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bpf: Add __bpf_dynptr_data* for in kernel use

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Different types of bpf dynptr have different internal data storage.
Specifically, SKB and XDP type of dynptr may have non-continuous data.
Therefore, it is not always safe to directly access dynptr->data.

Add __bpf_dynptr_data and __bpf_dynptr_data_rw to replace direct access to
dynptr->data.

Update bpf_verify_pkcs7_signature to use __bpf_dynptr_data instead of
dynptr->data.

Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://lore.kernel.org/bpf/20231107045725.2278852-2-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Song Liu 2023-11-06 20:57:23 -08:00 committed by Alexei Starovoitov
parent 9b75dbeb36
commit 74523c06ae
3 changed files with 29 additions and 4 deletions
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2
include/linux/bpf.h
View file

@ -1222,6 +1222,8 @@ enum bpf_dynptr_type {
int bpf_dynptr_check_size(u32 size);
u32 __bpf_dynptr_size(const struct bpf_dynptr_kern *ptr);
const void *__bpf_dynptr_data(const struct bpf_dynptr_kern *ptr, u32 len);
void *__bpf_dynptr_data_rw(const struct bpf_dynptr_kern *ptr, u32 len);
#ifdef CONFIG_BPF_JIT
int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr);

19
kernel/bpf/helpers.c
View file

@ -2618,3 +2618,22 @@ static int __init kfunc_init(void)
}
late_initcall(kfunc_init);
/* Get a pointer to dynptr data up to len bytes for read only access. If
* the dynptr doesn't have continuous data up to len bytes, return NULL.
*/
const void *__bpf_dynptr_data(const struct bpf_dynptr_kern *ptr, u32 len)
{
return bpf_dynptr_slice(ptr, 0, NULL, len);
}
/* Get a pointer to dynptr data up to len bytes for read write access. If
* the dynptr doesn't have continuous data up to len bytes, or the dynptr
* is read only, return NULL.
*/
void *__bpf_dynptr_data_rw(const struct bpf_dynptr_kern *ptr, u32 len)
{
if (__bpf_dynptr_is_rdonly(ptr))
return NULL;
return (void *)__bpf_dynptr_data(ptr, len);
}

12
kernel/trace/bpf_trace.c
View file

@ -1376,6 +1376,8 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr,
struct bpf_dynptr_kern *sig_ptr,
struct bpf_key *trusted_keyring)
{
const void *data, *sig;
u32 data_len, sig_len;
int ret;
if (trusted_keyring->has_ref) {
@ -1392,10 +1394,12 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr,
return ret;
}
return verify_pkcs7_signature(data_ptr->data,
__bpf_dynptr_size(data_ptr),
sig_ptr->data,
__bpf_dynptr_size(sig_ptr),
data_len = __bpf_dynptr_size(data_ptr);
data = __bpf_dynptr_data(data_ptr, data_len);
sig_len = __bpf_dynptr_size(sig_ptr);
sig = __bpf_dynptr_data(sig_ptr, sig_len);
return verify_pkcs7_signature(data, data_len, sig, sig_len,
trusted_keyring->key,
VERIFYING_UNSPECIFIED_SIGNATURE, NULL,
NULL);