ksmbd: use LOOKUP_BENEATH to prevent the out of share access

instead of removing '..' in a given path, call
kern_path with LOOKUP_BENEATH flag to prevent
the out of share access.

ran various test on this:
smb2-cat-async smb://127.0.0.1/homes/../out_of_share
smb2-cat-async smb://127.0.0.1/homes/foo/../../out_of_share
smbclient //127.0.0.1/homes -c "mkdir ../foo2"
smbclient //127.0.0.1/homes -c "rename bar ../bar"

Cc: Ronnie Sahlberg <[email protected]>
Cc: Ralph Boehme <[email protected]>
Tested-by: Steve French <[email protected]>
Tested-by: Namjae Jeon <[email protected]>
Acked-by: Namjae Jeon <[email protected]>
Signed-off-by: Hyunchul Lee <[email protected]>
Signed-off-by: Steve French <[email protected]>

Author: hclee

fs/ksmbd/misc.c

@@ -158,25 +158,21 @@ int parse_stream_name(char *filename, char **stream_name, int *s_type)
  * Return : windows path string or error
  */
 
-char *convert_to_nt_pathname(char *filename, char *sharepath)
+char *convert_to_nt_pathname(char *filename)
 {
 	char *ab_pathname;
-	int len, name_len;
 
-	name_len = strlen(filename);
-	ab_pathname = kmalloc(name_len, GFP_KERNEL);
-	if (!ab_pathname)
-		return NULL;
-
-	ab_pathname[0] = '\\';
-	ab_pathname[1] = '\0';
+	if (strlen(filename) == 0) {
+		ab_pathname = kmalloc(2, GFP_KERNEL);
+		ab_pathname[0] = '\\';
+		ab_pathname[1] = '\0';
+	} else {
+		ab_pathname = kstrdup(filename, GFP_KERNEL);
+		if (!ab_pathname)
+			return NULL;
 
-	len = strlen(sharepath);
-	if (!strncmp(filename, sharepath, len) && name_len != len) {
-		strscpy(ab_pathname, &filename[len], name_len);
 		ksmbd_conv_path_to_windows(ab_pathname);
 	}
-
 	return ab_pathname;
 }
 
@@ -191,77 +187,19 @@ int get_nlink(struct kstat *st)
 	return nlink;
 }
 
-char *ksmbd_conv_path_to_unix(char *path)
+void ksmbd_conv_path_to_unix(char *path)
 {
-	size_t path_len, remain_path_len, out_path_len;
-	char *out_path, *out_next;
-	int i, pre_dotdot_cnt = 0, slash_cnt = 0;
-	bool is_last;
-
 	strreplace(path, '\\', '/');
-	path_len = strlen(path);
-	remain_path_len = path_len;
-	if (path_len == 0)
-		return ERR_PTR(-EINVAL);
-
-	out_path = kzalloc(path_len + 2, GFP_KERNEL);
-	if (!out_path)
-		return ERR_PTR(-ENOMEM);
-	out_path_len = 0;
-	out_next = out_path;
-
-	do {
-		char *name = path + path_len - remain_path_len;
-		char *next = strchrnul(name, '/');
-		size_t name_len = next - name;
-
-		is_last = !next[0];
-		if (name_len == 2 && name[0] == '.' && name[1] == '.') {
-			pre_dotdot_cnt++;
-			/* handle the case that path ends with "/.." */
-			if (is_last)
-				goto follow_dotdot;
-		} else {
-			if (pre_dotdot_cnt) {
-follow_dotdot:
-				slash_cnt = 0;
-				for (i = out_path_len - 1; i >= 0; i--) {
-					if (out_path[i] == '/' &&
-					    ++slash_cnt == pre_dotdot_cnt + 1)
-						break;
-				}
-
-				if (i < 0 &&
-				    slash_cnt != pre_dotdot_cnt) {
-					kfree(out_path);
-					return ERR_PTR(-EINVAL);
-				}
-
-				out_next = &out_path[i+1];
-				*out_next = '\0';
-				out_path_len = i + 1;
-
-			}
-
-			if (name_len != 0 &&
-			    !(name_len == 1 && name[0] == '.') &&
-			    !(name_len == 2 && name[0] == '.' && name[1] == '.')) {
-				next[0] = '\0';
-				sprintf(out_next, "%s/", name);
-				out_next += name_len + 1;
-				out_path_len += name_len + 1;
-				next[0] = '/';
-			}
-			pre_dotdot_cnt = 0;
-		}
+}
 
-		remain_path_len -= name_len + 1;
-	} while (!is_last);
+void ksmbd_strip_last_slash(char *path)
+{
+	int len = strlen(path);
 
-	if (out_path_len > 0)
-		out_path[out_path_len-1] = '\0';
-	path[path_len] = '\0';
-	return out_path;
+	while (len && path[len - 1] == '/') {
+		path[len - 1] = '\0';
+		len--;
+	}
 }
 
 void ksmbd_conv_path_to_windows(char *path)
@@ -298,7 +236,7 @@ char *ksmbd_extract_sharename(char *treename)
  *
  * Return:	converted name on success, otherwise NULL
  */
-char *convert_to_unix_name(struct ksmbd_share_config *share, char *name)
+char *convert_to_unix_name(struct ksmbd_share_config *share, const char *name)
 {
 	int no_slash = 0, name_len, path_len;
 	char *new_name;

fs/ksmbd/misc.h

@@ -14,12 +14,13 @@ struct ksmbd_file;
 int match_pattern(const char *str, size_t len, const char *pattern);
 int ksmbd_validate_filename(char *filename);
 int parse_stream_name(char *filename, char **stream_name, int *s_type);
-char *convert_to_nt_pathname(char *filename, char *sharepath);
+char *convert_to_nt_pathname(char *filename);
 int get_nlink(struct kstat *st);
-char *ksmbd_conv_path_to_unix(char *path);
+void ksmbd_conv_path_to_unix(char *path);
+void ksmbd_strip_last_slash(char *path);
 void ksmbd_conv_path_to_windows(char *path);
 char *ksmbd_extract_sharename(char *treename);
-char *convert_to_unix_name(struct ksmbd_share_config *share, char *name);
+char *convert_to_unix_name(struct ksmbd_share_config *share, const char *name);
 
 #define KSMBD_DIR_INFO_ALIGNMENT	8
 struct ksmbd_dir_info;

fs/ksmbd/smb2pdu.c

@@ -634,31 +634,17 @@ static char *
 smb2_get_name(struct ksmbd_share_config *share, const char *src,
 	      const int maxlen, struct nls_table *local_nls)
 {
-	char *name, *norm_name, *unixname;
+	char *name;
 
 	name = smb_strndup_from_utf16(src, maxlen, 1, local_nls);
 	if (IS_ERR(name)) {
 		pr_err("failed to get name %ld\n", PTR_ERR(name));
 		return name;
 	}
 
-	/* change it to absolute unix name */
-	norm_name = ksmbd_conv_path_to_unix(name);
-	if (IS_ERR(norm_name)) {
-		kfree(name);
-		return norm_name;
-	}
-	kfree(name);
-
-	unixname = convert_to_unix_name(share, norm_name);
-	kfree(norm_name);
-	if (!unixname) {
-		pr_err("can not convert absolute name\n");
-		return ERR_PTR(-ENOMEM);
-	}
-
-	ksmbd_debug(SMB, "absolute name = %s\n", unixname);
-	return unixname;
+	ksmbd_conv_path_to_unix(name);
+	ksmbd_strip_last_slash(name);
+	return name;
 }
 
 int setup_async_work(struct ksmbd_work *work, void (*fn)(void **), void **arg)
@@ -2352,7 +2338,7 @@ static int smb2_creat(struct ksmbd_work *work, struct path *path, char *name,
 			return rc;
 	}
 
-	rc = ksmbd_vfs_kern_path(name, 0, path, 0);
+	rc = ksmbd_vfs_kern_path(work, name, 0, path, 0);
 	if (rc) {
 		pr_err("cannot get linux path (%s), err = %d\n",
 		       name, rc);
@@ -2427,7 +2413,7 @@ int smb2_open(struct ksmbd_work *work)
 	struct oplock_info *opinfo;
 	__le32 *next_ptr = NULL;
 	int req_op_level = 0, open_flags = 0, may_flags = 0, file_info = 0;
-	int rc = 0, len = 0;
+	int rc = 0;
 	int contxt_cnt = 0, query_disk_id = 0;
 	int maximal_access_ctxt = 0, posix_ctxt = 0;
 	int s_type = 0;
@@ -2499,17 +2485,11 @@ int smb2_open(struct ksmbd_work *work)
 			goto err_out1;
 		}
 	} else {
-		len = strlen(share->path);
-		ksmbd_debug(SMB, "share path len %d\n", len);
-		name = kmalloc(len + 1, GFP_KERNEL);
+		name = kstrdup("", GFP_KERNEL);
 		if (!name) {
-			rsp->hdr.Status = STATUS_NO_MEMORY;
 			rc = -ENOMEM;
 			goto err_out1;
 		}
-
-		memcpy(name, share->path, len);
-		*(name + len) = '\0';
 	}
 
 	req_op_level = req->RequestedOplockLevel;
@@ -2632,7 +2612,7 @@ int smb2_open(struct ksmbd_work *work)
 		goto err_out1;
 	}
 
-	rc = ksmbd_vfs_kern_path(name, LOOKUP_NO_SYMLINKS, &path, 1);
+	rc = ksmbd_vfs_kern_path(work, name, LOOKUP_NO_SYMLINKS, &path, 1);
 	if (!rc) {
 		if (req->CreateOptions & FILE_DELETE_ON_CLOSE_LE) {
 			/*
@@ -2661,11 +2641,8 @@ int smb2_open(struct ksmbd_work *work)
 	}
 
 	if (rc) {
-		if (rc == -EACCES) {
-			ksmbd_debug(SMB,
-				    "User does not have right permission\n");
+		if (rc != -ENOENT)
 			goto err_out;
-		}
 		ksmbd_debug(SMB, "can not get linux path for %s, rc = %d\n",
 			    name, rc);
 		rc = 0;
@@ -3161,7 +3138,7 @@ int smb2_open(struct ksmbd_work *work)
 			rsp->hdr.Status = STATUS_INVALID_PARAMETER;
 		else if (rc == -EOPNOTSUPP)
 			rsp->hdr.Status = STATUS_NOT_SUPPORTED;
-		else if (rc == -EACCES || rc == -ESTALE)
+		else if (rc == -EACCES || rc == -ESTALE || rc == -EXDEV)
 			rsp->hdr.Status = STATUS_ACCESS_DENIED;
 		else if (rc == -ENOENT)
 			rsp->hdr.Status = STATUS_OBJECT_NAME_INVALID;
@@ -4277,8 +4254,7 @@ static int get_file_all_info(struct ksmbd_work *work,
 		return -EACCES;
 	}
 
-	filename = convert_to_nt_pathname(fp->filename,
-					  work->tcon->share_conf->path);
+	filename = convert_to_nt_pathname(fp->filename);
 	if (!filename)
 		return -ENOMEM;
 
@@ -4733,7 +4709,7 @@ static int smb2_get_info_filesystem(struct ksmbd_work *work,
 	int rc = 0, len;
 	int fs_infoclass_size = 0;
 
-	rc = ksmbd_vfs_kern_path(share->path, LOOKUP_NO_SYMLINKS, &path, 0);
+	rc = kern_path(share->path, LOOKUP_NO_SYMLINKS, &path);
 	if (rc) {
 		pr_err("cannot create vfs path\n");
 		return -EIO;
@@ -5282,7 +5258,7 @@ static int smb2_rename(struct ksmbd_work *work,
 			goto out;
 
 		len = strlen(new_name);
-		if (new_name[len - 1] != '/') {
+		if (len > 0 && new_name[len - 1] != '/') {
 			pr_err("not allow base filename in rename\n");
 			rc = -ESHARE;
 			goto out;
@@ -5310,11 +5286,14 @@ static int smb2_rename(struct ksmbd_work *work,
 	}
 
 	ksmbd_debug(SMB, "new name %s\n", new_name);
-	rc = ksmbd_vfs_kern_path(new_name, LOOKUP_NO_SYMLINKS, &path, 1);
-	if (rc)
+	rc = ksmbd_vfs_kern_path(work, new_name, LOOKUP_NO_SYMLINKS, &path, 1);
+	if (rc) {
+		if (rc != -ENOENT)
+			goto out;
 		file_present = false;
-	else
+	} else {
 		path_put(&path);
+	}
 
 	if (ksmbd_share_veto_filename(share, new_name)) {
 		rc = -ENOENT;
@@ -5384,11 +5363,14 @@ static int smb2_create_link(struct ksmbd_work *work,
 	}
 
 	ksmbd_debug(SMB, "target name is %s\n", target_name);
-	rc = ksmbd_vfs_kern_path(link_name, LOOKUP_NO_SYMLINKS, &path, 0);
-	if (rc)
+	rc = ksmbd_vfs_kern_path(work, link_name, LOOKUP_NO_SYMLINKS, &path, 0);
+	if (rc) {
+		if (rc != -ENOENT)
+			goto out;
 		file_present = false;
-	else
+	} else {
 		path_put(&path);
+	}
 
 	if (file_info->ReplaceIfExists) {
 		if (file_present) {
@@ -5548,7 +5530,7 @@ static int set_file_allocation_info(struct ksmbd_work *work,
 		 * inode size is retained by backup inode size.
 		 */
 		size = i_size_read(inode);
-		rc = ksmbd_vfs_truncate(work, NULL, fp, alloc_blks * 512);
+		rc = ksmbd_vfs_truncate(work, fp, alloc_blks * 512);
 		if (rc) {
 			pr_err("truncate failed! filename : %s, err %d\n",
 			       fp->filename, rc);
@@ -5585,7 +5567,7 @@ static int set_end_of_file_info(struct ksmbd_work *work, struct ksmbd_file *fp,
 	if (inode->i_sb->s_magic != MSDOS_SUPER_MAGIC) {
 		ksmbd_debug(SMB, "filename : %s truncated to newsize %lld\n",
 			    fp->filename, newsize);
-		rc = ksmbd_vfs_truncate(work, NULL, fp, newsize);
+		rc = ksmbd_vfs_truncate(work, fp, newsize);
 		if (rc) {
 			ksmbd_debug(SMB, "truncate failed! filename : %s err %d\n",
 				    fp->filename, rc);
@@ -5862,7 +5844,7 @@ int smb2_set_info(struct ksmbd_work *work)
 	return 0;
 
 err_out:
-	if (rc == -EACCES || rc == -EPERM)
+	if (rc == -EACCES || rc == -EPERM || rc == -EXDEV)
 		rsp->hdr.Status = STATUS_ACCESS_DENIED;
 	else if (rc == -EINVAL)
 		rsp->hdr.Status = STATUS_INVALID_PARAMETER;