cifs: allow changing password during remount

There are cases where a session is disconnected and password has changed
on the server (or expired) for this user and this currently can not
be fixed without unmount and mounting again.  This patch allows
remount to change the password (for the non Kerberos case, Kerberos
ticket refresh is handled differently) when the session is disconnected
and the user can not reconnect due to still using old password.

Future patches should also allow us to setup the keyring (cifscreds)
to have an "alternate password" so we would be able to change
the password before the session drops (without the risk of races
between when the password changes and the disconnect occurs -
ie cases where the old password is still needed because the new
password has not fully rolled out to all servers yet).

Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/client/cifs_debug.c b/fs/smb/client/cifs_debug.c
index 3e4209f41c18f854a190c523b67e3c105689ca2f..23d2622b969f09237eff1d122565bc81039aebf2 100644 (file)
--- a/fs/smb/client/cifs_debug.c
+++ b/fs/smb/client/cifs_debug.c
@@ -488,6 +488,8 @@ skip_rdma:
                                ses->ses_count, ses->serverOS, ses->serverNOS,
                                ses->capabilities, ses->ses_status);
                        }
+                       if (ses->expired_pwd)
+                               seq_puts(m, "password no longer valid ");
                        spin_unlock(&ses->ses_lock);
 
                        seq_printf(m, "\n\tSecurity type: %s ",

diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 53c75cfb33ab9446740133e7f19da6229eeffd55..ec9a26bd05a122ef7ef0bbf6d480d95e9960dd02 100644 (file)
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -1066,6 +1066,7 @@ struct cifs_ses {
        enum securityEnum sectype; /* what security flavor was specified? */
        bool sign;              /* is signing required? */
        bool domainAuto:1;
+       bool expired_pwd;  /* track if access denied or expired pwd so can know if need to update */
        unsigned int flags;
        __u16 session_flags;
        __u8 smb3signingkey[SMB3_SIGN_KEY_SIZE];

diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
index 4b2f5aa2ea0e1de026302b9e543e2e13429107f9..415e87635d5aab3f217146fa3348b822c37090c8 100644 (file)
--- a/fs/smb/client/fs_context.c
+++ b/fs/smb/client/fs_context.c
@@ -772,7 +772,7 @@ static void smb3_fs_context_free(struct fs_context *fc)
  */
 static int smb3_verify_reconfigure_ctx(struct fs_context *fc,
                                       struct smb3_fs_context *new_ctx,
-                                      struct smb3_fs_context *old_ctx)
+                                      struct smb3_fs_context *old_ctx, bool need_recon)
 {
        if (new_ctx->posix_paths != old_ctx->posix_paths) {
                cifs_errorf(fc, "can not change posixpaths during remount\n");
@@ -798,8 +798,15 @@ static int smb3_verify_reconfigure_ctx(struct fs_context *fc,
        }
        if (new_ctx->password &&
            (!old_ctx->password || strcmp(new_ctx->password, old_ctx->password))) {
-               cifs_errorf(fc, "can not change password during remount\n");
-               return -EINVAL;
+               if (need_recon == false) {
+                       cifs_errorf(fc,
+                                   "can not change password of active session during remount\n");
+                       return -EINVAL;
+               } else if (old_ctx->sectype == Kerberos) {
+                       cifs_errorf(fc,
+                                   "can not change password for Kerberos via remount\n");
+                       return -EINVAL;
+               }
        }
        if (new_ctx->domainname &&
            (!old_ctx->domainname || strcmp(new_ctx->domainname, old_ctx->domainname))) {
@@ -843,9 +850,14 @@ static int smb3_reconfigure(struct fs_context *fc)
        struct smb3_fs_context *ctx = smb3_fc2context(fc);
        struct dentry *root = fc->root;
        struct cifs_sb_info *cifs_sb = CIFS_SB(root->d_sb);
+       struct cifs_ses *ses = cifs_sb_master_tcon(cifs_sb)->ses;
+       bool need_recon = false;
        int rc;
 
-       rc = smb3_verify_reconfigure_ctx(fc, ctx, cifs_sb->ctx);
+       if (ses->expired_pwd)
+               need_recon = true;
+
+       rc = smb3_verify_reconfigure_ctx(fc, ctx, cifs_sb->ctx, need_recon);
        if (rc)
                return rc;
 
@@ -858,7 +870,12 @@ static int smb3_reconfigure(struct fs_context *fc)
        STEAL_STRING(cifs_sb, ctx, UNC);
        STEAL_STRING(cifs_sb, ctx, source);
        STEAL_STRING(cifs_sb, ctx, username);
-       STEAL_STRING_SENSITIVE(cifs_sb, ctx, password);
+       if (need_recon == false)
+               STEAL_STRING_SENSITIVE(cifs_sb, ctx, password);
+       else  {
+               kfree_sensitive(ses->password);
+               ses->password = kstrdup(ctx->password, GFP_KERNEL);
+       }
        STEAL_STRING(cifs_sb, ctx, domainname);
        STEAL_STRING(cifs_sb, ctx, nodename);
        STEAL_STRING(cifs_sb, ctx, iocharset);

diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index 608ee05491e262c5cf4555c6b51b364cdc60a03b..a500380d1b2e9de3c67b10152f5a0711483a928b 100644 (file)
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -1536,6 +1536,11 @@ SMB2_sess_sendreceive(struct SMB2_sess_data *sess_data)
                            &sess_data->buf0_type,
                            CIFS_LOG_ERROR | CIFS_SESS_OP, &rsp_iov);
        cifs_small_buf_release(sess_data->iov[0].iov_base);
+       if (rc == 0)
+               sess_data->ses->expired_pwd = false;
+       else if ((rc == -EACCES) || (rc == -EKEYEXPIRED) || (rc == -EKEYREVOKED))
+               sess_data->ses->expired_pwd = true;
+
        memcpy(&sess_data->iov[0], &rsp_iov, sizeof(struct kvec));
 
        return rc;