LSM: generalize flag passing to security_capable

This patch provides a general mechanism for passing flags to the
security_capable LSM hook. It replaces the specific 'audit' flag that is
used to tell security_capable whether it should log an audit message for
the given capability check. The reason for generalizing this flag
passing is so we can add an additional flag that signifies whether
security_capable is being called by a setid syscall (which is needed by
the proposed SafeSetID LSM).

Signed-off-by: Micah Morton <mortonm@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.morris@microsoft.com>

9 files changed, 37 insertions, 39 deletions

diff --git a/security/apparmor/capability.c b/security/apparmor/capability.c
index 253ef6e9d445..752f73980e30 100644
--- a/security/apparmor/capability.c
+++ b/security/apparmor/capability.c
@@ -110,13 +110,13 @@ static int audit_caps(struct common_audit_data *sa, struct aa_profile *profile,
  * profile_capable - test if profile allows use of capability @cap
  * @profile: profile being enforced    (NOT NULL, NOT unconfined)
  * @cap: capability to test if allowed
- * @audit: whether an audit record should be generated
+ * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated
  * @sa: audit data (MAY BE NULL indicating no auditing)
  *
  * Returns: 0 if allowed else -EPERM
  */
-static int profile_capable(struct aa_profile *profile, int cap, int audit,
-			   struct common_audit_data *sa)
+static int profile_capable(struct aa_profile *profile, int cap,
+			   unsigned int opts, struct common_audit_data *sa)
 {
 	int error;
 
@@ -126,7 +126,7 @@ static int profile_capable(struct aa_profile *profile, int cap, int audit,
 	else
 		error = -EPERM;
 
-	if (audit == SECURITY_CAP_NOAUDIT) {
+	if (opts & CAP_OPT_NOAUDIT) {
 		if (!COMPLAIN_MODE(profile))
 			return error;
 		/* audit the cap request in complain mode but note that it
@@ -142,13 +142,13 @@ static int profile_capable(struct aa_profile *profile, int cap, int audit,
  * aa_capable - test permission to use capability
  * @label: label being tested for capability (NOT NULL)
  * @cap: capability to be tested
- * @audit: whether an audit record should be generated
+ * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated
  *
  * Look up capability in profile capability set.
  *
  * Returns: 0 on success, or else an error code.
  */
-int aa_capable(struct aa_label *label, int cap, int audit)
+int aa_capable(struct aa_label *label, int cap, unsigned int opts)
 {
 	struct aa_profile *profile;
 	int error = 0;
@@ -156,7 +156,7 @@ int aa_capable(struct aa_label *label, int cap, int audit)
 
 	sa.u.cap = cap;
 	error = fn_for_each_confined(label, profile,
-			profile_capable(profile, cap, audit, &sa));
+			profile_capable(profile, cap, opts, &sa));
 
 	return error;
 }
diff --git a/security/apparmor/include/capability.h b/security/apparmor/include/capability.h
index e0304e2aeb7f..1b3663b6ab12 100644
--- a/security/apparmor/include/capability.h
+++ b/security/apparmor/include/capability.h
@@ -40,7 +40,7 @@ struct aa_caps {
 
 extern struct aa_sfs_entry aa_sfs_entry_caps[];
 
-int aa_capable(struct aa_label *label, int cap, int audit);
+int aa_capable(struct aa_label *label, int cap, unsigned int opts);
 
 static inline void aa_free_cap_rules(struct aa_caps *caps)
 {
diff --git a/security/apparmor/ipc.c b/security/apparmor/ipc.c
index 527ea1557120..aacd1e95cb59 100644
--- a/security/apparmor/ipc.c
+++ b/security/apparmor/ipc.c
@@ -107,7 +107,8 @@ static int profile_tracer_perm(struct aa_profile *tracer,
 	aad(sa)->label = &tracer->label;
 	aad(sa)->peer = tracee;
 	aad(sa)->request = 0;
-	aad(sa)->error = aa_capable(&tracer->label, CAP_SYS_PTRACE, 1);
+	aad(sa)->error = aa_capable(&tracer->label, CAP_SYS_PTRACE,
+				    CAP_OPT_NONE);
 
 	return aa_audit(AUDIT_APPARMOR_AUTO, tracer, sa, audit_ptrace_cb);
 }
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 60ef71268ccf..b6c395e2acd0 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -172,14 +172,14 @@ static int apparmor_capget(struct task_struct *target, kernel_cap_t *effective,
 }
 
 static int apparmor_capable(const struct cred *cred, struct user_namespace *ns,
-			    int cap, int audit)
+			    int cap, unsigned int opts)
 {
 	struct aa_label *label;
 	int error = 0;
 
 	label = aa_get_newest_cred_label(cred);
 	if (!unconfined(label))
-		error = aa_capable(label, cap, audit);
+		error = aa_capable(label, cap, opts);
 	aa_put_label(label);
 
 	return error;
diff --git a/security/apparmor/resource.c b/security/apparmor/resource.c
index 95fd26d09757..552ed09cb47e 100644
--- a/security/apparmor/resource.c
+++ b/security/apparmor/resource.c
@@ -124,7 +124,7 @@ int aa_task_setrlimit(struct aa_label *label, struct task_struct *task,
 	 */
 
 	if (label != peer &&
-	    aa_capable(label, CAP_SYS_RESOURCE, SECURITY_CAP_NOAUDIT) != 0)
+	    aa_capable(label, CAP_SYS_RESOURCE, CAP_OPT_NOAUDIT) != 0)
 		error = fn_for_each(label, profile,
 				audit_resource(profile, resource,
 					       new_rlim->rlim_max, peer,
diff --git a/security/commoncap.c b/security/commoncap.c
index 52e04136bfa8..188eaf59f82f 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -68,7 +68,7 @@ static void warn_setuid_and_fcaps_mixed(const char *fname)
  * kernel's capable() and has_capability() returns 1 for this case.
  */
 int cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
-		int cap, int audit)
+		int cap, unsigned int opts)
 {
 	struct user_namespace *ns = targ_ns;
 
@@ -222,12 +222,11 @@ int cap_capget(struct task_struct *target, kernel_cap_t *effective,
  */
 static inline int cap_inh_is_capped(void)
 {
-
 	/* they are so limited unless the current task has the CAP_SETPCAP
 	 * capability
 	 */
 	if (cap_capable(current_cred(), current_cred()->user_ns,
-			CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0)
+			CAP_SETPCAP, CAP_OPT_NONE) == 0)
 		return 0;
 	return 1;
 }
@@ -1208,8 +1207,9 @@ int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
 		    || ((old->securebits & SECURE_ALL_LOCKS & ~arg2))	/*[2]*/
 		    || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS))	/*[3]*/
 		    || (cap_capable(current_cred(),
-				    current_cred()->user_ns, CAP_SETPCAP,
-				    SECURITY_CAP_AUDIT) != 0)		/*[4]*/
+				    current_cred()->user_ns,
+				    CAP_SETPCAP,
+				    CAP_OPT_NONE) != 0)			/*[4]*/
 			/*
 			 * [1] no changing of bits that are locked
 			 * [2] no unlocking of locks
@@ -1304,9 +1304,10 @@ int cap_vm_enough_memory(struct mm_struct *mm, long pages)
 {
 	int cap_sys_admin = 0;
 
-	if (cap_capable(current_cred(), &init_user_ns, CAP_SYS_ADMIN,
-			SECURITY_CAP_NOAUDIT) == 0)
+	if (cap_capable(current_cred(), &init_user_ns,
+				CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) == 0)
 		cap_sys_admin = 1;
+
 	return cap_sys_admin;
 }
 
@@ -1325,7 +1326,7 @@ int cap_mmap_addr(unsigned long addr)
 
 	if (addr < dac_mmap_min_addr) {
 		ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO,
-				  SECURITY_CAP_AUDIT);
+				  CAP_OPT_NONE);
 		/* set PF_SUPERPRIV if it turns out we allow the low mmap */
 		if (ret == 0)
 			current->flags |= PF_SUPERPRIV;
diff --git a/security/security.c b/security/security.c
index 953fc3ea18a9..a618e22df5c6 100644
--- a/security/security.c
+++ b/security/security.c
@@ -689,16 +689,12 @@ int security_capset(struct cred *new, const struct cred *old,
 				effective, inheritable, permitted);
 }
 
-int security_capable(const struct cred *cred, struct user_namespace *ns,
-		     int cap)
+int security_capable(const struct cred *cred,
+		     struct user_namespace *ns,
+		     int cap,
+		     unsigned int opts)
 {
-	return call_int_hook(capable, 0, cred, ns, cap, SECURITY_CAP_AUDIT);
-}
-
-int security_capable_noaudit(const struct cred *cred, struct user_namespace *ns,
-			     int cap)
-{
-	return call_int_hook(capable, 0, cred, ns, cap, SECURITY_CAP_NOAUDIT);
+	return call_int_hook(capable, 0, cred, ns, cap, opts);
 }
 
 int security_quotactl(int cmds, int type, int id, struct super_block *sb)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index d98e1d8d18f6..b2ee49f938f1 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1578,7 +1578,7 @@ static inline u32 signal_to_av(int sig)
 
 /* Check whether a task is allowed to use a capability. */
 static int cred_has_capability(const struct cred *cred,
-			       int cap, int audit, bool initns)
+			       int cap, unsigned int opts, bool initns)
 {
 	struct common_audit_data ad;
 	struct av_decision avd;
@@ -1605,7 +1605,7 @@ static int cred_has_capability(const struct cred *cred,
 
 	rc = avc_has_perm_noaudit(&selinux_state,
 				  sid, sid, sclass, av, 0, &avd);
-	if (audit == SECURITY_CAP_AUDIT) {
+	if (!(opts & CAP_OPT_NOAUDIT)) {
 		int rc2 = avc_audit(&selinux_state,
 				    sid, sid, sclass, av, &avd, rc, &ad, 0);
 		if (rc2)
@@ -2125,9 +2125,9 @@ static int selinux_capset(struct cred *new, const struct cred *old,
  */
 
 static int selinux_capable(const struct cred *cred, struct user_namespace *ns,
-			   int cap, int audit)
+			   int cap, unsigned int opts)
 {
-	return cred_has_capability(cred, cap, audit, ns == &init_user_ns);
+	return cred_has_capability(cred, cap, opts, ns == &init_user_ns);
 }
 
 static int selinux_quotactl(int cmds, int type, int id, struct super_block *sb)
@@ -2201,7 +2201,7 @@ static int selinux_vm_enough_memory(struct mm_struct *mm, long pages)
 	int rc, cap_sys_admin = 0;
 
 	rc = cred_has_capability(current_cred(), CAP_SYS_ADMIN,
-				 SECURITY_CAP_NOAUDIT, true);
+				 CAP_OPT_NOAUDIT, true);
 	if (rc == 0)
 		cap_sys_admin = 1;
 
@@ -2988,11 +2988,11 @@ static int selinux_inode_getattr(const struct path *path)
 static bool has_cap_mac_admin(bool audit)
 {
 	const struct cred *cred = current_cred();
-	int cap_audit = audit ? SECURITY_CAP_AUDIT : SECURITY_CAP_NOAUDIT;
+	unsigned int opts = audit ? CAP_OPT_NONE : CAP_OPT_NOAUDIT;
 
-	if (cap_capable(cred, &init_user_ns, CAP_MAC_ADMIN, cap_audit))
+	if (cap_capable(cred, &init_user_ns, CAP_MAC_ADMIN, opts))
 		return false;
-	if (cred_has_capability(cred, CAP_MAC_ADMIN, cap_audit, true))
+	if (cred_has_capability(cred, CAP_MAC_ADMIN, opts, true))
 		return false;
 	return true;
 }
@@ -3387,7 +3387,7 @@ static int selinux_file_ioctl(struct file *file, unsigned int cmd,
 	case KDSKBENT:
 	case KDSKBSENT:
 		error = cred_has_capability(cred, CAP_SYS_TTY_CONFIG,
-					    SECURITY_CAP_AUDIT, true);
+					    CAP_OPT_NONE, true);
 		break;
 
 	/* default case assumes that the command will go
diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
index 489d49a20b47..fe2ce3a65822 100644
--- a/security/smack/smack_access.c
+++ b/security/smack/smack_access.c
@@ -640,7 +640,7 @@ bool smack_privileged_cred(int cap, const struct cred *cred)
 	struct smack_known_list_elem *sklep;
 	int rc;
 
-	rc = cap_capable(cred, &init_user_ns, cap, SECURITY_CAP_AUDIT);
+	rc = cap_capable(cred, &init_user_ns, cap, CAP_OPT_NONE);
 	if (rc)
 		return false;