[PATCH v3] cifs: reinstate original behavior again for forceuid/forcegid

[Takayuki Nagata <tnagata@redhat.com>]

forceuid/forcegid should be enabled by default when uid=/gid= options are
specified, but commit 24e0a1eff9e2 ("cifs: switch to new mount api")
changed the behavior. Due to the change, a mounted share does not show
intentional uid/gid for files and directories even though uid=/gid=
options are specified since forceuid/forcegid are not enabled.

This patch reinstates original behavior that overrides uid/gid with
specified uid/gid by the options.

Fixes: 24e0a1eff9e2 ("cifs: switch to new mount api")
Signed-off-by: Takayuki Nagata <tnagata@redhat.com>
Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
Acked-by: Tom Talpey <tom@talpey.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
V1 -> V2: Revised commit message to clarify "what breaks".
V2 -> V3: Introduce forceuid_specified and forcegid_specified variables
          to identify if [no]forceuid/[no]forcegid options are specified,
          and it is used to allow uid=/gid= options with noforceuid/
          noforcegid options. In addition, add notify messages that are
          shown when uid=/gid= options are specified without [no]forceuid/
          [no]forcegid options.

 fs/smb/client/fs_context.c | 12 ++++++++++++
 fs/smb/client/fs_context.h |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
index bdcbe6ff2739..4698667e25a7 100644
--- a/fs/smb/client/fs_context.c
+++ b/fs/smb/client/fs_context.c
@@ -745,6 +745,16 @@ static int smb3_fs_context_validate(struct fs_context *fc)
 	/* set the port that we got earlier */
 	cifs_set_port((struct sockaddr *)&ctx->dstaddr, ctx->port);
 
+	if (ctx->uid_specified && !ctx->forceuid_specified) {
+		ctx->override_uid = 1;
+		pr_notice("enabling forceuid mount option implicitly because uid= option is specified\n");
+	}
+
+	if (ctx->gid_specified && !ctx->forcegid_specified) {
+		ctx->override_gid = 1;
+		pr_notice("enabling forcegid mount option implicitly because gid= option is specified\n");
+	}
+
 	if (ctx->override_uid && !ctx->uid_specified) {
 		ctx->override_uid = 0;
 		pr_notice("ignoring forceuid mount option specified with no uid= option\n");
@@ -1014,12 +1024,14 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
 			ctx->override_uid = 0;
 		else
 			ctx->override_uid = 1;
+		ctx->forceuid_specified = true;
 		break;
 	case Opt_forcegid:
 		if (result.negated)
 			ctx->override_gid = 0;
 		else
 			ctx->override_gid = 1;
+		ctx->forcegid_specified = true;
 		break;
 	case Opt_perm:
 		if (result.negated)
diff --git a/fs/smb/client/fs_context.h b/fs/smb/client/fs_context.h
index 7863f2248c4d..f559ed252cee 100644
--- a/fs/smb/client/fs_context.h
+++ b/fs/smb/client/fs_context.h
@@ -164,6 +164,8 @@ enum cifs_param {
 };
 
 struct smb3_fs_context {
+	bool forceuid_specified;
+	bool forcegid_specified;
 	bool uid_specified;
 	bool cruid_specified;
 	bool gid_specified;
-- 
2.44.0