This is a backport of two upstream patch-sets: 1. "exact states comparison for iterator convergence checks" https://lore.kernel.org/all/20231024000917.12153-1-eddyz87@gmail.com/ 2. "verify callbacks as if they are called unknown number of times" https://lore.kernel.org/all/20231121020701.26440-1-eddyz87@gmail.com/
Both patch-sets fix BPF verifier logic related to handling loops: for bpf iterators, and for helper functions that accept callback functions.
The backport of (2) was requested as a response to bug report by Mateusz Gienieczko mat.gienieczko@tum.de. The (1) is a dependency of (2).
The patch-set was tested by running BPF verifier selftests on my local qemu-based setup.
Most of the commits could be cherry-picked but three required merging:
| Action | Upstream commit | |--------+-------------------------------------------------------------------------------------------------| | pick | 3c4e420cb653 ("bpf: move explored_state() closer to the beginning of verifier.c ") | | pick | 4c97259abc9b ("bpf: extract same_callsites() as utility function ") | | merge | 2793a8b015f7 ("bpf: exact states comparison for iterator convergence checks ") | | pick | 389ede06c297 ("selftests/bpf: tests with delayed read/precision makrs in loop body ") | | pick | 2a0992829ea3 ("bpf: correct loop detection for iterators convergence ") | | pick | 64870feebecb ("selftests/bpf: test if state loops are detected in a tricky case ") | | pick | b4d8239534fd ("bpf: print full verifier states on infinite loop detection ") | | drop | dedd6c894110 ("Merge branch 'exact-states-comparison-for-iterator-convergence-checks' ") | |--------+-------------------------------------------------------------------------------------------------| | pick | 977bc146d4eb ("selftests/bpf: track tcp payload offset as scalar in xdp_synproxy ") | | pick | 87eb0152bcc1 ("selftests/bpf: track string payload offset as scalar in strobemeta ") | | pick | 683b96f9606a ("bpf: extract __check_reg_arg() utility function ") | | pick | 58124a98cb8e ("bpf: extract setup_func_entry() utility function ") | | merge | ab5cfac139ab ("bpf: verify callbacks as if they are called unknown number of times ") | | pick | 958465e217db ("selftests/bpf: tests for iterating callbacks ") | | pick | cafe2c21508a ("bpf: widening for callback iterators ") | | pick | 9f3330aa644d ("selftests/bpf: test widening for iterating callbacks ") | | merge | bb124da69c47 ("bpf: keep track of max number of bpf_loop callback iterations ") | | pick | 57e2a52deeb1 ("selftests/bpf: check if max number of bpf_loop iterations is tracked ") | | drop | acb12c859ac7 ("Merge branch 'verify-callbacks-as-if-they-are-called-unknown-number-of-times' ") |
Note: I don't know how deal with merge commits, so I just dropped those. These commits are empty but contain cover letters for both series, so it might be useful to pick those (how?).
Eduard Zingerman (17): bpf: move explored_state() closer to the beginning of verifier.c bpf: extract same_callsites() as utility function bpf: exact states comparison for iterator convergence checks selftests/bpf: tests with delayed read/precision makrs in loop body bpf: correct loop detection for iterators convergence selftests/bpf: test if state loops are detected in a tricky case bpf: print full verifier states on infinite loop detection selftests/bpf: track tcp payload offset as scalar in xdp_synproxy selftests/bpf: track string payload offset as scalar in strobemeta bpf: extract __check_reg_arg() utility function bpf: extract setup_func_entry() utility function bpf: verify callbacks as if they are called unknown number of times selftests/bpf: tests for iterating callbacks bpf: widening for callback iterators selftests/bpf: test widening for iterating callbacks bpf: keep track of max number of bpf_loop callback iterations selftests/bpf: check if max number of bpf_loop iterations is tracked
include/linux/bpf_verifier.h | 32 + kernel/bpf/verifier.c | 875 ++++++++++++++---- .../selftests/bpf/prog_tests/verifier.c | 2 + tools/testing/selftests/bpf/progs/cb_refs.c | 1 + tools/testing/selftests/bpf/progs/iters.c | 695 ++++++++++++++ .../testing/selftests/bpf/progs/strobemeta.h | 78 +- .../bpf/progs/verifier_iterating_callbacks.c | 242 +++++ .../bpf/progs/verifier_subprog_precision.c | 86 +- .../selftests/bpf/progs/xdp_synproxy_kern.c | 84 +- 9 files changed, 1830 insertions(+), 265 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c