| Message ID | 20210515101803.924427-6-arnd@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | asm-generic: strncpy_from_user/strnlen_user cleanup | expand |
On Sat, May 15, 2021 at 12:18:02PM +0200, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > Consolidate the asm-generic implementation with the library version > that is used everywhere else. > > These are the three versions for NOMMU kernels, I don't get the three versions part? > + select GENERIC_STRNCPY_FROM_USER > + select GENERIC_STRNLEN_USER Given that most architetures select the generic version I wonder if it might be worth to add another patch to invert the logic so that architectures with their own implementation need to sekect a symbol. > +extern long strncpy_from_user(char *dst, const char __user *src, long count); > +extern long strnlen_user(const char __user *src, long n); No need for the extern here.
On Mon, May 17, 2021 at 8:20 AM Christoph Hellwig <hch@lst.de> wrote: > > On Sat, May 15, 2021 at 12:18:02PM +0200, Arnd Bergmann wrote: > > From: Arnd Bergmann <arnd@arndb.de> > > > > Consolidate the asm-generic implementation with the library version > > that is used everywhere else. > > > > These are the three versions for NOMMU kernels, > > I don't get the three versions part? Right, that was confusing. Rewording to | The inline version is used on three NOMMU architectures and is | particularly inefficient when it scans the string one byte at a time | twice. It also lacks a check for user_addr_max(), but this is | probably ok on NOMMU targets. | | Consolidate the asm-generic implementation with the library version | that is used everywhere else. This version is generalized enough to | work efficiently on both MMU and NOMMU targets, and using the | same code everywhere reduces the potential for subtle bugs. > > + select GENERIC_STRNCPY_FROM_USER > > + select GENERIC_STRNLEN_USER > > Given that most architetures select the generic version I wonder > if it might be worth to add another patch to invert the logic so > that architectures with their own implementation need to sekect a symbol. Done now, using 'CONFIG_ARCH_HAS_{STRNCPY_FROM,STRNLEN}_USER'. There are still seven or eight architectures that provide their own though. > > +extern long strncpy_from_user(char *dst, const char __user *src, long count); > > +extern long strnlen_user(const char __user *src, long n); > > No need for the extern here. Removed. Arnd
diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig index 3e3e0f16f7e0..53dfd2d47e0e 100644 --- a/arch/h8300/Kconfig +++ b/arch/h8300/Kconfig @@ -11,6 +11,8 @@ config H8300 select GENERIC_IRQ_SHOW select FRAME_POINTER select GENERIC_CPU_DEVICES + select GENERIC_STRNCPY_FROM_USER + select GENERIC_STRNLEN_USER select MODULES_USE_ELF_RELA select COMMON_CLK select ARCH_WANT_FRAME_POINTERS diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig index ed6b8050e3ed..5f1aafa7b2e2 100644 --- a/arch/m68k/Kconfig +++ b/arch/m68k/Kconfig @@ -17,8 +17,8 @@ config M68K select GENERIC_CPU_DEVICES select GENERIC_IOMAP select GENERIC_IRQ_SHOW - select GENERIC_STRNCPY_FROM_USER if MMU - select GENERIC_STRNLEN_USER if MMU + select GENERIC_STRNCPY_FROM_USER + select GENERIC_STRNLEN_USER select HAVE_AOUT if MMU select HAVE_ASM_MODVERSIONS select HAVE_DEBUG_BUGVERBOSE diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index a8ad8eb76120..ada7a2918c05 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -55,8 +55,8 @@ config RISCV select GENERIC_PTDUMP if MMU select GENERIC_SCHED_CLOCK select GENERIC_SMP_IDLE_THREAD - select GENERIC_STRNCPY_FROM_USER if MMU - select GENERIC_STRNLEN_USER if MMU + select GENERIC_STRNCPY_FROM_USER + select GENERIC_STRNLEN_USER select GENERIC_TIME_VSYSCALL if MMU && 64BIT select HANDLE_DOMAIN_IRQ select HAVE_ARCH_AUDITSYSCALL diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h index c03889cc904c..83a48f430951 100644 --- a/include/asm-generic/uaccess.h +++ b/include/asm-generic/uaccess.h @@ -119,6 +119,11 @@ static inline void set_fs(mm_segment_t fs) #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)) @@ -243,44 +248,6 @@ static inline int __get_user_fn(size_t size, const void __user *ptr, void *x) extern int __get_user_bad(void) __attribute__((noreturn)); -/* - * Copy a null terminated string from userspace. - */ -#ifndef strncpy_from_user -static inline long -strncpy_from_user(char *dst, const char __user *src, long count) -{ - char *tmp; - - if (!access_ok(src, 1)) - return -EFAULT; - - strncpy(dst, (const char __force *)src, count); - for (tmp = dst; *tmp && count > 0; tmp++, count--) - ; - return (tmp - dst); -} -#endif - -#ifndef strnlen_user -/* - * Return the size of a string (including the ending 0) - * - * Return 0 on exception, a value greater than N if too long - * - * Unlike strnlen, strnlen_user includes the nul terminator in - * its returned count. Callers should check for a returned value - * greater than N as an indication the string is too long. - */ -static inline long strnlen_user(const char __user *src, long n) -{ - if (!access_ok(src, 1)) - return 0; - - return strnlen(src, n) + 1; -} -#endif - /* * Zero Userspace */ @@ -305,4 +272,7 @@ clear_user(void __user *to, unsigned long n) #include <asm/extable.h> +extern long strncpy_from_user(char *dst, const char __user *src, long count); +extern long strnlen_user(const char __user *src, long n); + #endif /* __ASM_GENERIC_UACCESS_H */