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capabilities: use intuitive names for id changes

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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>
This commit is contained in:
Richard Guy Briggs 2017-10-11 20:57:09 -04:00 committed by James Morris
parent 9304b46c91
commit 81a6a01299
1 changed files with 22 additions and 6 deletions
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28
security/commoncap.c
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@ -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;