[PATCH 5.15.y] smb: client: set correct id, uid and cruid for multiuser automounts

[Rahul Sharma]

From: Paulo Alcantara <pc@xxxxxxxxxxxxx>

[ Upstream commit 4508ec17357094e2075f334948393ddedbb75157 ]

When uid, gid and cruid are not specified, we need to dynamically
set them into the filesystem context used for automounting otherwise
they'll end up reusing the values from the parent mount.

Fixes: 9fd29a5bae6e ("cifs: use fs_context for automounts")
Reported-by: Shane Nehring <snehring@xxxxxxxxxxx>
Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2259257
Cc: stable@xxxxxxxxxxxxxxx # 6.2+
Signed-off-by: Paulo Alcantara (Red Hat) <pc@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
[ The context change is due to the commit 561f82a3a24c
("smb: client: rename cifs_dfs_ref.c to namespace.c") and the commit
0a049935e47e ("smb: client: get rid of dfs naming in automount code")
in v6.6 which are irrelevant to the logic of this patch. ]
Signed-off-by: Rahul Sharma <black.hawk@xxxxxxx>
---
 fs/cifs/cifs_dfs_ref.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index 020e71fe1454..2c6dee3f097b 100644
--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -258,6 +258,21 @@ char *cifs_compose_mount_options(const char *sb_mountdata,
 	goto compose_mount_options_out;
 }
 
+static void fs_context_set_ids(struct smb3_fs_context *ctx)
+{
+	kuid_t uid = current_fsuid();
+	kgid_t gid = current_fsgid();
+
+	if (ctx->multiuser) {
+		if (!ctx->uid_specified)
+			ctx->linux_uid = uid;
+		if (!ctx->gid_specified)
+			ctx->linux_gid = gid;
+	}
+	if (!ctx->cruid_specified)
+		ctx->cred_uid = uid;
+}
+
 /*
  * Create a vfsmount that we can automount
  */
@@ -309,6 +324,7 @@ static struct vfsmount *cifs_dfs_do_automount(struct path *path)
 	tmp.source = full_path;
 	tmp.UNC = tmp.prepath = NULL;
 
+	fs_context_set_ids(&tmp);
 	rc = smb3_fs_context_dup(ctx, &tmp);
 	if (rc) {
 		mnt = ERR_PTR(rc);
-- 
2.34.1