From 82f8dd28bd3abe181b7a66ea4ea132134d37a400 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Tue, 17 Oct 2017 16:55:53 +0200 Subject: bpf: fix splat for illegal devmap percpu allocation It was reported that syzkaller was able to trigger a splat on devmap percpu allocation due to illegal/unsupported allocation request size passed to __alloc_percpu(): [ 70.094249] illegal size (32776) or align (8) for percpu allocation [ 70.094256] ------------[ cut here ]------------ [ 70.094259] WARNING: CPU: 3 PID: 3451 at mm/percpu.c:1365 pcpu_alloc+0x96/0x630 [...] [ 70.094325] Call Trace: [ 70.094328] __alloc_percpu_gfp+0x12/0x20 [ 70.094330] dev_map_alloc+0x134/0x1e0 [ 70.094331] SyS_bpf+0x9bc/0x1610 [ 70.094333] ? selinux_task_setrlimit+0x5a/0x60 [ 70.094334] ? security_task_setrlimit+0x43/0x60 [ 70.094336] entry_SYSCALL_64_fastpath+0x1a/0xa5 This was due to too large max_entries for the map such that we surpassed the upper limit of PCPU_MIN_UNIT_SIZE. It's fine to fail naturally here, so switch to __alloc_percpu_gfp() and pass __GFP_NOWARN instead. Fixes: 11393cc9b9be ("xdp: Add batching support to redirect map") Reported-by: Mark Rutland Reported-by: Shankara Pailoor Reported-by: Richard Weinberger Signed-off-by: Daniel Borkmann Cc: John Fastabend Acked-by: Alexei Starovoitov Acked-by: John Fastabend Signed-off-by: David S. Miller --- kernel/bpf/devmap.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel/bpf/devmap.c') diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index e093d9a2c4dd..920428d84da2 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -111,8 +111,9 @@ static struct bpf_map *dev_map_alloc(union bpf_attr *attr) err = -ENOMEM; /* A per cpu bitfield with a bit per possible net device */ - dtab->flush_needed = __alloc_percpu(dev_map_bitmap_size(attr), - __alignof__(unsigned long)); + dtab->flush_needed = __alloc_percpu_gfp(dev_map_bitmap_size(attr), + __alignof__(unsigned long), + GFP_KERNEL | __GFP_NOWARN); if (!dtab->flush_needed) goto free_dtab; -- cgit v1.2.3 From 9ef2a8cd5c0dcb8e1f1534615c56eb13b630c363 Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Wed, 18 Oct 2017 07:11:44 -0700 Subject: bpf: require CAP_NET_ADMIN when using devmap Devmap is used with XDP which requires CAP_NET_ADMIN so lets also make CAP_NET_ADMIN required to use the map. Signed-off-by: John Fastabend Acked-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- kernel/bpf/devmap.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel/bpf/devmap.c') diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index 920428d84da2..52e0548ba548 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -78,6 +78,9 @@ static struct bpf_map *dev_map_alloc(union bpf_attr *attr) int err = -EINVAL; u64 cost; + if (!capable(CAP_NET_ADMIN)) + return ERR_PTR(-EPERM); + /* check sanity of attributes */ if (attr->max_entries == 0 || attr->key_size != 4 || attr->value_size != 4 || attr->map_flags & ~BPF_F_NUMA_NODE) -- cgit v1.2.3 From 8695a5395661fbb4a4f26c97f801f3800ae4754e Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Thu, 19 Oct 2017 09:03:52 -0700 Subject: bpf: devmap fix arithmetic overflow in bitmap_size calculation An integer overflow is possible in dev_map_bitmap_size() when calculating the BITS_TO_LONG logic which becomes, after macro replacement, (((n) + (d) - 1)/ (d)) where 'n' is a __u32 and 'd' is (8 * sizeof(long)). To avoid overflow cast to u64 before arithmetic. Reported-by: Richard Weinberger Acked-by: Daniel Borkmann Signed-off-by: John Fastabend Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- kernel/bpf/devmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/bpf/devmap.c') diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index 52e0548ba548..e745d6a88224 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -69,7 +69,7 @@ static LIST_HEAD(dev_map_list); static u64 dev_map_bitmap_size(const union bpf_attr *attr) { - return BITS_TO_LONGS(attr->max_entries) * sizeof(unsigned long); + return BITS_TO_LONGS((u64) attr->max_entries) * sizeof(unsigned long); } static struct bpf_map *dev_map_alloc(union bpf_attr *attr) -- cgit v1.2.3