From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765577AbXGYOnm (ORCPT ); Wed, 25 Jul 2007 10:43:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757377AbXGYOnf (ORCPT ); Wed, 25 Jul 2007 10:43:35 -0400 Received: from mailhub.sw.ru ([195.214.233.200]:13006 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755484AbXGYOne (ORCPT ); Wed, 25 Jul 2007 10:43:34 -0400 Message-ID: <46A76210.5020903@openvz.org> Date: Wed, 25 Jul 2007 18:45:36 +0400 From: Kirill Korotaev User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.13) Gecko/20060417 X-Accept-Language: en-us, en, ru MIME-Version: 1.0 To: Masoud Asgharifard Sharbiani CC: akpm@linux-foundation.org, ak@suse.de, linux-kernel@vger.kernel.org Subject: Re: i386-show-unhandled-signals-v3 References: <20070718154759.GA26425@google.com> In-Reply-To: <20070718154759.GA26425@google.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org plz don't enable it by default... :/ any user can spam syslog with these messages and if syslog is run as root can take the whole diskspace... Thanks, Kirill Masoud Asgharifard Sharbiani wrote: > Hello, > This patch makes the i386 behave the same way that x86_64 does when a > segfault happens. A line gets printed to the kernel log so that tools > that > need to check for failures can behave more uniformly between > debug.show_unhandled_signals sysctl variable to 0 (or by doing echo 0 > > /proc/sys/debug/exception-trace) > > Also, all of the lines being printed are now using printk_ratelimit() to > deny the ability of DoS from a local user with a program like the > following: > > main() > { > while (1) > if (!fork()) *(int *)0 = 0; > } > > This new revision also includes the fix that Andrew did which got rid of > new sysctl that was added to the system in earlier versions of this. > Also, 'show-unhandled-signals' sysctl has been renamed back to the old > 'exception-trace' to avoid breakage of people's scripts. > > cheers, > Masoud Sharbiani > > Signed-off-by: Masoud Sharbiani > Cc: Andi Kleen > > --- > arch/i386/kernel/signal.c | 7 +++++++ > arch/i386/kernel/traps.c | 7 +++++++ > arch/i386/mm/fault.c | 10 ++++++++++ > arch/x86_64/kernel/signal.c | 2 +- > arch/x86_64/kernel/traps.c | 6 ++++-- > arch/x86_64/mm/fault.c | 15 +++------------ > arch/x86_64/mm/init.c | 35 ----------------------------------- > include/asm-x86_64/proto.h | 2 -- > include/linux/signal.h | 3 +++ > kernel/signal.c | 10 ++++++++++ > kernel/sysctl.c | 10 ++++++++++ > 11 files changed, 55 insertions(+), 52 deletions(-) > > diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c > index d574e38..f5dd856 100644 > --- a/arch/i386/kernel/signal.c > +++ b/arch/i386/kernel/signal.c > @@ -199,6 +199,13 @@ asmlinkage int sys_sigreturn(unsigned long __unused) > return eax; > > badframe: > + if (show_unhandled_signals && printk_ratelimit()) > + printk("%s%s[%d] bad frame in sigreturn frame:%p eip:%lx" > + " esp:%lx oeax:%lx\n", > + current->pid > 1 ? KERN_INFO : KERN_EMERG, > + current->comm, current->pid, frame, regs->eip, > + regs->esp, regs->orig_eax); > + > force_sig(SIGSEGV, current); > return 0; > } > diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c > index 18c1c28..c20283c 100644 > --- a/arch/i386/kernel/traps.c > +++ b/arch/i386/kernel/traps.c > @@ -611,6 +611,13 @@ fastcall void __kprobes do_general_protection(struct pt_regs * regs, > > current->thread.error_code = error_code; > current->thread.trap_no = 13; > + if (show_unhandled_signals && unhandled_signal(current, SIGSEGV) && > + printk_ratelimit()) > + printk(KERN_INFO > + "%s[%d] general protection eip:%lx esp:%lx error:%lx\n", > + current->comm, current->pid, > + regs->eip, regs->esp, error_code); > + > force_sig(SIGSEGV, current); > return; > > diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c > index 1ecb3e4..52c940b 100644 > --- a/arch/i386/mm/fault.c > +++ b/arch/i386/mm/fault.c > @@ -283,6 +283,8 @@ static inline int vmalloc_fault(unsigned long address) > return 0; > } > > +int show_unhandled_signals = 1; > + > /* > * This routine handles page faults. It determines the address, > * and the problem, and then passes it off to one of the appropriate > @@ -470,6 +472,14 @@ bad_area_nosemaphore: > if (is_prefetch(regs, address, error_code)) > return; > > + if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && > + printk_ratelimit()) { > + printk("%s%s[%d]: segfault at %08lx eip %08lx " > + "esp %08lx error %lx\n", > + tsk->pid > 1 ? KERN_INFO : KERN_EMERG, > + tsk->comm, tsk->pid, address, regs->eip, > + regs->esp, error_code); > + } > tsk->thread.cr2 = address; > /* Kernel addresses are always protection faults */ > tsk->thread.error_code = error_code | (address >= TASK_SIZE); > diff --git a/arch/x86_64/kernel/signal.c b/arch/x86_64/kernel/signal.c > index 290f5d8..f9506f6 100644 > --- a/arch/x86_64/kernel/signal.c > +++ b/arch/x86_64/kernel/signal.c > @@ -480,7 +480,7 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) > void signal_fault(struct pt_regs *regs, void __user *frame, char *where) > { > struct task_struct *me = current; > - if (exception_trace) > + if (show_unhandled_signals && printk_ratelimit()) > printk("%s[%d] bad frame in %s frame:%p rip:%lx rsp:%lx orax:%lx\n", > me->comm,me->pid,where,frame,regs->rip,regs->rsp,regs->orig_rax); > > diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c > index 74cbeb2..b9660c4 100644 > --- a/arch/x86_64/kernel/traps.c > +++ b/arch/x86_64/kernel/traps.c > @@ -580,7 +580,8 @@ static void __kprobes do_trap(int trapnr, int signr, char *str, > tsk->thread.error_code = error_code; > tsk->thread.trap_no = trapnr; > > - if (exception_trace && unhandled_signal(tsk, signr)) > + if (show_unhandled_signals && unhandled_signal(tsk, signr) && > + printk_ratelimit()) > printk(KERN_INFO > "%s[%d] trap %s rip:%lx rsp:%lx error:%lx\n", > tsk->comm, tsk->pid, str, > @@ -684,7 +685,8 @@ asmlinkage void __kprobes do_general_protection(struct pt_regs * regs, > tsk->thread.error_code = error_code; > tsk->thread.trap_no = 13; > > - if (exception_trace && unhandled_signal(tsk, SIGSEGV)) > + if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && > + printk_ratelimit()) > printk(KERN_INFO > "%s[%d] general protection rip:%lx rsp:%lx error:%lx\n", > tsk->comm, tsk->pid, > diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c > index 635e58d..0412824 100644 > --- a/arch/x86_64/mm/fault.c > +++ b/arch/x86_64/mm/fault.c > @@ -221,16 +221,6 @@ static int is_errata93(struct pt_regs *regs, unsigned long address) > return 0; > } > > -int unhandled_signal(struct task_struct *tsk, int sig) > -{ > - if (is_init(tsk)) > - return 1; > - if (tsk->ptrace & PT_PTRACED) > - return 0; > - return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) || > - (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL); > -} > - > static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs, > unsigned long error_code) > { > @@ -302,7 +292,7 @@ static int vmalloc_fault(unsigned long address) > } > > int page_fault_trace = 0; > -int exception_trace = 1; > +int show_unhandled_signals = 1; > > /* > * This routine handles page faults. It determines the address, > @@ -495,7 +485,8 @@ bad_area_nosemaphore: > (address >> 32)) > return; > > - if (exception_trace && unhandled_signal(tsk, SIGSEGV)) { > + if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && > + printk_ratelimit()) { > printk( > "%s%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n", > tsk->pid > 1 ? KERN_INFO : KERN_EMERG, > diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c > index 9a0e98a..5096168 100644 > --- a/arch/x86_64/mm/init.c > +++ b/arch/x86_64/mm/init.c > @@ -697,41 +697,6 @@ int kern_addr_valid(unsigned long addr) > return pfn_valid(pte_pfn(*pte)); > } > > -#ifdef CONFIG_SYSCTL > -#include > - > -extern int exception_trace, page_fault_trace; > - > -static ctl_table debug_table2[] = { > - { > - .ctl_name = 99, > - .procname = "exception-trace", > - .data = &exception_trace, > - .maxlen = sizeof(int), > - .mode = 0644, > - .proc_handler = proc_dointvec > - }, > - {} > -}; > - > -static ctl_table debug_root_table2[] = { > - { > - .ctl_name = CTL_DEBUG, > - .procname = "debug", > - .mode = 0555, > - .child = debug_table2 > - }, > - {} > -}; > - > -static __init int x8664_sysctl_init(void) > -{ > - register_sysctl_table(debug_root_table2); > - return 0; > -} > -__initcall(x8664_sysctl_init); > -#endif > - > /* A pseudo VMA to allow ptrace access for the vsyscall page. This only > covers the 64bit vsyscall page now. 32bit has a real VMA now and does > not need special handling anymore. */ > diff --git a/include/asm-x86_64/proto.h b/include/asm-x86_64/proto.h > index 85255db..4fad501 100644 > --- a/include/asm-x86_64/proto.h > +++ b/include/asm-x86_64/proto.h > @@ -75,8 +75,6 @@ extern void setup_node_bootmem(int nodeid, unsigned long start, unsigned long en > extern void early_quirks(void); > extern void check_efer(void); > > -extern int unhandled_signal(struct task_struct *tsk, int sig); > - > extern void select_idle_routine(const struct cpuinfo_x86 *c); > > extern unsigned long table_start, table_end; > diff --git a/include/linux/signal.h b/include/linux/signal.h > index ea91abe..0ae3388 100644 > --- a/include/linux/signal.h > +++ b/include/linux/signal.h > @@ -237,12 +237,15 @@ extern int group_send_sig_info(int sig, struct siginfo *info, struct task_struct > extern int __group_send_sig_info(int, struct siginfo *, struct task_struct *); > extern long do_sigpending(void __user *, unsigned long); > extern int sigprocmask(int, sigset_t *, sigset_t *); > +extern int show_unhandled_signals; > > struct pt_regs; > extern int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, struct pt_regs *regs, void *cookie); > > extern struct kmem_cache *sighand_cachep; > > +int unhandled_signal(struct task_struct *tsk, int sig); > + > /* > * In POSIX a signal is sent either to a specific thread (Linux task) > * or to the process as a whole (Linux thread group). How the signal > diff --git a/kernel/signal.c b/kernel/signal.c > index 39d1227..ef8156a 100644 > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -255,6 +255,16 @@ flush_signal_handlers(struct task_struct *t, int force_default) > } > } > > +int unhandled_signal(struct task_struct *tsk, int sig) > +{ > + if (is_init(tsk)) > + return 1; > + if (tsk->ptrace & PT_PTRACED) > + return 0; > + return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) || > + (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL); > +} > + > > /* Notify the system that a driver wants to block all signals for this > * process, and wants to be notified if any signals at all were to be > diff --git a/kernel/sysctl.c b/kernel/sysctl.c > index 7063ebc..af7002f 100644 > --- a/kernel/sysctl.c > +++ b/kernel/sysctl.c > @@ -1153,6 +1153,16 @@ static ctl_table fs_table[] = { > }; > > static ctl_table debug_table[] = { > +#ifdef CONFIG_X86 > + { > + .ctl_name = CTL_UNNUMBERED, > + .procname = "exception-trace", > + .data = &show_unhandled_signals, > + .maxlen = sizeof(int), > + .mode = 0644, > + .proc_handler = proc_dointvec > + }, > +#endif > { .ctl_name = 0 } > }; > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >