| Message ID | 20211201073458.2731595-3-houtao1@huawei.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF |
| Headers | show |
| Series | clean-up for BPF_LOG_KERNEL log level | expand |
On Tue, Nov 30, 2021 at 11:19 PM Hou Tao <houtao1@huawei.com> wrote: > > BPF_LOG_KERNEL is only used internally, so disallow bpf_btf_load() > to set log level as BPF_LOG_KERNEL. The same checking has already > been done in bpf_check(), so factor out a helper to check the > validity of log attributes and use it in both places. > > Fixes: 8580ac9404f6 ("bpf: Process in-kernel BTF") > Signed-off-by: Hou Tao <houtao1@huawei.com> > Acked-by: Yonghong Song <yhs@fb.com> > Acked-by: Martin KaFai Lau <kafai@fb.com> > --- > include/linux/bpf_verifier.h | 7 +++++++ > kernel/bpf/btf.c | 3 +-- > kernel/bpf/verifier.c | 6 +++--- > 3 files changed, 11 insertions(+), 5 deletions(-) > > diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h > index c8a78e830fca..a3d17601a5a7 100644 > --- a/include/linux/bpf_verifier.h > +++ b/include/linux/bpf_verifier.h > @@ -396,6 +396,13 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) > log->level == BPF_LOG_KERNEL); > } > > +static inline bool > +bpf_verifier_log_attr_valid(const struct bpf_verifier_log *log, u32 max_total) > +{ > + return log->len_total >= 128 && log->len_total <= max_total && > + log->level && log->ubuf && !(log->level & ~BPF_LOG_MASK); > +} > + > #define BPF_MAX_SUBPROGS 256 > > struct bpf_subprog_info { > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index 6b9d23be1e99..308c345cd811 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -4472,8 +4472,7 @@ static struct btf *btf_parse(bpfptr_t btf_data, u32 btf_data_size, > log->len_total = log_size; > > /* log attributes have to be sane */ > - if (log->len_total < 128 || log->len_total > UINT_MAX >> 8 || > - !log->level || !log->ubuf) { > + if (!bpf_verifier_log_attr_valid(log, UINT_MAX >> 8)) { > err = -EINVAL; > goto errout; > } > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 722aea00d44e..f128e6799cb5 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -13969,11 +13969,11 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr) > log->ubuf = (char __user *) (unsigned long) attr->log_buf; > log->len_total = attr->log_size; > > - ret = -EINVAL; > /* log attributes have to be sane */ > - if (log->len_total < 128 || log->len_total > UINT_MAX >> 2 || > - !log->level || !log->ubuf || log->level & ~BPF_LOG_MASK) > + if (!bpf_verifier_log_attr_valid(log, UINT_MAX >> 2)) { > + ret = -EINVAL; It's actually quite bad that we have this discrepancy in limits. I've already sent a patch to make them the same. It was a pain to debug. https://lore.kernel.org/bpf/20211124060209.493-7-alexei.starovoitov@gmail.com/ " Otherwise tools that progressively increase log size and use the same log for BTF loading and program loading will be hitting hard to debug EINVAL. "
Hi, On 12/2/2021 1:42 AM, Alexei Starovoitov wrote: > On Tue, Nov 30, 2021 at 11:19 PM Hou Tao <houtao1@huawei.com> wrote: >> BPF_LOG_KERNEL is only used internally, so disallow bpf_btf_load() >> to set log level as BPF_LOG_KERNEL. The same checking has already >> been done in bpf_check(), so factor out a helper to check the >> validity of log attributes and use it in both places. >> >> snip >> - ret = -EINVAL; >> /* log attributes have to be sane */ >> - if (log->len_total < 128 || log->len_total > UINT_MAX >> 2 || >> - !log->level || !log->ubuf || log->level & ~BPF_LOG_MASK) >> + if (!bpf_verifier_log_attr_valid(log, UINT_MAX >> 2)) { >> + ret = -EINVAL; > It's actually quite bad that we have this discrepancy in limits. > I've already sent a patch to make them the same. > It was a pain to debug. > https://lore.kernel.org/bpf/20211124060209.493-7-alexei.starovoitov@gmail.com/ > " > Otherwise tools that progressively increase log size and use the same log > for BTF loading and program loading will be hitting hard to debug EINVAL. > " OK. Will send a single patch to handle that based on your patch set. Regards, Tao
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index c8a78e830fca..a3d17601a5a7 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -396,6 +396,13 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) log->level == BPF_LOG_KERNEL); } +static inline bool +bpf_verifier_log_attr_valid(const struct bpf_verifier_log *log, u32 max_total) +{ + return log->len_total >= 128 && log->len_total <= max_total && + log->level && log->ubuf && !(log->level & ~BPF_LOG_MASK); +} + #define BPF_MAX_SUBPROGS 256 struct bpf_subprog_info { diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 6b9d23be1e99..308c345cd811 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -4472,8 +4472,7 @@ static struct btf *btf_parse(bpfptr_t btf_data, u32 btf_data_size, log->len_total = log_size; /* log attributes have to be sane */ - if (log->len_total < 128 || log->len_total > UINT_MAX >> 8 || - !log->level || !log->ubuf) { + if (!bpf_verifier_log_attr_valid(log, UINT_MAX >> 8)) { err = -EINVAL; goto errout; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 722aea00d44e..f128e6799cb5 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -13969,11 +13969,11 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr) log->ubuf = (char __user *) (unsigned long) attr->log_buf; log->len_total = attr->log_size; - ret = -EINVAL; /* log attributes have to be sane */ - if (log->len_total < 128 || log->len_total > UINT_MAX >> 2 || - !log->level || !log->ubuf || log->level & ~BPF_LOG_MASK) + if (!bpf_verifier_log_attr_valid(log, UINT_MAX >> 2)) { + ret = -EINVAL; goto err_unlock; + } } if (IS_ERR(btf_vmlinux)) {
BPF_LOG_KERNEL is only used internally, so disallow bpf_btf_load() to set log level as BPF_LOG_KERNEL. The same checking has already been done in bpf_check(), so factor out a helper to check the validity of log attributes and use it in both places. Fixes: 8580ac9404f6 ("bpf: Process in-kernel BTF") Signed-off-by: Hou Tao <houtao1@huawei.com> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: Martin KaFai Lau <kafai@fb.com> --- include/linux/bpf_verifier.h | 7 +++++++ kernel/bpf/btf.c | 3 +-- kernel/bpf/verifier.c | 6 +++--- 3 files changed, 11 insertions(+), 5 deletions(-)