[PATCH 03/10] uaccess: add infrastructure for kernel builds with set_fs()

From: Christoph Hellwig
Date: Thu Aug 27 2020 - 11:02:22 EST

Add a CONFIG_SET_FS option that is selected by architecturess that
implement set_fs, which is all of them initially. If the option is not
set stubs for routines related to overriding the address space are
provided so that architectures can start to opt out of providing set_fs.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
arch/Kconfig | 3 +++
arch/alpha/Kconfig | 1 +
arch/arc/Kconfig | 1 +
arch/arm/Kconfig | 1 +
arch/arm64/Kconfig | 1 +
arch/c6x/Kconfig | 1 +
arch/csky/Kconfig | 1 +
arch/h8300/Kconfig | 1 +
arch/hexagon/Kconfig | 1 +
arch/ia64/Kconfig | 1 +
arch/m68k/Kconfig | 1 +
arch/microblaze/Kconfig | 1 +
arch/mips/Kconfig | 1 +
arch/nds32/Kconfig | 1 +
arch/nios2/Kconfig | 1 +
arch/openrisc/Kconfig | 1 +
arch/parisc/Kconfig | 1 +
arch/powerpc/Kconfig | 1 +
arch/riscv/Kconfig | 1 +
arch/s390/Kconfig | 1 +
arch/sh/Kconfig | 1 +
arch/sparc/Kconfig | 1 +
arch/um/Kconfig | 1 +
arch/x86/Kconfig | 1 +
arch/xtensa/Kconfig | 1 +
include/linux/uaccess.h | 18 ++++++++++++++++++
26 files changed, 45 insertions(+)

diff --git a/arch/Kconfig b/arch/Kconfig
index af14a567b493fc..3fab619a6aa51a 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -24,6 +24,9 @@ config KEXEC_ELF
config HAVE_IMA_KEXEC
bool

+config SET_FS
+ bool
+
config HOTPLUG_SMT
bool

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 9c5f06e8eb9bc0..d6e9fc7a7b19e2 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -39,6 +39,7 @@ config ALPHA
select OLD_SIGSUSPEND
select CPU_NO_EFFICIENT_FFS if !ALPHA_EV67
select MMU_GATHER_NO_RANGE
+ select SET_FS
help
The Alpha is a 64-bit general-purpose processor designed and
marketed by the Digital Equipment Corporation of blessed memory,
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index ba00c4e1e1c271..c49f5754a11e40 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -48,6 +48,7 @@ config ARC
select PCI_SYSCALL if PCI
select PERF_USE_VMALLOC if ARC_CACHE_VIPT_ALIASING
select HAVE_ARCH_JUMP_LABEL if ISA_ARCV2 && !CPU_ENDIAN_BE32
+ select SET_FS

config ARCH_HAS_CACHE_LINE_SIZE
def_bool y
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index e00d94b1665876..87e1478a42dc4f 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -118,6 +118,7 @@ config ARM
select PCI_SYSCALL if PCI
select PERF_USE_VMALLOC
select RTC_LIB
+ select SET_FS
select SYS_SUPPORTS_APM_EMULATION
# Above selects are sorted alphabetically; please add new ones
# according to that. Thanks.
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 6d232837cbeee8..fbd9e35bef096f 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -192,6 +192,7 @@ config ARM64
select PCI_SYSCALL if PCI
select POWER_RESET
select POWER_SUPPLY
+ select SET_FS
select SPARSE_IRQ
select SWIOTLB
select SYSCTL_EXCEPTION_TRACE
diff --git a/arch/c6x/Kconfig b/arch/c6x/Kconfig
index 6444ebfd06a665..48d66bf0465d68 100644
--- a/arch/c6x/Kconfig
+++ b/arch/c6x/Kconfig
@@ -22,6 +22,7 @@ config C6X
select GENERIC_CLOCKEVENTS
select MODULES_USE_ELF_RELA
select MMU_GATHER_NO_RANGE if MMU
+ select SET_FS

config MMU
def_bool n
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 3d5afb5f568543..2836f6e76fdb2d 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -78,6 +78,7 @@ config CSKY
select PCI_DOMAINS_GENERIC if PCI
select PCI_SYSCALL if PCI
select PCI_MSI if PCI
+ select SET_FS

config LOCKDEP_SUPPORT
def_bool y
diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig
index d11666d538fea8..7945de067e9fcc 100644
--- a/arch/h8300/Kconfig
+++ b/arch/h8300/Kconfig
@@ -25,6 +25,7 @@ config H8300
select HAVE_ARCH_KGDB
select HAVE_ARCH_HASH
select CPU_NO_EFFICIENT_FFS
+ select SET_FS
select UACCESS_MEMCPY

config CPU_BIG_ENDIAN
diff --git a/arch/hexagon/Kconfig b/arch/hexagon/Kconfig
index 667cfc511cf999..f2afabbadd430e 100644
--- a/arch/hexagon/Kconfig
+++ b/arch/hexagon/Kconfig
@@ -31,6 +31,7 @@ config HEXAGON
select GENERIC_CLOCKEVENTS_BROADCAST
select MODULES_USE_ELF_RELA
select GENERIC_CPU_DEVICES
+ select SET_FS
help
Qualcomm Hexagon is a processor architecture designed for high
performance and low power across a wide variety of applications.
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 5b4ec80bf5863a..22a6853840e235 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -56,6 +56,7 @@ config IA64
select NEED_DMA_MAP_STATE
select NEED_SG_DMA_LENGTH
select NUMA if !FLATMEM
+ select SET_FS
default y
help
The Itanium Processor Family is Intel's 64-bit successor to
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 6f2f38d05772ab..dcf4ae8c9b215f 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -32,6 +32,7 @@ config M68K
select OLD_SIGSUSPEND3
select OLD_SIGACTION
select MMU_GATHER_NO_RANGE if MMU
+ select SET_FS

config CPU_BIG_ENDIAN
def_bool y
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index d262ac0c8714bd..7e3d4583abf3e6 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -46,6 +46,7 @@ config MICROBLAZE
select CPU_NO_EFFICIENT_FFS
select MMU_GATHER_NO_RANGE if MMU
select SPARSE_IRQ
+ select SET_FS

# Endianness selection
choice
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index c95fa3a2484cf0..fbc26391b588f8 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -87,6 +87,7 @@ config MIPS
select MODULES_USE_ELF_RELA if MODULES && 64BIT
select PERF_USE_VMALLOC
select RTC_LIB
+ select SET_FS
select SYSCTL_EXCEPTION_TRACE
select VIRT_TO_BUS

diff --git a/arch/nds32/Kconfig b/arch/nds32/Kconfig
index e30298e99e1bdf..e8e541fd2267d0 100644
--- a/arch/nds32/Kconfig
+++ b/arch/nds32/Kconfig
@@ -48,6 +48,7 @@ config NDS32
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_DYNAMIC_FTRACE
+ select SET_FS
help
Andes(nds32) Linux support.

diff --git a/arch/nios2/Kconfig b/arch/nios2/Kconfig
index c6645141bb2a88..c7c6ba6bec9dfc 100644
--- a/arch/nios2/Kconfig
+++ b/arch/nios2/Kconfig
@@ -27,6 +27,7 @@ config NIOS2
select USB_ARCH_HAS_HCD if USB_SUPPORT
select CPU_NO_EFFICIENT_FFS
select MMU_GATHER_NO_RANGE if MMU
+ select SET_FS

config GENERIC_CSUM
def_bool y
diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
index 7e94fe37cb2fdf..6233c62931803f 100644
--- a/arch/openrisc/Kconfig
+++ b/arch/openrisc/Kconfig
@@ -39,6 +39,7 @@ config OPENRISC
select ARCH_WANT_FRAME_POINTERS
select GENERIC_IRQ_MULTI_HANDLER
select MMU_GATHER_NO_RANGE if MMU
+ select SET_FS

config CPU_BIG_ENDIAN
def_bool y
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 3b0f53dd70bc9b..be70af482b5a9a 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -63,6 +63,7 @@ config PARISC
select HAVE_FTRACE_MCOUNT_RECORD if HAVE_DYNAMIC_FTRACE
select HAVE_KPROBES_ON_FTRACE
select HAVE_DYNAMIC_FTRACE_WITH_REGS
+ select SET_FS

help
The PA-RISC microprocessor is designed by Hewlett-Packard and used
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 1f48bbfb3ce99d..3f09d6fdf89405 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -249,6 +249,7 @@ config PPC
select PCI_SYSCALL if PCI
select PPC_DAWR if PPC64
select RTC_LIB
+ select SET_FS
select SPARSE_IRQ
select SYSCTL_EXCEPTION_TRACE
select THREAD_INFO_IN_TASK
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index df18372861d8d2..ea0c1ad456d838 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -82,6 +82,7 @@ config RISCV
select PCI_MSI if PCI
select RISCV_INTC
select RISCV_TIMER if RISCV_SBI
+ select SET_FS
select SPARSEMEM_STATIC if 32BIT
select SPARSE_IRQ
select SYSCTL_EXCEPTION_TRACE
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 3d86e12e8e3c21..fd81385a7787cb 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -185,6 +185,7 @@ config S390
select OLD_SIGSUSPEND3
select PCI_DOMAINS if PCI
select PCI_MSI if PCI
+ select SET_FS
select SPARSE_IRQ
select SYSCTL_EXCEPTION_TRACE
select THREAD_INFO_IN_TASK
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index d20927128fce05..2bd1653f3b3fea 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -71,6 +71,7 @@ config SUPERH
select PERF_EVENTS
select PERF_USE_VMALLOC
select RTC_LIB
+ select SET_FS
select SPARSE_IRQ
help
The SuperH is a RISC processor targeted for use in embedded systems
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index efeff2c896a544..3e0cf0319a278a 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -49,6 +49,7 @@ config SPARC
select LOCKDEP_SMALL if LOCKDEP
select NEED_DMA_MAP_STATE
select NEED_SG_DMA_LENGTH
+ select SET_FS

config SPARC32
def_bool !64BIT
diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index eb51fec759484a..3aefcd81566809 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -19,6 +19,7 @@ config UML
select GENERIC_CPU_DEVICES
select GENERIC_CLOCKEVENTS
select HAVE_GCC_PLUGINS
+ select SET_FS
select TTY # Needed for line.c

config MMU
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7101ac64bb209d..f85c13355732fe 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -237,6 +237,7 @@ 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/xtensa/Kconfig b/arch/xtensa/Kconfig
index e997e0119c0251..94bad4d66b4bde 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -41,6 +41,7 @@ config XTENSA
select IRQ_DOMAIN
select MODULES_USE_ELF_RELA
select PERF_USE_VMALLOC
+ select SET_FS
select VIRT_TO_BUS
help
Xtensa processors are 32-bit RISC machines designed by Tensilica
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 94b28541165929..70073c802b48ed 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -8,6 +8,7 @@

#include <asm/uaccess.h>

+#ifdef CONFIG_SET_FS
/*
* Force the uaccess routines to be wired up for actual userspace access,
* overriding any possible set_fs(KERNEL_DS) still lingering around. Undone
@@ -25,6 +26,23 @@ static inline void force_uaccess_end(mm_segment_t oldfs)
{
set_fs(oldfs);
}
+#else /* CONFIG_SET_FS */
+typedef struct {
+ /* empty dummy */
+} mm_segment_t;
+
+#define uaccess_kernel() (false)
+#define user_addr_max() (TASK_SIZE_MAX)
+
+static inline mm_segment_t force_uaccess_begin(void)
+{
+ return (mm_segment_t) { };
+}
+
+static inline void force_uaccess_end(mm_segment_t oldfs)
+{
+}
+#endif /* CONFIG_SET_FS */

/*
* Architectures should provide two primitives (raw_copy_{to,from}_user())
--
2.28.0