ea923080c1
To fulfill the BPF signing contract, represented as Sig(I_loader ||
H_meta), the generated trusted loader program must verify the integrity
of the metadata. This signature cryptographically binds the loader's
instructions (I_loader) to a hash of the metadata (H_meta).
The verification process is embedded directly into the loader program.
Upon execution, the loader loads the runtime hash from struct bpf_map
i.e. BPF_PSEUDO_MAP_IDX and compares this runtime hash against an
expected hash value that has been hardcoded directly by
bpf_obj__gen_loader.
The load from bpf_map can be improved by calling
BPF_OBJ_GET_INFO_BY_FD from the kernel context after BPF_OBJ_GET_INFO_BY_FD
has been updated for being called from the kernel context.
The following instructions are generated:
ld_imm64 r1, const_ptr_to_map // insn[0].src_reg == BPF_PSEUDO_MAP_IDX
r2 = *(u64 *)(r1 + 0);
ld_imm64 r3, sha256_of_map_part1 // constant precomputed by
bpftool (part of H_meta)
if r2 != r3 goto out;
r2 = *(u64 *)(r1 + 8);
ld_imm64 r3, sha256_of_map_part2 // (part of H_meta)
if r2 != r3 goto out;
r2 = *(u64 *)(r1 + 16);
ld_imm64 r3, sha256_of_map_part3 // (part of H_meta)
if r2 != r3 goto out;
r2 = *(u64 *)(r1 + 24);
ld_imm64 r3, sha256_of_map_part4 // (part of H_meta)
if r2 != r3 goto out;
...
Signed-off-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/r/20250921160120.9711-4-kpsingh@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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|---|---|---|
| .. | ||
| api | ||
| bpf | ||
| perf | ||
| subcmd | ||
| symbol | ||
| thermal | ||
| argv_split.c | ||
| bitmap.c | ||
| cmdline.c | ||
| ctype.c | ||
| find_bit.c | ||
| hweight.c | ||
| list_sort.c | ||
| rbtree.c | ||
| slab.c | ||
| str_error_r.c | ||
| string.c | ||
| vsprintf.c | ||
| zalloc.c | ||