{"id":185,"date":"2009-05-14T09:18:09","date_gmt":"2009-05-14T17:18:09","guid":{"rendered":"http:\/\/www.outflux.net\/blog\/?p=185"},"modified":"2009-05-15T16:13:17","modified_gmt":"2009-05-16T00:13:17","slug":"nx-emulation-in-ubuntu","status":"publish","type":"post","link":"https:\/\/outflux.net\/blog\/archives\/2009\/05\/14\/nx-emulation-in-ubuntu\/","title":{"rendered":"partial NX emulation in Ubuntu"},"content":{"rendered":"

Now available for early testing, Ubuntu Karmic Alpha 1<\/a> has a kernel feature I’ve long wanted in Ubuntu: NX emulation. Basically, if your hardware lacks NX support<\/a>, the kernel will emulate the feature using memory segment limits and ordering. This was AFAIBT originally developed by PaX, and a similar version (with histories including work by Solar Designer and maybe OpenBSD?) has been carried in RedHat\/Fedora for a while now (under the larger project called “ExecShield”, covering multiple protection technologies).<\/p>\n

As more and more of the monolithic ExecShield kernel patch has been taken upstream (many thanks to Arjan van de Ven for pushing<\/a> them), the patch in RedHat has been shrinking. Recently, Dave Jones<\/a> split up the remaining pieces<\/a> into logical chunks small enough that I could actually read it without going cross-eyed. From this, I ported the nx-emulation patches<\/a> to Ubuntu’s kernel, and now they’re happily live in Karmic.<\/p>\n

So, instead of this:<\/p>\n

$ .\/vulnerable-setuid-program $OVERFLOW_AND_SHELLCODE
\n# id
\nuid=0(root) gid=0(root) groups=0(root)<\/code><\/p><\/blockquote>\n

We get this:<\/p>\n

$ .\/vulnerable-setuid-program $OVERFLOW_AND_SHELLCODE
\nSegmentation fault (core dumped)
\n$ dmesg | tail -n1
\n[170131.763976] vulnerable-set[16278]: general protection ip:80489c5 sp:bfa3e330 error:0 in vulnerable-setuid-program[8048000+1000]<\/code><\/p><\/blockquote>\n

Though, as always, please just use 64bit instead. :)<\/p>\n

Update:<\/strong> gave credit to PaX, thanks for the corrections!<\/p>\n

© 2009, Kees Cook<\/a>. This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 License<\/a>.
\"CC<\/a> <\/p>\n","protected":false},"excerpt":{"rendered":"

Now available for early testing, Ubuntu Karmic Alpha 1 has a kernel feature I’ve long wanted in Ubuntu: NX emulation. Basically, if your hardware lacks NX support, the kernel will emulate the feature using memory segment limits and ordering. This was AFAIBT originally developed by PaX, and a similar version (with histories including work by […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6,14],"tags":[],"_links":{"self":[{"href":"https:\/\/outflux.net\/blog\/wp-json\/wp\/v2\/posts\/185"}],"collection":[{"href":"https:\/\/outflux.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/outflux.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/outflux.net\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/outflux.net\/blog\/wp-json\/wp\/v2\/comments?post=185"}],"version-history":[{"count":8,"href":"https:\/\/outflux.net\/blog\/wp-json\/wp\/v2\/posts\/185\/revisions"}],"predecessor-version":[{"id":189,"href":"https:\/\/outflux.net\/blog\/wp-json\/wp\/v2\/posts\/185\/revisions\/189"}],"wp:attachment":[{"href":"https:\/\/outflux.net\/blog\/wp-json\/wp\/v2\/media?parent=185"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/outflux.net\/blog\/wp-json\/wp\/v2\/categories?post=185"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/outflux.net\/blog\/wp-json\/wp\/v2\/tags?post=185"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}