Author: stevek
Date: Sat Jul 14 17:21:16 2018
New Revision: 336289
URL: https://svnweb.freebsd.org/changeset/base/336289
Log:
Add mpo_vnode_check_setmode MAC method to MAC/veriexec.
In the method, disallow changing SUID/SGID on verified files.
Obtained from: Juniper Networks, Inc.
Modified:
head/sys/security/mac_veriexec/mac_veriexec.c
Modified: head/sys/security/mac_veriexec/mac_veriexec.c
==============================================================================
--- head/sys/security/mac_veriexec/mac_veriexec.c Sat Jul 14 17:20:27
2018 (r336288)
+++ head/sys/security/mac_veriexec/mac_veriexec.c Sat Jul 14 17:21:16
2018 (r336289)
@@ -550,6 +550,38 @@ mac_veriexec_vnode_check_open(struct ucred *cred, stru
}
/**
+ * @brief Check mode changes on file to ensure they should be allowed.
+ *
+ * We cannot allow chmod of SUID or SGID on verified files.
+ *
+ * @param cred credentials to use
+ * @param vp vnode of the file to open
+ * @param label vnode label assigned to the vnode
+ * @param mode mode flags to set
+ *
+ * @return 0 if the mode change should be allowed, EAUTH otherwise.
+ */
+static int
+mac_veriexec_vnode_check_setmode(struct ucred *cred, struct vnode *vp,
+ struct label *label __unused, mode_t mode)
+{
+ int error;
+
+ if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
+ return (0);
+
+ /*
+ * Do not allow chmod (set-[gu]id) of verified file
+ */
+ error = mac_veriexec_check_vp(cred, vp, VVERIFY);
+ if (error == EAUTH) /* it isn't verified */
+ return (0);
+ if (error == 0 && (mode & (S_ISUID|S_ISGID)) != 0)
+ return (EAUTH);
+ return (0);
+}
+
+/**
* @internal
* @brief Initialize the mac_veriexec MAC policy
*
@@ -673,6 +705,7 @@ static struct mac_policy_ops mac_veriexec_ops =
.mpo_proc_check_debug = mac_veriexec_proc_check_debug,
.mpo_vnode_check_exec = mac_veriexec_vnode_check_exec,
.mpo_vnode_check_open = mac_veriexec_vnode_check_open,
+ .mpo_vnode_check_setmode = mac_veriexec_vnode_check_setmode,
.mpo_vnode_copy_label = mac_veriexec_copy_label,
.mpo_vnode_destroy_label = mac_veriexec_vnode_destroy_label,
.mpo_vnode_init_label = mac_veriexec_vnode_init_label,
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