[PATCH v1] ceph: don't rely on error_string to validate blocklisted session.

[PATCH v1] ceph: don't rely on error_string to validate blocklisted session.

[khiremat]

From: Kotresh HR <khiremat@redhat.com>

The "error_string" in the metadata of MClientSession is being
parsed by kclient to validate whether the session is blocklisted.
The "error_string" is for humans and shouldn't be relied on it.
Hence added the flag to MClientsession to indicate the session
is blocklisted.

URL: https://tracker.ceph.com/issues/47450
Signed-off-by: Kotresh HR <khiremat@redhat.com>
---
 fs/ceph/mds_client.c         | 24 +++++++++++++++++++++---
 include/linux/ceph/ceph_fs.h |  2 ++
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 44bc780b2b0e..cc1137468b29 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -3396,9 +3396,15 @@ static void handle_session(struct ceph_mds_session *session,
 
 	if (msg_version >= 3) {
 		u32 len;
-		/* version >= 2, metadata */
-		if (__decode_session_metadata(&p, end, &blocklisted) < 0)
-			goto bad;
+		/* version >= 2 and < 5, decode metadata, skip otherwise
+		 * as it's handled via flags.
+		 */
+		if (msg_version >= 5) {
+			ceph_decode_skip_map(&p, end, string, string, bad);
+		} else {
+			if (__decode_session_metadata(&p, end, &blocklisted) < 0)
+				goto bad;
+		}
 		/* version >= 3, feature bits */
 		ceph_decode_32_safe(&p, end, len, bad);
 		if (len) {
@@ -3407,6 +3413,18 @@ static void handle_session(struct ceph_mds_session *session,
 		}
 	}
 
+	if (msg_version >= 5) {
+		u32 flags;
+		/* version >= 4, struct_v, struct_cv, len, metric_spec */
+	        ceph_decode_skip_n(&p, end, 2 + sizeof(u32) * 2, bad);
+		/* version >= 5, flags   */
+                ceph_decode_32_safe(&p, end, flags, bad);
+		if (flags & CEPH_SESSION_BLOCKLISTED) {
+		        pr_warn("mds%d session blocklisted\n", session->s_mds);
+			blocklisted = true;
+		}
+	}
+
 	mutex_lock(&mdsc->mutex);
 	if (op == CEPH_SESSION_CLOSE) {
 		ceph_get_mds_session(session);
diff --git a/include/linux/ceph/ceph_fs.h b/include/linux/ceph/ceph_fs.h
index bc2699feddbe..7ad6c3d0db7d 100644
--- a/include/linux/ceph/ceph_fs.h
+++ b/include/linux/ceph/ceph_fs.h
@@ -302,6 +302,8 @@ enum {
 	CEPH_SESSION_REQUEST_FLUSH_MDLOG,
 };
 
+#define CEPH_SESSION_BLOCKLISTED	(1 << 0)  /* session blocklisted */
+
 extern const char *ceph_session_op_name(int op);
 
 struct ceph_mds_session_head {
-- 
2.25.1

Re: [PATCH v1] ceph: don't rely on error_string to validate blocklisted session.

[Jeff Layton]

On Mon, 2021-09-27 at 19:22 +0530, khiremat@redhat.com wrote:
> From: Kotresh HR <khiremat@redhat.com>
> 

This looks good. For future reference, I'd have probably marked this as
[PATCH v2]. One minor style nit below, but you don't need to resend for
that. I'll fix it up when I merge it if you're OK with it.

> The "error_string" in the metadata of MClientSession is being
> parsed by kclient to validate whether the session is blocklisted.
> The "error_string" is for humans and shouldn't be relied on it.
> Hence added the flag to MClientsession to indicate the session
> is blocklisted.
> 
> URL: https://tracker.ceph.com/issues/47450
> Signed-off-by: Kotresh HR <khiremat@redhat.com>
> ---
>  fs/ceph/mds_client.c         | 24 +++++++++++++++++++++---
>  include/linux/ceph/ceph_fs.h |  2 ++
>  2 files changed, 23 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 44bc780b2b0e..cc1137468b29 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -3396,9 +3396,15 @@ static void handle_session(struct ceph_mds_session *session,
>  
>  	if (msg_version >= 3) {
>  		u32 len;
> -		/* version >= 2, metadata */
> -		if (__decode_session_metadata(&p, end, &blocklisted) < 0)
> -			goto bad;
> +		/* version >= 2 and < 5, decode metadata, skip otherwise
> +		 * as it's handled via flags.
> +		 */
> +		if (msg_version >= 5) {
> +			ceph_decode_skip_map(&p, end, string, string, bad);
> +		} else {
> +			if (__decode_session_metadata(&p, end, &blocklisted) < 0)

We can use an "else if" here and remove a level of indentation. Also,
the braces aren't necessary since both just cover a single-line
statements.

> +				goto bad;
> +		}
>  		/* version >= 3, feature bits */
>  		ceph_decode_32_safe(&p, end, len, bad);
>  		if (len) {
> @@ -3407,6 +3413,18 @@ static void handle_session(struct ceph_mds_session *session,
>  		}
>  	}
>  
> +	if (msg_version >= 5) {
> +		u32 flags;
> +		/* version >= 4, struct_v, struct_cv, len, metric_spec */
> +	        ceph_decode_skip_n(&p, end, 2 + sizeof(u32) * 2, bad);
> +		/* version >= 5, flags   */
> +                ceph_decode_32_safe(&p, end, flags, bad);
> +		if (flags & CEPH_SESSION_BLOCKLISTED) {
> +		        pr_warn("mds%d session blocklisted\n", session->s_mds);
> +			blocklisted = true;
> +		}
> +	}
> +
>  	mutex_lock(&mdsc->mutex);
>  	if (op == CEPH_SESSION_CLOSE) {
>  		ceph_get_mds_session(session);
> diff --git a/include/linux/ceph/ceph_fs.h b/include/linux/ceph/ceph_fs.h
> index bc2699feddbe..7ad6c3d0db7d 100644
> --- a/include/linux/ceph/ceph_fs.h
> +++ b/include/linux/ceph/ceph_fs.h
> @@ -302,6 +302,8 @@ enum {
>  	CEPH_SESSION_REQUEST_FLUSH_MDLOG,
>  };
>  
> +#define CEPH_SESSION_BLOCKLISTED	(1 << 0)  /* session blocklisted */
> +
>  extern const char *ceph_session_op_name(int op);
>  
>  struct ceph_mds_session_head {

Re: [PATCH v1] ceph: don't rely on error_string to validate blocklisted session.

[Jeff Layton]

On Mon, 2021-09-27 at 22:12 +0530, Kotresh Hiremath Ravishankar wrote:
> 
> 
> On Mon, Sep 27, 2021 at 9:45 PM Jeff Layton <jlayton@kernel.org>
> wrote:
> > 
> > On Mon, 2021-09-27 at 19:22 +0530, khiremat@redhat.com wrote:
> > > From: Kotresh HR <khiremat@redhat.com>
> > > 
> > 
> > This looks good. For future reference, I'd have probably marked this
> > as
> > [PATCH v2]. One minor style nit below, but you don't need to resend
> > for
> > that. I'll fix it up when I merge it if you're OK with it.
> 
> I did format it with [PATCH v2], not sure why 'git send-email' didn't
> pick it up.
> Sure, No problem. Thanks Jeff!
> 

Merged. Please take a look when you have time and let me know if you see
anything wrong with the final result.

Thanks,
Jeff
-- 
Jeff Layton <jlayton@kernel.org>