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Filename : sysc_pivot_root.stp
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# pivot_root _________________________________________________
#
# long sys_pivot_root(const char __user *new_root, const char __user *put_old)
#

@define _SYSCALL_PIVOT_ROOT_NAME
%(
	name = "pivot_root"
%)

@define _SYSCALL_PIVOT_ROOT_ARGSTR
%(
	argstr = sprintf("%s, %s", new_root_str, old_root_str)
%)

@define _SYSCALL_PIVOT_ROOT_REGARGS
%(
	new_root_str = user_string_quoted(pointer_arg(1))
	old_root_str = user_string_quoted(pointer_arg(2))
%)

probe syscall.pivot_root = dw_syscall.pivot_root !, nd_syscall.pivot_root ? {}
probe syscall.pivot_root.return = dw_syscall.pivot_root.return !,
                                  nd_syscall.pivot_root.return ? {}

# dw_pivot_root _____________________________________________________

probe dw_syscall.pivot_root = kernel.function("sys_pivot_root").call
{
	@_SYSCALL_PIVOT_ROOT_NAME
	new_root_str = user_string_quoted($new_root)
	old_root_str = user_string_quoted($put_old)
	@_SYSCALL_PIVOT_ROOT_ARGSTR
}
probe dw_syscall.pivot_root.return = kernel.function("sys_pivot_root").return
{
	@_SYSCALL_PIVOT_ROOT_NAME
	@SYSC_RETVALSTR($return)
}

# nd_pivot_root _____________________________________________________

probe nd_syscall.pivot_root = nd1_syscall.pivot_root!, nd2_syscall.pivot_root!, tp_syscall.pivot_root
  { }

probe nd1_syscall.pivot_root = kprobe.function("sys_pivot_root") ?
{
	@_SYSCALL_PIVOT_ROOT_NAME
	asmlinkage()
	@_SYSCALL_PIVOT_ROOT_REGARGS
	@_SYSCALL_PIVOT_ROOT_ARGSTR
}

/* kernel 4.17+ */
probe nd2_syscall.pivot_root = kprobe.function(@arch_syscall_prefix "sys_pivot_root") ?
{
	__set_syscall_pt_regs(pointer_arg(1))
	@_SYSCALL_PIVOT_ROOT_NAME
	@_SYSCALL_PIVOT_ROOT_REGARGS
	@_SYSCALL_PIVOT_ROOT_ARGSTR
}

/* kernel 3.5+, but undesirable because it affects all syscalls */
probe tp_syscall.pivot_root = kernel.trace("sys_enter")
{
	__set_syscall_pt_regs($regs)
	@__syscall_compat_gate(@const("__NR_pivot_root"), @const("__NR_compat_pivot_root"))
	@_SYSCALL_PIVOT_ROOT_NAME
	@_SYSCALL_PIVOT_ROOT_REGARGS
	@_SYSCALL_PIVOT_ROOT_ARGSTR
}

probe nd_syscall.pivot_root.return = nd1_syscall.pivot_root.return!, nd2_syscall.pivot_root.return!, tp_syscall.pivot_root.return
  { }
  
probe nd1_syscall.pivot_root.return = kprobe.function("sys_pivot_root").return ?
{
	@_SYSCALL_PIVOT_ROOT_NAME
	@SYSC_RETVALSTR(returnval())
}

/* kernel 4.17+ */
probe nd2_syscall.pivot_root.return = kprobe.function(@arch_syscall_prefix "sys_pivot_root").return ?
{
	@_SYSCALL_PIVOT_ROOT_NAME
	@SYSC_RETVALSTR(returnval())
}
 
/* kernel 3.5+, but undesirable because it affects all syscalls */
probe tp_syscall.pivot_root.return = kernel.trace("sys_exit")
{
	__set_syscall_pt_regs($regs)
	@__syscall_compat_gate(@const("__NR_pivot_root"), @const("__NR_compat_pivot_root"))
	@_SYSCALL_PIVOT_ROOT_NAME
	@SYSC_RETVALSTR($ret)
}