On Tue, Apr 28, 2020 at 09:56:26PM +0200, Arnd Bergmann wrote: > I think I found a way to improve the x32 handling: > > This is a simplification over Christoph's "[PATCH 2/7] signal: factor > copy_siginfo_to_external32 from copy_siginfo_to_user32", reducing the > x32 specifics in the common code to a single #ifdef/#endif check, in > order to keep it more readable for everyone else. > > Christoph, if you like it, please fold into your patch. What do you think of this version? This one always overrides copy_siginfo_to_user32 for the x86 compat case to keep the churn down, and improves the copy_siginfo_to_external32 documentation a bit. --- >From 5ca642c4c744ce6460ebb91fe30ec7a064d28e96 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig <hch@xxxxxx> Date: Wed, 29 Apr 2020 08:38:07 +0200 Subject: signal: factor copy_siginfo_to_external32 from copy_siginfo_to_user32 To remove the use of set_fs in the coredump code there needs to be a way to convert a kernel siginfo to a userspace compat siginfo. Factour out a copy_siginfo_to_external32 helper from copy_siginfo_to_user32 that fills out the compat_siginfo, but does so on a kernel space data structure. Handling of the x32 SIGCHLD magic is kept out of copy_siginfo_to_external32, as coredumps are never caused by SIGCHLD. To simplify the mess that the current copy_siginfo_to_user32 is, we allow architectures to override it, and keep thus keep the x32 SIGCHLD magic confined to x86-64. Contains improvements from Eric W. Biederman <ebiederm@xxxxxxxxxxxx> and Arnd Bergmann <arnd@xxxxxxxx>. Signed-off-by: Christoph Hellwig <hch@xxxxxx> --- arch/Kconfig | 3 ++ arch/x86/Kconfig | 1 + arch/x86/kernel/signal.c | 22 ++++++++ include/linux/compat.h | 2 + kernel/signal.c | 108 ++++++++++++++++++++------------------- 5 files changed, 83 insertions(+), 53 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index 786a85d4ad40d..d5bc9f1ee1747 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -815,6 +815,9 @@ config OLD_SIGACTION config COMPAT_OLD_SIGACTION bool +config ARCH_COPY_SIGINFO_TO_USER32 + bool + config COMPAT_32BIT_TIME bool "Provide system calls for 32-bit time_t" default !64BIT || COMPAT diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 1197b5596d5ad..ad13facbe9ffe 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2906,6 +2906,7 @@ config X86_X32 config COMPAT_32 def_bool y depends on IA32_EMULATION || X86_32 + select ARCH_COPY_SIGINFO_TO_USER32 select HAVE_UID16 select OLD_SIGSUSPEND3 diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 83b74fb38c8fc..d2b09866105a2 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -511,6 +511,28 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, } #endif /* CONFIG_X86_32 */ +#ifdef CONFIG_ARCH_COPY_SIGINFO_TO_USER32 +int __copy_siginfo_to_user32(struct compat_siginfo __user *to, + const struct kernel_siginfo *from, bool x32_ABI) +{ + struct compat_siginfo new; + + copy_siginfo_to_external32(&new, from); + if (x32_ABI && from->si_signo == SIGCHLD) { + new._sifields._sigchld_x32._utime = from->si_utime; + new._sifields._sigchld_x32._stime = from->si_stime; + } + if (copy_to_user(to, &new, sizeof(struct compat_siginfo))) + return -EFAULT; + return 0; +} +int copy_siginfo_to_user32(struct compat_siginfo __user *to, + const struct kernel_siginfo *from) +{ + return __copy_siginfo_to_user32(to, from, in_x32_syscall()); +} +#endif /* CONFIG_ARCH_COPY_SIGINFO_TO_USER32 */ + static int x32_setup_rt_frame(struct ksignal *ksig, compat_sigset_t *set, struct pt_regs *regs) diff --git a/include/linux/compat.h b/include/linux/compat.h index 0480ba4db5929..adbfe8f688d92 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -402,6 +402,8 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask, unsigned long bitmap_size); long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask, unsigned long bitmap_size); +void copy_siginfo_to_external32(struct compat_siginfo *to, + const struct kernel_siginfo *from); int copy_siginfo_from_user32(kernel_siginfo_t *to, const struct compat_siginfo __user *from); int copy_siginfo_to_user32(struct compat_siginfo __user *to, const kernel_siginfo_t *from); int get_compat_sigevent(struct sigevent *event, diff --git a/kernel/signal.c b/kernel/signal.c index 284fc1600063b..710655df1269d 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -3235,96 +3235,98 @@ int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from) } #ifdef CONFIG_COMPAT -int copy_siginfo_to_user32(struct compat_siginfo __user *to, - const struct kernel_siginfo *from) -#if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION) -{ - return __copy_siginfo_to_user32(to, from, in_x32_syscall()); -} -int __copy_siginfo_to_user32(struct compat_siginfo __user *to, - const struct kernel_siginfo *from, bool x32_ABI) -#endif +/** + * copy_siginfo_to_external32: copy a kernel signinfo into a 32-bit user one + * @to: compat siginfo destination + * @from: kernel siginfo source + * + * This function does not work properly for SIGCHLD on x32, but it does not need + * to as SIGCHLD never causes a coredump as this function is only intended to + * be used either by the coredump code or to implement copy_siginfo_to_user32, + * which can have its own arch version to deal with things like x32. + */ +void copy_siginfo_to_external32(struct compat_siginfo *to, + const struct kernel_siginfo *from) { - struct compat_siginfo new; - memset(&new, 0, sizeof(new)); + memset(to, 0, sizeof(*to)); - new.si_signo = from->si_signo; - new.si_errno = from->si_errno; - new.si_code = from->si_code; + to->si_signo = from->si_signo; + to->si_errno = from->si_errno; + to->si_code = from->si_code; switch(siginfo_layout(from->si_signo, from->si_code)) { case SIL_KILL: - new.si_pid = from->si_pid; - new.si_uid = from->si_uid; + to->si_pid = from->si_pid; + to->si_uid = from->si_uid; break; case SIL_TIMER: - new.si_tid = from->si_tid; - new.si_overrun = from->si_overrun; - new.si_int = from->si_int; + to->si_tid = from->si_tid; + to->si_overrun = from->si_overrun; + to->si_int = from->si_int; break; case SIL_POLL: - new.si_band = from->si_band; - new.si_fd = from->si_fd; + to->si_band = from->si_band; + to->si_fd = from->si_fd; break; case SIL_FAULT: - new.si_addr = ptr_to_compat(from->si_addr); + to->si_addr = ptr_to_compat(from->si_addr); #ifdef __ARCH_SI_TRAPNO - new.si_trapno = from->si_trapno; + to->si_trapno = from->si_trapno; #endif break; case SIL_FAULT_MCEERR: - new.si_addr = ptr_to_compat(from->si_addr); + to->si_addr = ptr_to_compat(from->si_addr); #ifdef __ARCH_SI_TRAPNO - new.si_trapno = from->si_trapno; + to->si_trapno = from->si_trapno; #endif - new.si_addr_lsb = from->si_addr_lsb; + to->si_addr_lsb = from->si_addr_lsb; break; case SIL_FAULT_BNDERR: - new.si_addr = ptr_to_compat(from->si_addr); + to->si_addr = ptr_to_compat(from->si_addr); #ifdef __ARCH_SI_TRAPNO - new.si_trapno = from->si_trapno; + to->si_trapno = from->si_trapno; #endif - new.si_lower = ptr_to_compat(from->si_lower); - new.si_upper = ptr_to_compat(from->si_upper); + to->si_lower = ptr_to_compat(from->si_lower); + to->si_upper = ptr_to_compat(from->si_upper); break; case SIL_FAULT_PKUERR: - new.si_addr = ptr_to_compat(from->si_addr); + to->si_addr = ptr_to_compat(from->si_addr); #ifdef __ARCH_SI_TRAPNO - new.si_trapno = from->si_trapno; + to->si_trapno = from->si_trapno; #endif - new.si_pkey = from->si_pkey; + to->si_pkey = from->si_pkey; break; case SIL_CHLD: - new.si_pid = from->si_pid; - new.si_uid = from->si_uid; - new.si_status = from->si_status; -#ifdef CONFIG_X86_X32_ABI - if (x32_ABI) { - new._sifields._sigchld_x32._utime = from->si_utime; - new._sifields._sigchld_x32._stime = from->si_stime; - } else -#endif - { - new.si_utime = from->si_utime; - new.si_stime = from->si_stime; - } + to->si_pid = from->si_pid; + to->si_uid = from->si_uid; + to->si_status = from->si_status; + to->si_utime = from->si_utime; + to->si_stime = from->si_stime; break; case SIL_RT: - new.si_pid = from->si_pid; - new.si_uid = from->si_uid; - new.si_int = from->si_int; + to->si_pid = from->si_pid; + to->si_uid = from->si_uid; + to->si_int = from->si_int; break; case SIL_SYS: - new.si_call_addr = ptr_to_compat(from->si_call_addr); - new.si_syscall = from->si_syscall; - new.si_arch = from->si_arch; + to->si_call_addr = ptr_to_compat(from->si_call_addr); + to->si_syscall = from->si_syscall; + to->si_arch = from->si_arch; break; } +} +#ifndef CONFIG_ARCH_COPY_SIGINFO_TO_USER32 +int copy_siginfo_to_user32(struct compat_siginfo __user *to, + const struct kernel_siginfo *from) +{ + struct compat_siginfo new; + + copy_siginfo_to_external32(&new, from); if (copy_to_user(to, &new, sizeof(struct compat_siginfo))) return -EFAULT; - return 0; } +#endif /* ARCH_COPY_SIGINFO_TO_USER32 */ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to, const struct compat_siginfo *from) -- 2.26.2