37 lines
1.6 KiB
JavaScript
37 lines
1.6 KiB
JavaScript
// Expression parser security
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//
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// Executing arbitrary expressions like enabled by the expression parser of
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// mathjs involves a risk in general. When you're using mathjs to let users
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// execute arbitrary expressions, it's good to take a moment to think about
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// possible security and stability implications, especially when running the
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// code server side.
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//
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// There is a small number of functions which yield the biggest security risk
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// in the expression parser of math.js:
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//
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// - `import` and `createUnit` which alter the built-in functionality and allow
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// overriding existing functions and units.
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// - `evaluate`, `parse`, `simplify`, and `derivative` which parse arbitrary input
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// into a manipulable expression tree.
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//
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// To make the expression parser less vulnerable whilst still supporting most
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// functionality, these functions can be disabled, as demonstrated in this
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// example.
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const { create, all } = require('../..')
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const math = create(all)
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const limitedEvaluate = math.evaluate
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math.import({
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import: function () { throw new Error('Function import is disabled') },
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createUnit: function () { throw new Error('Function createUnit is disabled') },
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evaluate: function () { throw new Error('Function evaluate is disabled') },
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parse: function () { throw new Error('Function parse is disabled') },
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simplify: function () { throw new Error('Function simplify is disabled') },
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derivative: function () { throw new Error('Function derivative is disabled') }
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}, { override: true })
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console.log(limitedEvaluate('sqrt(16)')) // Ok, 4
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console.log(limitedEvaluate('parse("2+3")')) // Error: Function parse is disabled
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