Messages in this thread | | | Date | Sat, 19 Jul 2014 22:06:16 +0200 | From | Richard Weinberger <> | Subject | Re: ls -l /proc/1/exe -> Permission denied |
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Am 18.07.2014 17:05, schrieb Joakim Tjernlund: > Joakim Tjernlund/Transmode wrote on 2014/07/18 15:49:17: >> >> Richard Weinberger <richard.weinberger@gmail.com> wrote on 2014/07/18 > 14:58:30: >>> >>> On Thu, Jul 17, 2014 at 1:18 PM, Joakim Tjernlund >>> <joakim.tjernlund@transmode.se> wrote: >>>> Trying to real /proc/<pid>/exe I noticed I could not read links not >>>> belonging to my user such as: >>>> jocke > ls -l /proc/1/exe >>>> ls: cannot read symbolic link /proc/1/exe: Permission > denied >>>> >>>> Is this expected? >>> >>> Why do you think this is unexpected? > >> It only shows the full path to the executable, compare with comm which > shows basename(app). >> >> I have an idea for qemu-user which needs to identify which processes >> are running /usr/bin/qemu-<arch> and which are not so it knows how >> to munge different /proc/ files. > > Just to be clear, I expect to read where /proc/1/exe points, not the > contents of the file > pointed to. > > It seems that any and all symlinks are forbidden: >> ls -l /proc/1 > ls: cannot read symbolic link /proc/1/cwd: Permission denied > ls: cannot read symbolic link /proc/1/root: Permission denied > ls: cannot read symbolic link /proc/1/exe: Permission denied
Because they all share the same implementation. See proc_pid_link_inode_operations() in fs/proc/base.c
Happy hacking. :-)
Thanks, //richard
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