From: rgb@redhat.com (Richard Guy Briggs) To: linux-security-module@vger.kernel.org Subject: [PATCH V3 10/10] capabilities: audit log other surprising conditions Date: Wed, 23 Aug 2017 06:13:01 -0400 [thread overview] Message-ID: <11df9e69904600785a8a609f471ff30431ef5464.1503459890.git.rgb@redhat.com> (raw) In-Reply-To: <cover.1503459890.git.rgb@redhat.com> The existing condition tested for process effective capabilities set by file attributes but intended to ignore the change if the result was unsurprisingly an effective full set in the case root is special with a setuid root executable file and we are root. Stated again: - When you execute a setuid root application, it is no surprise and expected that it got all capabilities, so we do not want capabilities recorded. if (pE_grew && !(pE_fullset && (eff_root || real_root) && root_priveleged) ) Now make sure we cover other cases: - If something prevented a setuid root app getting all capabilities and it wound up with one capability only, then it is a surprise and should be logged. When it is a setuid root file, we only want capabilities when the process does not get full capabilities.. root_priveleged && setuid_root && !pE_fullset - Similarly if a non-setuid program does pick up capabilities due to file system based capabilities, then we want to know what capabilities were picked up. When it has file system based capabilities we want the capabilities. !is_setuid && (has_fcap && pP_gained) - If it is a non-setuid file and it gets ambient capabilities, we want the capabilities. !is_setuid && pA_gained - These last two are combined into one due to the common first parameter. Related: https://github.com/linux-audit/audit-kernel/issues/16 Signed-off-by: Richard Guy Briggs <rgb@redhat.com> --- security/commoncap.c | 28 ++++++++++++++++++++-------- 1 files changed, 20 insertions(+), 8 deletions(-) diff --git a/security/commoncap.c b/security/commoncap.c index 49cce06..8da965c 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -536,7 +536,7 @@ static inline bool is_setgid(struct cred *new, const struct cred *old) { return !gid_eq(new->egid, old->gid); } /* - * Audit candidate if current->cap_effective is set + * 1) Audit candidate if current->cap_effective is set * * We do not bother to audit if 3 things are true: * 1) cap_effective has all caps @@ -546,16 +546,28 @@ static inline bool is_setgid(struct cred *new, const struct cred *old) * * Number 1 above might fail if you don't have a full bset, but I think * that is interesting information to audit. + * + * A number of other conditions require logging: + * 2) something prevented setuid root getting all caps + * 3) non-setuid root gets fcaps + * 4) non-setuid root gets ambient */ -static inline bool nonroot_raised_pE(struct cred *cred, kuid_t root) +static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old, kuid_t root, bool has_fcap) { bool ret = false; - if (cap_grew(effective, ambient, cred) && - !(cap_full(effective, cred) && - (is_eff(root, cred) || - is_real(root, cred)) && - root_privileged())) + if ((cap_grew(effective, ambient, new) && + !(cap_full(effective, new) && + (is_eff(root, new) || + is_real(root, new)) && + root_privileged())) || + (root_privileged() && + is_suid(root, new) && + !cap_full(effective, new)) || + (!is_setuid(new, old) && + ((has_fcap && + cap_gained(permitted, new, old)) || + cap_gained(ambient, new, old)))) ret = true; return ret; } @@ -639,7 +651,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) bprm->cap_effective = effective; - if (nonroot_raised_pE(new, root_uid)) { + if (nonroot_raised_pE(new, old, root_uid, has_fcap)) { ret = audit_log_bprm_fcaps(bprm, new, old); if (ret < 0) return ret; -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info@ http://vger.kernel.org/majordomo-info.html
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From: Richard Guy Briggs <rgb@redhat.com> To: linux-security-module@vger.kernel.org, linux-audit@redhat.com Cc: Richard Guy Briggs <rgb@redhat.com>, Andy Lutomirski <luto@kernel.org>, "Serge E. Hallyn" <serge.hallyn@ubuntu.com>, Kees Cook <keescook@chromium.org>, James Morris <james.l.morris@oracle.com>, Eric Paris <eparis@redhat.com>, Paul Moore <pmoore@redhat.com>, Steve Grubb <sgrubb@redhat.com> Subject: [PATCH V3 10/10] capabilities: audit log other surprising conditions Date: Wed, 23 Aug 2017 06:13:01 -0400 [thread overview] Message-ID: <11df9e69904600785a8a609f471ff30431ef5464.1503459890.git.rgb@redhat.com> (raw) In-Reply-To: <cover.1503459890.git.rgb@redhat.com> In-Reply-To: <cover.1503459890.git.rgb@redhat.com> The existing condition tested for process effective capabilities set by file attributes but intended to ignore the change if the result was unsurprisingly an effective full set in the case root is special with a setuid root executable file and we are root. Stated again: - When you execute a setuid root application, it is no surprise and expected that it got all capabilities, so we do not want capabilities recorded. if (pE_grew && !(pE_fullset && (eff_root || real_root) && root_priveleged) ) Now make sure we cover other cases: - If something prevented a setuid root app getting all capabilities and it wound up with one capability only, then it is a surprise and should be logged. When it is a setuid root file, we only want capabilities when the process does not get full capabilities.. root_priveleged && setuid_root && !pE_fullset - Similarly if a non-setuid program does pick up capabilities due to file system based capabilities, then we want to know what capabilities were picked up. When it has file system based capabilities we want the capabilities. !is_setuid && (has_fcap && pP_gained) - If it is a non-setuid file and it gets ambient capabilities, we want the capabilities. !is_setuid && pA_gained - These last two are combined into one due to the common first parameter. Related: https://github.com/linux-audit/audit-kernel/issues/16 Signed-off-by: Richard Guy Briggs <rgb@redhat.com> --- security/commoncap.c | 28 ++++++++++++++++++++-------- 1 files changed, 20 insertions(+), 8 deletions(-) diff --git a/security/commoncap.c b/security/commoncap.c index 49cce06..8da965c 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -536,7 +536,7 @@ static inline bool is_setgid(struct cred *new, const struct cred *old) { return !gid_eq(new->egid, old->gid); } /* - * Audit candidate if current->cap_effective is set + * 1) Audit candidate if current->cap_effective is set * * We do not bother to audit if 3 things are true: * 1) cap_effective has all caps @@ -546,16 +546,28 @@ static inline bool is_setgid(struct cred *new, const struct cred *old) * * Number 1 above might fail if you don't have a full bset, but I think * that is interesting information to audit. + * + * A number of other conditions require logging: + * 2) something prevented setuid root getting all caps + * 3) non-setuid root gets fcaps + * 4) non-setuid root gets ambient */ -static inline bool nonroot_raised_pE(struct cred *cred, kuid_t root) +static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old, kuid_t root, bool has_fcap) { bool ret = false; - if (cap_grew(effective, ambient, cred) && - !(cap_full(effective, cred) && - (is_eff(root, cred) || - is_real(root, cred)) && - root_privileged())) + if ((cap_grew(effective, ambient, new) && + !(cap_full(effective, new) && + (is_eff(root, new) || + is_real(root, new)) && + root_privileged())) || + (root_privileged() && + is_suid(root, new) && + !cap_full(effective, new)) || + (!is_setuid(new, old) && + ((has_fcap && + cap_gained(permitted, new, old)) || + cap_gained(ambient, new, old)))) ret = true; return ret; } @@ -639,7 +651,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) bprm->cap_effective = effective; - if (nonroot_raised_pE(new, root_uid)) { + if (nonroot_raised_pE(new, old, root_uid, has_fcap)) { ret = audit_log_bprm_fcaps(bprm, new, old); if (ret < 0) return ret; -- 1.7.1
next prev parent reply other threads:[~2017-08-23 10:13 UTC|newest] Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-08-23 10:12 [PATCH V3 00/10] capabilities: do not audit log BPRM_FCAPS on set*id Richard Guy Briggs 2017-08-23 10:12 ` Richard Guy Briggs 2017-08-23 10:12 ` [PATCH V3 01/10] capabilities: factor out cap_bprm_set_creds privileged root Richard Guy Briggs 2017-08-23 10:12 ` Richard Guy Briggs 2017-08-24 15:42 ` Serge E. Hallyn 2017-08-24 15:42 ` Serge E. Hallyn 2017-08-25 5:55 ` James Morris 2017-08-25 5:55 ` James Morris 2017-08-25 10:49 ` Richard Guy Briggs 2017-08-25 10:49 ` Richard Guy Briggs 2017-08-23 10:12 ` [PATCH V3 02/10] capabilities: intuitive names for cap gain status Richard Guy Briggs 2017-08-23 10:12 ` Richard Guy Briggs 2017-08-24 16:03 ` Serge E. Hallyn 2017-08-24 16:03 ` Serge E. Hallyn 2017-08-24 16:19 ` Richard Guy Briggs 2017-08-24 16:19 ` Richard Guy Briggs 2017-08-24 16:37 ` Serge E. Hallyn 2017-08-24 16:37 ` Serge E. Hallyn 2017-08-24 19:06 ` Kees Cook 2017-08-24 19:06 ` Kees Cook 2017-08-24 21:17 ` Paul Moore 2017-08-24 21:17 ` Paul Moore 2017-08-28 9:19 ` Richard Guy Briggs 2017-08-28 9:19 ` Richard Guy Briggs 2017-08-28 11:08 ` Richard Guy Briggs 2017-08-28 11:08 ` Richard Guy Briggs 2017-09-01 10:18 ` Richard Guy Briggs 2017-09-01 10:18 ` Richard Guy Briggs 2017-09-02 5:37 ` Serge E. Hallyn 2017-09-02 5:37 ` Serge E. Hallyn 2017-09-04 6:57 ` Richard Guy Briggs 2017-09-04 6:57 ` Richard Guy Briggs 2017-09-05 6:45 ` Richard Guy Briggs 2017-09-05 6:45 ` Richard Guy Briggs 2017-08-25 5:56 ` James Morris 2017-08-25 5:56 ` James Morris 2017-08-25 15:08 ` Andy Lutomirski 2017-08-25 15:08 ` Andy Lutomirski 2017-08-25 18:47 ` Serge E. Hallyn 2017-08-25 18:47 ` Serge E. Hallyn 2017-08-23 10:12 ` [PATCH V3 03/10] capabilities: rename has_cap to has_fcap Richard Guy Briggs 2017-08-23 10:12 ` Richard Guy Briggs 2017-08-24 16:10 ` Serge E. Hallyn 2017-08-24 16:10 ` Serge E. Hallyn 2017-08-25 5:56 ` James Morris 2017-08-25 5:56 ` James Morris 2017-08-23 10:12 ` [PATCH V3 04/10] capabilities: use root_priveleged inline to clarify logic Richard Guy Briggs 2017-08-23 10:12 ` Richard Guy Briggs 2017-08-24 16:14 ` Serge E. Hallyn 2017-08-24 16:14 ` Serge E. Hallyn 2017-08-25 5:58 ` James Morris 2017-08-25 5:58 ` James Morris 2017-08-28 12:03 ` Richard Guy Briggs 2017-08-28 12:03 ` Richard Guy Briggs 2017-08-31 14:49 ` Serge E. Hallyn 2017-08-31 14:49 ` Serge E. Hallyn 2017-08-23 10:12 ` [PATCH V3 05/10] capabilities: use intuitive names for id changes Richard Guy Briggs 2017-08-23 10:12 ` Richard Guy Briggs 2017-08-24 16:17 ` Serge E. Hallyn 2017-08-24 16:17 ` Serge E. Hallyn 2017-08-25 5:59 ` James Morris 2017-08-25 5:59 ` James Morris 2017-08-25 15:06 ` Andy Lutomirski 2017-08-25 15:06 ` Andy Lutomirski 2017-08-25 18:51 ` Serge E. Hallyn 2017-08-25 18:51 ` Serge E. Hallyn 2017-08-25 19:45 ` Andy Lutomirski 2017-08-25 19:45 ` Andy Lutomirski 2017-08-25 20:06 ` Serge E. Hallyn 2017-08-25 20:06 ` Serge E. Hallyn 2017-08-28 1:32 ` James Morris 2017-08-28 1:32 ` James Morris 2017-08-28 9:12 ` Richard Guy Briggs 2017-08-28 9:12 ` Richard Guy Briggs 2017-08-28 20:12 ` Andy Lutomirski 2017-08-28 20:12 ` Andy Lutomirski 2017-08-23 10:12 ` [PATCH V3 06/10] capabilities: move audit log decision to function Richard Guy Briggs 2017-08-23 10:12 ` Richard Guy Briggs 2017-08-24 16:18 ` Serge E. Hallyn 2017-08-24 16:18 ` Serge E. Hallyn 2017-08-25 6:01 ` James Morris 2017-08-25 6:01 ` James Morris 2017-08-23 10:12 ` [PATCH V3 07/10] capabilities: remove a layer of conditional logic Richard Guy Briggs 2017-08-23 10:12 ` Richard Guy Briggs 2017-08-24 16:20 ` Serge E. Hallyn 2017-08-24 16:20 ` Serge E. Hallyn 2017-08-25 5:47 ` James Morris 2017-08-25 5:47 ` James Morris 2017-08-25 15:11 ` Andy Lutomirski 2017-08-25 15:11 ` Andy Lutomirski 2017-08-25 18:53 ` Serge E. Hallyn 2017-08-25 18:53 ` Serge E. Hallyn 2017-08-23 10:12 ` [PATCH V3 08/10] capabilities: invert logic for clarity Richard Guy Briggs 2017-08-23 10:12 ` Richard Guy Briggs 2017-08-24 16:23 ` Serge E. Hallyn 2017-08-24 16:23 ` Serge E. Hallyn 2017-08-25 5:47 ` James Morris 2017-08-25 5:47 ` James Morris 2017-08-23 10:13 ` [PATCH V3 09/10] capabilities: fix logic for effective root or real root Richard Guy Briggs 2017-08-23 10:13 ` Richard Guy Briggs 2017-08-24 16:29 ` Serge E. Hallyn 2017-08-24 16:29 ` Serge E. Hallyn 2017-08-24 16:44 ` Richard Guy Briggs 2017-08-24 16:44 ` Richard Guy Briggs 2017-08-24 16:47 ` Serge E. Hallyn 2017-08-24 16:47 ` Serge E. Hallyn 2017-08-25 5:48 ` James Morris 2017-08-25 5:48 ` James Morris 2017-08-23 10:13 ` Richard Guy Briggs [this message] 2017-08-23 10:13 ` [PATCH V3 10/10] capabilities: audit log other surprising conditions Richard Guy Briggs 2017-08-24 16:35 ` Serge E. Hallyn 2017-08-24 16:35 ` Serge E. Hallyn 2017-08-25 5:50 ` James Morris 2017-08-25 5:50 ` James Morris
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