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>
---
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
--
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