markus moeller utyfecmoellerpluscom magic nose goblin wrote message news47c561a66050908gmailcom markus moeller wrote su root another id anymore list links procpid original process creates problem example running perl root switching id using circumstances perl tries start procselfexe link usrbinperl fails didnt notice doesnt depend su normal user list links procpid known bug basic security violation disagree file permissions allow new forkedoff process root mentioned valid non root processuser forked process dont trust permisssions symbolic links irrelevant seems overwriting control kernel proc filesystem think inline correct behaviour thank markus whoami root echo 13924 ls al proc13924 total 0 drxrxrx 6 root root 0 20080222 2101 drxrxrx 124 root root 0 20080218 2011 drxrxrx 2 root root 0 20080226 2148 attr r 1 root root 0 20080226 2148 auxv w 1 root root 0 20080226 2148 clear_refs rrr 1 root root 0 20080225 1218 cmdline rrr 1 root root 0 20080226 2148 cpuset lrwxrwxrwx 1 root root 0 20080226 2148 cwd homemarkus r 1 root root 0 20080226 2148 environ lrwxrwxrwx 1 root root 0 20080226 1216 exe libastbinksh drx 2 root root 0 20080226 2148 fd drx 2 root root 0 20080226 2148 fdinfo rwrr 1 root root 0 20080226 2148 loginuid rrr 1 root root 0 20080226 2148 maps rw 1 root root 0 20080226 2148 mem rrr 1 root root 0 20080226 2148 mounts r 1 root root 0 20080226 2148 mountstats rwrr 1 root root 0 20080226 2148 oom_adj rrr 1 root root 0 20080226 2148 oom_score lrwxrwxrwx 1 root root 0 20080226 2148 root rw 1 root root 0 20080226 2148 seccomp rrr 1 root root 0 20080226 2148 smaps rrr 1 root root 0 20080226 2147 stat rrr 1 root root 0 20080226 1216 statm rrr 1 root root 0 20080225 1218 status drxrxrx 3 root root 0 20080226 2148 task rrr 1 root root 0 20080226 2148 wchan su nobody gdqoxqopensusehomemarkus ls al proc13924 ls read symbolic link proc13924cwd permission denied ls read symbolic link proc13924root permission denied ls read symbolic link proc13924exe permission denied total 0 drxrxrx 6 root root 0 20080222 2101 drxrxrx 126 root root 0 20080218 2011 drxrxrx 2 root root 0 20080226 2148 attr r 1 root root 0 20080226 2148 auxv w 1 root root 0 20080226 2148 clear_refs rrr 1 root root 0 20080225 1218 cmdline rrr 1 root root 0 20080226 2148 cpuset lrwxrwxrwx 1 root root 0 20080226 2148 cwd r 1 root root 0 20080226 2148 environ lrwxrwxrwx 1 root root 0 20080226 1216 exe drx 2 root root 0 20080226 2148 fd drx 2 root root 0 20080226 2148 fdinfo rwrr 1 root root 0 20080226 2148 loginuid rrr 1 root root 0 20080226 2148 maps rw 1 root root 0 20080226 2148 mem rrr 1 root root 0 20080226 2148 mounts r 1 root root 0 20080226 2148 mountstats rwrr 1 root root 0 20080226 2148 oom_adj rrr 1 root root 0 20080226 2148 oom_score lrwxrwxrwx 1 root root 0 20080226 2148 root rw 1 root root 0 20080226 2148 seccomp rrr 1 root root 0 20080226 2148 smaps rrr 1 root root 0 20080226 2147 stat rrr 1 root root 0 20080226 1216 statm rrr 1 root root 0 20080225 1218 status drxrxrx 3 root root 0 20080226 2148 task rrr 1 root root 0 20080226 2148 wchan ark markus fri 08 aug 2008 035853 0000 opensuse proc link permission problemquestion