^^&&^^

Edit File: sysc_setfsuid.stp

# setfsuid ___________________________________________________
# long sys_setfsuid(uid_t uid)
# long sys_setfsuid16(old_uid_t uid)
#

@define _SYSCALL_SETFSUID_NAME
%(
	name = "setfsuid"
%)

@define _SYSCALL_SETFSUID_ARGSTR
%(
	argstr = sprint(fsuid)
%)

@define _SYSCALL_GATE
%(
    %( arch == "x86_64" %?
	// There are actually 3 x86_64 setfsuid syscalls numbers (which
	// get mapped to 2 syscall functions:
	//   - __NR_setfsuid which gets mapped to sys_setfsuid()
	//   - __NR_ia32_setfsuid32 which also gets mapped to
	//     sys_setfsuid() 
	//   - __NR_ia32_setfsuid which gets mapped to sys_setfsuid16()
	//     (which is a wrapper around sys_setfsuid())
	// So, we need to avoid sys_setfsuid() calls that come from
	// sys_setfsuid16().
	@__syscall_compat_gate(@const("__NR_setfsuid"),
			       @const("__NR_ia32_setfsuid32"))
    %:
	%( arch == "i386" %?
	    // On i386, there are 2 setfsuid syscall numbers:
	    //   - __NR_setfsuid which gets mapped to sys_setfsuid16
	    //   - __NR_setfsuid32 which gets mapped to sys_setfsuid
	    // Since this gets called from a probe on sys_setfsuid, we'll
	    // make sure this is really __NR_setfsuid32.
	    @__syscall_nr_gate(@const("__NR_setfsuid32"))
	%)
    %)
%)

@define _SYSCALL_SETFSUID_REGARGS
%(
	fsuid = int_arg(1)
%)

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

# dw_setfsuid _____________________________________________________

probe dw_syscall.setfsuid = kernel.function("sys_setfsuid16").call ?,
			    __syscall.setfsuid ?
{
	@_SYSCALL_SETFSUID_NAME
	fsuid = __int32($uid)
	@_SYSCALL_SETFSUID_ARGSTR
}
probe __syscall.setfsuid = kernel.function("sys_setfsuid").call ?
{
	@_SYSCALL_GATE
}
probe dw_syscall.setfsuid.return = kernel.function("sys_setfsuid16").return ?,
				   __syscall.setfsuid.return ?
{
	@_SYSCALL_SETFSUID_NAME
	@SYSC_RETVALSTR($return)
}
probe __syscall.setfsuid.return = kernel.function("sys_setfsuid").return ?
{
	@_SYSCALL_GATE
}

# nd_setfsuid _____________________________________________________

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

probe nd1_syscall.setfsuid = kprobe.function("sys_setfsuid16") ?,
                             __nd1_syscall.setfsuid ?
{
	@_SYSCALL_SETFSUID_NAME
	asmlinkage()
	@_SYSCALL_SETFSUID_REGARGS
	@_SYSCALL_SETFSUID_ARGSTR
}
probe __nd1_syscall.setfsuid = kprobe.function("sys_setfsuid") ?
{
	@_SYSCALL_GATE
}

/* kernel 4.17+ */
probe nd2_syscall.setfsuid = kprobe.function(@arch_syscall_prefix "sys_setfsuid") ?,
                             kprobe.function(@arch_syscall_prefix "sys_setfsuid16") ?
{
	__set_syscall_pt_regs(pointer_arg(1))
	@_SYSCALL_SETFSUID_NAME
	@_SYSCALL_SETFSUID_REGARGS
	@_SYSCALL_SETFSUID_ARGSTR
}

/* kernel 3.5+, but undesirable because it affects all syscalls */
probe tp_syscall.setfsuid = __tp_syscall.setfsuid, __tp_syscall.setfsuid16
{
	__set_syscall_pt_regs($regs)
	@_SYSCALL_SETFSUID_NAME
	@_SYSCALL_SETFSUID_REGARGS
	@_SYSCALL_SETFSUID_ARGSTR
}
probe __tp_syscall.setfsuid = kernel.trace("sys_enter")
{
	@__syscall_compat_gate(@const("__NR_setfsuid"), @const("__NR_compat_setfsuid32"))
}
probe __tp_syscall.setfsuid16 = kernel.trace("sys_enter")
{
	@__compat_syscall_gate(@const("__NR_compat_setfsuid"))
}

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

probe nd1_syscall.setfsuid.return = kprobe.function("sys_setfsuid16").return ?,
                                    __nd1_syscall.setfsuid.return ?
{
	@_SYSCALL_SETFSUID_NAME
	@SYSC_RETVALSTR(returnval())
}
probe __nd1_syscall.setfsuid.return = kprobe.function("sys_setfsuid").return ?
{
	@_SYSCALL_GATE
}

/* kernel 4.17+ */
probe nd2_syscall.setfsuid.return =
	kprobe.function(@arch_syscall_prefix "sys_setfsuid").return ?,
	kprobe.function(@arch_syscall_prefix "sys_setfsuid16").return ?
{
	@_SYSCALL_SETFSUID_NAME
	@SYSC_RETVALSTR(returnval())
}

/* kernel 3.5+, but undesirable because it affects all syscalls */
probe tp_syscall.setfsuid.return = __tp_syscall.setfsuid.return, __tp_syscall.setfsuid16.return
{
	__set_syscall_pt_regs($regs)
	@_SYSCALL_SETFSUID_NAME
	@SYSC_RETVALSTR($ret)
}
probe __tp_syscall.setfsuid.return = kernel.trace("sys_exit")
{
	@__syscall_compat_gate(@const("__NR_setfsuid"), @const("__NR_compat_setfsuid32"))
}
probe __tp_syscall.setfsuid16.return = kernel.trace("sys_exit")
{
	@__compat_syscall_gate(@const("__NR_compat_setfsuid"))
}