* Anton Arapov <an...@redhat.com> [2013-04-03 18:00:33]:
> Hijack the return address and replace it with a trampoline address.
>
> v1 changes:
> * use force_sig_info()
> * rework and simplify logic
>
> RFCv5 changes:
> * change the fail return code, because orig_ret_vaddr=0 is possible
> * style fixup
> RFCv2 changes:
> * remove ->doomed flag, kill task immediately
>
> Signed-off-by: Anton Arapov <an...@redhat.com>
Acked-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
> ---
> arch/x86/include/asm/uprobes.h | 1 +
> arch/x86/kernel/uprobes.c | 29 +++++++++++++++++++++++++++++
> 2 files changed, 30 insertions(+)
>
> diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
> index 8ff8be7..6e51979 100644
> --- a/arch/x86/include/asm/uprobes.h
> +++ b/arch/x86/include/asm/uprobes.h
> @@ -55,4 +55,5 @@ extern int arch_uprobe_post_xol(struct arch_uprobe *aup,
> struct pt_regs *regs);
> extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk);
> extern int arch_uprobe_exception_notify(struct notifier_block *self,
> unsigned long val, void *data);
> extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs
> *regs);
> +extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long
> trampoline_vaddr, struct pt_regs *regs);
> #endif /* _ASM_UPROBES_H */
> diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
> index 0ba4cfb..2ed8459 100644
> --- a/arch/x86/kernel/uprobes.c
> +++ b/arch/x86/kernel/uprobes.c
> @@ -697,3 +697,32 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe,
> struct pt_regs *regs)
> send_sig(SIGTRAP, current, 0);
> return ret;
> }
> +
> +unsigned long
> +arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct
> pt_regs *regs)
> +{
> + int rasize, ncopied;
> + unsigned long orig_ret_vaddr = 0; /* clear high bits for 32-bit apps */
> +
> + rasize = is_ia32_task() ? 4 : 8;
> + ncopied = copy_from_user(&orig_ret_vaddr, (void __user *)regs->sp,
> rasize);
> + if (unlikely(ncopied))
> + return -1;
> +
> + /* check whether address has been already hijacked */
> + if (orig_ret_vaddr == trampoline_vaddr)
> + return orig_ret_vaddr;
> +
> + ncopied = copy_to_user((void __user *)regs->sp, &trampoline_vaddr,
> rasize);
> + if (likely(!ncopied))
> + return orig_ret_vaddr;
> +
> + if (ncopied != rasize) {
> + pr_err("uprobe: return address clobbered: pid=%d, %%sp=%#lx, "
> + "%%ip=%#lx\n", current->pid, regs->sp, regs->ip);
> +
> + force_sig_info(SIGSEGV, SEND_SIG_FORCED, current);
> + }
> +
> + return -1;
> +}
> --
> 1.8.1.4
>
--
Thanks and Regards
Srikar Dronamraju
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
