*: add privilege check for slow_query and cluster memory table

[crazycs520]

What problem does this PR solve?

Before this PR, TiDB doesn't have a privilege check on below tables:

• SLOW_QUERY
• CLUSTER_SLOW_QUERY
• CLUSTER_PROCESSLIST

Mainly, there is 2 points need to do:

First

For doing privilege checks in the cluster table, we need to add user and host info to RPC request. It needs to change the tipb protobuf, see PR: pingcap/tipb#169

Second

What kind of privilege is needed for query SLOW_QUERY? I think the information in SLOW_QUERY and PROCESSLIST is the same, So I use the same PROCESS privilege for checking SLOW_QUERY and CLUSTER_SLOW_QUERY privilege.

eg:

-- For user root: 
mysql -u root -h 127.0.0.1 -P 4000
tidb>select user,count(*) from `CLUSTER_SLOW_QUERY` group by user;
+------+----------+
| user | count(*) |
+------+----------+
| test | 2        |
| root | 95622    |
|      | 743      |       -- name is "" means it is a internal sql.
+------+----------+
tidb>select * from `CLUSTER_PROCESSLIST`;
+---------------+----+------+-----------+--------------------+---------+------+-------+-------------------------------------+-----+----------------------------------------+
| ADDRESS       | ID | USER | HOST      | DB                 | COMMAND | TIME | STATE | INFO                                | MEM | TxnStart                               |
+---------------+----+------+-----------+--------------------+---------+------+-------+-------------------------------------+-----+----------------------------------------+
| 0.0.0.0:10080 | 4  | test | 127.0.0.1 | information_schema | Sleep   | 131  | 2     | <null>                              | 0   |                                        |
| 0.0.0.0:10080 | 8  | test | 127.0.0.1 | <null>             | Query   | 40   | 2     | select sleep(100)                   | 0   |                                        |
| 0.0.0.0:10080 | 10 | root | 127.0.0.1 | <null>             | Query   | 27   | 2     | select sleep(100)                   | 0   |                                        |
| 0.0.0.0:10080 | 1  | root | 127.0.0.1 | information_schema | Query   | 0    | 2     | select * from `CLUSTER_PROCESSLIST` | 0   | 01-11 15:02:32.451(413853588508114945) |
+---------------+----+------+-----------+--------------------+---------+------+-------+-------------------------------------+-----+----------------------------------------+

-- At the same time:
-- For user test:
mysql -u test -h 127.0.0.1 -P 4000
tidb>select user,count(*) from `CLUSTER_SLOW_QUERY` group by user;
+------+----------+
| user | count(*) |
+------+----------+
| test | 2        |
+------+----------+
tidb>select * from `CLUSTER_PROCESSLIST`;
+---------------+----+------+-----------+--------------------+---------+------+-------+-------------------------------------+-----+----------------------------------------+
| ADDRESS       | ID | USER | HOST      | DB                 | COMMAND | TIME | STATE | INFO                                | MEM | TxnStart                               |
+---------------+----+------+-----------+--------------------+---------+------+-------+-------------------------------------+-----+----------------------------------------+
| 0.0.0.0:10080 | 8  | test | 127.0.0.1 | <null>             | Query   | 62   | 2     | select sleep(100)                   | 0   |                                        |
| 0.0.0.0:10080 | 4  | test | 127.0.0.1 | information_schema | Query   | 0    | 2     | select * from `CLUSTER_PROCESSLIST` | 0   | 01-11 15:02:54.450(413853594275020801) |
+---------------+----+------+-----------+--------------------+---------+------+-------+-------------------------------------+-----+----------------------------------------+

What is changed and how it works?

Check List

Tests

• Unit test
• Manual test (add detailed scripts or steps below)

Code changes

• Has exported function/method change

Side effects

Related changes

• Need to cherry-pick to the release branch

Release note

• Add privilege check for slow_query.

[crazycs520]

CI failed in go.mod, after tipb pr pingcap/tipb#169 merged and update go.mod, ci will happy.

[crazycs520]

@tiancaiamao PTAL

[tiancaiamao]

LGTM

[AilinKid]

Rest LGTM.

[reafans]

Rest LGTM. Wait for the CI fixed.

[crazycs520]

/run-all-tests

[crazycs520]

/rebuild

[crazycs520]

/rebuild

[crazycs520]

/rebuild

[crazycs520]

/rebuild

[crazycs520]

/rebuild

[crazycs520]

/rebuild

[crazycs520]

/rebuild

[crazycs520]

/rebuild

[crazycs520]

/rebuild

[reafans]

lgtm