capabilities: intuitive names for cap gain status
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> Acked-by: Kees Cook <keescook@chromium.org> Okay-ished-by: Paul Moore <paul@paul-moore.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
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@ -741,6 +741,12 @@ static void handle_privileged_root(struct linux_binprm *bprm, bool has_cap,
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*effective = true;
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*effective = true;
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}
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}
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#define __cap_gained(field, target, source) \
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!cap_issubset(target->cap_##field, source->cap_##field)
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#define __cap_grew(target, source, cred) \
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!cap_issubset(cred->cap_##target, cred->cap_##source)
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#define __cap_full(field, cred) \
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cap_issubset(CAP_FULL_SET, cred->cap_##field)
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/**
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/**
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* cap_bprm_set_creds - Set up the proposed credentials for execve().
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* cap_bprm_set_creds - Set up the proposed credentials for execve().
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* @bprm: The execution parameters, including the proposed creds
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* @bprm: The execution parameters, including the proposed creds
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@ -769,10 +775,9 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
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handle_privileged_root(bprm, has_cap, &effective, root_uid);
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handle_privileged_root(bprm, has_cap, &effective, root_uid);
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/* if we have fs caps, clear dangerous personality flags */
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/* if we have fs caps, clear dangerous personality flags */
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if (!cap_issubset(new->cap_permitted, old->cap_permitted))
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if (__cap_gained(permitted, new, old))
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bprm->per_clear |= PER_CLEAR_ON_SETID;
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bprm->per_clear |= PER_CLEAR_ON_SETID;
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/* Don't let someone trace a set[ug]id/setpcap binary with the revised
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/* Don't let someone trace a set[ug]id/setpcap binary with the revised
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* credentials unless they have the appropriate permit.
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* credentials unless they have the appropriate permit.
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*
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*
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@ -780,8 +785,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
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*/
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*/
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is_setid = !uid_eq(new->euid, old->uid) || !gid_eq(new->egid, old->gid);
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is_setid = !uid_eq(new->euid, old->uid) || !gid_eq(new->egid, old->gid);
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if ((is_setid ||
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if ((is_setid || __cap_gained(permitted, new, old)) &&
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!cap_issubset(new->cap_permitted, old->cap_permitted)) &&
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((bprm->unsafe & ~LSM_UNSAFE_PTRACE) ||
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((bprm->unsafe & ~LSM_UNSAFE_PTRACE) ||
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!ptracer_capable(current, new->user_ns))) {
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!ptracer_capable(current, new->user_ns))) {
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/* downgrade; they get no more than they had, and maybe less */
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/* downgrade; they get no more than they had, and maybe less */
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@ -831,8 +835,8 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
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* Number 1 above might fail if you don't have a full bset, but I think
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* Number 1 above might fail if you don't have a full bset, but I think
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* that is interesting information to audit.
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* that is interesting information to audit.
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*/
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*/
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if (!cap_issubset(new->cap_effective, new->cap_ambient)) {
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if (__cap_grew(effective, ambient, new)) {
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if (!cap_issubset(CAP_FULL_SET, new->cap_effective) ||
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if (!__cap_full(effective, new) ||
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!uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid) ||
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!uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid) ||
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issecure(SECURE_NOROOT)) {
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issecure(SECURE_NOROOT)) {
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ret = audit_log_bprm_fcaps(bprm, new, old);
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ret = audit_log_bprm_fcaps(bprm, new, old);
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@ -852,7 +856,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
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bprm->cap_elevated = 1;
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bprm->cap_elevated = 1;
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} else if (!uid_eq(new->uid, root_uid)) {
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} else if (!uid_eq(new->uid, root_uid)) {
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if (effective ||
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if (effective ||
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!cap_issubset(new->cap_permitted, new->cap_ambient))
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__cap_grew(permitted, ambient, new))
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bprm->cap_elevated = 1;
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bprm->cap_elevated = 1;
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}
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}
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