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uprobes/x86: Introduce sizeof_long(), cleanup adjust_ret_addr() and arch_uretprobe_hijack_return_addr()

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1. Add the trivial sizeof_long() helper and change other callers of
   is_ia32_task() to use it.

   TODO: is_ia32_task() is not what we actually want, TS_COMPAT does
   not necessarily mean 32bit. Fortunately syscall-like insns can't be
   probed so it actually works, but it would be better to rename and
   use is_ia32_frame().

2. As Jim pointed out "ncopied" in arch_uretprobe_hijack_return_addr()
   and adjust_ret_addr() should be named "nleft". And in fact only the
   last copy_to_user() in arch_uretprobe_hijack_return_addr() actually
   needs to inspect the non-zero error code.

TODO: adjust_ret_addr() should die. We can always calculate the value
we need to write into *regs->sp, just UPROBE_FIX_CALL should record
insn->length.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
This commit is contained in:
Oleg Nesterov 2014-04-06 17:16:10 +02:00
parent 75f9ef0b7f
commit 8faaed1b9f
1 changed files with 15 additions and 22 deletions
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37
arch/x86/kernel/uprobes.c
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@ -408,6 +408,11 @@ struct uprobe_xol_ops {
int (*post_xol)(struct arch_uprobe *, struct pt_regs *);
};
static inline int sizeof_long(void)
{
return is_ia32_task() ? 4 : 8;
}
static int default_pre_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
pre_xol_rip_insn(auprobe, regs, &current->utask->autask);
@ -419,21 +424,14 @@ static int default_pre_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
*/
static int adjust_ret_addr(unsigned long sp, long correction)
{
int rasize, ncopied;
long ra = 0;
int rasize = sizeof_long();
long ra;
if (is_ia32_task())
rasize = 4;
else
rasize = 8;
ncopied = copy_from_user(&ra, (void __user *)sp, rasize);
if (unlikely(ncopied))
if (copy_from_user(&ra, (void __user *)sp, rasize))
return -EFAULT;
ra += correction;
ncopied = copy_to_user((void __user *)sp, &ra, rasize);
if (unlikely(ncopied))
if (copy_to_user((void __user *)sp, &ra, rasize))
return -EFAULT;
return 0;
@ -450,10 +448,7 @@ static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs
if (auprobe->fixups & UPROBE_FIX_CALL) {
if (adjust_ret_addr(regs->sp, correction)) {
if (is_ia32_task())
regs->sp += 4;
else
regs->sp += 8;
regs->sp += sizeof_long();
return -ERESTART;
}
}
@ -714,23 +709,21 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
unsigned long
arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs)
{
int rasize, ncopied;
int rasize = sizeof_long(), nleft;
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))
if (copy_from_user(&orig_ret_vaddr, (void __user *)regs->sp, rasize))
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))
nleft = copy_to_user((void __user *)regs->sp, &trampoline_vaddr, rasize);
if (likely(!nleft))
return orig_ret_vaddr;
if (ncopied != rasize) {
if (nleft != rasize) {
pr_err("uprobe: return address clobbered: pid=%d, %%sp=%#lx, "
"%%ip=%#lx\n", current->pid, regs->sp, regs->ip);