diff options
author | Alexei Starovoitov <ast@kernel.org> | 2021-12-01 10:10:28 -0800 |
---|---|---|
committer | Andrii Nakryiko <andrii@kernel.org> | 2021-12-02 11:18:35 -0800 |
commit | fbd94c7afcf99c9f3b1ba1168657ecc428eb2c8d (patch) | |
tree | 75f25a9954857b70ea8647853faf35f7e6f2c76b /kernel/bpf/verifier.c | |
parent | 46334a0cd21bed70d6f1ddef1464f75a0ebe1774 (diff) | |
download | linux-fbd94c7afcf99c9f3b1ba1168657ecc428eb2c8d.tar.gz linux-fbd94c7afcf99c9f3b1ba1168657ecc428eb2c8d.tar.bz2 linux-fbd94c7afcf99c9f3b1ba1168657ecc428eb2c8d.zip |
bpf: Pass a set of bpf_core_relo-s to prog_load command.
struct bpf_core_relo is generated by llvm and processed by libbpf.
It's a de-facto uapi.
With CO-RE in the kernel the struct bpf_core_relo becomes uapi de-jure.
Add an ability to pass a set of 'struct bpf_core_relo' to prog_load command
and let the kernel perform CO-RE relocations.
Note the struct bpf_line_info and struct bpf_func_info have the same
layout when passed from LLVM to libbpf and from libbpf to the kernel
except "insn_off" fields means "byte offset" when LLVM generates it.
Then libbpf converts it to "insn index" to pass to the kernel.
The struct bpf_core_relo's "insn_off" field is always "byte offset".
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-6-alexei.starovoitov@gmail.com
Diffstat (limited to 'kernel/bpf/verifier.c')
-rw-r--r-- | kernel/bpf/verifier.c | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6c9c0d9a04a0..6522ffdea487 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10273,6 +10273,78 @@ err_free: return err; } +#define MIN_CORE_RELO_SIZE sizeof(struct bpf_core_relo) +#define MAX_CORE_RELO_SIZE MAX_FUNCINFO_REC_SIZE + +static int check_core_relo(struct bpf_verifier_env *env, + const union bpf_attr *attr, + bpfptr_t uattr) +{ + u32 i, nr_core_relo, ncopy, expected_size, rec_size; + struct bpf_core_relo core_relo = {}; + struct bpf_prog *prog = env->prog; + const struct btf *btf = prog->aux->btf; + struct bpf_core_ctx ctx = { + .log = &env->log, + .btf = btf, + }; + bpfptr_t u_core_relo; + int err; + + nr_core_relo = attr->core_relo_cnt; + if (!nr_core_relo) + return 0; + if (nr_core_relo > INT_MAX / sizeof(struct bpf_core_relo)) + return -EINVAL; + + rec_size = attr->core_relo_rec_size; + if (rec_size < MIN_CORE_RELO_SIZE || + rec_size > MAX_CORE_RELO_SIZE || + rec_size % sizeof(u32)) + return -EINVAL; + + u_core_relo = make_bpfptr(attr->core_relos, uattr.is_kernel); + expected_size = sizeof(struct bpf_core_relo); + ncopy = min_t(u32, expected_size, rec_size); + + /* Unlike func_info and line_info, copy and apply each CO-RE + * relocation record one at a time. + */ + for (i = 0; i < nr_core_relo; i++) { + /* future proofing when sizeof(bpf_core_relo) changes */ + err = bpf_check_uarg_tail_zero(u_core_relo, expected_size, rec_size); + if (err) { + if (err == -E2BIG) { + verbose(env, "nonzero tailing record in core_relo"); + if (copy_to_bpfptr_offset(uattr, + offsetof(union bpf_attr, core_relo_rec_size), + &expected_size, sizeof(expected_size))) + err = -EFAULT; + } + break; + } + + if (copy_from_bpfptr(&core_relo, u_core_relo, ncopy)) { + err = -EFAULT; + break; + } + + if (core_relo.insn_off % 8 || core_relo.insn_off / 8 >= prog->len) { + verbose(env, "Invalid core_relo[%u].insn_off:%u prog->len:%u\n", + i, core_relo.insn_off, prog->len); + err = -EINVAL; + break; + } + + err = bpf_core_apply(&ctx, &core_relo, i, + &prog->insnsi[core_relo.insn_off / 8]); + if (err) + break; + bpfptr_add(&u_core_relo, rec_size); + } + return err; +} + static int check_btf_info(struct bpf_verifier_env *env, const union bpf_attr *attr, bpfptr_t uattr) @@ -10303,6 +10375,10 @@ static int check_btf_info(struct bpf_verifier_env *env, if (err) return err; + err = check_core_relo(env, attr, uattr); + if (err) + return err; + return 0; } |