This problem is predestined for a recursive function, even though you don't seem to expect a depth of more than one.

#!/usr/bin/perl -w

use strict;
use warnings;

use Data::Dumper;
$Data::Dumper::Indent = 1;

my @lines = <DATA>;
chomp @lines;


my @list = [q{div}, {id => q{article}},recorddiv()];


sub recorddiv { 
    my @data;
    while( my $line= shift @lines ) {
    my ($tag, $txt) = $line =~ /^;([^;]+);(.*)/;
  
    if ($tag eq q{greybox_start}){
        push @data, [q{div}, {class => q{greybox}}, recorddiv() ];
        next;
    }
    elsif ($tag eq q{greybox_end}){
        return @data;
    }
  
    push @data, [$tag, $txt];
    }
    return @data;
}    
    

print Dumper(\@list),

__DATA__
;p;one
;greybox_start;
;h2;two
;greybox_end;
;p;three
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