1 files changed, 195 insertions, 95 deletions

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index af986587841d..a0bd4919a9d9 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -963,6 +963,42 @@ static int smack_inode_alloc_security(struct inode *inode)
 }
 
 /**
+ * smk_rule_transmutes - does access rule for (subject,object) contain 't'?
+ * @subject: a pointer to the subject's Smack label entry
+ * @object: a pointer to the object's Smack label entry
+ */
+static bool
+smk_rule_transmutes(struct smack_known *subject,
+	      const struct smack_known *object)
+{
+	int may;
+
+	rcu_read_lock();
+	may = smk_access_entry(subject->smk_known, object->smk_known,
+			       &subject->smk_rules);
+	rcu_read_unlock();
+	return (may > 0) && (may & MAY_TRANSMUTE);
+}
+
+static int
+xattr_dupval(struct xattr *xattrs, int *xattr_count,
+	     const char *name, const void *value, unsigned int vallen)
+{
+	struct xattr * const xattr = lsm_get_xattr_slot(xattrs, xattr_count);
+
+	if (!xattr)
+		return 0;
+
+	xattr->value = kmemdup(value, vallen, GFP_NOFS);
+	if (!xattr->value)
+		return -ENOMEM;
+
+	xattr->value_len = vallen;
+	xattr->name = name;
+	return 0;
+}
+
+/**
  * smack_inode_init_security - copy out the smack from an inode
  * @inode: the newly created inode
  * @dir: containing directory object
@@ -977,23 +1013,30 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir,
 				     struct xattr *xattrs, int *xattr_count)
 {
 	struct task_smack *tsp = smack_cred(current_cred());
-	struct inode_smack *issp = smack_inode(inode);
-	struct smack_known *skp = smk_of_task(tsp);
-	struct smack_known *isp = smk_of_inode(inode);
+	struct inode_smack * const issp = smack_inode(inode);
 	struct smack_known *dsp = smk_of_inode(dir);
-	struct xattr *xattr = lsm_get_xattr_slot(xattrs, xattr_count);
-	int may;
+	int rc = 0;
+	int transflag = 0;
+	bool trans_cred;
+	bool trans_rule;
 
 	/*
+	 * UNIX domain sockets use lower level socket data. Let
+	 * UDS inode have fixed * label to keep smack_inode_permission() calm
+	 * when called from unix_find_bsd()
+	 */
+	if (S_ISSOCK(inode->i_mode)) {
+		/* forced label, no need to save to xattrs */
+		issp->smk_inode = &smack_known_star;
+		goto instant_inode;
+	}
+	/*
 	 * If equal, transmuting already occurred in
 	 * smack_dentry_create_files_as(). No need to check again.
 	 */
-	if (tsp->smk_task != tsp->smk_transmuted) {
-		rcu_read_lock();
-		may = smk_access_entry(skp->smk_known, dsp->smk_known,
-				       &skp->smk_rules);
-		rcu_read_unlock();
-	}
+	trans_cred = (tsp->smk_task == tsp->smk_transmuted);
+	if (!trans_cred)
+		trans_rule = smk_rule_transmutes(smk_of_task(tsp), dsp);
 
 	/*
 	 * In addition to having smk_task equal to smk_transmuted,
@@ -1001,47 +1044,38 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir,
 	 * requests transmutation then by all means transmute.
 	 * Mark the inode as changed.
 	 */
-	if ((tsp->smk_task == tsp->smk_transmuted) ||
-	    (may > 0 && ((may & MAY_TRANSMUTE) != 0) &&
-	     smk_inode_transmutable(dir))) {
-		struct xattr *xattr_transmute;
-
+	if (trans_cred || (trans_rule && smk_inode_transmutable(dir))) {
 		/*
 		 * The caller of smack_dentry_create_files_as()
 		 * should have overridden the current cred, so the
 		 * inode label was already set correctly in
 		 * smack_inode_alloc_security().
 		 */
-		if (tsp->smk_task != tsp->smk_transmuted)
-			isp = issp->smk_inode = dsp;
-
-		issp->smk_flags |= SMK_INODE_TRANSMUTE;
-		xattr_transmute = lsm_get_xattr_slot(xattrs,
-						     xattr_count);
-		if (xattr_transmute) {
-			xattr_transmute->value = kmemdup(TRANS_TRUE,
-							 TRANS_TRUE_SIZE,
-							 GFP_NOFS);
-			if (!xattr_transmute->value)
-				return -ENOMEM;
+		if (!trans_cred)
+			issp->smk_inode = dsp;
 
-			xattr_transmute->value_len = TRANS_TRUE_SIZE;
-			xattr_transmute->name = XATTR_SMACK_TRANSMUTE;
+		if (S_ISDIR(inode->i_mode)) {
+			transflag = SMK_INODE_TRANSMUTE;
+
+			if (xattr_dupval(xattrs, xattr_count,
+				XATTR_SMACK_TRANSMUTE,
+				TRANS_TRUE,
+				TRANS_TRUE_SIZE
+			))
+				rc = -ENOMEM;
 		}
 	}
 
-	issp->smk_flags |= SMK_INODE_INSTANT;
-
-	if (xattr) {
-		xattr->value = kstrdup(isp->smk_known, GFP_NOFS);
-		if (!xattr->value)
-			return -ENOMEM;
-
-		xattr->value_len = strlen(isp->smk_known);
-		xattr->name = XATTR_SMACK_SUFFIX;
-	}
-
-	return 0;
+	if (rc == 0)
+		if (xattr_dupval(xattrs, xattr_count,
+			    XATTR_SMACK_SUFFIX,
+			    issp->smk_inode->smk_known,
+		     strlen(issp->smk_inode->smk_known)
+		))
+			rc = -ENOMEM;
+instant_inode:
+	issp->smk_flags |= (SMK_INODE_INSTANT | transflag);
+	return rc;
 }
 
 /**
@@ -1315,13 +1349,23 @@ static int smack_inode_setxattr(struct mnt_idmap *idmap,
 	int check_import = 0;
 	int check_star = 0;
 	int rc = 0;
+	umode_t const i_mode = d_backing_inode(dentry)->i_mode;
 
 	/*
 	 * Check label validity here so import won't fail in post_setxattr
 	 */
-	if (strcmp(name, XATTR_NAME_SMACK) == 0 ||
-	    strcmp(name, XATTR_NAME_SMACKIPIN) == 0 ||
-	    strcmp(name, XATTR_NAME_SMACKIPOUT) == 0) {
+	if (strcmp(name, XATTR_NAME_SMACK) == 0) {
+		/*
+		 * UDS inode has fixed label
+		 */
+		if (S_ISSOCK(i_mode)) {
+			rc = -EINVAL;
+		} else {
+			check_priv = 1;
+			check_import = 1;
+		}
+	} else if (strcmp(name, XATTR_NAME_SMACKIPIN) == 0 ||
+		   strcmp(name, XATTR_NAME_SMACKIPOUT) == 0) {
 		check_priv = 1;
 		check_import = 1;
 	} else if (strcmp(name, XATTR_NAME_SMACKEXEC) == 0 ||
@@ -1331,7 +1375,7 @@ static int smack_inode_setxattr(struct mnt_idmap *idmap,
 		check_star = 1;
 	} else if (strcmp(name, XATTR_NAME_SMACKTRANSMUTE) == 0) {
 		check_priv = 1;
-		if (!S_ISDIR(d_backing_inode(dentry)->i_mode) ||
+		if (!S_ISDIR(i_mode) ||
 		    size != TRANS_TRUE_SIZE ||
 		    strncmp(value, TRANS_TRUE, TRANS_TRUE_SIZE) != 0)
 			rc = -EINVAL;
@@ -1462,12 +1506,15 @@ static int smack_inode_removexattr(struct mnt_idmap *idmap,
 	 * Don't do anything special for these.
 	 *	XATTR_NAME_SMACKIPIN
 	 *	XATTR_NAME_SMACKIPOUT
+	 *	XATTR_NAME_SMACK if S_ISSOCK (UDS inode has fixed label)
 	 */
 	if (strcmp(name, XATTR_NAME_SMACK) == 0) {
-		struct super_block *sbp = dentry->d_sb;
-		struct superblock_smack *sbsp = smack_superblock(sbp);
+		if (!S_ISSOCK(d_backing_inode(dentry)->i_mode)) {
+			struct super_block *sbp = dentry->d_sb;
+			struct superblock_smack *sbsp = smack_superblock(sbp);
 
-		isp->smk_inode = sbsp->smk_default;
+			isp->smk_inode = sbsp->smk_default;
+		}
 	} else if (strcmp(name, XATTR_NAME_SMACKEXEC) == 0)
 		isp->smk_task = NULL;
 	else if (strcmp(name, XATTR_NAME_SMACKMMAP) == 0)
@@ -3585,7 +3632,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
 		 */
 
 		/*
-		 * UNIX domain sockets use lower level socket data.
+		 * UDS inode has fixed label (*)
 		 */
 		if (S_ISSOCK(inode->i_mode)) {
 			final = &smack_known_star;
@@ -3663,7 +3710,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
  * @attr: which attribute to fetch
  * @ctx: buffer to receive the result
  * @size: available size in, actual size out
- * @flags: unused
+ * @flags: reserved, currently zero
  *
  * Fill the passed user space @ctx with the details of the requested
  * attribute.
@@ -3724,47 +3771,55 @@ static int smack_getprocattr(struct task_struct *p, const char *name, char **val
  * Sets the Smack value of the task. Only setting self
  * is permitted and only with privilege
  *
- * Returns the length of the smack label or an error code
+ * Returns zero on success or an error code
  */
-static int do_setattr(u64 attr, void *value, size_t size)
+static int do_setattr(unsigned int attr, void *value, size_t size)
 {
 	struct task_smack *tsp = smack_cred(current_cred());
 	struct cred *new;
 	struct smack_known *skp;
-	struct smack_known_list_elem *sklep;
-	int rc;
-
-	if (!smack_privileged(CAP_MAC_ADMIN) && list_empty(&tsp->smk_relabel))
-		return -EPERM;
+	int label_len;
 
+	/*
+	 * let unprivileged user validate input, check permissions later
+	 */
 	if (value == NULL || size == 0 || size >= SMK_LONGLABEL)
 		return -EINVAL;
 
-	if (attr != LSM_ATTR_CURRENT)
-		return -EOPNOTSUPP;
-
-	skp = smk_import_entry(value, size);
-	if (IS_ERR(skp))
-		return PTR_ERR(skp);
+	label_len = smk_parse_label_len(value, size);
+	if (label_len < 0 || label_len != size)
+		return -EINVAL;
 
 	/*
 	 * No process is ever allowed the web ("@") label
 	 * and the star ("*") label.
 	 */
-	if (skp == &smack_known_web || skp == &smack_known_star)
-		return -EINVAL;
+	if (label_len == 1 /* '@', '*' */) {
+		const char c = *(const char *)value;
+
+		if (c == *smack_known_web.smk_known ||
+		    c == *smack_known_star.smk_known)
+			return -EPERM;
+	}
 
 	if (!smack_privileged(CAP_MAC_ADMIN)) {
-		rc = -EPERM;
-		list_for_each_entry(sklep, &tsp->smk_relabel, list)
-			if (sklep->smk_label == skp) {
-				rc = 0;
-				break;
-			}
-		if (rc)
-			return rc;
+		const struct smack_known_list_elem *sklep;
+		list_for_each_entry(sklep, &tsp->smk_relabel, list) {
+			const char *cp = sklep->smk_label->smk_known;
+
+			if (strlen(cp) == label_len &&
+			    strncmp(cp, value, label_len) == 0)
+				goto in_relabel;
+		}
+		return -EPERM;
+in_relabel:
+		;
 	}
 
+	skp = smk_import_valid_label(value, label_len, GFP_KERNEL);
+	if (IS_ERR(skp))
+		return PTR_ERR(skp);
+
 	new = prepare_creds();
 	if (new == NULL)
 		return -ENOMEM;
@@ -3777,7 +3832,7 @@ static int do_setattr(u64 attr, void *value, size_t size)
 	smk_destroy_label_list(&tsp->smk_relabel);
 
 	commit_creds(new);
-	return size;
+	return 0;
 }
 
 /**
@@ -3785,7 +3840,7 @@ static int do_setattr(u64 attr, void *value, size_t size)
  * @attr: which attribute to set
  * @ctx: buffer containing the data
  * @size: size of @ctx
- * @flags: unused
+ * @flags: reserved, must be zero
  *
  * Fill the passed user space @ctx with the details of the requested
  * attribute.
@@ -3795,12 +3850,26 @@ static int do_setattr(u64 attr, void *value, size_t size)
 static int smack_setselfattr(unsigned int attr, struct lsm_ctx *ctx,
 			     u32 size, u32 flags)
 {
-	int rc;
+	if (attr != LSM_ATTR_CURRENT)
+		return -EOPNOTSUPP;
 
-	rc = do_setattr(attr, ctx->ctx, ctx->ctx_len);
-	if (rc > 0)
-		return 0;
-	return rc;
+	if (ctx->flags)
+		return -EINVAL;
+	/*
+	 * string must have \0 terminator, included in ctx->ctx
+	 * (see description of struct lsm_ctx)
+	 */
+	if (ctx->ctx_len == 0)
+		return -EINVAL;
+
+	if (ctx->ctx[ctx->ctx_len - 1] != '\0')
+		return -EINVAL;
+	/*
+	 * other do_setattr() caller, smack_setprocattr(),
+	 * does not count \0 into size, so
+	 * decreasing length by 1 to accommodate the divergence.
+	 */
+	return do_setattr(attr, ctx->ctx, ctx->ctx_len - 1);
 }
 
 /**
@@ -3812,15 +3881,39 @@ static int smack_setselfattr(unsigned int attr, struct lsm_ctx *ctx,
  * Sets the Smack value of the task. Only setting self
  * is permitted and only with privilege
  *
- * Returns the length of the smack label or an error code
+ * Returns the size of the input value or an error code
  */
 static int smack_setprocattr(const char *name, void *value, size_t size)
 {
-	int attr = lsm_name_to_attr(name);
+	size_t realsize = size;
+	unsigned int attr = lsm_name_to_attr(name);
 
-	if (attr != LSM_ATTR_UNDEF)
-		return do_setattr(attr, value, size);
-	return -EINVAL;
+	switch (attr) {
+	case LSM_ATTR_UNDEF:   return -EINVAL;
+	default:               return -EOPNOTSUPP;
+	case LSM_ATTR_CURRENT:
+		;
+	}
+
+	/*
+	 * The value for the "current" attribute is the label
+	 * followed by one of the 4 trailers: none, \0, \n, \n\0
+	 *
+	 * I.e. following inputs are accepted as 3-characters long label "foo":
+	 *
+	 *   "foo"     (3 characters)
+	 *   "foo\0"   (4 characters)
+	 *   "foo\n"   (4 characters)
+	 *   "foo\n\0" (5 characters)
+	 */
+
+	if (realsize && (((const char *)value)[realsize - 1] == '\0'))
+		--realsize;
+
+	if (realsize && (((const char *)value)[realsize - 1] == '\n'))
+		--realsize;
+
+	return do_setattr(attr, value, realsize) ? : size;
 }
 
 /**
@@ -4850,6 +4943,11 @@ static int smack_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
 
 static int smack_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen)
 {
+	/*
+	 * UDS inode has fixed label. Ignore nfs label.
+	 */
+	if (S_ISSOCK(inode->i_mode))
+		return 0;
 	return smack_inode_setsecurity(inode, XATTR_SMACK_SUFFIX, ctx,
 				       ctxlen, 0);
 }
@@ -4915,7 +5013,6 @@ static int smack_dentry_create_files_as(struct dentry *dentry, int mode,
 	struct task_smack *otsp = smack_cred(old);
 	struct task_smack *ntsp = smack_cred(new);
 	struct inode_smack *isp;
-	int may;
 
 	/*
 	 * Use the process credential unless all of
@@ -4929,18 +5026,12 @@ static int smack_dentry_create_files_as(struct dentry *dentry, int mode,
 	isp = smack_inode(d_inode(dentry->d_parent));
 
 	if (isp->smk_flags & SMK_INODE_TRANSMUTE) {
-		rcu_read_lock();
-		may = smk_access_entry(otsp->smk_task->smk_known,
-				       isp->smk_inode->smk_known,
-				       &otsp->smk_task->smk_rules);
-		rcu_read_unlock();
-
 		/*
 		 * If the directory is transmuting and the rule
 		 * providing access is transmuting use the containing
 		 * directory label instead of the process label.
 		 */
-		if (may > 0 && (may & MAY_TRANSMUTE)) {
+		if (smk_rule_transmutes(otsp->smk_task, isp->smk_inode)) {
 			ntsp->smk_task = isp->smk_inode;
 			ntsp->smk_transmuted = ntsp->smk_task;
 		}
@@ -5275,13 +5366,22 @@ static __init int smack_init(void)
 	return 0;
 }
 
+int __init smack_initcall(void)
+{
+	int rc_fs = init_smk_fs();
+	int rc_nf = smack_nf_ip_init();
+
+	return rc_fs ? rc_fs : rc_nf;
+}
+
 /*
  * Smack requires early initialization in order to label
  * all processes and objects when they are created.
  */
 DEFINE_LSM(smack) = {
-	.name = "smack",
+	.id = &smack_lsmid,
 	.flags = LSM_FLAG_LEGACY_MAJOR | LSM_FLAG_EXCLUSIVE,
 	.blobs = &smack_blob_sizes,
 	.init = smack_init,
+	.initcall_device = smack_initcall,
 };