3 ksmbd fixes: including an important security fix for path processing, and a buffer overflow check, and a trivial fix for incorrect header inclusion

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Merge tag '5.15-rc1-ksmbd' of git://git.samba.org/ksmbd

Pull ksmbd server fixes from Steve French:
 "Three ksmbd fixes, including an important security fix for path
  processing, and a buffer overflow check, and a trivial fix for
  incorrect header inclusion"

* tag '5.15-rc1-ksmbd' of git://git.samba.org/ksmbd:
  ksmbd: add validation for FILE_FULL_EA_INFORMATION of smb2_get_info
  ksmbd: prevent out of share access
  ksmbd: transport_rdma: Don't include rwlock.h directly

fs/ksmbd/misc.c

@@ -191,19 +191,77 @@ int get_nlink(struct kstat *st)
 	return nlink;
 }
 
-void ksmbd_conv_path_to_unix(char *path)
+char *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);
 
-void ksmbd_strip_last_slash(char *path)
-{
-	int len = strlen(path);
+	out_path = kzalloc(path_len + 2, GFP_KERNEL);
+	if (!out_path)
+		return ERR_PTR(-ENOMEM);
+	out_path_len = 0;
+	out_next = out_path;
 
-	while (len && path[len - 1] == '/') {
-		path[len - 1] = '\0';
-		len--;
-	}
+	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);
+
+	if (out_path_len > 0)
+		out_path[out_path_len-1] = '\0';
+	path[path_len] = '\0';
+	return out_path;
 }
 
 void ksmbd_conv_path_to_windows(char *path)

fs/ksmbd/misc.h

@@ -16,8 +16,7 @@ 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);
 int get_nlink(struct kstat *st);
-void ksmbd_conv_path_to_unix(char *path);
-void ksmbd_strip_last_slash(char *path);
+char *ksmbd_conv_path_to_unix(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);

fs/ksmbd/smb2pdu.c

@@ -634,7 +634,7 @@ static char *
 smb2_get_name(struct ksmbd_share_config *share, const char *src,
 	      const int maxlen, struct nls_table *local_nls)
 {
-	char *name, *unixname;
+	char *name, *norm_name, *unixname;
 
 	name = smb_strndup_from_utf16(src, maxlen, 1, local_nls);
 	if (IS_ERR(name)) {
@@ -643,11 +643,15 @@ smb2_get_name(struct ksmbd_share_config *share, const char *src,
 	}
 
 	/* change it to absolute unix name */
-	ksmbd_conv_path_to_unix(name);
-	ksmbd_strip_last_slash(name);
-
-	unixname = convert_to_unix_name(share, 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);
@@ -4041,6 +4045,10 @@ static int smb2_get_ea(struct ksmbd_work *work, struct ksmbd_file *fp,
 	path = &fp->filp->f_path;
 	/* single EA entry is requested with given user.* name */
 	if (req->InputBufferLength) {
+		if (le32_to_cpu(req->InputBufferLength) <
+		    sizeof(struct smb2_ea_info_req))
+			return -EINVAL;
+
 		ea_req = (struct smb2_ea_info_req *)req->Buffer;
 	} else {
 		/* need to send all EAs, if no specific EA is requested*/

fs/ksmbd/transport_rdma.c

@@ -20,7 +20,6 @@
 #define SUBMOD_NAME	"smb_direct"
 
 #include <linux/kthread.h>
-#include <linux/rwlock.h>
 #include <linux/list.h>
 #include <linux/mempool.h>
 #include <linux/highmem.h>