| Message ID | 20191009160907.10981-2-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]) check_zeroed_user() which > does what bpf_check_uarg_tail_zero() is doing generically. We're slowly > switching such codepaths over to use check_zeroed_user() instead of > using their own hand-rolled version. > > [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 | 22 +++++++--------------- > 1 file changed, 7 insertions(+), 15 deletions(-) > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index 82eabd4e38ad..78790778f101 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -63,30 +63,22 @@ int bpf_check_uarg_tail_zero(void __user *uaddr, > size_t expected_size, > size_t actual_size) > { > - unsigned char __user *addr; > - unsigned char __user *end; > - unsigned char val; > + size_t size = min(expected_size, actual_size); > + size_t rest = max(expected_size, actual_size) - size; > int err; > > if (unlikely(actual_size > PAGE_SIZE)) /* silly large */ > return -E2BIG; > > - if (unlikely(!access_ok(uaddr, actual_size))) > - return -EFAULT; > - > if (actual_size <= expected_size) > return 0; > > - addr = uaddr + expected_size; > - end = uaddr + actual_size; > + err = check_zeroed_user(uaddr + expected_size, rest); > + if (err < 0) > + return err; > > - for (; addr < end; addr++) { > - err = get_user(val, addr); > - if (err) > - return err; > - if (val) > - return -E2BIG; > - } > + if (err) > + return -E2BIG; > > return 0; > }
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 82eabd4e38ad..78790778f101 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -63,30 +63,22 @@ int bpf_check_uarg_tail_zero(void __user *uaddr, size_t expected_size, size_t actual_size) { - unsigned char __user *addr; - unsigned char __user *end; - unsigned char val; + size_t size = min(expected_size, actual_size); + size_t rest = max(expected_size, actual_size) - size; int err; if (unlikely(actual_size > PAGE_SIZE)) /* silly large */ return -E2BIG; - if (unlikely(!access_ok(uaddr, actual_size))) - return -EFAULT; - if (actual_size <= expected_size) return 0; - addr = uaddr + expected_size; - end = uaddr + actual_size; + err = check_zeroed_user(uaddr + expected_size, rest); + if (err < 0) + return err; - for (; addr < end; addr++) { - err = get_user(val, addr); - if (err) - return err; - if (val) - return -E2BIG; - } + if (err) + return -E2BIG; return 0; }
In v5.4-rc2 we added a new helper (cf. [1]) check_zeroed_user() which does what bpf_check_uarg_tail_zero() is doing generically. We're slowly switching such codepaths over to use check_zeroed_user() instead of using their own hand-rolled version. [1]: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper") Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> --- kernel/bpf/syscall.c | 22 +++++++--------------- 1 file changed, 7 insertions(+), 15 deletions(-)