This patch adds a new security attribute to Smack called

SMACK64EXEC. It defines label that is used while task is
running.

Exception: in smack_task_wait() child task is checked
for write access to parent task using label inherited
from the task that forked it.

Fixed issues from previous submit:
- SMACK64EXEC was not read when SMACK64 was not set.
- inode security blob was not updated after setting
  SMACK64EXEC
- inode security blob was not updated when removing
  SMACK64EXEC

include/linux/xattr.h

@@ -40,9 +40,11 @@
 #define XATTR_SMACK_SUFFIX "SMACK64"
 #define XATTR_SMACK_IPIN "SMACK64IPIN"
 #define XATTR_SMACK_IPOUT "SMACK64IPOUT"
+#define XATTR_SMACK_EXEC "SMACK64EXEC"
 #define XATTR_NAME_SMACK XATTR_SECURITY_PREFIX XATTR_SMACK_SUFFIX
 #define XATTR_NAME_SMACKIPIN	XATTR_SECURITY_PREFIX XATTR_SMACK_IPIN
 #define XATTR_NAME_SMACKIPOUT	XATTR_SECURITY_PREFIX XATTR_SMACK_IPOUT
+#define XATTR_NAME_SMACKEXEC	XATTR_SECURITY_PREFIX XATTR_SMACK_EXEC
 
 #define XATTR_CAPS_SUFFIX "capability"
 #define XATTR_NAME_CAPS XATTR_SECURITY_PREFIX XATTR_CAPS_SUFFIX

security/smack/smack.h

@@ -51,10 +51,16 @@ struct socket_smack {
  */
 struct inode_smack {
 	char		*smk_inode;	/* label of the fso */
+	char		*smk_task;	/* label of the task */
 	struct mutex	smk_lock;	/* initialization lock */
 	int		smk_flags;	/* smack inode flags */
 };
 
+struct task_smack {
+	char		*smk_task;	/* label used for access control */
+	char		*smk_forked;	/* label when forked */
+};
+
 #define	SMK_INODE_INSTANT	0x01	/* inode is instantiated */
 
 /*
@@ -242,6 +248,30 @@ static inline char *smk_of_inode(const struct inode *isp)
 	return sip->smk_inode;
 }
 
+/*
+ * Present a pointer to the smack label in an task blob.
+ */
+static inline char *smk_of_task(const struct task_smack *tsp)
+{
+	return tsp->smk_task;
+}
+
+/*
+ * Present a pointer to the forked smack label in an task blob.
+ */
+static inline char *smk_of_forked(const struct task_smack *tsp)
+{
+	return tsp->smk_forked;
+}
+
+/*
+ * Present a pointer to the smack label in the curren task blob.
+ */
+static inline char *smk_of_current(void)
+{
+	return smk_of_task(current_security());
+}
+
 /*
  * logging functions
  */

security/smack/smack_access.c

@@ -185,7 +185,7 @@ int smk_access(char *subject_label, char *object_label, int request,
 int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
 {
 	int rc;
-	char *sp = current_security();
+	char *sp = smk_of_current();
 
 	rc = smk_access(sp, obj_label, mode, NULL);
 	if (rc == 0)
@@ -196,7 +196,7 @@ int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
 	 * only one that gets privilege and current does not
 	 * have that label.
 	 */
-	if (smack_onlycap != NULL && smack_onlycap != current->cred->security)
+	if (smack_onlycap != NULL && smack_onlycap != sp)
 		goto out_audit;
 
 	if (capable(CAP_MAC_OVERRIDE))

security/smack/smack_lsm.c

@@ -43,7 +43,7 @@
  * Returns a pointer to the master list entry for the Smack label
  * or NULL if there was no label to fetch.
  */
-static char *smk_fetch(struct inode *ip, struct dentry *dp)
+static char *smk_fetch(const char *name, struct inode *ip, struct dentry *dp)
 {
 	int rc;
 	char in[SMK_LABELLEN];
@@ -51,7 +51,7 @@ static char *smk_fetch(struct inode *ip, struct dentry *dp)
 	if (ip->i_op->getxattr == NULL)
 		return NULL;
 
-	rc = ip->i_op->getxattr(dp, XATTR_NAME_SMACK, in, SMK_LABELLEN);
+	rc = ip->i_op->getxattr(dp, name, in, SMK_LABELLEN);
 	if (rc < 0)
 		return NULL;
 
@@ -103,8 +103,8 @@ static int smack_ptrace_access_check(struct task_struct *ctp, unsigned int mode)
 	if (rc != 0)
 		return rc;
 
-	sp = current_security();
-	tsp = task_security(ctp);
+	sp = smk_of_current();
+	tsp = smk_of_task(task_security(ctp));
 	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
 	smk_ad_setfield_u_tsk(&ad, ctp);
 
@@ -138,8 +138,8 @@ static int smack_ptrace_traceme(struct task_struct *ptp)
 	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
 	smk_ad_setfield_u_tsk(&ad, ptp);
 
-	sp = current_security();
-	tsp = task_security(ptp);
+	sp = smk_of_current();
+	tsp = smk_of_task(task_security(ptp));
 	/* we won't log here, because rc can be overriden */
 	rc = smk_access(tsp, sp, MAY_READWRITE, NULL);
 	if (rc != 0 && has_capability(ptp, CAP_MAC_OVERRIDE))
@@ -160,7 +160,7 @@ static int smack_ptrace_traceme(struct task_struct *ptp)
 static int smack_syslog(int typefrom_file)
 {
 	int rc = 0;
-	char *sp = current_security();
+	char *sp = smk_of_current();
 
 	if (capable(CAP_MAC_OVERRIDE))
 		return 0;
@@ -390,6 +390,40 @@ static int smack_sb_umount(struct vfsmount *mnt, int flags)
 	return smk_curacc(sbp->smk_floor, MAY_WRITE, &ad);
 }
 
+/*
+ * BPRM hooks
+ */
+
+static int smack_bprm_set_creds(struct linux_binprm *bprm)
+{
+	struct task_smack *tsp = bprm->cred->security;
+	struct inode_smack *isp;
+	struct dentry *dp;
+	int rc;
+
+	rc = cap_bprm_set_creds(bprm);
+	if (rc != 0)
+		return rc;
+
+	if (bprm->cred_prepared)
+		return 0;
+
+	if (bprm->file == NULL || bprm->file->f_dentry == NULL)
+		return 0;
+
+	dp = bprm->file->f_dentry;
+
+	if (dp->d_inode == NULL)
+		return 0;
+
+	isp = dp->d_inode->i_security;
+
+	if (isp->smk_task != NULL)
+		tsp->smk_task = isp->smk_task;
+
+	return 0;
+}
+
 /*
  * Inode hooks
  */
@@ -402,7 +436,7 @@ static int smack_sb_umount(struct vfsmount *mnt, int flags)
  */
 static int smack_inode_alloc_security(struct inode *inode)
 {
-	inode->i_security = new_inode_smack(current_security());
+	inode->i_security = new_inode_smack(smk_of_current());
 	if (inode->i_security == NULL)
 		return -ENOMEM;
 	return 0;
@@ -664,7 +698,8 @@ static int smack_inode_setxattr(struct dentry *dentry, const char *name,
 
 	if (strcmp(name, XATTR_NAME_SMACK) == 0 ||
 	    strcmp(name, XATTR_NAME_SMACKIPIN) == 0 ||
-	    strcmp(name, XATTR_NAME_SMACKIPOUT) == 0) {
+	    strcmp(name, XATTR_NAME_SMACKIPOUT) == 0 ||
+	    strcmp(name, XATTR_NAME_SMACKEXEC) == 0) {
 		if (!capable(CAP_MAC_ADMIN))
 			rc = -EPERM;
 		/*
@@ -704,9 +739,10 @@ static void smack_inode_post_setxattr(struct dentry *dentry, const char *name,
 	char *nsp;
 
 	/*
-	 * Not SMACK
+	 * Not SMACK or SMACKEXEC
 	 */
-	if (strcmp(name, XATTR_NAME_SMACK))
+	if (strcmp(name, XATTR_NAME_SMACK) &&
+	    strcmp(name, XATTR_NAME_SMACKEXEC))
 		return;
 
 	isp = dentry->d_inode->i_security;
@@ -716,10 +752,18 @@ static void smack_inode_post_setxattr(struct dentry *dentry, const char *name,
 	 * assignment.
 	 */
 	nsp = smk_import(value, size);
+
+	if (strcmp(name, XATTR_NAME_SMACK) == 0) {
 		if (nsp != NULL)
 			isp->smk_inode = nsp;
 		else
 			isp->smk_inode = smack_known_invalid.smk_known;
+	} else {
+		if (nsp != NULL)
+			isp->smk_task = nsp;
+		else
+			isp->smk_task = smack_known_invalid.smk_known;
+	}
 
 	return;
 }
@@ -752,12 +796,14 @@ static int smack_inode_getxattr(struct dentry *dentry, const char *name)
  */
 static int smack_inode_removexattr(struct dentry *dentry, const char *name)
 {
+	struct inode_smack *isp;
 	struct smk_audit_info ad;
 	int rc = 0;
 
 	if (strcmp(name, XATTR_NAME_SMACK) == 0 ||
 	    strcmp(name, XATTR_NAME_SMACKIPIN) == 0 ||
-	    strcmp(name, XATTR_NAME_SMACKIPOUT) == 0) {
+	    strcmp(name, XATTR_NAME_SMACKIPOUT) == 0 ||
+	    strcmp(name, XATTR_NAME_SMACKEXEC) == 0) {
 		if (!capable(CAP_MAC_ADMIN))
 			rc = -EPERM;
 	} else
@@ -768,6 +814,11 @@ static int smack_inode_removexattr(struct dentry *dentry, const char *name)
 	if (rc == 0)
 		rc = smk_curacc(smk_of_inode(dentry->d_inode), MAY_WRITE, &ad);
 
+	if (rc == 0) {
+		isp = dentry->d_inode->i_security;
+		isp->smk_task = NULL;
+	}
+
 	return rc;
 }
 
@@ -895,7 +946,7 @@ static int smack_file_permission(struct file *file, int mask)
  */
 static int smack_file_alloc_security(struct file *file)
 {
-	file->f_security = current_security();
+	file->f_security = smk_of_current();
 	return 0;
 }
 
@@ -1005,7 +1056,7 @@ static int smack_file_fcntl(struct file *file, unsigned int cmd,
  */
 static int smack_file_set_fowner(struct file *file)
 {
-	file->f_security = current_security();
+	file->f_security = smk_of_current();
 	return 0;
 }
 
@@ -1025,7 +1076,7 @@ static int smack_file_send_sigiotask(struct task_struct *tsk,
 {
 	struct file *file;
 	int rc;
-	char *tsp = tsk->cred->security;
+	char *tsp = smk_of_task(tsk->cred->security);
 	struct smk_audit_info ad;
 
 	/*
@@ -1082,7 +1133,9 @@ static int smack_file_receive(struct file *file)
  */
 static int smack_cred_alloc_blank(struct cred *cred, gfp_t gfp)
 {
-	cred->security = NULL;
+	cred->security = kzalloc(sizeof(struct task_smack), gfp);
+	if (cred->security == NULL)
+		return -ENOMEM;
 	return 0;
 }
 
@@ -1097,7 +1150,7 @@ static int smack_cred_alloc_blank(struct cred *cred, gfp_t gfp)
  */
 static void smack_cred_free(struct cred *cred)
 {
-	cred->security = NULL;
+	kfree(cred->security);
 }
 
 /**
@@ -1111,7 +1164,16 @@ static void smack_cred_free(struct cred *cred)
 static int smack_cred_prepare(struct cred *new, const struct cred *old,
 			      gfp_t gfp)
 {
-	new->security = old->security;
+	struct task_smack *old_tsp = old->security;
+	struct task_smack *new_tsp;
+
+	new_tsp = kzalloc(sizeof(struct task_smack), gfp);
+	if (new_tsp == NULL)
+		return -ENOMEM;
+
+	new_tsp->smk_task = old_tsp->smk_task;
+	new_tsp->smk_forked = old_tsp->smk_task;
+	new->security = new_tsp;
 	return 0;
 }
 
@@ -1124,7 +1186,11 @@ static int smack_cred_prepare(struct cred *new, const struct cred *old,
  */
 static void smack_cred_transfer(struct cred *new, const struct cred *old)
 {
-	new->security = old->security;
+	struct task_smack *old_tsp = old->security;
+	struct task_smack *new_tsp = new->security;
+
+	new_tsp->smk_task = old_tsp->smk_task;
+	new_tsp->smk_forked = old_tsp->smk_task;
 }
 
 /**
@@ -1136,12 +1202,13 @@ static void smack_cred_transfer(struct cred *new, const struct cred *old)
  */
 static int smack_kernel_act_as(struct cred *new, u32 secid)
 {
+	struct task_smack *new_tsp = new->security;
 	char *smack = smack_from_secid(secid);
 
 	if (smack == NULL)
 		return -EINVAL;
 
-	new->security = smack;
+	new_tsp->smk_task = smack;
 	return 0;
 }
 
@@ -1157,8 +1224,10 @@ static int smack_kernel_create_files_as(struct cred *new,
 					struct inode *inode)
 {
 	struct inode_smack *isp = inode->i_security;
+	struct task_smack *tsp = new->security;
 
-	new->security = isp->smk_inode;
+	tsp->smk_forked = isp->smk_inode;
+	tsp->smk_task = isp->smk_inode;
 	return 0;
 }
 
@@ -1175,7 +1244,7 @@ static int smk_curacc_on_task(struct task_struct *p, int access)
 
 	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
 	smk_ad_setfield_u_tsk(&ad, p);
-	return smk_curacc(task_security(p), access, &ad);
+	return smk_curacc(smk_of_task(task_security(p)), access, &ad);
 }
 
 /**
@@ -1221,7 +1290,7 @@ static int smack_task_getsid(struct task_struct *p)
  */
 static void smack_task_getsecid(struct task_struct *p, u32 *secid)
 {
-	*secid = smack_to_secid(task_security(p));
+	*secid = smack_to_secid(smk_of_task(task_security(p)));
 }
 
 /**
@@ -1333,14 +1402,15 @@ static int smack_task_kill(struct task_struct *p, struct siginfo *info,
 	 * can write the receiver.
 	 */
 	if (secid == 0)
-		return smk_curacc(task_security(p), MAY_WRITE, &ad);
+		return smk_curacc(smk_of_task(task_security(p)), MAY_WRITE,
+				  &ad);
 	/*
 	 * If the secid isn't 0 we're dealing with some USB IO
 	 * specific behavior. This is not clean. For one thing
 	 * we can't take privilege into account.
 	 */
-	return smk_access(smack_from_secid(secid), task_security(p),
-			  MAY_WRITE, &ad);
+	return smk_access(smack_from_secid(secid),
+			  smk_of_task(task_security(p)), MAY_WRITE, &ad);
 }
 
 /**
@@ -1352,12 +1422,12 @@ static int smack_task_kill(struct task_struct *p, struct siginfo *info,
 static int smack_task_wait(struct task_struct *p)
 {
 	struct smk_audit_info ad;
-	char *sp = current_security();
-	char *tsp = task_security(p);
+	char *sp = smk_of_current();
+	char *tsp = smk_of_forked(task_security(p));
 	int rc;
 
 	/* we don't log here, we can be overriden */
-	rc = smk_access(sp, tsp, MAY_WRITE, NULL);
+	rc = smk_access(tsp, sp, MAY_WRITE, NULL);
 	if (rc == 0)
 		goto out_log;
 
@@ -1378,7 +1448,7 @@ static int smack_task_wait(struct task_struct *p)
  out_log:
 	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
 	smk_ad_setfield_u_tsk(&ad, p);
-	smack_log(sp, tsp, MAY_WRITE, rc, &ad);
+	smack_log(tsp, sp, MAY_WRITE, rc, &ad);
 	return rc;
 }
 
@@ -1392,7 +1462,7 @@ static int smack_task_wait(struct task_struct *p)
 static void smack_task_to_inode(struct task_struct *p, struct inode *inode)
 {
 	struct inode_smack *isp = inode->i_security;
-	isp->smk_inode = task_security(p);
+	isp->smk_inode = smk_of_task(task_security(p));
 }
 
 /*
@@ -1411,7 +1481,7 @@ static void smack_task_to_inode(struct task_struct *p, struct inode *inode)
  */
 static int smack_sk_alloc_security(struct sock *sk, int family, gfp_t gfp_flags)
 {
-	char *csp = current_security();
+	char *csp = smk_of_current();
 	struct socket_smack *ssp;
 
 	ssp = kzalloc(sizeof(struct socket_smack), gfp_flags);
@@ -1752,7 +1822,7 @@ static int smack_flags_to_may(int flags)
  */
 static int smack_msg_msg_alloc_security(struct msg_msg *msg)
 {
-	msg->security = current_security();
+	msg->security = smk_of_current();
 	return 0;
 }
 
@@ -1788,7 +1858,7 @@ static int smack_shm_alloc_security(struct shmid_kernel *shp)
 {
 	struct kern_ipc_perm *isp = &shp->shm_perm;
 
-	isp->security = current_security();
+	isp->security = smk_of_current();
 	return 0;
 }
 
@@ -1911,7 +1981,7 @@ static int smack_sem_alloc_security(struct sem_array *sma)
 {
 	struct kern_ipc_perm *isp = &sma->sem_perm;
 
-	isp->security = current_security();
+	isp->security = smk_of_current();
 	return 0;
 }
 
@@ -2029,7 +2099,7 @@ static int smack_msg_queue_alloc_security(struct msg_queue *msq)
 {
 	struct kern_ipc_perm *kisp = &msq->q_perm;
 
-	kisp->security = current_security();
+	kisp->security = smk_of_current();
 	return 0;
 }
 
@@ -2201,7 +2271,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
 	struct super_block *sbp;
 	struct superblock_smack *sbsp;
 	struct inode_smack *isp;
-	char *csp = current_security();
+	char *csp = smk_of_current();
 	char *fetched;
 	char *final;
 	struct dentry *dp;
@@ -2321,9 +2391,12 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
 		 * Get the dentry for xattr.
 		 */
 		dp = dget(opt_dentry);
-		fetched = smk_fetch(inode, dp);
+		fetched = smk_fetch(XATTR_NAME_SMACK, inode, dp);
 		if (fetched != NULL)
 			final = fetched;
+		isp->smk_task = smk_fetch(XATTR_NAME_SMACKEXEC, inode,
+					  dp);
+
 		dput(dp);
 		break;
 	}
@@ -2358,7 +2431,7 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value)
 	if (strcmp(name, "current") != 0)
 		return -EINVAL;
 
-	cp = kstrdup(task_security(p), GFP_KERNEL);
+	cp = kstrdup(smk_of_task(task_security(p)), GFP_KERNEL);
 	if (cp == NULL)
 		return -ENOMEM;
 
@@ -2382,6 +2455,7 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value)
 static int smack_setprocattr(struct task_struct *p, char *name,
 			     void *value, size_t size)
 {
+	struct task_smack *tsp;
 	struct cred *new;
 	char *newsmack;
 
@@ -2414,7 +2488,13 @@ static int smack_setprocattr(struct task_struct *p, char *name,
 	new = prepare_creds();
 	if (new == NULL)
 		return -ENOMEM;
-	new->security = newsmack;
+	tsp = kzalloc(sizeof(struct task_smack), GFP_KERNEL);
+	if (tsp == NULL) {
+		kfree(new);
+		return -ENOMEM;
+	}
+	tsp->smk_task = newsmack;
+	new->security = tsp;
 	commit_creds(new);
 	return size;
 }
@@ -2715,7 +2795,7 @@ static void smack_sock_graft(struct sock *sk, struct socket *parent)
 		return;
 
 	ssp = sk->sk_security;
-	ssp->smk_in = ssp->smk_out = current_security();
+	ssp->smk_in = ssp->smk_out = smk_of_current();
 	/* cssp->smk_packet is already set in smack_inet_csk_clone() */
 }
 
@@ -2836,7 +2916,7 @@ static void smack_inet_csk_clone(struct sock *sk,
 static int smack_key_alloc(struct key *key, const struct cred *cred,
 			   unsigned long flags)
 {
-	key->security = cred->security;
+	key->security = smk_of_task(cred->security);
 	return 0;
 }
 
@@ -2865,6 +2945,7 @@ static int smack_key_permission(key_ref_t key_ref,
 {
 	struct key *keyp;
 	struct smk_audit_info ad;
+	char *tsp = smk_of_task(cred->security);
 
 	keyp = key_ref_to_ptr(key_ref);
 	if (keyp == NULL)
@@ -2878,14 +2959,14 @@ static int smack_key_permission(key_ref_t key_ref,
 	/*
 	 * This should not occur
 	 */
-	if (cred->security == NULL)
+	if (tsp == NULL)
 		return -EACCES;
 #ifdef CONFIG_AUDIT
 	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_KEY);
 	ad.a.u.key_struct.key = keyp->serial;
 	ad.a.u.key_struct.key_desc = keyp->description;
 #endif
-	return smk_access(cred->security, keyp->security,
+	return smk_access(tsp, keyp->security,
 				 MAY_READWRITE, &ad);
 }
 #endif /* CONFIG_KEYS */
@@ -3087,6 +3168,8 @@ struct security_operations smack_ops = {
 	.sb_mount = 			smack_sb_mount,
 	.sb_umount = 			smack_sb_umount,
 
+	.bprm_set_creds =		smack_bprm_set_creds,
+
 	.inode_alloc_security = 	smack_inode_alloc_security,
 	.inode_free_security = 		smack_inode_free_security,
 	.inode_init_security = 		smack_inode_init_security,
@@ -3223,9 +3306,16 @@ static __init void init_smack_know_list(void)
 static __init int smack_init(void)
 {
 	struct cred *cred;
+	struct task_smack *tsp;
 
-	if (!security_module_enable(&smack_ops))
+	tsp = kzalloc(sizeof(struct task_smack), GFP_KERNEL);
+	if (tsp == NULL)
+		return -ENOMEM;
+
+	if (!security_module_enable(&smack_ops)) {
+		kfree(tsp);
 		return 0;
+	}
 
 	printk(KERN_INFO "Smack:  Initializing.\n");
 
@@ -3233,7 +3323,9 @@ static __init int smack_init(void)
 	 * Set the security state for the initial task.
 	 */
 	cred = (struct cred *) current->cred;
-	cred->security = &smack_known_floor.smk_known;
+	tsp->smk_forked = smack_known_floor.smk_known;
+	tsp->smk_task = smack_known_floor.smk_known;
+	cred->security = tsp;
 
 	/* initialize the smack_know_list */
 	init_smack_know_list();

security/smack/smackfs.c

@@ -121,7 +121,7 @@ static void smk_netlabel_audit_set(struct netlbl_audit *nap)
 {
 	nap->loginuid = audit_get_loginuid(current);
 	nap->sessionid = audit_get_sessionid(current);
-	nap->secid = smack_to_secid(current_security());
+	nap->secid = smack_to_secid(smk_of_current());
 }
 
 /*
@@ -1160,7 +1160,7 @@ static ssize_t smk_write_onlycap(struct file *file, const char __user *buf,
 				 size_t count, loff_t *ppos)
 {
 	char in[SMK_LABELLEN];
-	char *sp = current->cred->security;
+	char *sp = smk_of_task(current->cred->security);
 
 	if (!capable(CAP_MAC_ADMIN))
 		return -EPERM;