smb3: fix broken reconnect when password changing on the server by allowing password...

[ Upstream commit 35f834265e0dc78b003aa0d1af65cafb89666b76 ]

There are various use cases that are becoming more common in which password
changes are scheduled on a server(s) periodically but the clients connected
to this server need to stay connected (even in the face of brief network
reconnects) due to mounts which can not be easily unmounted and mounted at
will, and servers that do password rotation do not always have the ability
to tell the clients exactly when to the new password will be effective,
so add support for an alt password ("password2=") on mount (and also
remount) so that we can anticipate the upcoming change to the server
without risking breaking existing mounts.

An alternative would have been to use the kernel keyring for this but the
processes doing the reconnect do not have access to the keyring but do
have access to the ses structure.

Reviewed-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 0c3311de5dc0a590fce1681af94010015a198f1d..a393d505e847a248a43bb9c9c772b693893b6bb4 100644 (file)
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -1063,6 +1063,7 @@ struct cifs_ses {
                                   and after mount option parsing we fill it */
        char *domainName;
        char *password;
+       char *password2; /* When key rotation used, new password may be set before it expires */
        char workstation_name[CIFS_MAX_WORKSTATION_LEN];
        struct session_key auth_key;
        struct ntlmssp_auth *ntlmssp; /* ciphertext, flags, server challenge */

diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index 7516c7d4558d86ea839843cfdc904ad485515adf..e28f011f11d6c1b0dd1bd5c6b0b39103e5254960 100644 (file)
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -2186,6 +2186,7 @@ cifs_set_cifscreds(struct smb3_fs_context *ctx, struct cifs_ses *ses)
        }
 
        ++delim;
+       /* BB consider adding support for password2 (Key Rotation) for multiuser in future */
        ctx->password = kstrndup(delim, len, GFP_KERNEL);
        if (!ctx->password) {
                cifs_dbg(FYI, "Unable to allocate %zd bytes for password\n",
@@ -2209,6 +2210,7 @@ cifs_set_cifscreds(struct smb3_fs_context *ctx, struct cifs_ses *ses)
                        kfree(ctx->username);
                        ctx->username = NULL;
                        kfree_sensitive(ctx->password);
+                       /* no need to free ctx->password2 since not allocated in this path */
                        ctx->password = NULL;
                        goto out_key_put;
                }
@@ -2320,6 +2322,12 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
                if (!ses->password)
                        goto get_ses_fail;
        }
+       /* ctx->password freed at unmount */
+       if (ctx->password2) {
+               ses->password2 = kstrdup(ctx->password2, GFP_KERNEL);
+               if (!ses->password2)
+                       goto get_ses_fail;
+       }
        if (ctx->domainname) {
                ses->domainName = kstrdup(ctx->domainname, GFP_KERNEL);
                if (!ses->domainName)

diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
index 775b0ca605892b84291faf59a96612894f2839b9..f119035a827250b1dffa57f354283f0b2ea39ea8 100644 (file)
--- a/fs/smb/client/fs_context.c
+++ b/fs/smb/client/fs_context.c
@@ -162,6 +162,7 @@ const struct fs_parameter_spec smb3_fs_parameters[] = {
        fsparam_string("username", Opt_user),
        fsparam_string("pass", Opt_pass),
        fsparam_string("password", Opt_pass),
+       fsparam_string("password2", Opt_pass2),
        fsparam_string("ip", Opt_ip),
        fsparam_string("addr", Opt_ip),
        fsparam_string("domain", Opt_domain),
@@ -315,6 +316,7 @@ smb3_fs_context_dup(struct smb3_fs_context *new_ctx, struct smb3_fs_context *ctx
        new_ctx->nodename = NULL;
        new_ctx->username = NULL;
        new_ctx->password = NULL;
+       new_ctx->password2 = NULL;
        new_ctx->server_hostname = NULL;
        new_ctx->domainname = NULL;
        new_ctx->UNC = NULL;
@@ -327,6 +329,7 @@ smb3_fs_context_dup(struct smb3_fs_context *new_ctx, struct smb3_fs_context *ctx
        DUP_CTX_STR(prepath);
        DUP_CTX_STR(username);
        DUP_CTX_STR(password);
+       DUP_CTX_STR(password2);
        DUP_CTX_STR(server_hostname);
        DUP_CTX_STR(UNC);
        DUP_CTX_STR(source);
@@ -885,6 +888,8 @@ static int smb3_reconfigure(struct fs_context *fc)
        else  {
                kfree_sensitive(ses->password);
                ses->password = kstrdup(ctx->password, GFP_KERNEL);
+               kfree_sensitive(ses->password2);
+               ses->password2 = kstrdup(ctx->password2, GFP_KERNEL);
        }
        STEAL_STRING(cifs_sb, ctx, domainname);
        STEAL_STRING(cifs_sb, ctx, nodename);
@@ -1287,6 +1292,18 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
                        goto cifs_parse_mount_err;
                }
                break;
+       case Opt_pass2:
+               kfree_sensitive(ctx->password2);
+               ctx->password2 = NULL;
+               if (strlen(param->string) == 0)
+                       break;
+
+               ctx->password2 = kstrdup(param->string, GFP_KERNEL);
+               if (ctx->password2 == NULL) {
+                       cifs_errorf(fc, "OOM when copying password2 string\n");
+                       goto cifs_parse_mount_err;
+               }
+               break;
        case Opt_ip:
                if (strlen(param->string) == 0) {
                        ctx->got_ip = false;
@@ -1586,6 +1603,8 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
  cifs_parse_mount_err:
        kfree_sensitive(ctx->password);
        ctx->password = NULL;
+       kfree_sensitive(ctx->password2);
+       ctx->password2 = NULL;
        return -EINVAL;
 }
 
@@ -1690,6 +1709,8 @@ smb3_cleanup_fs_context_contents(struct smb3_fs_context *ctx)
        ctx->username = NULL;
        kfree_sensitive(ctx->password);
        ctx->password = NULL;
+       kfree_sensitive(ctx->password2);
+       ctx->password2 = NULL;
        kfree(ctx->server_hostname);
        ctx->server_hostname = NULL;
        kfree(ctx->UNC);

diff --git a/fs/smb/client/fs_context.h b/fs/smb/client/fs_context.h
index 61776572b8d2d067bf922d49de6f51cfe37ad2fa..369a3fea1dfe0b7f6bb5c2d5dd993a08fbfa2a12 100644 (file)
--- a/fs/smb/client/fs_context.h
+++ b/fs/smb/client/fs_context.h
@@ -138,6 +138,7 @@ enum cifs_param {
        Opt_source,
        Opt_user,
        Opt_pass,
+       Opt_pass2,
        Opt_ip,
        Opt_domain,
        Opt_srcaddr,
@@ -171,6 +172,7 @@ struct smb3_fs_context {
 
        char *username;
        char *password;
+       char *password2;
        char *domainname;
        char *source;
        char *server_hostname;

diff --git a/fs/smb/client/misc.c b/fs/smb/client/misc.c
index 0d13db80e67c90eda6bdb3c3aab95cc14830656f..d56959d02e36d7ce29a5a8fa728395f820e4f217 100644 (file)
--- a/fs/smb/client/misc.c
+++ b/fs/smb/client/misc.c
@@ -101,6 +101,7 @@ sesInfoFree(struct cifs_ses *buf_to_free)
        kfree(buf_to_free->serverDomain);
        kfree(buf_to_free->serverNOS);
        kfree_sensitive(buf_to_free->password);
+       kfree_sensitive(buf_to_free->password2);
        kfree(buf_to_free->user_name);
        kfree(buf_to_free->domainName);
        kfree_sensitive(buf_to_free->auth_key.response);

diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index b71e32d66eba78ea612a55b4a392f42a2f865d57..60793143e24c630009ae196e671860d8deb6dc5b 100644 (file)
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -367,6 +367,17 @@ again:
                }
 
                rc = cifs_setup_session(0, ses, server, nls_codepage);
+               if ((rc == -EACCES) || (rc == -EKEYEXPIRED) || (rc == -EKEYREVOKED)) {
+                       /*
+                        * Try alternate password for next reconnect (key rotation
+                        * could be enabled on the server e.g.) if an alternate
+                        * password is available and the current password is expired,
+                        * but do not swap on non pwd related errors like host down
+                        */
+                       if (ses->password2)
+                               swap(ses->password2, ses->password);
+               }
+
                if ((rc == -EACCES) && !tcon->retry) {
                        mutex_unlock(&ses->session_mutex);
                        rc = -EHOSTDOWN;