Messages in this thread | | | Date | Thu, 8 Mar 2012 11:31:58 -0800 | Subject | Re: [RFC] c/r: prctl: Add ability to set new mm_struct::exe_file v3 | From | Kees Cook <> |
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On Thu, Mar 8, 2012 at 8:51 AM, Cyrill Gorcunov <gorcunov@openvz.org> wrote: > When we do restore we would like to have a way to setup > a former mm_struct::exe_file so that /proc/pid/exe would > point to the original executable file a process had at > checkpoint time. > > For this the PR_SET_MM_EXE_FILE code is introduced. > This option takes a file descriptor which will be > set as new /proc/$pid/exe symlink. > > This feature is available iif CONFIG_CHECKPOINT_RESTORE is set. > [...] > Index: linux-2.6.git/kernel/sys.c > =================================================================== > --- linux-2.6.git.orig/kernel/sys.c > +++ linux-2.6.git/kernel/sys.c > [...] > + exe_file = fget(fd); > + if (!exe_file) > + return -EBADF; > + > + dentry = exe_file->f_path.dentry; > + > + /* > + * Because the original mm->exe_file > + * points to executable file, make sure > + * this one is executable as well to not > + * break "big" picture and proc/pid/exe > + * symlink will be still pointing to > + * executable one. > + */ > + err = -EACCES; > + if (!S_ISREG(dentry->d_inode->i_mode) || > + exe_file->f_path.mnt->mnt_flags & MNT_NOEXEC) > + goto exit;
I'm starting to notice that this pattern (testing ISREG and MNT_NOEXEC) is getting repeated a few times in the kernel, and at least the no-new-privs patch (not yet in -mm but hopefully soon given the seccomp_filter work) updates this pattern everywhere. Perhaps this should be extracted into a helper first, and then this patch can call that helper here? (And then nnp can just update the single helper.)
-Kees
-- Kees Cook ChromeOS Security -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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