I was thinking more like this: int override = secure(SECURE_AMBIENT_PRIVS) && cap_isclear(caps->inheritable.cap);
CAP_FOR_EACH_U32(i) { __u32 permitted = caps->permitted.cap[i]; __u32 inheritable = override ? new->cap_bset.cap[i] : caps->inheritable.cap[i]; [...] Cheers Andrew On Wed, Feb 4, 2015 at 7:56 AM, Serge E. Hallyn <se...@hallyn.com> wrote: > Quoting Christoph Lameter (c...@linux.com): >> 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) >> */ > > Not quite - I think more like > > if (secure(SECURE_AMBIENT_PRIVS)) > new->cap_inheritable.cap[i] = inheritable; > > Then ns_capable(CAP_INHERIT_BY_DEFAULT), or perhaps rather > ns_capable(CAP_SETPCAP), would be required in order to set > SECURE_AMBIENT_PRIVS, which is off by default. -- 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/