New upstream version 1.26.0

10 files changed, 500 insertions, 243 deletions

diff --git a/docs/admin_api/media_admin_api.md b/docs/admin_api/media_admin_api.md
index dfb8c5d7..90faeaae 100644
--- a/docs/admin_api/media_admin_api.md
+++ b/docs/admin_api/media_admin_api.md
@@ -4,6 +4,7 @@
   * [Quarantining media by ID](#quarantining-media-by-id)
   * [Quarantining media in a room](#quarantining-media-in-a-room)
   * [Quarantining all media of a user](#quarantining-all-media-of-a-user)
+  * [Protecting media from being quarantined](#protecting-media-from-being-quarantined)
 - [Delete local media](#delete-local-media)
   * [Delete a specific local media](#delete-a-specific-local-media)
   * [Delete local media by date or size](#delete-local-media-by-date-or-size)
@@ -123,6 +124,29 @@ The following fields are returned in the JSON response body:
 
 * `num_quarantined`: integer - The number of media items successfully quarantined
 
+## Protecting media from being quarantined
+
+This API protects a single piece of local media from being quarantined using the
+above APIs. This is useful for sticker packs and other shared media which you do
+not want to get quarantined, especially when
+[quarantining media in a room](#quarantining-media-in-a-room).
+
+Request:
+
+```
+POST /_synapse/admin/v1/media/protect/<media_id>
+
+{}
+```
+
+Where `media_id` is in the  form of `abcdefg12345...`.
+
+Response:
+
+```json
+{}
+```
+
 # Delete local media
 This API deletes the *local* media from the disk of your own server.
 This includes any local thumbnails and copies of media downloaded from
diff --git a/docs/admin_api/user_admin_api.rst b/docs/admin_api/user_admin_api.rst
index e4d6f820..b3d413cf 100644
--- a/docs/admin_api/user_admin_api.rst
+++ b/docs/admin_api/user_admin_api.rst
@@ -98,6 +98,8 @@ Body parameters:
 
 - ``deactivated``, optional. If unspecified, deactivation state will be left
   unchanged on existing accounts and set to ``false`` for new accounts.
+  A user cannot be erased by deactivating with this API. For details on deactivating users see
+  `Deactivate Account <#deactivate-account>`_.
 
 If the user already exists then optional parameters default to the current value.
 
@@ -248,6 +250,25 @@ server admin: see `README.rst <README.rst>`_.
 The erase parameter is optional and defaults to ``false``.
 An empty body may be passed for backwards compatibility.
 
+The following actions are performed when deactivating an user:
+
+- Try to unpind 3PIDs from the identity server
+- Remove all 3PIDs from the homeserver
+- Delete all devices and E2EE keys
+- Delete all access tokens
+- Delete the password hash
+- Removal from all rooms the user is a member of
+- Remove the user from the user directory
+- Reject all pending invites
+- Remove all account validity information related to the user
+
+The following additional actions are performed during deactivation if``erase``
+is set to ``true``:
+
+- Remove the user's display name
+- Remove the user's avatar URL
+- Mark the user as erased
+
 
 Reset password
 ==============
@@ -337,6 +358,10 @@ A response body like the following is returned:
         "total": 2
     }
 
+The server returns the list of rooms of which the user and the server
+are member. If the user is local, all the rooms of which the user is
+member are returned.
+
 **Parameters**
 
 The following parameters should be set in the URL:
diff --git a/docs/auth_chain_diff.dot b/docs/auth_chain_diff.dot
new file mode 100644
index 00000000..978d579a
--- /dev/null
+++ b/docs/auth_chain_diff.dot
@@ -0,0 +1,32 @@
+digraph auth {
+    nodesep=0.5;
+    rankdir="RL";
+
+    C [label="Create (1,1)"];
+
+    BJ [label="Bob's Join (2,1)", color=red];
+    BJ2 [label="Bob's Join (2,2)", color=red];
+    BJ2 -> BJ [color=red, dir=none];
+
+    subgraph cluster_foo {
+        A1 [label="Alice's invite (4,1)", color=blue];
+        A2 [label="Alice's Join (4,2)", color=blue];
+        A3 [label="Alice's Join (4,3)", color=blue];
+        A3 -> A2 -> A1 [color=blue, dir=none];
+        color=none;
+    }
+
+    PL1 [label="Power Level (3,1)", color=darkgreen];
+    PL2 [label="Power Level (3,2)", color=darkgreen];
+    PL2 -> PL1 [color=darkgreen, dir=none];
+
+    {rank = same; C; BJ; PL1; A1;}
+
+    A1 -> C [color=grey];
+    A1 -> BJ [color=grey];
+    PL1 -> C [color=grey];
+    BJ2 -> PL1 [penwidth=2];
+
+    A3 -> PL2 [penwidth=2];
+    A1 -> PL1 -> BJ -> C [penwidth=2];
+}
diff --git a/docs/auth_chain_diff.dot.png b/docs/auth_chain_diff.dot.png
new file mode 100644
index 00000000..771c0730
--- /dev/null
+++ b/docs/auth_chain_diff.dot.png
diff --git a/docs/auth_chain_difference_algorithm.md b/docs/auth_chain_difference_algorithm.md
new file mode 100644
index 00000000..30f72a70
--- /dev/null
+++ b/docs/auth_chain_difference_algorithm.md
@@ -0,0 +1,108 @@
+# Auth Chain Difference Algorithm
+
+The auth chain difference algorithm is used by V2 state resolution, where a
+naive implementation can be a significant source of CPU and DB usage.
+
+### Definitions
+
+A *state set* is a set of state events; e.g. the input of a state resolution
+algorithm is a collection of state sets.
+
+The *auth chain* of a set of events are all the events' auth events and *their*
+auth events, recursively (i.e. the events reachable by walking the graph induced
+by an event's auth events links).
+
+The *auth chain difference* of a collection of state sets is the union minus the
+intersection of the sets of auth chains corresponding to the state sets, i.e an
+event is in the auth chain difference if it is reachable by walking the auth
+event graph from at least one of the state sets but not from *all* of the state
+sets.
+
+## Breadth First Walk Algorithm
+
+A way of calculating the auth chain difference without calculating the full auth
+chains for each state set is to do a parallel breadth first walk (ordered by
+depth) of each state set's auth chain. By tracking which events are reachable
+from each state set we can finish early if every pending event is reachable from
+every state set.
+
+This can work well for state sets that have a small auth chain difference, but
+can be very inefficient for larger differences. However, this algorithm is still
+used if we don't have a chain cover index for the room (e.g. because we're in
+the process of indexing it).
+
+## Chain Cover Index
+
+Synapse computes auth chain differences by pre-computing a "chain cover" index
+for the auth chain in a room, allowing efficient reachability queries like "is
+event A in the auth chain of event B". This is done by assigning every event a
+*chain ID* and *sequence number* (e.g. `(5,3)`), and having a map of *links*
+between chains (e.g. `(5,3) -> (2,4)`) such that A is reachable by B (i.e. `A`
+is in the auth chain of `B`) if and only if either:
+
+1. A and B have the same chain ID and `A`'s sequence number is less than `B`'s
+   sequence number; or
+2. there is a link `L` between `B`'s chain ID and `A`'s chain ID such that
+   `L.start_seq_no` <= `B.seq_no` and `A.seq_no` <= `L.end_seq_no`.
+
+There are actually two potential implementations, one where we store links from
+each chain to every other reachable chain (the transitive closure of the links
+graph), and one where we remove redundant links (the transitive reduction of the
+links graph) e.g. if we have chains `C3 -> C2 -> C1` then the link `C3 -> C1`
+would not be stored. Synapse uses the former implementations so that it doesn't
+need to recurse to test reachability between chains.
+
+### Example
+
+An example auth graph would look like the following, where chains have been
+formed based on type/state_key and are denoted by colour and are labelled with
+`(chain ID, sequence number)`. Links are denoted by the arrows (links in grey
+are those that would be remove in the second implementation described above).
+
+![Example](auth_chain_diff.dot.png)
+
+Note that we don't include all links between events and their auth events, as
+most of those links would be redundant. For example, all events point to the
+create event, but each chain only needs the one link from it's base to the
+create event.
+
+## Using the Index
+
+This index can be used to calculate the auth chain difference of the state sets
+by looking at the chain ID and sequence numbers reachable from each state set:
+
+1. For every state set lookup the chain ID/sequence numbers of each state event
+2. Use the index to find all chains and the maximum sequence number reachable
+   from each state set.
+3. The auth chain difference is then all events in each chain that have sequence
+   numbers between the maximum sequence number reachable from *any* state set and
+   the minimum reachable by *all* state sets (if any).
+
+Note that steps 2 is effectively calculating the auth chain for each state set
+(in terms of chain IDs and sequence numbers), and step 3 is calculating the
+difference between the union and intersection of the auth chains.
+
+### Worked Example
+
+For example, given the above graph, we can calculate the difference between
+state sets consisting of:
+
+1. `S1`: Alice's invite `(4,1)` and Bob's second join `(2,2)`; and
+2. `S2`: Alice's second join `(4,3)` and Bob's first join `(2,1)`.
+
+Using the index we see that the following auth chains are reachable from each
+state set:
+
+1. `S1`: `(1,1)`, `(2,2)`, `(3,1)` & `(4,1)`
+2. `S2`: `(1,1)`, `(2,1)`, `(3,2)` & `(4,3)`
+
+And so, for each the ranges that are in the auth chain difference:
+1. Chain 1: None, (since everything can reach the create event).
+2. Chain 2: The range `(1, 2]` (i.e. just `2`), as `1` is reachable by all state
+   sets and the maximum reachable is `2` (corresponding to Bob's second join).
+3. Chain 3: Similarly the range `(1, 2]` (corresponding to the second power
+   level).
+4. Chain 4: The range `(1, 3]` (corresponding to both of Alice's joins).
+
+So the final result is: Bob's second join `(2,2)`, the second power level
+`(3,2)` and both of Alice's joins `(4,2)` & `(4,3)`.
diff --git a/docs/openid.md b/docs/openid.md
index da391f74..b86ae897 100644
--- a/docs/openid.md
+++ b/docs/openid.md
@@ -42,11 +42,10 @@ as follows:
  * For other installation mechanisms, see the documentation provided by the
    maintainer.
 
-To enable the OpenID integration, you should then add an `oidc_config` section
-to your configuration file (or uncomment the `enabled: true` line in the
-existing section). See [sample_config.yaml](./sample_config.yaml) for some
-sample settings, as well as the text below for example configurations for
-specific providers.
+To enable the OpenID integration, you should then add a section to the `oidc_providers`
+setting in your configuration file (or uncomment one of the existing examples).
+See [sample_config.yaml](./sample_config.yaml) for some sample settings, as well as 
+the text below for example configurations for specific providers.
 
 ## Sample configs
 
@@ -62,20 +61,21 @@ Directory (tenant) ID as it will be used in the Azure links.
 Edit your Synapse config file and change the `oidc_config` section:
 
 ```yaml
-oidc_config:
-   enabled: true
-   issuer: "https://login.microsoftonline.com/<tenant id>/v2.0"
-   client_id: "<client id>"
-   client_secret: "<client secret>"
-   scopes: ["openid", "profile"]
-   authorization_endpoint: "https://login.microsoftonline.com/<tenant id>/oauth2/v2.0/authorize"
-   token_endpoint: "https://login.microsoftonline.com/<tenant id>/oauth2/v2.0/token"
-   userinfo_endpoint: "https://graph.microsoft.com/oidc/userinfo"
-
-   user_mapping_provider:
-     config:
-       localpart_template: "{{ user.preferred_username.split('@')[0] }}"
-       display_name_template: "{{ user.name }}"
+oidc_providers:
+  - idp_id: microsoft
+    idp_name: Microsoft
+    issuer: "https://login.microsoftonline.com/<tenant id>/v2.0"
+    client_id: "<client id>"
+    client_secret: "<client secret>"
+    scopes: ["openid", "profile"]
+    authorization_endpoint: "https://login.microsoftonline.com/<tenant id>/oauth2/v2.0/authorize"
+    token_endpoint: "https://login.microsoftonline.com/<tenant id>/oauth2/v2.0/token"
+    userinfo_endpoint: "https://graph.microsoft.com/oidc/userinfo"
+
+    user_mapping_provider:
+      config:
+        localpart_template: "{{ user.preferred_username.split('@')[0] }}"
+        display_name_template: "{{ user.name }}"
 ```
 
 ### [Dex][dex-idp]
@@ -103,17 +103,18 @@ Run with `dex serve examples/config-dev.yaml`.
 Synapse config:
 
 ```yaml
-oidc_config:
-   enabled: true
-   skip_verification: true # This is needed as Dex is served on an insecure endpoint
-   issuer: "http://127.0.0.1:5556/dex"
-   client_id: "synapse"
-   client_secret: "secret"
-   scopes: ["openid", "profile"]
-   user_mapping_provider:
-     config:
-       localpart_template: "{{ user.name }}"
-       display_name_template: "{{ user.name|capitalize }}"
+oidc_providers:
+  - idp_id: dex
+    idp_name: "My Dex server"
+    skip_verification: true # This is needed as Dex is served on an insecure endpoint
+    issuer: "http://127.0.0.1:5556/dex"
+    client_id: "synapse"
+    client_secret: "secret"
+    scopes: ["openid", "profile"]
+    user_mapping_provider:
+      config:
+        localpart_template: "{{ user.name }}"
+        display_name_template: "{{ user.name|capitalize }}"
 ```
 ### [Keycloak][keycloak-idp]
 
@@ -152,12 +153,17 @@ Follow the [Getting Started Guide](https://www.keycloak.org/getting-started) to
 8. Copy Secret
 
 ```yaml
-oidc_config:
-   enabled: true
-   issuer: "https://127.0.0.1:8443/auth/realms/{realm_name}"
-   client_id: "synapse"
-   client_secret: "copy secret generated from above"
-   scopes: ["openid", "profile"]
+oidc_providers:
+  - idp_id: keycloak
+    idp_name: "My KeyCloak server"
+    issuer: "https://127.0.0.1:8443/auth/realms/{realm_name}"
+    client_id: "synapse"
+    client_secret: "copy secret generated from above"
+    scopes: ["openid", "profile"]
+    user_mapping_provider:
+      config:
+        localpart_template: "{{ user.preferred_username }}"
+        display_name_template: "{{ user.name }}"
 ```
 ### [Auth0][auth0]
 
@@ -187,16 +193,17 @@ oidc_config:
 Synapse config:
 
 ```yaml
-oidc_config:
-   enabled: true
-   issuer: "https://your-tier.eu.auth0.com/" # TO BE FILLED
-   client_id: "your-client-id" # TO BE FILLED
-   client_secret: "your-client-secret" # TO BE FILLED
-   scopes: ["openid", "profile"]
-   user_mapping_provider:
-     config:
-       localpart_template: "{{ user.preferred_username }}"
-       display_name_template: "{{ user.name }}"
+oidc_providers:
+  - idp_id: auth0 
+    idp_name: Auth0
+    issuer: "https://your-tier.eu.auth0.com/" # TO BE FILLED
+    client_id: "your-client-id" # TO BE FILLED
+    client_secret: "your-client-secret" # TO BE FILLED
+    scopes: ["openid", "profile"]
+    user_mapping_provider:
+      config:
+        localpart_template: "{{ user.preferred_username }}"
+        display_name_template: "{{ user.name }}"
 ```
 
 ### GitHub
@@ -215,21 +222,22 @@ does not return a `sub` property, an alternative `subject_claim` has to be set.
 Synapse config:
 
 ```yaml
-oidc_config:
-   enabled: true
-   discover: false
-   issuer: "https://github.com/"
-   client_id: "your-client-id" # TO BE FILLED
-   client_secret: "your-client-secret" # TO BE FILLED
-   authorization_endpoint: "https://github.com/login/oauth/authorize"
-   token_endpoint: "https://github.com/login/oauth/access_token"
-   userinfo_endpoint: "https://api.github.com/user"
-   scopes: ["read:user"]
-   user_mapping_provider:
-     config:
-       subject_claim: "id"
-       localpart_template: "{{ user.login }}"
-       display_name_template: "{{ user.name }}"
+oidc_providers:
+  - idp_id: github
+    idp_name: Github
+    discover: false
+    issuer: "https://github.com/"
+    client_id: "your-client-id" # TO BE FILLED
+    client_secret: "your-client-secret" # TO BE FILLED
+    authorization_endpoint: "https://github.com/login/oauth/authorize"
+    token_endpoint: "https://github.com/login/oauth/access_token"
+    userinfo_endpoint: "https://api.github.com/user"
+    scopes: ["read:user"]
+    user_mapping_provider:
+      config:
+        subject_claim: "id"
+        localpart_template: "{{ user.login }}"
+        display_name_template: "{{ user.name }}"
 ```
 
 ### [Google][google-idp]
@@ -239,16 +247,17 @@ oidc_config:
 2. add an "OAuth Client ID" for a Web Application under "Credentials".
 3. Copy the Client ID and Client Secret, and add the following to your synapse config:
    ```yaml
-   oidc_config:
-     enabled: true
-     issuer: "https://accounts.google.com/"
-     client_id: "your-client-id" # TO BE FILLED
-     client_secret: "your-client-secret" # TO BE FILLED
-     scopes: ["openid", "profile"]
-     user_mapping_provider:
-       config:
-         localpart_template: "{{ user.given_name|lower }}"
-         display_name_template: "{{ user.name }}"
+   oidc_providers:
+     - idp_id: google
+       idp_name: Google
+       issuer: "https://accounts.google.com/"
+       client_id: "your-client-id" # TO BE FILLED
+       client_secret: "your-client-secret" # TO BE FILLED
+       scopes: ["openid", "profile"]
+       user_mapping_provider:
+         config:
+           localpart_template: "{{ user.given_name|lower }}"
+           display_name_template: "{{ user.name }}"
    ```
 4. Back in the Google console, add this Authorized redirect URI: `[synapse
    public baseurl]/_synapse/oidc/callback`.
@@ -262,16 +271,17 @@ oidc_config:
 Synapse config:
 
 ```yaml
-oidc_config:
-  enabled: true
-  issuer: "https://id.twitch.tv/oauth2/"
-  client_id: "your-client-id" # TO BE FILLED
-  client_secret: "your-client-secret" # TO BE FILLED
-  client_auth_method: "client_secret_post"
-  user_mapping_provider:
-    config:
-      localpart_template: "{{ user.preferred_username }}"
-      display_name_template: "{{ user.name }}"
+oidc_providers:
+  - idp_id: twitch
+    idp_name: Twitch
+    issuer: "https://id.twitch.tv/oauth2/"
+    client_id: "your-client-id" # TO BE FILLED
+    client_secret: "your-client-secret" # TO BE FILLED
+    client_auth_method: "client_secret_post"
+    user_mapping_provider:
+      config:
+        localpart_template: "{{ user.preferred_username }}"
+        display_name_template: "{{ user.name }}"
 ```
 
 ### GitLab
@@ -283,16 +293,17 @@ oidc_config:
 Synapse config:
 
 ```yaml
-oidc_config:
-  enabled: true
-  issuer: "https://gitlab.com/"
-  client_id: "your-client-id" # TO BE FILLED
-  client_secret: "your-client-secret" # TO BE FILLED
-  client_auth_method: "client_secret_post"
-  scopes: ["openid", "read_user"]
-  user_profile_method: "userinfo_endpoint"
-  user_mapping_provider:
-    config:
-      localpart_template: '{{ user.nickname }}'
-      display_name_template: '{{ user.name }}'
+oidc_providers:
+  - idp_id: gitlab
+    idp_name: Gitlab
+    issuer: "https://gitlab.com/"
+    client_id: "your-client-id" # TO BE FILLED
+    client_secret: "your-client-secret" # TO BE FILLED
+    client_auth_method: "client_secret_post"
+    scopes: ["openid", "read_user"]
+    user_profile_method: "userinfo_endpoint"
+    user_mapping_provider:
+      config:
+        localpart_template: '{{ user.nickname }}'
+        display_name_template: '{{ user.name }}'
 ```
diff --git a/docs/postgres.md b/docs/postgres.md
index c30cc1fd..680685d0 100644
--- a/docs/postgres.md
+++ b/docs/postgres.md
@@ -18,7 +18,7 @@ connect to a postgres database.
     virtualenv](../INSTALL.md#installing-from-source), you can install
     the library with:
 
-        ~/synapse/env/bin/pip install matrix-synapse[postgres]
+        ~/synapse/env/bin/pip install "matrix-synapse[postgres]"
 
     (substituting the path to your virtualenv for `~/synapse/env`, if
     you used a different path). You will require the postgres
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index dd981609..87bfe222 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -67,11 +67,16 @@ pid_file: DATADIR/homeserver.pid
 #
 #web_client_location: https://riot.example.com/
 
-# The public-facing base URL that clients use to access this HS
-# (not including _matrix/...). This is the same URL a user would
-# enter into the 'custom HS URL' field on their client. If you
-# use synapse with a reverse proxy, this should be the URL to reach
-# synapse via the proxy.
+# The public-facing base URL that clients use to access this Homeserver (not
+# including _matrix/...). This is the same URL a user might enter into the
+# 'Custom Homeserver URL' field on their client. If you use Synapse with a
+# reverse proxy, this should be the URL to reach Synapse via the proxy.
+# Otherwise, it should be the URL to reach Synapse's client HTTP listener (see
+# 'listeners' below).
+#
+# If this is left unset, it defaults to 'https://<server_name>/'. (Note that
+# that will not work unless you configure Synapse or a reverse-proxy to listen
+# on port 443.)
 #
 #public_baseurl: https://example.com/
 
@@ -1150,8 +1155,9 @@ account_validity:
   # send an email to the account's email address with a renewal link. By
   # default, no such emails are sent.
   #
-  # If you enable this setting, you will also need to fill out the 'email' and
-  # 'public_baseurl' configuration sections.
+  # If you enable this setting, you will also need to fill out the 'email'
+  # configuration section. You should also check that 'public_baseurl' is set
+  # correctly.
   #
   #renew_at: 1w
 
@@ -1242,8 +1248,7 @@ account_validity:
 # The identity server which we suggest that clients should use when users log
 # in on this server.
 #
-# (By default, no suggestion is made, so it is left up to the client.
-# This setting is ignored unless public_baseurl is also set.)
+# (By default, no suggestion is made, so it is left up to the client.)
 #
 #default_identity_server: https://matrix.org
 
@@ -1268,8 +1273,6 @@ account_validity:
 # by the Matrix Identity Service API specification:
 # https://matrix.org/docs/spec/identity_service/latest
 #
-# If a delegate is specified, the config option public_baseurl must also be filled out.
-#
 account_threepid_delegates:
     #email: https://example.com     # Delegate email sending to example.com
     #msisdn: http://localhost:8090  # Delegate SMS sending to this local process
@@ -1709,141 +1712,158 @@ saml2_config:
   #idp_entityid: 'https://our_idp/entityid'
 
 
-# Enable OpenID Connect (OIDC) / OAuth 2.0 for registration and login.
+# List of OpenID Connect (OIDC) / OAuth 2.0 identity providers, for registration
+# and login.
 #
-# See https://github.com/matrix-org/synapse/blob/master/docs/openid.md
-# for some example configurations.
+# Options for each entry include:
 #
-oidc_config:
-  # Uncomment the following to enable authorization against an OpenID Connect
-  # server. Defaults to false.
-  #
-  #enabled: true
-
-  # Uncomment the following to disable use of the OIDC discovery mechanism to
-  # discover endpoints. Defaults to true.
-  #
-  #discover: false
-
-  # the OIDC issuer. Used to validate tokens and (if discovery is enabled) to
-  # discover the provider's endpoints.
-  #
-  # Required if 'enabled' is true.
-  #
-  #issuer: "https://accounts.example.com/"
-
-  # oauth2 client id to use.
-  #
-  # Required if 'enabled' is true.
-  #
-  #client_id: "provided-by-your-issuer"
-
-  # oauth2 client secret to use.
-  #
-  # Required if 'enabled' is true.
-  #
-  #client_secret: "provided-by-your-issuer"
-
-  # auth method to use when exchanging the token.
-  # Valid values are 'client_secret_basic' (default), 'client_secret_post' and
-  # 'none'.
-  #
-  #client_auth_method: client_secret_post
-
-  # list of scopes to request. This should normally include the "openid" scope.
-  # Defaults to ["openid"].
-  #
-  #scopes: ["openid", "profile"]
-
-  # the oauth2 authorization endpoint. Required if provider discovery is disabled.
-  #
-  #authorization_endpoint: "https://accounts.example.com/oauth2/auth"
-
-  # the oauth2 token endpoint. Required if provider discovery is disabled.
-  #
-  #token_endpoint: "https://accounts.example.com/oauth2/token"
-
-  # the OIDC userinfo endpoint. Required if discovery is disabled and the
-  # "openid" scope is not requested.
-  #
-  #userinfo_endpoint: "https://accounts.example.com/userinfo"
-
-  # URI where to fetch the JWKS. Required if discovery is disabled and the
-  # "openid" scope is used.
-  #
-  #jwks_uri: "https://accounts.example.com/.well-known/jwks.json"
-
-  # Uncomment to skip metadata verification. Defaults to false.
-  #
-  # Use this if you are connecting to a provider that is not OpenID Connect
-  # compliant.
-  # Avoid this in production.
-  #
-  #skip_verification: true
-
-  # Whether to fetch the user profile from the userinfo endpoint. Valid
-  # values are: "auto" or "userinfo_endpoint".
-  #
-  # Defaults to "auto", which fetches the userinfo endpoint if "openid" is included
-  # in `scopes`. Uncomment the following to always fetch the userinfo endpoint.
-  #
-  #user_profile_method: "userinfo_endpoint"
-
-  # Uncomment to allow a user logging in via OIDC to match a pre-existing account instead
-  # of failing. This could be used if switching from password logins to OIDC. Defaults to false.
-  #
-  #allow_existing_users: true
-
-  # An external module can be provided here as a custom solution to mapping
-  # attributes returned from a OIDC provider onto a matrix user.
-  #
-  user_mapping_provider:
-    # The custom module's class. Uncomment to use a custom module.
-    # Default is 'synapse.handlers.oidc_handler.JinjaOidcMappingProvider'.
-    #
-    # See https://github.com/matrix-org/synapse/blob/master/docs/sso_mapping_providers.md#openid-mapping-providers
-    # for information on implementing a custom mapping provider.
-    #
-    #module: mapping_provider.OidcMappingProvider
-
-    # Custom configuration values for the module. This section will be passed as
-    # a Python dictionary to the user mapping provider module's `parse_config`
-    # method.
-    #
-    # The examples below are intended for the default provider: they should be
-    # changed if using a custom provider.
-    #
-    config:
-      # name of the claim containing a unique identifier for the user.
-      # Defaults to `sub`, which OpenID Connect compliant providers should provide.
-      #
-      #subject_claim: "sub"
-
-      # Jinja2 template for the localpart of the MXID.
-      #
-      # When rendering, this template is given the following variables:
-      #   * user: The claims returned by the UserInfo Endpoint and/or in the ID
-      #     Token
-      #
-      # If this is not set, the user will be prompted to choose their
-      # own username.
-      #
-      #localpart_template: "{{ user.preferred_username }}"
-
-      # Jinja2 template for the display name to set on first login.
-      #
-      # If unset, no displayname will be set.
-      #
-      #display_name_template: "{{ user.given_name }} {{ user.last_name }}"
-
-      # Jinja2 templates for extra attributes to send back to the client during
-      # login.
-      #
-      # Note that these are non-standard and clients will ignore them without modifications.
-      #
-      #extra_attributes:
-        #birthdate: "{{ user.birthdate }}"
-
+#   idp_id: a unique identifier for this identity provider. Used internally
+#       by Synapse; should be a single word such as 'github'.
+#
+#       Note that, if this is changed, users authenticating via that provider
+#       will no longer be recognised as the same user!
+#
+#   idp_name: A user-facing name for this identity provider, which is used to
+#       offer the user a choice of login mechanisms.
+#
+#   idp_icon: An optional icon for this identity provider, which is presented
+#       by identity picker pages. If given, must be an MXC URI of the format
+#       mxc://<server-name>/<media-id>. (An easy way to obtain such an MXC URI
+#       is to upload an image to an (unencrypted) room and then copy the "url"
+#       from the source of the event.)
+#
+#   discover: set to 'false' to disable the use of the OIDC discovery mechanism
+#       to discover endpoints. Defaults to true.
+#
+#   issuer: Required. The OIDC issuer. Used to validate tokens and (if discovery
+#       is enabled) to discover the provider's endpoints.
+#
+#   client_id: Required. oauth2 client id to use.
+#
+#   client_secret: Required. oauth2 client secret to use.
+#
+#   client_auth_method: auth method to use when exchanging the token. Valid
+#       values are 'client_secret_basic' (default), 'client_secret_post' and
+#       'none'.
+#
+#   scopes: list of scopes to request. This should normally include the "openid"
+#       scope. Defaults to ["openid"].
+#
+#   authorization_endpoint: the oauth2 authorization endpoint. Required if
+#       provider discovery is disabled.
+#
+#   token_endpoint: the oauth2 token endpoint. Required if provider discovery is
+#       disabled.
+#
+#   userinfo_endpoint: the OIDC userinfo endpoint. Required if discovery is
+#       disabled and the 'openid' scope is not requested.
+#
+#   jwks_uri: URI where to fetch the JWKS. Required if discovery is disabled and
+#       the 'openid' scope is used.
+#
+#   skip_verification: set to 'true' to skip metadata verification. Use this if
+#       you are connecting to a provider that is not OpenID Connect compliant.
+#       Defaults to false. Avoid this in production.
+#
+#   user_profile_method: Whether to fetch the user profile from the userinfo
+#       endpoint. Valid values are: 'auto' or 'userinfo_endpoint'.
+#
+#       Defaults to 'auto', which fetches the userinfo endpoint if 'openid' is
+#       included in 'scopes'. Set to 'userinfo_endpoint' to always fetch the
+#       userinfo endpoint.
+#
+#   allow_existing_users: set to 'true' to allow a user logging in via OIDC to
+#       match a pre-existing account instead of failing. This could be used if
+#       switching from password logins to OIDC. Defaults to false.
+#
+#   user_mapping_provider: Configuration for how attributes returned from a OIDC
+#       provider are mapped onto a matrix user. This setting has the following
+#       sub-properties:
+#
+#       module: The class name of a custom mapping module. Default is
+#           'synapse.handlers.oidc_handler.JinjaOidcMappingProvider'.
+#           See https://github.com/matrix-org/synapse/blob/master/docs/sso_mapping_providers.md#openid-mapping-providers
+#           for information on implementing a custom mapping provider.
+#
+#       config: Configuration for the mapping provider module. This section will
+#           be passed as a Python dictionary to the user mapping provider
+#           module's `parse_config` method.
+#
+#           For the default provider, the following settings are available:
+#
+#             sub: name of the claim containing a unique identifier for the
+#                 user. Defaults to 'sub', which OpenID Connect compliant
+#                 providers should provide.
+#
+#             localpart_template: Jinja2 template for the localpart of the MXID.
+#                 If this is not set, the user will be prompted to choose their
+#                 own username.
+#
+#             display_name_template: Jinja2 template for the display name to set
+#                 on first login. If unset, no displayname will be set.
+#
+#             extra_attributes: a map of Jinja2 templates for extra attributes
+#                 to send back to the client during login.
+#                 Note that these are non-standard and clients will ignore them
+#                 without modifications.
+#
+#           When rendering, the Jinja2 templates are given a 'user' variable,
+#           which is set to the claims returned by the UserInfo Endpoint and/or
+#           in the ID Token.
+#
+# See https://github.com/matrix-org/synapse/blob/master/docs/openid.md
+# for information on how to configure these options.
+#
+# For backwards compatibility, it is also possible to configure a single OIDC
+# provider via an 'oidc_config' setting. This is now deprecated and admins are
+# advised to migrate to the 'oidc_providers' format. (When doing that migration,
+# use 'oidc' for the idp_id to ensure that existing users continue to be
+# recognised.)
+#
+oidc_providers:
+  # Generic example
+  #
+  #- idp_id: my_idp
+  #  idp_name: "My OpenID provider"
+  #  idp_icon: "mxc://example.com/mediaid"
+  #  discover: false
+  #  issuer: "https://accounts.example.com/"
+  #  client_id: "provided-by-your-issuer"
+  #  client_secret: "provided-by-your-issuer"
+  #  client_auth_method: client_secret_post
+  #  scopes: ["openid", "profile"]
+  #  authorization_endpoint: "https://accounts.example.com/oauth2/auth"
+  #  token_endpoint: "https://accounts.example.com/oauth2/token"
+  #  userinfo_endpoint: "https://accounts.example.com/userinfo"
+  #  jwks_uri: "https://accounts.example.com/.well-known/jwks.json"
+  #  skip_verification: true
+
+  # For use with Keycloak
+  #
+  #- idp_id: keycloak
+  #  idp_name: Keycloak
+  #  issuer: "https://127.0.0.1:8443/auth/realms/my_realm_name"
+  #  client_id: "synapse"
+  #  client_secret: "copy secret generated in Keycloak UI"
+  #  scopes: ["openid", "profile"]
+
+  # For use with Github
+  #
+  #- idp_id: github
+  #  idp_name: Github
+  #  discover: false
+  #  issuer: "https://github.com/"
+  #  client_id: "your-client-id" # TO BE FILLED
+  #  client_secret: "your-client-secret" # TO BE FILLED
+  #  authorization_endpoint: "https://github.com/login/oauth/authorize"
+  #  token_endpoint: "https://github.com/login/oauth/access_token"
+  #  userinfo_endpoint: "https://api.github.com/user"
+  #  scopes: ["read:user"]
+  #  user_mapping_provider:
+  #    config:
+  #      subject_claim: "id"
+  #      localpart_template: "{ user.login }"
+  #      display_name_template: "{ user.name }"
 
 
 # Enable Central Authentication Service (CAS) for registration and login.
@@ -1893,9 +1913,9 @@ sso:
     # phishing attacks from evil.site. To avoid this, include a slash after the
     # hostname: "https://my.client/".
     #
-    # If public_baseurl is set, then the login fallback page (used by clients
-    # that don't natively support the required login flows) is whitelisted in
-    # addition to any URLs in this list.
+    # The login fallback page (used by clients that don't natively support the
+    # required login flows) is automatically whitelisted in addition to any URLs
+    # in this list.
     #
     # By default, this list is empty.
     #
@@ -1909,6 +1929,31 @@ sso:
     #
     # Synapse will look for the following templates in this directory:
     #
+    # * HTML page to prompt the user to choose an Identity Provider during
+    #   login: 'sso_login_idp_picker.html'.
+    #
+    #   This is only used if multiple SSO Identity Providers are configured.
+    #
+    #   When rendering, this template is given the following variables:
+    #     * redirect_url: the URL that the user will be redirected to after
+    #       login. Needs manual escaping (see
+    #       https://jinja.palletsprojects.com/en/2.11.x/templates/#html-escaping).
+    #
+    #     * server_name: the homeserver's name.
+    #
+    #     * providers: a list of available Identity Providers. Each element is
+    #       an object with the following attributes:
+    #         * idp_id: unique identifier for the IdP
+    #         * idp_name: user-facing name for the IdP
+    #
+    #   The rendered HTML page should contain a form which submits its results
+    #   back as a GET request, with the following query parameters:
+    #
+    #     * redirectUrl: the client redirect URI (ie, the `redirect_url` passed
+    #       to the template)
+    #
+    #     * idp: the 'idp_id' of the chosen IDP.
+    #
     # * HTML page for a confirmation step before redirecting back to the client
     #   with the login token: 'sso_redirect_confirm.html'.
     #
@@ -1944,6 +1989,14 @@ sso:
     #
     #   This template has no additional variables.
     #
+    # * HTML page shown after a user-interactive authentication session which
+    #   does not map correctly onto the expected user: 'sso_auth_bad_user.html'.
+    #
+    #   When rendering, this template is given the following variables:
+    #     * server_name: the homeserver's name.
+    #     * user_id_to_verify: the MXID of the user that we are trying to
+    #       validate.
+    #
     # * HTML page shown during single sign-on if a deactivated user (according to Synapse's database)
     #   attempts to login: 'sso_account_deactivated.html'.
     #
diff --git a/docs/systemd-with-workers/README.md b/docs/systemd-with-workers/README.md
index 8e57d4f6..cfa36be7 100644
--- a/docs/systemd-with-workers/README.md
+++ b/docs/systemd-with-workers/README.md
@@ -31,7 +31,7 @@ There is no need for a separate configuration file for the master process.
 1. Adjust synapse configuration files as above.
 1. Copy the `*.service` and `*.target` files in [system](system) to
 `/etc/systemd/system`.
-1. Run `systemctl deamon-reload` to tell systemd to load the new unit files.
+1. Run `systemctl daemon-reload` to tell systemd to load the new unit files.
 1. Run `systemctl enable matrix-synapse.service`. This will configure the
 synapse master process to be started as part of the `matrix-synapse.target`
 target.
diff --git a/docs/workers.md b/docs/workers.md
index 298adf86..d0168368 100644
--- a/docs/workers.md
+++ b/docs/workers.md
@@ -16,6 +16,9 @@ workers only work with PostgreSQL-based Synapse deployments. SQLite should only
 be used for demo purposes and any admin considering workers should already be
 running PostgreSQL.
 
+See also https://matrix.org/blog/2020/11/03/how-we-fixed-synapses-scalability
+for a higher level overview.
+
 ## Main process/worker communication
 
 The processes communicate with each other via a Synapse-specific protocol called
@@ -56,7 +59,7 @@ The appropriate dependencies must also be installed for Synapse. If using a
 virtualenv, these can be installed with:
 
 ```sh
-pip install matrix-synapse[redis]
+pip install "matrix-synapse[redis]"
 ```
 
 Note that these dependencies are included when synapse is installed with `pip
@@ -214,6 +217,7 @@ expressions:
     ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/members$
     ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/state$
     ^/_matrix/client/(api/v1|r0|unstable)/account/3pid$
+    ^/_matrix/client/(api/v1|r0|unstable)/devices$
     ^/_matrix/client/(api/v1|r0|unstable)/keys/query$
     ^/_matrix/client/(api/v1|r0|unstable)/keys/changes$
     ^/_matrix/client/versions$