Restrict comparisons with pointers to legal operations #758
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Signed-off-by: Alan Jowett <[email protected]>
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Actionable comments posted: 1
🧹 Outside diff range and nitpick comments (4)
src/assertions.cpp (1)
140-164: LGTM! Consider using a lookup table for operation types.The implementation correctly restricts pointer comparisons to specific operations and ensures they're only allowed in 64-bit context, which is a good security measure. The logic is clear and well-structured.
Consider using a lookup table to simplify the switch statement:
- switch (cond.op) { - case Condition::Op::EQ: allow_pointers = true; break; - case Condition::Op::NE: allow_pointers = true; break; - case Condition::Op::SET: allow_pointers = true; break; - case Condition::Op::NSET: allow_pointers = true; break; - case Condition::Op::LT: allow_pointers = true; break; - case Condition::Op::LE: allow_pointers = true; break; - case Condition::Op::GT: allow_pointers = true; break; - case Condition::Op::GE: allow_pointers = true; break; - case Condition::Op::SLT: allow_pointers = false; break; - case Condition::Op::SLE: allow_pointers = false; break; - case Condition::Op::SGT: allow_pointers = false; break; - case Condition::Op::SGE: allow_pointers = false; break; - default: assert(!"unexpected condition"); - } + static const std::unordered_map<Condition::Op, bool> POINTER_ALLOWED = { + {Condition::Op::EQ, true}, + {Condition::Op::NE, true}, + {Condition::Op::SET, true}, + {Condition::Op::NSET, true}, + {Condition::Op::LT, true}, + {Condition::Op::LE, true}, + {Condition::Op::GT, true}, + {Condition::Op::GE, true}, + {Condition::Op::SLT, false}, + {Condition::Op::SLE, false}, + {Condition::Op::SGT, false}, + {Condition::Op::SGE, false} + }; + auto it = POINTER_ALLOWED.find(cond.op); + assert(it != POINTER_ALLOWED.end() && "unexpected condition"); + allow_pointers = it->second;src/test/ebpf_yaml.cpp (1)
195-196: Consider adding documentation for the new option.The addition of the
assume_assertionsoption looks correct, but it would be helpful to document its purpose and impact, especially since it affects the verifier's behavior. Consider adding a comment explaining:
- What assertions are assumed when this option is enabled
- The implications of enabling this option
- Any potential interactions with other options
+ } else if (name == "assume_assertions") { + // When enabled, the verifier assumes assertions during analysis, + // affecting how pointer comparisons are validated. + options.assume_assertions = true;test-data/jump.yaml (2)
720-1257: Consider improving test organization and documentation.While the test cases are comprehensive and well-structured, there are opportunities for improvement:
- The test cases follow a repetitive pattern that could be better organized by grouping similar operations (e.g., all equality comparisons, all inequality comparisons, etc.)
- Consider adding comments to explain the rationale behind expected behaviors, particularly for cases where the code becomes unreachable
Here's a suggested structure:
# Test cases for special case of comparison of not a number against a number when immediate is 0 +# Equality comparisons (==, !=) test-case: JEQ with imm 0 and pointer ... test-case: JNE with imm 0 and pointer ... + +# Bitwise comparisons (&==, &!=) test-case: JSET with imm 0 and pointer ... + +# Unsigned comparisons (<, <=, >, >=) test-case: JLT with imm 0 and pointer ... + +# Signed comparisons (s<, s<=, s>, s>=) test-case: JSLT with imm 0 and pointer ...🧰 Tools
🪛 GitHub Check: validate-yaml
[failure] 1006-1006:
1006:1 [empty-lines] too many blank lines (7 > 2)
[failure] 1006-1006:
1006:1 [empty-lines] too many blank lines (7 > 2)
1002-1007: Fix formatting: Remove extra blank lines.The file contains too many consecutive blank lines (7) where the maximum allowed is 2.
Apply this diff to fix the formatting:
test-case: JSGE with imm 0 and pointer ... messages: - "0: Code is unreachable after 0" - "0: Invalid type (r1.type == number)" - - - - - --- test-case: JEQ32 with imm 0 and pointer🧰 Tools
🪛 GitHub Check: validate-yaml
[failure] 1006-1006:
1006:1 [empty-lines] too many blank lines (7 > 2)
[failure] 1006-1006:
1006:1 [empty-lines] too many blank lines (7 > 2)
📜 Review details
Configuration used: CodeRabbit UI
Review profile: CHILL
📒 Files selected for processing (3)
- src/assertions.cpp (2 hunks)
- src/test/ebpf_yaml.cpp (1 hunks)
- test-data/jump.yaml (1 hunks)
🧰 Additional context used
🪛 GitHub Check: validate-yaml
test-data/jump.yaml
[failure] 1006-1006:
1006:1 [empty-lines] too many blank lines (7 > 2)
[failure] 1006-1006:
1006:1 [empty-lines] too many blank lines (7 > 2)
🔇 Additional comments (3)
src/assertions.cpp (1)
270-271: LGTM! Clear and descriptive comment.The updated comment clearly explains the requirements for both the destination register and source operands in binary operations.
src/test/ebpf_yaml.cpp (1)
195-196: Verify test coverage for the new option.Let's ensure there are test cases that exercise this new option.
✅ Verification successful
Let me check the content of the test case that uses assume_assertions to verify its proper implementation.
Test coverage for
assume_assertionsoption is well implementedThe test file
test-data/jump.yamlcontains comprehensive test cases for theassume_assertionsoption, specifically focusing on pointer comparison restrictions. The test cases include:
- Multiple variations of pointer comparisons with immediate value 0
- Tests for both 64-bit and 32-bit pointer comparisons
- Coverage for all comparison operators (EQ, NE, SET, LT, LE, GT, GE)
- Tests with signed and unsigned comparisons
- Verification of error messages for invalid pointer comparisons
🏁 Scripts executed
The following scripts were executed for the analysis:
Script:
#!/bin/bash # Description: Check for test cases using the new assume_assertions option # Test: Search for test cases using assume_assertions echo "Searching for test cases using assume_assertions..." rg -l "assume_assertions" test-data/ # Test: Search for any related pointer comparison tests echo "Searching for pointer comparison test cases..." rg -l "ptr|pointer" test-data/Length of output: 474
Script:
#!/bin/bash # Check the content of the test case using assume_assertions echo "Content of test-data/jump.yaml:" cat test-data/jump.yamlLength of output: 23039
test-data/jump.yaml (1)
718-719: LGTM!Clear and descriptive comment header for the new test cases.
Signed-off-by: Alan Jowett <[email protected]>
Signed-off-by: Alan Jowett <[email protected]>
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Actionable comments posted: 2
📜 Review details
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Review profile: ASSERTIVE
📒 Files selected for processing (2)
- src/test/ebpf_yaml.cpp (2 hunks)
- test-data/jump.yaml (1 hunks)
🔇 Additional comments (4)
src/test/ebpf_yaml.cpp (2)
182-184: LGTM!The default initialization is correct, though its placement has already been addressed in a previous review comment.
198-199: Verify test coverage for the new option.Let's check if there are any test cases using this new option to ensure it's properly tested.
✅ Verification successful
Test coverage exists for the
assume_assertionsoptionThe verification shows that the
assume_assertionsoption is well-tested:
- The option is properly implemented in
test-data/jump.yamlwith multiple test cases using theoptions: ["assume_assertions"]configuration- Test cases cover various scenarios including pointer comparisons and different types of jumps (JEQ, JNE, JSET, etc.)
- The implementation in
src/main/check.cppshows it's a configurable flag with proper documentationThe test coverage is comprehensive and validates the option's behavior across different use cases.
🏁 Scripts executed
The following scripts were executed for the analysis:
Script:
#!/bin/bash # Description: Search for test cases using the new assume_assertions option # Test: Look for YAML test files using assume_assertions. Expect: At least one test case using this option. echo "Searching for test cases using assume_assertions option..." rg -l "assume_assertions" "test-data/*.yaml"Length of output: 228
Script:
#!/bin/bash # Let's first find the correct test data directory structure fd -t d "test" # Then search for yaml files in the repository fd -e yaml # Finally, let's look for the actual usage of assume_assertions in any file rg -l "assume_assertions"Length of output: 704
Script:
#!/bin/bash # Let's examine the usage in test-data/jump.yaml to see how the option is used cat test-data/jump.yaml # Also check the implementation in src/main/check.cpp to understand how it's handled rg -A 5 -B 5 "assume_assertions" src/main/check.cppLength of output: 23768
test-data/jump.yaml (2)
718-1251: Well-structured comprehensive test suite for pointer comparisons.The test suite thoroughly covers pointer comparison validation across different operators:
- Basic comparisons (==, !=)
- Bitwise operations (&==, &!=)
- Unsigned comparisons (<, <=, >, >=)
- Signed comparisons (s<, s<=, s>, s>=)
- 32-bit variants of all operators
The consistent structure and error validation patterns make the test cases easy to understand and maintain.
934-937: Consistent error handling patterns across test cases.The error messages follow a well-defined pattern:
- For signed and 32-bit operations: Both type validation ("Invalid type (r1.type == number)") and unreachability checks
- For basic operations: Appropriate unreachability checks
This consistent approach helps verify that the verifier correctly prevents invalid pointer comparisons.
Also applies to: 1018-1021, 1081-1084, 1144-1147, 1186-1189, 1228-1231
Signed-off-by: Alan Jowett <[email protected]>
This pull request includes several key changes to the
src/assertions.cppandsrc/test/ebpf_yaml.cppfiles, focusing on enhancing the handling of condition checks and adding new options for assertions. The most important changes are summarized below:Enhancements to Condition Handling:
src/assertions.cpp: Added a newallow_pointersflag to manage pointer comparisons based on the operation type and whether the operation is 64-bit. This ensures that only certain operations allow pointer comparisons.src/assertions.cpp: Updated comments for better readability and clarity, particularly for binary operations.Addition of New Options:
src/test/ebpf_yaml.cpp: Introduced theassume_assertionsoption to theebpf_verifier_options_tstructure, allowing the verifier to assume assertions during its operation.Summary by CodeRabbit
New Features
Tests