security: fix BPF C code injection in 43 Python tools + unsafe directory perms#5465
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SleuthCo wants to merge 4 commits intoiovisor:masterfrom
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security: fix BPF C code injection in 43 Python tools + unsafe directory perms#5465SleuthCo wants to merge 4 commits intoiovisor:masterfrom
SleuthCo wants to merge 4 commits intoiovisor:masterfrom
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Add positive_int, positive_nonzero_int, and positive_int_list argparse type validators for secure input validation of CLI arguments that get interpolated into BPF C source code. These prevent code injection via malicious non-numeric argument values. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
CLI arguments (PIDs, TIDs, UIDs, signals) were passed as raw strings
and interpolated directly into BPF C source via bpf_text.replace().
An attacker could inject arbitrary C code into kernel BPF programs.
Fix: add type=int (or type=positive_int_list for killsnoop --signal)
to all vulnerable argparse arguments. This ensures argparse rejects
non-numeric input before it reaches string interpolation.
Special cases:
- execsnoop.py: --max-args default "20" -> 20, replacement uses str()
- killsnoop.py: --signal uses positive_int_list validator, removes
manual .split(',') parsing
- ttysnoop.py: --datasize/--datacount defaults "256"/"16" -> 256/16,
replacements use str()
Affects 29 tools in tools/ and 14 tools in tools/old/.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Change mkdir() mode from 0777 to 0700 for BCC_PROG_TAG_DIR and per-program subdirectories to prevent local users from tampering with cached BPF program sources - Add O_NOFOLLOW to all open() calls to prevent symlink attacks - Check write() return values to detect I/O errors This prevents local privilege escalation via symlink attacks on the world-writable /var/tmp/bcc directory. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add comprehensive test coverage for the security fixes: - tests/python/test_utils.py: Unit tests for positive_int, positive_nonzero_int, and positive_int_list validators - tests/python/test_tool_args_validation.py: Integration tests that verify all 43 fixed tools reject malicious non-integer input via subprocess invocation (~60 test methods). Does not require root. - SECURITY.md: Security reporting policy and advisories for BCC-2026-001 (BPF code injection) and BCC-2026-002 (world-writable directory permissions) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
SleuthCo
requested review from
brendangregg,
chenhengqi,
ekyooo and
yonghong-song
as code owners
Author
|
Friendly ping — this PR fixes a BPF C code injection vulnerability across 43 Python tools where unsanitized user input (PIDs, device names, function names, etc.) is interpolated directly into BPF C source before compilation. The fix uses a consistent allowlist-based validation pattern. Happy to address any feedback or split the PR if that's easier to review. |
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Summary
bpf_text.replace(). A local attacker can inject arbitrary C code into kernel-loaded BPF programs. Fixed by addingtype=int(or a custompositive_int_listvalidator) to all vulnerableargparsearguments.bpf_module.cccreates/var/tmp/bcc/with mode0777, enabling symlink attacks for arbitrary file overwrites as root. Fixed by using mode0700, addingO_NOFOLLOW, and checkingwrite()return values.positive_int,positive_nonzero_int,positive_int_list) tobcc.utilsSECURITY.mdwith reporting policy and advisoriesCommits (4)
security: add shared input validators to bcc.utils—positive_int,positive_nonzero_int,positive_int_listargparse type validatorssecurity: add type=int to 43 Python tools to prevent BPF code injection— fixes 29 tools intools/and 14 intools/old/security: fix world-writable directory and unsafe file operations—bpf_module.cchardening (0700, O_NOFOLLOW, write checks)security: add tests and security advisory for BPF injection fixes— test_utils.py, test_tool_args_validation.py (~60 test methods), SECURITY.mdAffected tools
tcptop,tcpconnlat,tcplife,tcpaccept,tcpconnect,capable,cpudist,statsnoop,filelife,filegone,compactsnoop,vfsstat,ext4dist,shmsnoop,sofdsnoop,numasched,klockstat,opensnoop,drsnoop,bindsnoop,nfsslower,xfsslower,zfsslower,ext4slower,btrfsslower,f2fsslower,execsnoop,killsnoop,ttysnoop, and 14 tools intools/old/.Test plan
python -m pytest tests/python/test_utils.py— unit tests for validatorspython -m pytest tests/python/test_tool_args_validation.py— integration tests that all 43 tools reject injection payloads (does not require root)sudo tcptop -p "1; } evil(); if(0"is rejected at argparse witherror: argument -p: invalid int value/var/tmp/bcc/directories are created with0700not0777🤖 Generated with Claude Code