On Mon, Sep 4, 2017 at 11:46 PM, Richard Guy Briggs <[email protected]> wrote: > Introduce macros cap_gained, cap_grew, cap_full to make the use of the > negation of is_subset() easier to read and analyse. > > Signed-off-by: Richard Guy Briggs <[email protected]> > Reviewed-by: Serge Hallyn <[email protected]> > Acked-by: James Morris <[email protected]>
I still find these hard to read, but it IS better than it was before. ;) Acked-by: Kees Cook <[email protected]> > --- > security/commoncap.c | 18 +++++++++++------- > 1 files changed, 11 insertions(+), 7 deletions(-) > > diff --git a/security/commoncap.c b/security/commoncap.c > index 927fe93..cf6e2b0 100644 > --- a/security/commoncap.c > +++ b/security/commoncap.c > @@ -505,6 +505,12 @@ static void handle_privileged_root(struct linux_binprm > *bprm, bool has_cap, > *effective = true; > } > > +#define __cap_gained(field, target, source) \ > + !cap_issubset(target->cap_##field, source->cap_##field) > +#define __cap_grew(target, source, cred) \ > + !cap_issubset(cred->cap_##target, cred->cap_##source) > +#define __cap_full(field, cred) \ > + cap_issubset(CAP_FULL_SET, cred->cap_##field) > > /** > * cap_bprm_set_creds - Set up the proposed credentials for execve(). > * @bprm: The execution parameters, including the proposed creds > @@ -533,10 +539,9 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) > handle_privileged_root(bprm, has_cap, &effective, root_uid); > > /* if we have fs caps, clear dangerous personality flags */ > - if (!cap_issubset(new->cap_permitted, old->cap_permitted)) > + if (__cap_gained(permitted, new, old)) > bprm->per_clear |= PER_CLEAR_ON_SETID; > > - > /* Don't let someone trace a set[ug]id/setpcap binary with the revised > * credentials unless they have the appropriate permit. > * > @@ -544,8 +549,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) > */ > is_setid = !uid_eq(new->euid, old->uid) || !gid_eq(new->egid, > old->gid); > > - if ((is_setid || > - !cap_issubset(new->cap_permitted, old->cap_permitted)) && > + if ((is_setid || __cap_gained(permitted, new, old)) && > ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) || > !ptracer_capable(current, new->user_ns))) { > /* downgrade; they get no more than they had, and maybe less > */ > @@ -595,8 +599,8 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) > * Number 1 above might fail if you don't have a full bset, but I > think > * that is interesting information to audit. > */ > - if (!cap_issubset(new->cap_effective, new->cap_ambient)) { > - if (!cap_issubset(CAP_FULL_SET, new->cap_effective) || > + if (__cap_grew(effective, ambient, new)) { > + if (!__cap_full(effective, new) || > !uid_eq(new->euid, root_uid) || !uid_eq(new->uid, > root_uid) || > issecure(SECURE_NOROOT)) { > ret = audit_log_bprm_fcaps(bprm, new, old); > @@ -616,7 +620,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) > bprm->cap_elevated = 1; > } else if (!uid_eq(new->uid, root_uid)) { > if (effective || > - !cap_issubset(new->cap_permitted, new->cap_ambient)) > + __cap_grew(permitted, ambient, new)) > bprm->cap_elevated = 1; > } > > -- > 1.7.1 > -- Kees Cook Pixel Security -- Linux-audit mailing list [email protected] https://www.redhat.com/mailman/listinfo/linux-audit
