On Mon, 23 Jan 2012 13:21:15 -0800 Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > Add the "proc_pid_mem" sysctl to control whether or not /proc/pid/mem is > allowed to work: 0: disabled, 1: read only, 2: read/write (default). > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > --- > v3: > - document the default, thanks to Randy Dunlap. > - remove needless CONFIG_PROC_FS checks, thanks to Eric W. Biederman. I was wondering about that. Is CONFIG_PROC_FS=n, CONFIG_SYSCTL=y an impossible combination? If so, why? > --- a/Documentation/sysctl/kernel.txt > +++ b/Documentation/sysctl/kernel.txt > @@ -56,6 +56,7 @@ show up in /proc/sys/kernel: > - printk_delay > - printk_ratelimit > - printk_ratelimit_burst > +- proc_pid_mem > - randomize_va_space > - real-root-dev ==> Documentation/initrd.txt > - reboot-cmd [ SPARC only ] > @@ -477,6 +478,20 @@ send before ratelimiting kicks in. > > ============================================================== > > +proc_pid_mem: > + > +This option can be used to select the level of access given to potential > +ptracers when using the per-process "mem" file in /proc/pid/mem. > + > +0 - Disable entirely. > + > +1 - Allow potential ptracers read access to process memory, but not writes. > + > +2 - Allow potential ptracers read and write access to process memory. This > + is the default. > + > +============================================================== I agree with Colin on this (he stole my line!). Overall, the patch looks really hacky and random. I felt the same way as Vasily: it's easy to see how a significant number of similar (and hacky and random) patches could be added, resulting in a regrettable mess. Is there some better designed, more organized way of approaching all of this? Random ideas: - A parallel /procfs-perms filesystem. You write a number into /procfs-perms/stat to affect access to /proc/stat (although why the heck not just run `chmod /proc/stat'?) It's unclear how to handle /proc/pid/. Perhaps literally have a /procfs-perms/pid/ directory. - Make tasks inherit their /proc/pid/* permissions across fork, do a chmod /proc/1/whatever in initscripts. - Other and better things ;) This particular approach makes my toes curl. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
