Messages in this thread | | | Date | Mon, 5 Mar 2012 15:26:55 +0100 | From | Oleg Nesterov <> | Subject | Re: [RFC] c/r: prctl: Add ability to set new mm_struct::exe_file |
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On 03/05, Oleg Nesterov wrote: > > On 03/04, Cyrill Gorcunov wrote: > > > > + err = -EACCES; > > + if (!S_ISREG(dentry->d_inode->i_mode) || > > + exe_file->f_path.mnt->mnt_flags & MNT_NOEXEC) > > + goto exit; > > + > > + if ((exe_file->f_flags & O_ACCMODE) != O_RDONLY) > > + goto exit; > > + > > + err = inode_permission(dentry->d_inode, MAY_EXEC); > > + if (err) > > + goto exit; > > OK, I won't argue, probably this makes sense to make sure that > admin can't get a heart attack looking at /proc/pid/exe. > > But the O_RDONLY check looks strange. We are not going to write > to this file, we only set the name (and that is why I think it > should be mm->exe_path). What is the point to check that the file > was opened without FMODE_WRITE? Even if there were any security > risk the apllication can open this file again with the different > flags.
Seriously, I think we should cleanup this before c/r adds more ugliness. I'll try to make the patch today.
And with all these checks I am no longer sure that fd is better than filename ;)
Oleg.
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