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Filename : sysc_unlink.stp
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# unlink _____________________________________________________
# long sys_unlink(const char __user * pathname)
#

@define _SYSCALL_UNLINK_NAME
%(
	name = "unlink"
%)

@define _SYSCALL_UNLINK_ARGSTR
%(
	argstr = pathname
%)

@define _SYSCALL_UNLINK_REGARGS
%(
	pathname_uaddr = pointer_arg(1)
	pathname = user_string_quoted(pathname_uaddr)
%)

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

# dw_unlink _____________________________________________________

probe dw_syscall.unlink = kernel.function("sys_unlink").call
{
	@_SYSCALL_UNLINK_NAME
	pathname_uaddr = $pathname
	pathname = user_string_quoted($pathname)
	@_SYSCALL_UNLINK_ARGSTR
}
probe dw_syscall.unlink.return = kernel.function("sys_unlink").return
{
	@_SYSCALL_UNLINK_NAME
	@SYSC_RETVALSTR($return)
}

# nd_unlink _____________________________________________________

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

probe nd1_syscall.unlink = kprobe.function("sys_unlink") ?
{
	@_SYSCALL_UNLINK_NAME
	asmlinkage()
	@_SYSCALL_UNLINK_REGARGS
	@_SYSCALL_UNLINK_ARGSTR
}

/* kernel 4.17+ */
probe nd2_syscall.unlink = kprobe.function(@arch_syscall_prefix "sys_unlink") ?
{
	__set_syscall_pt_regs(pointer_arg(1))
	@_SYSCALL_UNLINK_NAME
	@_SYSCALL_UNLINK_REGARGS
	@_SYSCALL_UNLINK_ARGSTR
}

/* kernel 3.5+, but undesirable because it affects all syscalls */
probe tp_syscall.unlink = kernel.trace("sys_enter")
{
	__set_syscall_pt_regs($regs)
	@__syscall_compat_gate(@const("__NR_unlink"), @const("__NR_compat_unlink"))
	@_SYSCALL_UNLINK_NAME
	@_SYSCALL_UNLINK_REGARGS
	@_SYSCALL_UNLINK_ARGSTR
}

probe nd_syscall.unlink.return = nd1_syscall.unlink.return!, nd2_syscall.unlink.return!, tp_syscall.unlink.return
  { }

probe nd1_syscall.unlink.return = kprobe.function("sys_unlink").return ?
{
	@_SYSCALL_UNLINK_NAME
	@SYSC_RETVALSTR(returnval())
}

/* kernel 4.17+ */
probe nd2_syscall.unlink.return = kprobe.function(@arch_syscall_prefix "sys_unlink").return ?
{
	@_SYSCALL_UNLINK_NAME
	@SYSC_RETVALSTR(returnval())
}

/* kernel 3.5+, but undesirable because it affects all syscalls */
probe tp_syscall.unlink.return = kernel.trace("sys_exit")
{
	__set_syscall_pt_regs($regs)
	@__syscall_compat_gate(@const("__NR_unlink"), @const("__NR_compat_unlink"))
	@_SYSCALL_UNLINK_NAME
	@SYSC_RETVALSTR($ret)
}