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Filename : sysc_setfsgid.stp
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# setfsgid ___________________________________________________
# long sys_setfsgid(gid_t gid)
# long sys_setfsgid16(old_gid_t gid)
#

@define _SYSCALL_SETFSGID_NAME
%(
	name = "setfsgid"
%)

@define _SYSCALL_SETFSGID_ARGSTR
%(
	argstr = sprint(fsgid)
%)

@define _SYSCALL_GATE
%(
    %( arch == "x86_64" %?
	// There are actually 3 x86_64 setfsgid syscalls numbers (which
	// get mapped to 2 syscall functions:
	//   - __NR_setfsgid which gets mapped to sys_setfsgid()
	//   - __NR_ia32_setfsgid32 which also gets mapped to
	//     sys_setfsgid() 
	//   - __NR_ia32_setfsgid which gets mapped to sys_setfsgid16()
	//     (which is a wrapper around sys_setfsgid())
	// So, we need to avoid sys_setfsgid() calls that come from
	// sys_setfsgid16().
	@__syscall_compat_gate(@const("__NR_setfsgid"),
			       @const("__NR_ia32_setfsgid32"))
   %:
	%( arch == "i386" %?
	    // On i386, there are 2 setfsgid syscall numbers:
	    //   - __NR_setfsgid which gets mapped to sys_setfsgid16
	    //   - __NR_setfsgid32 which gets mapped to sys_setfsgid
	    // Since this gets called from a probe on sys_setfsgid, we'll
	    // make sure this is really __NR_setfsgid32.
	    @__syscall_nr_gate(@const("__NR_setfsgid32"))
	%)
    %)
%)

@define _SYSCALL_SETFSGID_REGARGS
%(
	fsgid = int_arg(1)
%)

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

# dw_setfsgid _____________________________________________________

probe dw_syscall.setfsgid = kernel.function("sys_setfsgid16").call ?,
			    __syscall.setfsgid ?
{
	@_SYSCALL_SETFSGID_NAME
	fsgid = __int32($gid)
	@_SYSCALL_SETFSGID_ARGSTR
}
probe __syscall.setfsgid = kernel.function("sys_setfsgid").call ?
{
	@_SYSCALL_GATE
}
probe dw_syscall.setfsgid.return = kernel.function("sys_setfsgid16").return ?,
				   __syscall.setfsgid.return ?
{
	@_SYSCALL_SETFSGID_NAME
	@SYSC_RETVALSTR($return)
}
probe __syscall.setfsgid.return = kernel.function("sys_setfsgid").return ?
{
	@_SYSCALL_GATE
}

# nd_setfsgid _____________________________________________________

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

probe nd1_syscall.setfsgid = kprobe.function("sys_setfsgid16") ?,
			     __nd1_syscall.setfsgid ?
{
	@_SYSCALL_SETFSGID_NAME
	asmlinkage()
	@_SYSCALL_SETFSGID_REGARGS
	@_SYSCALL_SETFSGID_ARGSTR
}
probe __nd1_syscall.setfsgid = kprobe.function("sys_setfsgid") ?
{
	@_SYSCALL_GATE
}

/* kernel 4.17+ */
probe nd2_syscall.setfsgid = kprobe.function(@arch_syscall_prefix "sys_setfsgid") ?,
                             kprobe.function(@arch_syscall_prefix "sys_setfsgid16") ?
{
	__set_syscall_pt_regs(pointer_arg(1))
	@_SYSCALL_SETFSGID_NAME
	@_SYSCALL_SETFSGID_REGARGS
	@_SYSCALL_SETFSGID_ARGSTR
}

/* kernel 3.5+, but undesirable because it affects all syscalls */
probe tp_syscall.setfsgid = __tp_syscall.setfsgid, __tp_syscall.setfsgid16
{
	__set_syscall_pt_regs($regs)
	@_SYSCALL_SETFSGID_NAME
	@_SYSCALL_SETFSGID_REGARGS
	@_SYSCALL_SETFSGID_ARGSTR
}
probe __tp_syscall.setfsgid = kernel.trace("sys_enter")
{
	@__syscall_compat_gate(@const("__NR_setfsgid"), @const("__NR_compat_setfsgid32"))
}
probe __tp_syscall.setfsgid16 = kernel.trace("sys_enter")
{
	@__compat_syscall_gate(@const("__NR_compat_setfsgid"))
}

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

probe nd1_syscall.setfsgid.return = kprobe.function("sys_setfsgid16").return ?,
				    __nd1_syscall.setfsgid.return ?
{
	@_SYSCALL_SETFSGID_NAME
	@SYSC_RETVALSTR(returnval())
}
probe __nd1_syscall.setfsgid.return = kprobe.function("sys_setfsgid").return ?
{
	@_SYSCALL_GATE
}

/* kernel 4.17+ */
probe nd2_syscall.setfsgid.return =
	kprobe.function(@arch_syscall_prefix "sys_setfsgid").return ?,
	kprobe.function(@arch_syscall_prefix "sys_setfsgid16").return ?
{
	@_SYSCALL_SETFSGID_NAME
	@SYSC_RETVALSTR(returnval())
}

/* kernel 3.5+, but undesirable because it affects all syscalls */
probe tp_syscall.setfsgid.return = __tp_syscall.setfsgid.return, __tp_syscall.setfsgid16.return
{
	__set_syscall_pt_regs($regs)
	@_SYSCALL_SETFSGID_NAME
	@SYSC_RETVALSTR($ret)
}
probe __tp_syscall.setfsgid.return = kernel.trace("sys_exit")
{
	@__syscall_compat_gate(@const("__NR_setfsgid"), @const("__NR_compat_setfsgid32"))
}
probe __tp_syscall.setfsgid16.return = kernel.trace("sys_exit")
{
	@__compat_syscall_gate(@const("__NR_compat_setfsgid"))
}