diff mbox series

[bpf-next,v3,2/4] bpf_trace: support 32-bit kernels in bpf_kprobe_multi_link_attach

Message ID 525b99881dc144b986e381eb23b12617a311f243.1652772731.git.esyr@redhat.com (mailing list archive)
State New
Headers show
Series Fix 32-bit arch and compat support for the kprobe_multi attach type | expand

Commit Message

Eugene Syromiatnikov May 17, 2022, 7:36 a.m. UTC
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 | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

Comments

Jiri Olsa May 17, 2022, 9:12 a.m. UTC | #1
On Tue, May 17, 2022 at 09:36:26AM +0200, 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 | 17 ++++++++---------
>  1 file changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 9c041be..a93a54f 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2435,16 +2435,12 @@ 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;
>  
> @@ -2454,6 +2450,7 @@ 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;
>  
> @@ -2461,8 +2458,11 @@ 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;
> +	}
>  	addrs = kvmalloc(size, GFP_KERNEL);
>  	if (!addrs)
>  		return -ENOMEM;
> @@ -2486,14 +2486,13 @@ 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) {

could we check all that in here? so the ucookies checks are on the
one place.. also you would not need cookies_size

jirka

> -		cookies = kvmalloc(size, GFP_KERNEL);
> +		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
>
Andrii Nakryiko May 18, 2022, 11:31 p.m. UTC | #2
On Tue, May 17, 2022 at 12:36 AM Eugene Syromiatnikov <esyr@redhat.com> 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 | 17 ++++++++---------
>  1 file changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 9c041be..a93a54f 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2435,16 +2435,12 @@ 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;
>
> @@ -2454,6 +2450,7 @@ 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;
>
> @@ -2461,8 +2458,11 @@ 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;
> +       }
>         addrs = kvmalloc(size, GFP_KERNEL);
>         if (!addrs)
>                 return -ENOMEM;
> @@ -2486,14 +2486,13 @@ 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 = kvmalloc(cookies_size, GFP_KERNEL);

same question about consistent use of kvmalloc_array() and delegating
all the overflow checks to it?

>                 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
>
diff mbox series

Patch

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 9c041be..a93a54f 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2435,16 +2435,12 @@  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;
 
@@ -2454,6 +2450,7 @@  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;
 
@@ -2461,8 +2458,11 @@  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;
+	}
 	addrs = kvmalloc(size, GFP_KERNEL);
 	if (!addrs)
 		return -ENOMEM;
@@ -2486,14 +2486,13 @@  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 = 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;
 		}