CODEWITHSUNDEEP
sqlpython-2.7security
chmike
chmike

Reputation: 22154

Protecting against SQL injection in python

I have some code in Python that sets a char(80) value in an sqlite DB.

The string is obtained directly from the user through a text input field and sent back to the server with a POST method in a JSON structure.

On the server side I currently pass the string to a method calling the SQL UPDATE operation.

It works, but I'm aware it is not safe at all.

I expect that the client side is unsafe anyway, so any protection is to be put on the server side. What can I do to secure the UPDATE operation agains SQL injection ?

A function that would "quote" the text so that it can't confuse the SQL parser is what I'm looking for. I expect such function exist but couldn't find it.

Edit: Here is my current code setting the char field name label:

def setLabel( self, userId, refId, label ):
    self._db.cursor().execute( """
        UPDATE items SET label = ? WHERE userId IS ? AND refId IS ?""", ( label, userId, refId) )
    self._db.commit()

Upvotes: 18

Views: 55017

Answers (3)

Martijn
Martijn

Reputation: 12102

From the documentation:

con.execute("insert into person(firstname) values (?)", ("Joe",))

This escapes "Joe", so what you want is

con.execute("insert into person(firstname) values (?)", (firstname_from_client,))

Upvotes: 13

Gerrat
Gerrat

Reputation: 29690

Noooo... USE BIND VARIABLES! That's what they're there for. See this

Another name for the technique is parameterized sql (I think "bind variables" may be the name used with Oracle specifically).

Upvotes: 1

Alex K.
Alex K.

Reputation: 175776

The DB-API's .execute() supports parameter substitution which will take care of escaping for you, its mentioned near the top of the docs; http://docs.python.org/library/sqlite3.html above Never do this -- insecure.

Upvotes: 4

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