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authorRichard Guy Briggs <rgb@redhat.com>2017-10-11 20:57:09 -0400
committerJames Morris <james.l.morris@oracle.com>2017-10-20 15:22:44 +1100
commit81a6a012996b3fd47608d87b16e79412dd73578e (patch)
treeb20231b7838d106cf0524028e2a614c23e382e37 /security/commoncap.c
parent9304b46c912d65a103a68f093b456ba3c02dca3b (diff)
downloadlinux-81a6a012996b3fd47608d87b16e79412dd73578e.tar.bz2
capabilities: use intuitive names for id changes
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 <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>
Diffstat (limited to 'security/commoncap.c')
-rw-r--r--security/commoncap.c28
1 files changed, 22 insertions, 6 deletions
diff --git a/security/commoncap.c b/security/commoncap.c
index 9b8a6e79d858..421f7438d3c8 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -697,6 +697,15 @@ out:
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); }
+
/*
* handle_privileged_root - Handle case of privileged root
* @bprm: The execution parameters, including the proposed creds
@@ -722,7 +731,7 @@ 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;
}
@@ -731,7 +740,7 @@ static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap,
* executables under compatibility mode, we override the
* capability sets for the file.
*/
- 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);
@@ -739,7 +748,7 @@ 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))
+ if (__is_eff(root_uid, new))
*effective = true;
}
@@ -749,6 +758,13 @@ 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
@@ -785,7 +801,7 @@ 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) ||
@@ -839,7 +855,7 @@ 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)
@@ -856,7 +872,7 @@ 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;