linux-kernel - [PATCH] smb: client: fix null auth

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Date:   Tue, 15 Aug 2023 13:49:50 -0400
From:   Scott Mayhew <smayhew@...hat.com>
To:     Steve French <sfrench@...ba.org>,
        Paulo Alcantara <pc@...guebit.com>,
        Ronnie Sahlberg <lsahlber@...hat.com>,
        Shyam Prasad N <sprasad@...rosoft.com>,
        Tom Talpey <tom@...pey.com>,
        "Paulo Alcantara (SUSE)" <pc@....nz>
Cc:     Steve French <stfrench@...rosoft.com>, linux-cifs@...r.kernel.org,
        samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org,
        Scott Mayhew <smayhew@...hat.com>
Subject: [PATCH] smb: client: fix null auth

Commit abdb1742a312 removed code that clears ctx->username when
sec=none, so attempting to mount with '-o sec=none' now fails with
-EACCES.  Fix it by adding that logic to the parsing of the 'sec'
option, as well as checking if the mount is using null auth before
setting the username when parsing the 'user' option.

Fixes: abdb1742a312 ("cifs: get rid of mount options string parsing")
Signed-off-by: Scott Mayhew <smayhew@...hat.com>
---
 fs/smb/client/fs_context.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
index 4946a0c59600..67e16c2ac90e 100644
--- a/fs/smb/client/fs_context.c
+++ b/fs/smb/client/fs_context.c
@@ -231,6 +231,8 @@ cifs_parse_security_flavors(struct fs_context *fc, char *value, struct smb3_fs_c
 		break;
 	case Opt_sec_none:
 		ctx->nullauth = 1;
+		kfree(ctx->username);
+		ctx->username = NULL;
 		break;
 	default:
 		cifs_errorf(fc, "bad security option: %s\n", value);
@@ -1201,6 +1203,8 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
 	case Opt_user:
 		kfree(ctx->username);
 		ctx->username = NULL;
+		if (ctx->nullauth)
+			break;
 		if (strlen(param->string) == 0) {
 			/* null user, ie. anonymous authentication */
 			ctx->nullauth = 1;

---
base-commit: 91aa6c412d7f85e48aead7b00a7d9e91f5cf5863
change-id: 20230815-fix-cifs-null-auth-40c53f41c327

Best regards,
-- 
Scott Mayhew <smayhew@...hat.com>