You have encountered fairly typical policies for assessment: limit to one grade level above for reading, no above-level for math.
For better or worse, the teacher is being held responsible to each child to make one year of growth each year in each subject. For children learning slowly, their focus will be making sure those children make the year of growth. As "fast out of the gates" kids often hit plateaus in reading and math development relative to the assessments, there is a fear of evaluating a child at a 4th grade level in the start of 1st grade. They very well may still evaluate at a 4th grade level at the end of the year. Of course, a child taught at this level through the year might be making progress in story interpretation, vocabulary, and other skills not well-tested by their reading test.
Here are some strategies I've used with mixed success:
*Ask the teacher what her goals are your your son this year in reading/math. "What are your goals for my son this year in reading?" "How will he be led to make one year's worth of progress this year?" "What skills does he need to work on, and how are you doing this?" "Can you tell me what his reading instruction looks like from day to day?" This will the open the discussion either to the assessment limitation, or you will discover that the teacher is aware of the issue and has secondary goals that she's working on.
*Discuss engagement. Don't use the word bored. "Is this material engaging for Johnny?" "Why isn't it engaging?" "What can be done to make it more engaging?"
*Send in books from home to read during reading. Some teachers view this as passive aggressive, some see it as relief as their supply of above-level books might be limited. Fetching books for these kids from another class is sometimes surprisingly hard to make happen.
*For math, you might ask for her to pretest material and to provide extension work when he scores >90% on a given unit. Extension work is part of the second edition of Everyday Math (I'm guessing that's what you have because of the @#$% journal), but many teachers aren't aware it's there because the first edition didn't.
If the above fails, ask the principal to evaluate your child for a single-subject acceleration (grade skip for that subject) to allow your child to take these subjects with the next grade level up. If the school day is unchallenging across the board, consider a full grade acceleration. Often this requires an IQ test and a broad-spectrum achievement test. Even if the school turns you down on the acceleration, this is a good time to discuss regular (daily) differentiation with a teacher to meet your child's academic needs.
Whatever you do, work to keep the relationship between you, the teacher, and the administration as positive as possible, as you will need their continued support as you go through the grades. I take feedback on my kid's behavior very seriously, and I work to interpret it from the teacher's point of view. I don't make excuses for my child's behavior, but I do discuss the ways in which it sounds similar or different to what I see at home. I'll describe contrasts to what I observe in soccer or violin lessons if relevant. I take an approach of "wow, the teacher's got a problem, what can we do in putting together information about school and home to figure this out to help the child?"
I work very hard to avoid burning bridges. In our case, we burnt a bridge with my daughter's 2nd grade teacher. The consequence was that it negatively effected the outcome of an acceleration discussion for my son 3 years later. Because we've managed to keep the rest of the relationships positive, we've now seen multiple subject and whole-grade accelerations for my kids, such that an otherwise rigid school with limited above-level assessment has quite effectively met my kids' wacky needs.