SERVER-74124 Disallow shard key pattern with fields that have parts that start with '$'

(cherry picked from commit 71372698d18785a374aa09bdd646d3c5dc2f227a)

4 files changed, 77 insertions, 0 deletions

diff --git a/etc/backports_required_for_multiversion_tests.yml b/etc/backports_required_for_multiversion_tests.yml
index b936889ae67..16df2fce80a 100644
--- a/etc/backports_required_for_multiversion_tests.yml
+++ b/etc/backports_required_for_multiversion_tests.yml
@@ -310,6 +310,8 @@ last-continuous:
     ticket: SERVER-73822
   - test_file: jstests/sharding/internal_txns/incomplete_transaction_history_during_migration.js
     ticket: SERVER-73938
+  - test_file: jstests/sharding/shard_keys_with_dollar_sign.js
+    ticket: SERVER-74124
   suites: null
 last-lts:
   all:
@@ -695,4 +697,6 @@ last-lts:
     ticket: SERVER-73822
   - test_file: jstests/sharding/internal_txns/incomplete_transaction_history_during_migration.js
     ticket: SERVER-73938
+  - test_file: jstests/sharding/shard_keys_with_dollar_sign.js
+    ticket: SERVER-74124
   suites: null
diff --git a/jstests/sharding/shard_keys_with_dollar_sign.js b/jstests/sharding/shard_keys_with_dollar_sign.js
new file mode 100644
index 00000000000..5d18d6ab7ab
--- /dev/null
+++ b/jstests/sharding/shard_keys_with_dollar_sign.js
@@ -0,0 +1,57 @@
+/**
+ * Tests that the shardCollection command and reshardCollection command correctly reject a shard key
+ * that has a field name with parts that start with '$'.
+ */
+(function() {
+"use strict";
+
+const st = new ShardingTest({shards: 1});
+
+const dbName = "testDb";
+const ns0 = dbName + ".testColl0";
+const ns1 = dbName + ".testColl1";
+const ns2 = dbName + ".testColl2";
+const db = st.s.getDB(dbName);
+
+function testValidation(key, {isValidIndexKey, isValidShardKey}) {
+    jsTest.log(`Testing ${tojson({key, isValidIndexKey, isValidShardKey})}`);
+    assert.commandWorked(st.s.adminCommand({enableSharding: dbName}));
+    st.ensurePrimaryShard(dbName, st.shard0.name);
+
+    const createIndexRes = db.getCollection(ns0).createIndex(key);
+    if (isValidIndexKey) {
+        assert.commandWorked(createIndexRes);
+    } else {
+        assert.commandFailedWithCode(createIndexRes, ErrorCodes.CannotCreateIndex);
+    }
+
+    const shardCollectionRes = st.s.adminCommand({shardCollection: ns1, key});
+    if (isValidShardKey) {
+        assert.commandWorked(shardCollectionRes);
+    } else {
+        assert.commandFailedWithCode(shardCollectionRes, ErrorCodes.BadValue);
+    }
+
+    assert.commandWorked(st.s.adminCommand({shardCollection: ns2, key: {_id: 1}}));
+    const reshardCollectionRes = st.s.adminCommand({reshardCollection: ns2, key});
+    if (isValidShardKey) {
+        assert.commandWorked(reshardCollectionRes);
+    } else {
+        assert.commandFailedWithCode(reshardCollectionRes, ErrorCodes.BadValue);
+    }
+
+    assert.commandWorked(db.dropDatabase());
+}
+
+testValidation({"$x": 1}, {isValidIndexKey: false, isValidShardKey: false});
+testValidation({"x.$y": 1}, {isValidIndexKey: false, isValidShardKey: false});
+testValidation({"$**": 1}, {isValidIndexKey: true, isValidShardKey: false});
+testValidation({"x.$**": 1}, {isValidIndexKey: true, isValidShardKey: false});
+testValidation({"$": 1}, {isValidIndexKey: false, isValidShardKey: false});
+
+testValidation({"x$": 1}, {isValidIndexKey: true, isValidShardKey: true});
+testValidation({"x$.y": 1}, {isValidIndexKey: true, isValidShardKey: true});
+testValidation({"x.y$": 1}, {isValidIndexKey: true, isValidShardKey: true});
+
+st.stop();
+})();
diff --git a/src/mongo/s/shard_key_pattern.cpp b/src/mongo/s/shard_key_pattern.cpp
index db4dce94066..b782f426cc6 100644
--- a/src/mongo/s/shard_key_pattern.cpp
+++ b/src/mongo/s/shard_key_pattern.cpp
@@ -76,6 +76,11 @@ std::vector<std::unique_ptr<FieldRef>> parseShardKeyPattern(const BSONObj& keyPa
                     str::stream() << "Field " << patternEl.fieldNameStringData()
                                   << " contains empty parts",
                     !newFieldRef->getPart(i).empty());
+
+            uassert(ErrorCodes::BadValue,
+                    str::stream() << "Field " << patternEl.fieldNameStringData()
+                                  << " contains parts that start with '$'",
+                    newFieldRef->getPart(i).find("$") != 0);
         }
 
         // Numeric and ascending (1.0), or "hashed" with exactly hashed field.
diff --git a/src/mongo/s/shard_key_pattern_test.cpp b/src/mongo/s/shard_key_pattern_test.cpp
index a59f0494f73..bbbf6136ec7 100644
--- a/src/mongo/s/shard_key_pattern_test.cpp
+++ b/src/mongo/s/shard_key_pattern_test.cpp
@@ -66,6 +66,7 @@ TEST_F(ShardKeyPatternTest, SingleFieldShardKeyPatternsValidityCheck) {
     ShardKeyPattern s3(BSON("a" << (long long)1L));
     ShardKeyPattern s4(BSON("a"
                             << "hashed"));
+    ShardKeyPattern s5(BSON("a$" << 1));
 
     ASSERT_THROWS(ShardKeyPattern(BSONObj()), DBException);
     ASSERT_THROWS(ShardKeyPattern(BSON("a" << -1)), DBException);
@@ -78,6 +79,9 @@ TEST_F(ShardKeyPatternTest, SingleFieldShardKeyPatternsValidityCheck) {
                   DBException);
     ASSERT_THROWS(ShardKeyPattern(BSON("" << 1)), DBException);
     ASSERT_THROWS(ShardKeyPattern(BSON("." << 1)), DBException);
+    ASSERT_THROWS(ShardKeyPattern(BSON("$" << 1)), DBException);
+    ASSERT_THROWS(ShardKeyPattern(BSON("$a" << 1)), DBException);
+    ASSERT_THROWS(ShardKeyPattern(BSON("$**" << 1)), DBException);
 }
 
 TEST_F(ShardKeyPatternTest, CompositeShardKeyPatternsValidityCheck) {
@@ -91,6 +95,9 @@ TEST_F(ShardKeyPatternTest, CompositeShardKeyPatternsValidityCheck) {
                   DBException);
     ASSERT_THROWS(ShardKeyPattern(BSON("a" << 1 << "b." << 1.0)), DBException);
     ASSERT_THROWS(ShardKeyPattern(BSON("a" << 1 << "" << 1.0)), DBException);
+    ASSERT_THROWS(ShardKeyPattern(BSON("a" << 1 << "$" << 1.0)), DBException);
+    ASSERT_THROWS(ShardKeyPattern(BSON("a" << 1 << "$b" << 1.0)), DBException);
+    ASSERT_THROWS(ShardKeyPattern(BSON("a" << 1 << "$**" << 1.0)), DBException);
 }
 
 TEST_F(ShardKeyPatternTest, NestedShardKeyPatternsValidtyCheck) {
@@ -98,6 +105,7 @@ TEST_F(ShardKeyPatternTest, NestedShardKeyPatternsValidtyCheck) {
     ShardKeyPattern s2(BSON("a.b.c.d" << 1.0));
     ShardKeyPattern s3(BSON("a" << 1 << "c.d" << 1.0 << "e.f.g" << 1.0f));
     ShardKeyPattern s4(BSON("a" << 1 << "a.b" << 1.0 << "a.b.c" << 1.0f));
+    ShardKeyPattern s6(BSON("a.b$" << 1));
 
     ASSERT_THROWS(ShardKeyPattern(BSON("a.b" << -1)), DBException);
     ASSERT_THROWS(ShardKeyPattern(BSON("a" << BSON("b" << 1))), DBException);
@@ -106,6 +114,9 @@ TEST_F(ShardKeyPatternTest, NestedShardKeyPatternsValidtyCheck) {
     ASSERT_THROWS(ShardKeyPattern(BSON("a..b" << 1)), DBException);
     ASSERT_THROWS(ShardKeyPattern(BSON("a" << 1 << "a.b." << 1.0)), DBException);
     ASSERT_THROWS(ShardKeyPattern(BSON("a" << BSON("b" << 1) << "c.d" << 1.0)), DBException);
+    ASSERT_THROWS(ShardKeyPattern(BSON("a.$" << 1)), DBException);
+    ASSERT_THROWS(ShardKeyPattern(BSON("a.$b" << 1)), DBException);
+    ASSERT_THROWS(ShardKeyPattern(BSON("a.$**" << 1)), DBException);
 }
 
 TEST_F(ShardKeyPatternTest, IsShardKey) {