Am 18.07.2014 17:05, schrieb Joakim Tjernlund: > Joakim Tjernlund/Transmode wrote on 2014/07/18 15:49:17: >> >> Richard Weinberger <richard.weinber...@gmail.com> wrote on 2014/07/18 > 14:58:30: >>> >>> On Thu, Jul 17, 2014 at 1:18 PM, Joakim Tjernlund >>> <joakim.tjernl...@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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
