| Message ID | a36af00bd25e0cfe7eeea37bd99b82b9350de1e0.1504591358.git.rgb@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Sep 4, 2017 at 11:46 PM, Richard Guy Briggs <rgb@redhat.com> 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 <rgb@redhat.com> > Reviewed-by: Serge Hallyn <serge@hallyn.com> > Acked-by: James Morris <james.l.morris@oracle.com> I still find these hard to read, but it IS better than it was before. ;) Acked-by: Kees Cook <keescook@chromium.org> > --- > 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 >
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; }