I have to sanitize a part of sql query. I can do something like this:
class << ActiveRecord::Base
public :sanitize_sql
end
str = ActiveRecord::Base.sanitize_sql(["AND column1 = ?", "two's"], '')
But it is not safe because I expose protected method. What is a better way to do it?
You can just use:
ActiveRecord::Base::sanitize_sql(string)
ActiveRecord::Base.connection.quote (at least in Rails 4)
sanitize) to the current working version as of Rails 6 (sanitize_sql). If someone wants a full explanation of all the sanitization methods, I'd suggest the docs.
This question does not specify that the answer has to come from ActiveRecord nor does it specify for which version of Rails it should be. For that reason (and because it is one of the top and few) answers on how to sanitize parameters in Rails...
Here a solution that works with Rails 4:
In ActiveRecord::Sanitization::ClassMethods you have sanitize_sql_for_conditions and its two other aliases:
sanitize_conditions and sanitize_sql. The three do literally the exact same thing.
sanitize_sql_for_conditions
Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a WHERE clause.
Also in ActiveRecord you have
sanitize_sql_for_assignment which
Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a SET clause.
See docs
Also, however, in ActionController you have ActionController::Parameters which allows you to
choose which attributes should be whitelisted for mass updating and thus prevent accidentally exposing that which shouldn't be exposed. Provides two methods for this purpose: require and permit.
params = ActionController::Parameters.new(user: { name: 'Bryan', age: 21 })
req = params.require(:user) # will throw exception if user not present
opt = params.permit(:name) # name parameter is optional, returns nil if not present
user = params.require(:user).permit(:name, :age) # user hash is required while `name` and `age` keys are optional
The "Parameters magic" is called Strong Parameters (docs here) and you can use that to sanitize parameters in a controller before sending it to a model.
ActionController::Base and therefore are included in any Rails controller.I hope that helps anyone, if only to learn and demystify Rails! :)
require and permit sanitize parameters against SQL injection, or just validate their presence?
require and permit don't do any sanitizing by themselves. But ActionController::Parameters.new does the sanitizing, so all of your controllers should already be sanitizing all parameters. I'll update my answer later when I have time because I also found this very cool gem called rails-html-sanitizer github.com/rails/rails-html-sanitizer
ActiveRecord::Base.connection.quote does the trick in Rails 3.x
As of rails 5 the recomended way is to use: ActiveRecord::Base.connection.quote(string)
as stated here: https://github.com/rails/rails/issues/28947
ActiveRecord::Base::sanitize(string) is deprecated
Note that when it comes to sanitizing SQL WHERE conditions, the best solution was sanitize_sql_hash_for_conditions, because it correctly handled NULL conditions (e.g. would generate IS NULL instead of = NULL if a nil attribute was passed).
For some reason, it was deprecated in Rails 5. So I rolled a future-proofed version, see here: https://stackoverflow.com/a/53948665/165673
sanitize_sqland friends are often called inside AR::Base-derived classes, without needing to alter visibility