack_canary, task_struct, stack_canary);
#endif
- BLANK();
- OFFSET(TASK_addr_limit, task_struct, thread.addr_limit);
-
BLANK();
OFFSET(crypto_tfm_ctx_offset, crypto_tfm, __crt_ctx);
diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S
index c8a85b512796e1..94f7be4971ed04 100644
--- a/arch/x86/lib/getuser.S
+++ b/arch/x86/lib/getuser.S
@@ -35,10 +35,19 @@
#include <asm/smap.h>
#include <asm/export.h>
+#ifdef CONFIG_X86_5LEVEL
+#define LOAD_TASK_SIZE_MINUS_N(n) \
+ ALTERNATIVE "mov $((1 << 47) - 4096 - (n)),%rdx", \
+ "mov $((1 << 56) - 4096 - (n)),%rdx", X86_FEATURE_LA57
+#else
+#define LOAD_TASK_SIZE_MINUS_N(n) \
+ mov $(TASK_SIZE_MAX - (n)),%_ASM_DX
+#endif
+
.text
SYM_FUNC_START(__get_user_1)
- mov PER_CPU_VAR(current_task), %_ASM_DX
- cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
+ LOAD_TASK_SIZE_MINUS_N(0)
+ cmp %_ASM_DX,%_ASM_AX
jae bad_get_user
sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */
and %_ASM_DX, %_ASM_AX
@@ -51,15 +60,13 @@ SYM_FUNC_END(__get_user_1)
EXPORT_SYMBOL(__get_user_1)
SYM_FUNC_START(__get_user_2)
- add $1,%_ASM_AX
- jc bad_get_user
- mov PER_CPU_VAR(current_task), %_ASM_DX
- cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
+ LOAD_TASK_SIZE_MINUS_N(1)
+ cmp %_ASM_DX,%_ASM_AX
jae bad_get_user
sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */
and %_ASM_DX, %_ASM_AX
ASM_STAC
-2: movzwl -1(%_ASM_AX),%edx
+2: movzwl (%_ASM_AX),%edx
xor %eax,%eax
ASM_CLAC
ret
@@ -67,15 +74,13 @@ SYM_FUNC_END(__get_user_2)
EXPORT_SYMBOL(__get_user_2)
SYM_FUNC_START(__get_user_4)
- add $3,%_ASM_AX
- jc bad_get_user
- mov PER_CPU_VAR(current_task), %_ASM_DX
- cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
+ LOAD_TASK_SIZE_MINUS_N(3)
+ cmp %_ASM_DX,%_ASM_AX
jae bad_get_user
sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */
and %_ASM_DX, %_ASM_AX
ASM_STAC
-3: movl -3(%_ASM_AX),%edx
+3: movl (%_ASM_AX),%edx
xor %eax,%eax
ASM_CLAC
ret
@@ -84,29 +89,25 @@ EXPORT_SYMBOL(__get_user_4)
SYM_FUNC_START(__get_user_8)
#ifdef CONFIG_X86_64
- add $7,%_ASM_AX
- jc bad_get_user
- mov PER_CPU_VAR(current_task), %_ASM_DX
- cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
+ LOAD_TASK_SIZE_MINUS_N(7)
+ cmp %_ASM_DX,%_ASM_AX
jae bad_get_user
sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */
and %_ASM_DX, %_ASM_AX
ASM_STAC
-4: movq -7(%_ASM_AX),%rdx
+4: movq (%_ASM_AX),%rdx
xor %eax,%eax
ASM_CLAC
ret
#else
- add $7,%_ASM_AX
- jc bad_get_user_8
- mov PER_CPU_VAR(current_task), %_ASM_DX
- cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
+ LOAD_TASK_SIZE_MINUS_N(7)
+ cmp %_ASM_DX,%_ASM_AX
jae bad_get_user_8
sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */
and %_ASM_DX, %_ASM_AX
ASM_STAC
-4: movl -7(%_ASM_AX),%edx
-5: movl -3(%_ASM_AX),%ecx
+4: movl (%_ASM_AX),%edx
+5: movl 4(%_ASM_AX),%ecx
xor %eax,%eax
ASM_CLAC
ret
diff --git a/arch/x86/lib/putuser.S b/arch/x86/lib/putuser.S
index 7c7c92db8497af..445374885153bf 100644
--- a/arch/x86/lib/putuser.S
+++ b/arch/x86/lib/putuser.S
@@ -31,12 +31,19 @@
* as they get called from within inline assembly.
*/
-#define ENTER mov PER_CPU_VAR(current_task), %_ASM_BX
+#ifdef CONFIG_X86_5LEVEL
+#define LOAD_TASK_SIZE_MINUS_N(n) \
+ ALTERNATIVE "mov $((1 << 47) - 4096 - (n)),%rbx", \
+ "mov $((1 << 56) - 4096 - (n)),%rbx", X86_FEATURE_LA57
+#else
+#define LOAD_TASK_SIZE_MINUS_N(n) \
+ mov $(TASK_SIZE_MAX - (n)),%_ASM_BX
+#endif
.text
SYM_FUNC_START(__put_user_1)
- ENTER
- cmp TASK_addr_limit(%_ASM_BX),%_ASM_CX
+ LOAD_TASK_SIZE_MINUS_N(0)
+ cmp %_ASM_BX,%_ASM_CX
jae .Lbad_put_user
ASM_STAC
1: movb %al,(%_ASM_CX)
@@ -47,9 +54,7 @@ SYM_FUNC_END(__put_user_1)
EXPORT_SYMBOL(__put_user_1)
SYM_FUNC_START(__put_user_2)
- ENTER
- mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
- sub $1,%_ASM_BX
+ LOAD_TASK_SIZE_MINUS_N(1)
cmp %_ASM_BX,%_ASM_CX
jae .Lbad_put_user
ASM_STAC
@@ -61,9 +66,7 @@ SYM_FUNC_END(__put_user_2)
EXPORT_SYMBOL(__put_user_2)
SYM_FUNC_START(__put_user_4)
- ENTER
- mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
- sub $3,%_ASM_BX
+ LOAD_TASK_SIZE_MINUS_N(3)
cmp %_ASM_BX,%_ASM_CX
jae .Lbad_put_user
ASM_STAC
@@ -75,9 +78,7 @@ SYM_FUNC_END(__put_user_4)
EXPORT_SYMBOL(__put_user_4)
SYM_FUNC_START(__put_user_8)
- ENTER
- mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
- sub $7,%_ASM_BX
+ LOAD_TASK_SIZE_MINUS_N(7)
cmp %_ASM_BX,%_ASM_CX
jae .Lbad_put_user
ASM_STAC
--
2.28.0
next prev parent reply other threads:[~2020-09-03 14:46 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-03 14:22 remove the last set_fs() in common code, and remove it for x86 and powerpc v3 Christoph Hellwig
2020-09-03 14:22 ` [PATCH 01/14] proc: remove a level of indentation in proc_get_inode Christoph Hellwig
2020-09-03 14:22 ` [PATCH 02/14] proc: cleanup the compat vs no compat file ops Christoph Hellwig
2020-09-03 14:22 ` [PATCH 03/14] proc: add a read_iter method to proc proc_ops Christoph Hellwig
2020-09-03 14:22 ` [PATCH 04/14] sysctl: Convert to iter interfaces Christoph Hellwig
2020-09-03 14:22 ` [PATCH 05/14] fs: don't allow kernel reads and writes without iter ops Christoph Hellwig
2020-10-01 22:38 ` Eric Biggers
2020-10-01 22:40 ` Al Viro
2020-10-02 16:27 ` Linus Torvalds
2020-10-09 22:06 ` Eric Biggers
2020-10-10 1:03 ` Linus Torvalds
2020-10-10 1:19 ` Eric Biggers
2020-10-10 1:29 ` Linus Torvalds
2020-10-10 1:55 ` Alexander Viro
2020-10-14 5:51 ` Christoph Hellwig
2020-09-03 14:22 ` [PATCH 06/14] fs: don't allow splice read/write without explicit ops Christoph Hellwig
2020-09-03 14:22 ` [PATCH 07/14] uaccess: add infrastructure for kernel builds with set_fs() Christoph Hellwig
2020-09-03 14:22 ` [PATCH 08/14] test_bitmap: remove user bitmap tests Christoph Hellwig
2020-09-03 14:22 ` [PATCH 09/14] lkdtm: remove set_fs-based tests Christoph Hellwig
2020-09-03 14:22 ` [PATCH 10/14] x86: move PAGE_OFFSET, TASK_SIZE & friends to page_{32,64}_types.h Christoph Hellwig
2020-09-03 14:22 ` [PATCH 11/14] x86: make TASK_SIZE_MAX usable from assembly code Christoph Hellwig
2020-09-03 14:22 ` Christoph Hellwig [this message]
2020-09-03 21:30 ` [PATCH 12/14] x86: remove address space overrides using set_fs() David Laight
2020-09-03 23:25 ` Linus Torvalds
2020-09-04 7:59 ` David Laight
2020-09-04 2:55 ` Al Viro
2020-09-04 4:41 ` Al Viro
2020-09-04 6:38 ` Christoph Hellwig
2020-09-04 7:47 ` Christoph Hellwig
2020-09-03 14:22 ` [PATCH 13/14] powerpc: use non-set_fs based maccess routines Christoph Hellwig
2020-09-03 14:22 ` [PATCH 14/14] powerpc: remove address space overrides using set_fs() Christoph Hellwig
2020-09-03 15:43 ` Christophe Leroy
2020-09-03 15:49 ` Christoph Hellwig
2020-09-03 15:56 ` Christoph Hellwig
2020-09-03 16:03 ` Christophe Leroy
2020-09-03 14:28 ` remove the last set_fs() in common code, and remove it for x86 and powerpc v3 Al Viro
2020-09-03 14:30 ` Christoph Hellwig
2020-09-03 14:36 ` Al Viro
2020-09-03 14:40 ` Christoph Hellwig
2020-09-09 17:31 ` Linus Torvalds
2020-09-09 18:40 ` Segher Boessenkool
2020-09-09 21:33 ` Linus Torvalds
2020-09-10 8:04 ` David Laight
2020-09-10 8:13 ` Christophe Leroy
2020-09-10 9:26 ` David Laight
2020-09-10 12:26 ` David Laight
2020-09-10 15:20 ` Segher Boessenkool
2020-09-10 15:31 ` David Laight
2020-09-10 17:15 ` Segher Boessenkool
2020-09-10 15:16 ` Segher Boessenkool
2020-09-10 15:44 ` Segher Boessenkool
2020-09-03 15:49 ` Linus Torvalds
2020-09-04 6:00 ` Ingo Molnar
2020-09-04 17:58 ` Alexey Dobriyan
2020-09-04 18:42 ` Linus Torvalds
2020-09-04 21:01 ` David Laight
2020-09-05 7:16 ` Christophe Leroy
2020-09-05 10:13 ` David Laight
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