* [PATCH bpf v2 2/4] bpf_trace: support 32-bit kernels in bpf_kprobe_multi_link_attach
@ 2022-05-16 23:05 Eugene Syromiatnikov
2022-05-17 7:08 ` Yonghong Song
0 siblings, 1 reply; 2+ messages in thread
From: Eugene Syromiatnikov @ 2022-05-16 23:05 UTC (permalink / raw)
To: Jiri Olsa, Masami Hiramatsu, Steven Rostedt, Ingo Molnar,
Alexei Starovoitov, Daniel Borkmann
Cc: Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, netdev, bpf, linux-kernel, Shuah Khan,
linux-kselftest
It seems that there is no reason not to support 32-bit architectures;
doing so requires a bit of rework with respect to cookies handling,
however, as the current code implicitly assumes
that sizeof(long) == sizeof(u64).
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
---
kernel/trace/bpf_trace.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index f1d4e68..bf5bcfb 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2406,16 +2406,12 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
struct bpf_link_primer link_primer;
void __user *ucookies;
unsigned long *addrs;
- u32 flags, cnt, size;
+ u32 flags, cnt, size, cookies_size;
void __user *uaddrs;
u64 *cookies = NULL;
void __user *usyms;
int err;
- /* no support for 32bit archs yet */
- if (sizeof(u64) != sizeof(void *))
- return -EOPNOTSUPP;
-
if (prog->expected_attach_type != BPF_TRACE_KPROBE_MULTI)
return -EINVAL;
@@ -2425,6 +2421,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
uaddrs = u64_to_user_ptr(attr->link_create.kprobe_multi.addrs);
usyms = u64_to_user_ptr(attr->link_create.kprobe_multi.syms);
+ ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies);
if (!!uaddrs == !!usyms)
return -EINVAL;
@@ -2432,8 +2429,11 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
if (!cnt)
return -EINVAL;
- if (check_mul_overflow(cnt, (u32)sizeof(*addrs), &size))
+ if (check_mul_overflow(cnt, (u32)sizeof(*addrs), &size) ||
+ (ucookies &&
+ check_mul_overflow(cnt, (u32)sizeof(*cookies), &cookies_size))) {
return -EOVERFLOW;
+ }
size = cnt * sizeof(*addrs);
addrs = kvmalloc(size, GFP_KERNEL);
if (!addrs)
@@ -2450,14 +2450,14 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
goto error;
}
- ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies);
if (ucookies) {
- cookies = kvmalloc(size, GFP_KERNEL);
+ cookies_size = cnt * sizeof(*cookies);
+ cookies = kvmalloc(cookies_size, GFP_KERNEL);
if (!cookies) {
err = -ENOMEM;
goto error;
}
- if (copy_from_user(cookies, ucookies, size)) {
+ if (copy_from_user(cookies, ucookies, cookies_size)) {
err = -EFAULT;
goto error;
}
--
2.1.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH bpf v2 2/4] bpf_trace: support 32-bit kernels in bpf_kprobe_multi_link_attach
2022-05-16 23:05 [PATCH bpf v2 2/4] bpf_trace: support 32-bit kernels in bpf_kprobe_multi_link_attach Eugene Syromiatnikov
@ 2022-05-17 7:08 ` Yonghong Song
0 siblings, 0 replies; 2+ messages in thread
From: Yonghong Song @ 2022-05-17 7:08 UTC (permalink / raw)
To: Eugene Syromiatnikov, Jiri Olsa, Masami Hiramatsu,
Steven Rostedt, Ingo Molnar, Alexei Starovoitov, Daniel Borkmann
Cc: Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend,
KP Singh, netdev, bpf, linux-kernel, Shuah Khan, linux-kselftest
On 5/16/22 4:05 PM, Eugene Syromiatnikov wrote:
> It seems that there is no reason not to support 32-bit architectures;
> doing so requires a bit of rework with respect to cookies handling,
> however, as the current code implicitly assumes
> that sizeof(long) == sizeof(u64).
>
> Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
> ---
> kernel/trace/bpf_trace.c | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index f1d4e68..bf5bcfb 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2406,16 +2406,12 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> struct bpf_link_primer link_primer;
> void __user *ucookies;
> unsigned long *addrs;
> - u32 flags, cnt, size;
> + u32 flags, cnt, size, cookies_size;
> void __user *uaddrs;
> u64 *cookies = NULL;
> void __user *usyms;
> int err;
>
> - /* no support for 32bit archs yet */
> - if (sizeof(u64) != sizeof(void *))
> - return -EOPNOTSUPP;
> -
> if (prog->expected_attach_type != BPF_TRACE_KPROBE_MULTI)
> return -EINVAL;
>
> @@ -2425,6 +2421,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
>
> uaddrs = u64_to_user_ptr(attr->link_create.kprobe_multi.addrs);
> usyms = u64_to_user_ptr(attr->link_create.kprobe_multi.syms);
> + ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies);
> if (!!uaddrs == !!usyms)
> return -EINVAL;
>
> @@ -2432,8 +2429,11 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> if (!cnt)
> return -EINVAL;
>
> - if (check_mul_overflow(cnt, (u32)sizeof(*addrs), &size))
> + if (check_mul_overflow(cnt, (u32)sizeof(*addrs), &size) ||
> + (ucookies &&
> + check_mul_overflow(cnt, (u32)sizeof(*cookies), &cookies_size))) {
> return -EOVERFLOW;
> + }
> size = cnt * sizeof(*addrs);
size has been calculated, no need to calculate again.
> addrs = kvmalloc(size, GFP_KERNEL);
> if (!addrs)
> @@ -2450,14 +2450,14 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> goto error;
> }
>
> - ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies);
> if (ucookies) {
> - cookies = kvmalloc(size, GFP_KERNEL);
> + cookies_size = cnt * sizeof(*cookies);
same for cookies_size.
> + cookies = kvmalloc(cookies_size, GFP_KERNEL);
> if (!cookies) {
> err = -ENOMEM;
> goto error;
> }
> - if (copy_from_user(cookies, ucookies, size)) {
> + if (copy_from_user(cookies, ucookies, cookies_size)) {
> err = -EFAULT;
> goto error;
> }
^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-05-17 7:08 ` Yonghong Song
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