On Fri, Aug 9, 2019 at 8:26 PM Paul Chaignon <[email protected]> wrote: > > We need BPF_MOD to match system calls against whitelists encoded as 32-bit > bit arrays. The selection of the syscall's bit in the appropriate bit > array requires a modulo operation such that X = 1 << nr % 32.
Of course, X = 1 << nr & 0x1F, and we can do without BPF_MOD in our case. I'll put that on a lack of sleep... > > Signed-off-by: Paul Chaignon <[email protected]> > --- > kernel/seccomp.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/seccomp.c b/kernel/seccomp.c > index 811b4a86cdf6..87de6532ff6d 100644 > --- a/kernel/seccomp.c > +++ b/kernel/seccomp.c > @@ -205,6 +205,8 @@ static int seccomp_check_filter(struct sock_filter > *filter, unsigned int flen) > case BPF_ALU | BPF_MUL | BPF_X: > case BPF_ALU | BPF_DIV | BPF_K: > case BPF_ALU | BPF_DIV | BPF_X: > + case BPF_ALU | BPF_MOD | BPF_K: > + case BPF_ALU | BPF_MOD | BPF_X: > case BPF_ALU | BPF_AND | BPF_K: > case BPF_ALU | BPF_AND | BPF_X: > case BPF_ALU | BPF_OR | BPF_K: > -- > 2.17.1
