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KwstubbsKwstubbs
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Added support for Gin CORS
1 parent 70aa490 commit dafcd5e

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4 files changed

+153
-15
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4 files changed

+153
-15
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‎go/ql/lib/go.qll

+1
Original file line numberDiff line numberDiff line change
@@ -41,6 +41,7 @@ import semmle.go.frameworks.Email
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import semmle.go.frameworks.Encoding
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import semmle.go.frameworks.Fiber
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import semmle.go.frameworks.Gin
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import semmle.go.frameworks.GinCors
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import semmle.go.frameworks.Glog
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import semmle.go.frameworks.GoKit
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import semmle.go.frameworks.GoMicro

‎go/ql/lib/semmle/go/frameworks/GinCors.qll

+80
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@@ -0,0 +1,80 @@
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/**
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* Provides classes for working with untrusted flow sources from the `github.com/gin-gonic/gin` package.
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*/
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import go
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module GinCors {
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/** Gets the package name `github.com/gin-gonic/gin`. */
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string packagePath() { result = package("github.com/gin-contrib/cors", "") }
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/**
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* Data from a `Context` struct, considered as a source of untrusted flow.
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*/
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class New extends Function{
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New() {
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exists(Function f | f.hasQualifiedName(packagePath(), "New") | this = f)
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}
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}
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class Config extends Variable {
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Config() { this.hasQualifiedName(packagePath(), "Config") }
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// Field getAllowCredentials() {
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// result = this.getField("AllowCredentials")
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// }
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}
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class AllowCredentialsWrite extends DataFlow::ExprNode {
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DataFlow::Node base;
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GinConfig gc;
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AllowCredentialsWrite() {
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exists(Field f, Write w |
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f.hasQualifiedName(packagePath(), "Config", "AllowCredentials") and
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w.writesField(base, f, this) and
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this.getType() instanceof BoolType and
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(gc.getV().getBaseVariable().getDefinition().(SsaExplicitDefinition).getRhs() = base.asInstruction() or
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gc.getV().getAUse() = base)
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)
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}
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GinConfig getConfig() { result = gc}
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}
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class AllowOriginsWrite extends DataFlow::ExprNode {
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DataFlow::Node base;
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GinConfig gc;
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AllowOriginsWrite() {
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exists(Field f, Write w |
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f.hasQualifiedName(packagePath(), "Config", "AllowOrigins") and
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w.writesField(base, f, this) and
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this.asExpr() instanceof SliceLit and
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(gc.getV().getBaseVariable().getDefinition().(SsaExplicitDefinition).getRhs() = base.asInstruction() or
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gc.getV().getAUse() = base)
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)
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}
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GinConfig getConfig() { result = gc}
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}
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class AllowAllOriginsWrite extends DataFlow::ExprNode {
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DataFlow::Node base;
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AllowAllOriginsWrite() {
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exists(Field f, Write w |
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f.hasQualifiedName(packagePath(), "Config", "AllowAllOrigins") and
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w.writesField(base, f, this) and
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this.getType() instanceof BoolType
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//and this.asExpr().(SliceLit).getAnElement().toString().matches("%null%")
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)
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}
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DataFlow::Node getBase() { result = base}
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}
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class GinConfig extends Variable {
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SsaWithFields v;
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GinConfig() {
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this = v.getBaseVariable().getSourceVariable() and
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exists(Type t | t.hasQualifiedName(packagePath(), "Config") | v.getType() = t)
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}
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SsaWithFields getV() { result = v}
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}
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}
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‎go/ql/src/experimental/CWE-942/CorsMisconfiguration.ql

+46-15
Original file line numberDiff line numberDiff line change
@@ -69,22 +69,45 @@ module UntrustedToAllowOriginHeaderConfig implements DataFlow::ConfigSig {
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predicate isSink(DataFlow::Node sink) { isSinkHW(sink, _) }
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}
7171

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module UntrustedToAllowOriginConfigConfig implements DataFlow::ConfigSig {
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predicate isSource(DataFlow::Node source) { source instanceof UntrustedFlowSource }
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additional predicate isSinkWrite(DataFlow::Node sink, GinCors::AllowOriginsWrite w) {
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sink = w
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}
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predicate isSink(DataFlow::Node sink) { isSinkWrite(sink, _) }
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}
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/**
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* Tracks taint flowfor reasoning about when an `UntrustedFlowSource` flows to
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* a `HeaderWrite` that writes an `Access-Control-Allow-Origin` header's value.
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*/
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module UntrustedToAllowOriginHeaderFlow = TaintTracking::Global<UntrustedToAllowOriginHeaderConfig>;
7787

88+
module UntrustedToAllowOriginConfigFlow = TaintTracking::Global<UntrustedToAllowOriginConfigConfig>;
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7890
/**
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* Holds if the provided `allowOriginHW` HeaderWrite's parent ResponseWriter
8092
* also has another HeaderWrite that sets a `Access-Control-Allow-Credentials`
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* header to `true`.
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*/
83-
predicate allowCredentialsIsSetToTrue(AllowOriginHeaderWrite allowOriginHW) {
95+
predicate allowCredentialsIsSetToTrue(DataFlow::ExprNode allowOrigin) {
8496
exists(AllowCredentialsHeaderWrite allowCredentialsHW |
8597
allowCredentialsHW.getHeaderValue().toLowerCase() = "true"
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|
87-
allowOriginHW.getResponseWriter() = allowCredentialsHW.getResponseWriter()
99+
allowOrigin.(AllowOriginHeaderWrite).getResponseWriter() = allowCredentialsHW.getResponseWriter()
100+
)
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or
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exists(GinCors::AllowCredentialsWrite allowCredentialsGin |
103+
allowCredentialsGin.toString() = "true"
104+
|
105+
//flow only goes in one direction so fix this before PR
106+
allowCredentialsGin.getConfig() = allowOrigin.(GinCors::AllowOriginsWrite).getConfig()
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and
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not exists(GinCors::AllowAllOriginsWrite allowAllOrigins |
109+
allowAllOrigins.toString() = "true" //and DataFlow::localFlow(allowCredentialsGin.getBase(), allowAllOrigins.getBase())
110+
)
88111
)
89112
}
90113

@@ -93,10 +116,12 @@ predicate allowCredentialsIsSetToTrue(AllowOriginHeaderWrite allowOriginHW) {
93116
* UntrustedFlowSource.
94117
* The `message` parameter is populated with the warning message to be returned by the query.
95118
*/
96-
predicate flowsFromUntrustedToAllowOrigin(AllowOriginHeaderWrite allowOriginHW, string message) {
119+
predicate flowsFromUntrustedToAllowOrigin(DataFlow::ExprNode allowOriginHW, string message) {
97120
exists(DataFlow::Node sink |
98121
UntrustedToAllowOriginHeaderFlow::flowTo(sink) and
99-
UntrustedToAllowOriginHeaderConfig::isSinkHW(sink, allowOriginHW)
122+
UntrustedToAllowOriginHeaderConfig::isSinkHW(sink, allowOriginHW) or
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UntrustedToAllowOriginConfigFlow::flowTo(sink) and
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UntrustedToAllowOriginConfigConfig::isSinkWrite(sink, allowOriginHW)
100125
|
101126
message =
102127
headerAllowOrigin() + " header is set to a user-defined value, and " +
@@ -108,11 +133,17 @@ predicate flowsFromUntrustedToAllowOrigin(AllowOriginHeaderWrite allowOriginHW,
108133
* Holds if the provided `allowOriginHW` HeaderWrite is for a `Access-Control-Allow-Origin`
109134
* header and the value is set to `null`.
110135
*/
111-
predicate allowOriginIsNull(AllowOriginHeaderWrite allowOriginHW, string message) {
112-
allowOriginHW.getHeaderValue().toLowerCase() = "null" and
136+
predicate allowOriginIsNull(DataFlow::ExprNode allowOrigin, string message) {
137+
allowOrigin.(AllowOriginHeaderWrite).getHeaderValue().toLowerCase() = "null" and
113138
message =
114-
headerAllowOrigin() + " header is set to `" + allowOriginHW.getHeaderValue() + "`, and " +
139+
headerAllowOrigin() + " header is set to `" + allowOrigin.(AllowOriginHeaderWrite).getHeaderValue() + "`, and " +
115140
headerAllowCredentials() + " is set to `true`"
141+
or
142+
allowOrigin.(GinCors::AllowOriginsWrite).asExpr().(SliceLit).getAnElement().toString().matches("\"null%\"") and
143+
message =
144+
headerAllowOrigin() + " header is set to `" + allowOrigin.(GinCors::AllowOriginsWrite).asExpr().(SliceLit).getAnElement().toString() + "`, and " +
145+
headerAllowCredentials() + " is set to `true`"
146+
116147
}
117148

118149
/**
@@ -170,26 +201,26 @@ module FromUntrustedFlow = TaintTracking::Global<FromUntrustedConfig>;
170201
/**
171202
* Holds if the provided `allowOriginHW` is also destination of a `UntrustedFlowSource`.
172203
*/
173-
predicate flowsToGuardedByCheckOnUntrusted(AllowOriginHeaderWrite allowOriginHW) {
204+
predicate flowsToGuardedByCheckOnUntrusted(DataFlow::ExprNode allowOriginHW) {
174205
exists(DataFlow::Node sink, ControlFlow::ConditionGuardNode cgn |
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FromUntrustedFlow::flowTo(sink) and FromUntrustedConfig::isSinkCgn(sink, cgn)
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|
177208
cgn.dominates(allowOriginHW.getBasicBlock())
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)
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}
180211

181-
from AllowOriginHeaderWrite allowOriginHW, string message
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from DataFlow::ExprNode allowOrigin, string message
182213
where
183-
allowCredentialsIsSetToTrue(allowOriginHW) and
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allowCredentialsIsSetToTrue(allowOrigin) and
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(
185-
flowsFromUntrustedToAllowOrigin(allowOriginHW, message)
216+
flowsFromUntrustedToAllowOrigin(allowOrigin, message)
186217
or
187-
allowOriginIsNull(allowOriginHW, message)
218+
allowOriginIsNull(allowOrigin, message)
188219
) and
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not flowsToGuardedByCheckOnUntrusted(allowOriginHW) and
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not flowsToGuardedByCheckOnUntrusted(allowOrigin) and
190221
not exists(ControlFlow::ConditionGuardNode cgn |
191222
cgn.ensures(any(AllowedFlag f).getAFlag().getANode(), _)
192223
|
193-
cgn.dominates(allowOriginHW.getBasicBlock())
224+
cgn.dominates(allowOrigin.getBasicBlock())
194225
)
195-
select allowOriginHW, message
226+
select allowOrigin, message

‎go/ql/src/experimental/CWE-942/GinCors.ql

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@@ -0,0 +1,26 @@
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/**
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* @name CORS misconfiguration
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* @description If a CORS policy is configured to accept an origin value obtained from the request data,
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* or is set to `null`, and it allows credential sharing, then the users of the
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* application are vulnerable to the same range of attacks as in XSS (credential stealing, etc.).
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* @kind problem
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* @problem.severity warning
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* @id go/cors-misconfiguration
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* @tags security
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* experimental
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* external/cwe/cwe-942
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* external/cwe/cwe-346
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*/
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import go
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// from GinCors::New n, GinCors::Config cfg, DataFlow::CallNode c
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// //where n.getACall() = c and c.getArgument(0) = cfg
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// where cfg.getAllowCredentials() = "*"
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// select cfg, "hello"
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from GinCors::GinConfig gc
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select gc.getV().getBaseVariable().getDefinition().(SsaExplicitDefinition).getRhs(), "test"
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//where s.getAnElement().toString().matches("%https://foo.com%")
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//where a.getBase() = b.getBase()
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//select a.getBase(), b.getBase()

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