Messages in this thread Patch in this message | | | Date | Wed, 4 Feb 2015 09:50:04 -0600 (CST) | From | Christoph Lameter <> | Subject | Re: [capabilities] Allow normal inheritance for a configurable set of capabilities |
| |
On Wed, 4 Feb 2015, Andrew G. Morgan wrote:
> I'm not generally in favor of this. Mostly because this seems to be a > mini-root kind of inheritance that propagates privilege to binaries > that aren't prepared for privilege. I don't really buy the mmap code > concern because the model as it stands says that you trust the binary > (and all of the various ways it was programmed to execute code) with > specific privileges. If the binary mmap's some code (PAM modules come > to mind) then that is part of what it was programmed to/allowed to do. > > That being said, if you really really want this kind of thing, then > make it a single secure bit (with another lock on/off bit) which, when > set, makes: fI default to X. > > pP' = (X & fP) | (pI & fI) > > That way the per-process bounding set still works as advertised and > you don't need to worry about the existing semantics being violated.
Ok but then also fI needs to be set to X so that the binary f invokes can also inherit. So if we copy the inheritable flags to fI then we wont be needing the bounding set anymore.
The changes to brpm_caps_from_vfs_cap would then be only the following? (substitute capable(CAP_INHERIT_BY_DEFAULT through any other means like PRCTL if wanted).
Index: linux/security/commoncap.c =================================================================== --- linux.orig/security/commoncap.c 2015-02-04 09:44:25.000000000 -0600 +++ linux/security/commoncap.c 2015-02-04 09:45:59.381572756 -0600 @@ -350,6 +350,9 @@ static inline int bprm_caps_from_vfs_cap __u32 permitted = caps->permitted.cap[i]; __u32 inheritable = caps->inheritable.cap[i];
+ if (capable(CAP_INHERIT_BY_DEFAULT) + new->cap_inheritable.cap[i] = inheritable; + /* * pP' = (X & fP) | (pI & fI) */
| |