WIP ROX-33217: Instrument inode tracking on directory being created#449
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JoukoVirtanen wants to merge 20 commits intomainfrom
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WIP ROX-33217: Instrument inode tracking on directory being created#449JoukoVirtanen wants to merge 20 commits intomainfrom
JoukoVirtanen wants to merge 20 commits intomainfrom
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JoukoVirtanen
commented
Mar 30, 2026
| // x86_64 -> x86, aarch64 -> arm64 | ||
| let bpf_arch = match cargo_arch.as_str() { | ||
| "x86_64" => "x86", | ||
| "aarch64" => "arm64", |
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These changes are need because of
args.dir = (struct inode*)PT_REGS_PARM2_CORE(ctx);
args.dentry = (struct dentry*)PT_REGS_PARM3_CORE(ctx);
Which expects __TARGET_ARCH_x86 or __TARGET_ARCH_arm64 instead of __TARGET_ARCH_x86_64 or _TARGET_ARCH_aarch64. Currently both versions are used. One for PT_REGS_PARM2_CORE and one for fact-ebpf/src/bpf/vmlinux.h. Perhaps that file could be edited to use __TARGET_ARCH_x86 or __TARGET_ARCH_arm64. I don't know if that would cause other problems.
JoukoVirtanen
commented
Mar 30, 2026
| } | ||
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| __always_inline static struct bound_path_t* _path_read(struct path* path, bound_path_buffer_t key, bool use_bpf_d_path) { | ||
| __always_inline static struct bound_path_t* _path_read(const struct path* path, bound_path_buffer_t key, bool use_bpf_d_path) { |
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I found that I needed to cast from const in one place, so I changed some function signatures to take in const to avoid that. I ended up using a cast from const in fact-ebpf/src/bpf/d_path.h anyways. I will likely change these back.
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Description
Directory creation events need to be handled correctly. When a directory is created in a tracked directory its inode should be added to a hash set in kernel space. In user space an entry needs to be added into a map with the inode as the key and file path as the value.
A downside of this approach is that it does not currently handle recursive cases, though I believe that this can be overcome.
I tried a few alternatives.
I started out trying to use a path_mkdir LSM hook, but as the design document suggested, it doesn't have the new inode. So, I tried tracepoints on the mkdir and mkdirat syscalls, which the design document suggested as an alternative. Neither of them worked. I also tried an LSM hook on
inode_mkdir, that didn't work either.Checklist
Automated testing
If any of these don't apply, please comment below.
Testing Performed
CI is sufficient.