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x86: remove address space overrides using set_fs()
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> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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@ -237,7 +237,6 @@ config X86
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select HAVE_ARCH_KCSAN if X86_64
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select X86_FEATURE_NAMES if PROC_FS
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select PROC_PID_ARCH_STATUS if PROC_FS
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select SET_FS
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imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
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config INSTRUCTION_DECODER
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@ -239,7 +239,6 @@ beyond_if:
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(regs)->ss = __USER32_DS;
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regs->r8 = regs->r9 = regs->r10 = regs->r11 =
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regs->r12 = regs->r13 = regs->r14 = regs->r15 = 0;
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set_fs(USER_DS);
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return 0;
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}
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@ -482,10 +482,6 @@ extern unsigned int fpu_user_xstate_size;
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struct perf_event;
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typedef struct {
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unsigned long seg;
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} mm_segment_t;
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struct thread_struct {
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/* Cached TLS descriptors: */
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struct desc_struct tls_array[GDT_ENTRY_TLS_ENTRIES];
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@ -538,8 +534,6 @@ struct thread_struct {
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*/
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unsigned long iopl_emul;
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mm_segment_t addr_limit;
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unsigned int sig_on_uaccess_err:1;
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/* Floating point and extended processor state */
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@ -785,15 +779,12 @@ static inline void spin_lock_prefetch(const void *x)
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#define INIT_THREAD { \
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.sp0 = TOP_OF_INIT_STACK, \
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.sysenter_cs = __KERNEL_CS, \
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.addr_limit = KERNEL_DS, \
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}
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#define KSTK_ESP(task) (task_pt_regs(task)->sp)
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#else
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#define INIT_THREAD { \
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.addr_limit = KERNEL_DS, \
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}
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#define INIT_THREAD { }
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extern unsigned long KSTK_ESP(struct task_struct *task);
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@ -102,7 +102,6 @@ struct thread_info {
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#define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
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#define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
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#define TIF_X32 30 /* 32-bit native x86-64 binary */
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#define TIF_FSCHECK 31 /* Check FS is USER_DS on return */
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#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
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#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
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@ -131,7 +130,6 @@ struct thread_info {
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#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
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#define _TIF_ADDR32 (1 << TIF_ADDR32)
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#define _TIF_X32 (1 << TIF_X32)
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#define _TIF_FSCHECK (1 << TIF_FSCHECK)
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/* flags to check in __switch_to() */
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#define _TIF_WORK_CTXSW_BASE \
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@ -12,30 +12,6 @@
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#include <asm/smap.h>
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#include <asm/extable.h>
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/*
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* The fs value determines whether argument validity checking should be
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* performed or not. If get_fs() == USER_DS, checking is performed, with
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* get_fs() == KERNEL_DS, checking is bypassed.
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*
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* For historical reasons, these macros are grossly misnamed.
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*/
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#define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
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#define KERNEL_DS MAKE_MM_SEG(-1UL)
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#define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX)
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#define get_fs() (current->thread.addr_limit)
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static inline void set_fs(mm_segment_t fs)
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{
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current->thread.addr_limit = fs;
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/* On user-mode return, check fs is correct */
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set_thread_flag(TIF_FSCHECK);
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}
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#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
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#define user_addr_max() (current->thread.addr_limit.seg)
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/*
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* Test whether a block of memory is a valid user space address.
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* Returns 0 if the range is valid, nonzero otherwise.
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@ -93,7 +69,7 @@ static inline bool pagefault_disabled(void);
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#define access_ok(addr, size) \
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({ \
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WARN_ON_IN_IRQ(); \
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likely(!__range_not_ok(addr, size, user_addr_max())); \
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likely(!__range_not_ok(addr, size, TASK_SIZE_MAX)); \
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})
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/*
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@ -37,9 +37,6 @@ static void __used common(void)
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OFFSET(TASK_stack_canary, task_struct, stack_canary);
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#endif
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BLANK();
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OFFSET(TASK_addr_limit, task_struct, thread.addr_limit);
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BLANK();
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OFFSET(crypto_tfm_ctx_offset, crypto_tfm, __crt_ctx);
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@ -35,10 +35,19 @@
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#include <asm/smap.h>
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#include <asm/export.h>
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#ifdef CONFIG_X86_5LEVEL
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#define LOAD_TASK_SIZE_MINUS_N(n) \
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ALTERNATIVE __stringify(mov $((1 << 47) - 4096 - (n)),%rdx), \
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__stringify(mov $((1 << 56) - 4096 - (n)),%rdx), X86_FEATURE_LA57
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#else
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#define LOAD_TASK_SIZE_MINUS_N(n) \
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mov $(TASK_SIZE_MAX - (n)),%_ASM_DX
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#endif
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.text
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SYM_FUNC_START(__get_user_1)
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mov PER_CPU_VAR(current_task), %_ASM_DX
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cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
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LOAD_TASK_SIZE_MINUS_N(0)
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cmp %_ASM_DX,%_ASM_AX
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jae bad_get_user
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sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */
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and %_ASM_DX, %_ASM_AX
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@ -51,15 +60,13 @@ SYM_FUNC_END(__get_user_1)
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EXPORT_SYMBOL(__get_user_1)
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SYM_FUNC_START(__get_user_2)
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add $1,%_ASM_AX
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jc bad_get_user
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mov PER_CPU_VAR(current_task), %_ASM_DX
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cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
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LOAD_TASK_SIZE_MINUS_N(1)
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cmp %_ASM_DX,%_ASM_AX
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jae bad_get_user
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sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */
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and %_ASM_DX, %_ASM_AX
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ASM_STAC
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2: movzwl -1(%_ASM_AX),%edx
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2: movzwl (%_ASM_AX),%edx
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xor %eax,%eax
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ASM_CLAC
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ret
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@ -67,15 +74,13 @@ SYM_FUNC_END(__get_user_2)
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EXPORT_SYMBOL(__get_user_2)
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SYM_FUNC_START(__get_user_4)
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add $3,%_ASM_AX
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jc bad_get_user
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mov PER_CPU_VAR(current_task), %_ASM_DX
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cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
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LOAD_TASK_SIZE_MINUS_N(3)
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cmp %_ASM_DX,%_ASM_AX
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jae bad_get_user
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sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */
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and %_ASM_DX, %_ASM_AX
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ASM_STAC
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3: movl -3(%_ASM_AX),%edx
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3: movl (%_ASM_AX),%edx
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xor %eax,%eax
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ASM_CLAC
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ret
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@ -84,29 +89,25 @@ EXPORT_SYMBOL(__get_user_4)
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SYM_FUNC_START(__get_user_8)
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#ifdef CONFIG_X86_64
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add $7,%_ASM_AX
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jc bad_get_user
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mov PER_CPU_VAR(current_task), %_ASM_DX
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cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
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LOAD_TASK_SIZE_MINUS_N(7)
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cmp %_ASM_DX,%_ASM_AX
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jae bad_get_user
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sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */
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and %_ASM_DX, %_ASM_AX
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ASM_STAC
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4: movq -7(%_ASM_AX),%rdx
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4: movq (%_ASM_AX),%rdx
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xor %eax,%eax
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ASM_CLAC
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ret
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#else
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add $7,%_ASM_AX
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jc bad_get_user_8
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mov PER_CPU_VAR(current_task), %_ASM_DX
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cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
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LOAD_TASK_SIZE_MINUS_N(7)
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cmp %_ASM_DX,%_ASM_AX
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jae bad_get_user_8
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sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */
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and %_ASM_DX, %_ASM_AX
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ASM_STAC
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4: movl -7(%_ASM_AX),%edx
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5: movl -3(%_ASM_AX),%ecx
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4: movl (%_ASM_AX),%edx
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5: movl 4(%_ASM_AX),%ecx
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xor %eax,%eax
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ASM_CLAC
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ret
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@ -31,12 +31,19 @@
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* as they get called from within inline assembly.
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*/
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#define ENTER mov PER_CPU_VAR(current_task), %_ASM_BX
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#ifdef CONFIG_X86_5LEVEL
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#define LOAD_TASK_SIZE_MINUS_N(n) \
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ALTERNATIVE __stringify(mov $((1 << 47) - 4096 - (n)),%rbx), \
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__stringify(mov $((1 << 56) - 4096 - (n)),%rbx), X86_FEATURE_LA57
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#else
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#define LOAD_TASK_SIZE_MINUS_N(n) \
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mov $(TASK_SIZE_MAX - (n)),%_ASM_BX
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#endif
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.text
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SYM_FUNC_START(__put_user_1)
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ENTER
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cmp TASK_addr_limit(%_ASM_BX),%_ASM_CX
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LOAD_TASK_SIZE_MINUS_N(0)
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cmp %_ASM_BX,%_ASM_CX
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jae .Lbad_put_user
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ASM_STAC
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1: movb %al,(%_ASM_CX)
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@ -47,9 +54,7 @@ SYM_FUNC_END(__put_user_1)
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EXPORT_SYMBOL(__put_user_1)
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SYM_FUNC_START(__put_user_2)
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ENTER
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mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
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sub $1,%_ASM_BX
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LOAD_TASK_SIZE_MINUS_N(1)
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cmp %_ASM_BX,%_ASM_CX
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jae .Lbad_put_user
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ASM_STAC
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@ -61,9 +66,7 @@ SYM_FUNC_END(__put_user_2)
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EXPORT_SYMBOL(__put_user_2)
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SYM_FUNC_START(__put_user_4)
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ENTER
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mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
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sub $3,%_ASM_BX
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LOAD_TASK_SIZE_MINUS_N(3)
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cmp %_ASM_BX,%_ASM_CX
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jae .Lbad_put_user
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ASM_STAC
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@ -75,9 +78,7 @@ SYM_FUNC_END(__put_user_4)
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EXPORT_SYMBOL(__put_user_4)
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SYM_FUNC_START(__put_user_8)
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ENTER
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mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
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sub $7,%_ASM_BX
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LOAD_TASK_SIZE_MINUS_N(7)
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cmp %_ASM_BX,%_ASM_CX
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jae .Lbad_put_user
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ASM_STAC
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