| Message ID | 20191009160907.10981-4-christian.brauner@ubuntu.com |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | bpf: switch to new usercopy helpers | expand |
On 2019-10-09, Christian Brauner <christian.brauner@ubuntu.com> wrote: > In v5.4-rc2 we added a new helper (cf. [1]) copy_struct_from_user(). > This helper is intended for all codepaths that copy structs from > userspace that are versioned by size. The bpf() syscall does exactly > what copy_struct_from_user() is doing. > Note that copy_struct_from_user() is calling min() already. So > technically, the min_t() call could go. But the size is used further > below so leave it. > > [1]: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper") > Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Acked-by: Aleksa Sarai <cyphar@cyphar.com> > --- > kernel/bpf/syscall.c | 9 +++------ > 1 file changed, 3 insertions(+), 6 deletions(-) > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index 6f4f9097b1fe..6fdcbdb27501 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -2819,14 +2819,11 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz > if (sysctl_unprivileged_bpf_disabled && !capable(CAP_SYS_ADMIN)) > return -EPERM; > > - err = bpf_check_uarg_tail_zero(uattr, sizeof(attr), size); > - if (err) > - return err; > size = min_t(u32, size, sizeof(attr)); > - > /* copy attributes from user space, may be less than sizeof(bpf_attr) */ > - if (copy_from_user(&attr, uattr, size) != 0) > - return -EFAULT; > + err = copy_struct_from_user(&attr, sizeof(attr), uattr, size); > + if (err) > + return err; > > err = security_bpf(cmd, &attr, size); > if (err < 0) > -- > 2.23.0
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 6f4f9097b1fe..6fdcbdb27501 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2819,14 +2819,11 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz if (sysctl_unprivileged_bpf_disabled && !capable(CAP_SYS_ADMIN)) return -EPERM; - err = bpf_check_uarg_tail_zero(uattr, sizeof(attr), size); - if (err) - return err; size = min_t(u32, size, sizeof(attr)); - /* copy attributes from user space, may be less than sizeof(bpf_attr) */ - if (copy_from_user(&attr, uattr, size) != 0) - return -EFAULT; + err = copy_struct_from_user(&attr, sizeof(attr), uattr, size); + if (err) + return err; err = security_bpf(cmd, &attr, size); if (err < 0)
In v5.4-rc2 we added a new helper (cf. [1]) copy_struct_from_user(). This helper is intended for all codepaths that copy structs from userspace that are versioned by size. The bpf() syscall does exactly what copy_struct_from_user() is doing. Note that copy_struct_from_user() is calling min() already. So technically, the min_t() call could go. But the size is used further below so leave it. [1]: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper") Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> --- kernel/bpf/syscall.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)