[PATCH V4 05/10] capabilities: use intuitive names for id changes
From: Richard Guy Briggs <hidden>
Date: 2017-09-05 06:46:05
Subsystem:
capabilities, security subsystem, the rest · Maintainers:
Serge Hallyn, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
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 <redacted> Reviewed-by: Serge Hallyn <serge@hallyn.com> Acked-by: James Morris <redacted> --- 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
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