On Mon, Sep 4, 2017 at 11:46 PM, Richard Guy Briggs <[email protected]> wrote: > Introduce a number of inlines to make the use of the negation of > uid_eq() 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]>
Acked-by: Kees Cook <[email protected]> -Kees > --- > security/commoncap.c | 28 ++++++++++++++++++++++------ > 1 files changed, 22 insertions(+), 6 deletions(-) > > diff --git a/security/commoncap.c b/security/commoncap.c > index 1904f49..d37ebec 100644 > --- a/security/commoncap.c > +++ b/security/commoncap.c > @@ -474,6 +474,15 @@ static int get_file_caps(struct linux_binprm *bprm, bool > *effective, bool *has_f > > static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); } > > +static inline bool __is_real(kuid_t uid, struct cred *cred) > +{ return uid_eq(cred->uid, uid); } > + > +static inline bool __is_eff(kuid_t uid, struct cred *cred) > +{ return uid_eq(cred->euid, uid); } > + > +static inline bool __is_suid(kuid_t uid, struct cred *cred) > +{ return !__is_real(uid, cred) && __is_eff(uid, cred); } > + > static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap, > bool *effective, kuid_t root_uid) > { > @@ -485,7 +494,7 @@ static void handle_privileged_root(struct linux_binprm > *bprm, bool has_fcap, > * for a setuid root binary run by a non-root user. Do set it > * for a root user just to cause least surprise to an admin. > */ > - if (has_fcap && !uid_eq(new->uid, root_uid) && uid_eq(new->euid, > root_uid)) { > + if (has_fcap && __is_suid(root_uid, new)) { > warn_setuid_and_fcaps_mixed(bprm->filename); > return; > } > @@ -496,12 +505,12 @@ static void handle_privileged_root(struct linux_binprm > *bprm, bool has_fcap, > * > * If only the real uid is 0, we do not set the effective bit. > */ > - if (uid_eq(new->euid, root_uid) || uid_eq(new->uid, root_uid)) { > + if (__is_eff(root_uid, new) || __is_real(root_uid, new)) { > /* pP' = (cap_bset & ~0) | (pI & ~0) */ > new->cap_permitted = cap_combine(old->cap_bset, > old->cap_inheritable); > } > - if (uid_eq(new->euid, root_uid)) > + if (__is_eff(root_uid, new)) > *effective = true; > } > > @@ -511,6 +520,13 @@ static void handle_privileged_root(struct linux_binprm > *bprm, bool has_fcap, > !cap_issubset(cred->cap_##target, cred->cap_##source) > #define __cap_full(field, cred) \ > cap_issubset(CAP_FULL_SET, cred->cap_##field) > + > +static inline bool __is_setuid(struct cred *new, const struct cred *old) > +{ return !uid_eq(new->euid, old->uid); } > + > +static inline bool __is_setgid(struct cred *new, const struct cred *old) > +{ return !gid_eq(new->egid, old->gid); } > + > /** > * cap_bprm_set_creds - Set up the proposed credentials for execve(). > * @bprm: The execution parameters, including the proposed creds > @@ -548,7 +564,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) > * > * In addition, if NO_NEW_PRIVS, then ensure we get no new privs. > */ > - is_setid = !uid_eq(new->euid, old->uid) || !gid_eq(new->egid, > old->gid); > + is_setid = __is_setuid(new, old) || __is_setgid(new, old); > > if ((is_setid || __cap_gained(permitted, new, old)) && > ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) || > @@ -602,7 +618,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) > */ > if (__cap_grew(effective, ambient, new)) { > if (!__cap_full(effective, new) || > - !uid_eq(new->euid, root_uid) || !uid_eq(new->uid, > root_uid) || > + !__is_eff(root_uid, new) || !__is_real(root_uid, new) || > !root_privileged()) { > ret = audit_log_bprm_fcaps(bprm, new, old); > if (ret < 0) > @@ -619,7 +635,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) > bprm->cap_elevated = 0; > if (is_setid) { > bprm->cap_elevated = 1; > - } else if (!uid_eq(new->uid, root_uid)) { > + } else if (!__is_real(root_uid, new)) { > if (effective || > __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
