cifs: Add support for reading attributes on SMB2+

SMB1 already has support to read attributes. This adds similar support
to SMB2+.

With this patch, tools such as 'getfattr' will now work with SMB2+ shares.

RH-bz: 1110709

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

4 files changed, 169 insertions, 0 deletions

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index cfacf2c97e94..78516d3a133c 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -426,6 +426,138 @@ smb2_query_file_info(const unsigned int xid, struct cifs_tcon *tcon,
         return rc;
 }
 
+static ssize_t
+move_smb2_ea_to_cifs(char *dst, size_t dst_size,
+                     struct smb2_file_full_ea_info *src, size_t src_size,
+                     const unsigned char *ea_name)
+{
+        int rc = 0;
+        unsigned int ea_name_len = ea_name ? strlen(ea_name) : 0;
+        char *name, *value;
+        size_t name_len, value_len, user_name_len;
+
+        while (src_size > 0) {
+                name = &src->ea_data[0];
+                name_len = (size_t)src->ea_name_length;
+                value = &src->ea_data[src->ea_name_length + 1];
+                value_len = (size_t)le16_to_cpu(src->ea_value_length);
+
+                if (name_len == 0) {
+                        break;
+                }
+
+                if (src_size < 8 + name_len + 1 + value_len) {
+                        cifs_dbg(FYI, "EA entry goes beyond length of list\n");
+                        rc = -EIO;
+                        goto out;
+                }
+
+                if (ea_name) {
+                        if (ea_name_len == name_len &&
+                            memcmp(ea_name, name, name_len) == 0) {
+                                rc = value_len;
+                                if (dst_size == 0)
+                                        goto out;
+                                if (dst_size < value_len) {
+                                        rc = -ERANGE;
+                                        goto out;
+                                }
+                                memcpy(dst, value, value_len);
+                                goto out;
+                        }
+                } else {
+                        /* 'user.' plus a terminating null */
+                        user_name_len = 5 + 1 + name_len;
+
+                        rc += user_name_len;
+
+                        if (dst_size >= user_name_len) {
+                                dst_size -= user_name_len;
+                                memcpy(dst, "user.", 5);
+                                dst += 5;
+                                memcpy(dst, src->ea_data, name_len);
+                                dst += name_len;
+                                *dst = 0;
+                                ++dst;
+                        } else if (dst_size == 0) {
+                                /* skip copy - calc size only */
+                        } else {
+                                /* stop before overrun buffer */
+                                rc = -ERANGE;
+                                break;
+                        }
+                }
+
+                if (!src->next_entry_offset)
+                        break;
+
+                if (src_size < le32_to_cpu(src->next_entry_offset)) {
+                        /* stop before overrun buffer */
+                        rc = -ERANGE;
+                        break;
+                }
+                src_size -= le32_to_cpu(src->next_entry_offset);
+                src = (void *)((char *)src +
+                               le32_to_cpu(src->next_entry_offset));
+        }
+
+        /* didn't find the named attribute */
+        if (ea_name)
+                rc = -ENODATA;
+
+out:
+        return (ssize_t)rc;
+}
+
+static ssize_t
+smb2_query_eas(const unsigned int xid, struct cifs_tcon *tcon,
+               const unsigned char *path, const unsigned char *ea_name,
+               char *ea_data, size_t buf_size,
+               struct cifs_sb_info *cifs_sb)
+{
+        int rc;
+        __le16 *utf16_path;
+        __u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
+        struct cifs_open_parms oparms;
+        struct cifs_fid fid;
+        struct smb2_file_full_ea_info *smb2_data;
+
+        utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
+        if (!utf16_path)
+                return -ENOMEM;
+
+        oparms.tcon = tcon;
+        oparms.desired_access = FILE_READ_EA;
+        oparms.disposition = FILE_OPEN;
+        oparms.create_options = 0;
+        oparms.fid = &fid;
+        oparms.reconnect = false;
+
+        rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, NULL);
+        kfree(utf16_path);
+        if (rc) {
+                cifs_dbg(FYI, "open failed rc=%d\n", rc);
+                return rc;
+        }
+
+        smb2_data = kzalloc(SMB2_MAX_EA_BUF, GFP_KERNEL);
+        if (smb2_data == NULL) {
+                SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
+                return -ENOMEM;
+        }
+
+        rc = SMB2_query_eas(xid, tcon, fid.persistent_fid, fid.volatile_fid,
+                            smb2_data);
+        SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
+
+        if (!rc)
+                rc = move_smb2_ea_to_cifs(ea_data, buf_size, smb2_data,
+                                          SMB2_MAX_EA_BUF, ea_name);
+
+        kfree(smb2_data);
+        return rc;
+}
+
 static bool
 smb2_can_echo(struct TCP_Server_Info *server)
 {
@@ -2572,6 +2704,9 @@ struct smb_version_operations smb20_operations = {
         .dir_needs_close = smb2_dir_needs_close,
         .get_dfs_refer = smb2_get_dfs_refer,
         .select_sectype = smb2_select_sectype,
+#ifdef CONFIG_CIFS_XATTR
+        .query_all_EAs = smb2_query_eas,
+#endif /* CIFS_XATTR */
 #ifdef CONFIG_CIFS_ACL
         .get_acl = get_smb2_acl,
         .get_acl_by_fid = get_smb2_acl_by_fid,
@@ -2662,6 +2797,9 @@ struct smb_version_operations smb21_operations = {
         .enum_snapshots = smb3_enum_snapshots,
         .get_dfs_refer = smb2_get_dfs_refer,
         .select_sectype = smb2_select_sectype,
+#ifdef CONFIG_CIFS_XATTR
+        .query_all_EAs = smb2_query_eas,
+#endif /* CIFS_XATTR */
 #ifdef CONFIG_CIFS_ACL
         .get_acl = get_smb2_acl,
         .get_acl_by_fid = get_smb2_acl_by_fid,
@@ -2762,6 +2900,9 @@ struct smb_version_operations smb30_operations = {
         .receive_transform = smb3_receive_transform,
         .get_dfs_refer = smb2_get_dfs_refer,
         .select_sectype = smb2_select_sectype,
+#ifdef CONFIG_CIFS_XATTR
+        .query_all_EAs = smb2_query_eas,
+#endif /* CIFS_XATTR */
 #ifdef CONFIG_CIFS_ACL
         .get_acl = get_smb2_acl,
         .get_acl_by_fid = get_smb2_acl_by_fid,
@@ -2863,6 +3004,9 @@ struct smb_version_operations smb311_operations = {
         .receive_transform = smb3_receive_transform,
         .get_dfs_refer = smb2_get_dfs_refer,
         .select_sectype = smb2_select_sectype,
+#ifdef CONFIG_CIFS_XATTR
+        .query_all_EAs = smb2_query_eas,
+#endif /* CIFS_XATTR */
 };
 #endif /* CIFS_SMB311 */
 
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 7aa67206f6da..bf0ba3c15b63 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2145,6 +2145,18 @@ qinf_exit:
         return rc;
 }
 
+int SMB2_query_eas(const unsigned int xid, struct cifs_tcon *tcon,
+        u64 persistent_fid, u64 volatile_fid,
+        struct smb2_file_full_ea_info *data)
+{
+        return query_info(xid, tcon, persistent_fid, volatile_fid,
+                          FILE_FULL_EA_INFORMATION, SMB2_O_INFO_FILE, 0,
+                          SMB2_MAX_EA_BUF,
+                          sizeof(struct smb2_file_full_ea_info),
+                          (void **)&data,
+                          NULL);
+}
+
 int SMB2_query_info(const unsigned int xid, struct cifs_tcon *tcon,
         u64 persistent_fid, u64 volatile_fid, struct smb2_file_all_info *data)
 {
diff --git a/fs/cifs/smb2pdu.h b/fs/cifs/smb2pdu.h
index 2826882c81d1..393ed5f4e1b6 100644
--- a/fs/cifs/smb2pdu.h
+++ b/fs/cifs/smb2pdu.h
@@ -1178,6 +1178,16 @@ struct smb2_file_link_info { /* encoding of request for level 11 */
         char   FileName[0];     /* Name to be assigned to new link */
 } __packed; /* level 11 Set */
 
+#define SMB2_MAX_EA_BUF 2048
+
+struct smb2_file_full_ea_info { /* encoding of response for level 15 */
+        __le32 next_entry_offset;
+        __u8   flags;
+        __u8   ea_name_length;
+        __le16 ea_value_length;
+        char   ea_data[0]; /* \0 terminated name plus value */
+} __packed; /* level 15 Set */
+
 /*
  * This level 18, although with struct with same name is different from cifs
  * level 0x107. Level 0x107 has an extra u64 between AccessFlags and
diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
index 1cadaf9f3c58..183389bfc8f6 100644
--- a/fs/cifs/smb2proto.h
+++ b/fs/cifs/smb2proto.h
@@ -132,6 +132,9 @@ extern int SMB2_close(const unsigned int xid, struct cifs_tcon *tcon,
                       u64 persistent_file_id, u64 volatile_file_id);
 extern int SMB2_flush(const unsigned int xid, struct cifs_tcon *tcon,
                       u64 persistent_file_id, u64 volatile_file_id);
+extern int SMB2_query_eas(const unsigned int xid, struct cifs_tcon *tcon,
+                          u64 persistent_file_id, u64 volatile_file_id,
+                          struct smb2_file_full_ea_info *data);
 extern int SMB2_query_info(const unsigned int xid, struct cifs_tcon *tcon,
                            u64 persistent_file_id, u64 volatile_file_id,
                            struct smb2_file_all_info *data);