From patchwork Fri Dec 8 11:29:44 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Fijalkowski, Maciej" X-Patchwork-Id: 13485316 X-Patchwork-Delegate: bpf@iogearbox.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="mJlRDwhu" Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06E30173B; Fri, 8 Dec 2023 03:30:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1702035014; x=1733571014; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=9xOiHFY/NjuYEpSXolTOwDQvfMaL1Aomxzg9M+GrkL4=; b=mJlRDwhugMfWWUsX4pOZoOfwgCzBpKxARGjN76u+67+unkOROZOdE/le 2V+tKGm3jProVwWEygkb26sD5/PqhU/uIUdX+KLBHgfb47nete3Ikmj54 aOqxPlbSJuXnumMf/jVdM/VVsi6ZGwftjFGpmwCAJOStjC+DgMZJGJ9IO pgaqUN/X3e0Lq3j1USDDOrjuUQF3loDWSUreMqMv3ws+HDaZ4zpvjB1gm R1iCOc5We+1kBN07u4rz5G+qNV6N5J7O3tv0Wm6nk5v6AhOh7WlIRFLlD lyoIuBoE88yK8z/siJguc22YgcZbn7TarUtgAmcGxvyteYYhYa3oKosYN Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10917"; a="458705897" X-IronPort-AV: E=Sophos;i="6.04,260,1695711600"; d="scan'208";a="458705897" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Dec 2023 03:30:13 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10917"; a="862828155" X-IronPort-AV: E=Sophos;i="6.04,260,1695711600"; d="scan'208";a="862828155" Received: from boxer.igk.intel.com ([10.102.20.173]) by FMSMGA003.fm.intel.com with ESMTP; 08 Dec 2023 03:30:10 -0800 From: Maciej Fijalkowski To: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org Cc: netdev@vger.kernel.org, magnus.karlsson@intel.com, bjorn@kernel.org, maciej.fijalkowski@intel.com, echaudro@redhat.com, lorenzo@kernel.org Subject: [PATCH bpf 2/3] net: fix usage of multi-buffer BPF helper for ZC AF_XDP Date: Fri, 8 Dec 2023 12:29:44 +0100 Message-Id: <20231208112945.313687-3-maciej.fijalkowski@intel.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20231208112945.313687-1-maciej.fijalkowski@intel.com> References: <20231208112945.313687-1-maciej.fijalkowski@intel.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Currently when packet is shrunk via bpf_xdp_adjust_tail(), null ptr dereference happens: [1136314.192256] BUG: kernel NULL pointer dereference, address: 0000000000000034 [1136314.203943] #PF: supervisor read access in kernel mode [1136314.213768] #PF: error_code(0x0000) - not-present page [1136314.223550] PGD 0 P4D 0 [1136314.230684] Oops: 0000 [#1] PREEMPT SMP NOPTI [1136314.239621] CPU: 8 PID: 54203 Comm: xdpsock Not tainted 6.6.0+ #257 [1136314.250469] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019 [1136314.265615] RIP: 0010:__xdp_return+0x6c/0x210 [1136314.274653] Code: ad 00 48 8b 47 08 49 89 f8 a8 01 0f 85 9b 01 00 00 0f 1f 44 00 00 f0 41 ff 48 34 75 32 4c 89 c7 e9 79 cd 80 ff 83 fe 03 75 17 41 34 01 0f 85 02 01 00 00 48 89 cf e9 22 cc 1e 00 e9 3d d2 86 [1136314.302907] RSP: 0018:ffffc900089f8db0 EFLAGS: 00010246 [1136314.312967] RAX: ffffc9003168aed0 RBX: ffff8881c3300000 RCX: 0000000000000000 [1136314.324953] RDX: 0000000000000000 RSI: 0000000000000003 RDI: ffffc9003168c000 [1136314.336929] RBP: 0000000000000ae0 R08: 0000000000000002 R09: 0000000000010000 [1136314.348844] R10: ffffc9000e495000 R11: 0000000000000040 R12: 0000000000000001 [1136314.360706] R13: 0000000000000524 R14: ffffc9003168aec0 R15: 0000000000000001 [1136314.373298] FS: 00007f8df8bbcb80(0000) GS:ffff8897e0e00000(0000) knlGS:0000000000000000 [1136314.386105] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [1136314.396532] CR2: 0000000000000034 CR3: 00000001aa912002 CR4: 00000000007706f0 [1136314.408377] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [1136314.420173] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [1136314.431890] PKRU: 55555554 [1136314.439143] Call Trace: [1136314.446058] [1136314.452465] ? __die+0x20/0x70 [1136314.459881] ? page_fault_oops+0x15b/0x440 [1136314.468305] ? exc_page_fault+0x6a/0x150 [1136314.476491] ? asm_exc_page_fault+0x22/0x30 [1136314.484927] ? __xdp_return+0x6c/0x210 [1136314.492863] bpf_xdp_adjust_tail+0x155/0x1d0 [1136314.501269] bpf_prog_ccc47ae29d3b6570_xdp_sock_prog+0x15/0x60 [1136314.511263] ice_clean_rx_irq_zc+0x206/0xc60 [ice] [1136314.520222] ? ice_xmit_zc+0x6e/0x150 [ice] [1136314.528506] ice_napi_poll+0x467/0x670 [ice] [1136314.536858] ? ttwu_do_activate.constprop.0+0x8f/0x1a0 [1136314.546010] __napi_poll+0x29/0x1b0 [1136314.553462] net_rx_action+0x133/0x270 [1136314.561619] __do_softirq+0xbe/0x28e [1136314.569303] do_softirq+0x3f/0x60 This comes from __xdp_return() call with xdp_buff argument passed as NULL which is supposed to be consumed by xsk_buff_free() call. To address this properly, in ZC case, a node that represents the frag being removed has to be pulled out of xskb_list. Introduce appriopriate xsk helpers to do such node operation and use them accordingly within bpf_xdp_adjust_tail(). Fixes: 24ea50127ecf ("xsk: support mbuf on ZC RX") Signed-off-by: Maciej Fijalkowski --- include/net/xdp_sock_drv.h | 17 ++++++++++++++++ net/core/filter.c | 41 +++++++++++++++++++++++++++++--------- 2 files changed, 49 insertions(+), 9 deletions(-) diff --git a/include/net/xdp_sock_drv.h b/include/net/xdp_sock_drv.h index 81e02de3f453..bb953bb0ab3e 100644 --- a/include/net/xdp_sock_drv.h +++ b/include/net/xdp_sock_drv.h @@ -147,6 +147,23 @@ static inline struct xdp_buff *xsk_buff_get_frag(struct xdp_buff *first) return ret; } +static inline void xsk_buff_tail_del(struct xdp_buff *tail) +{ + struct xdp_buff_xsk *xskb = container_of(tail, struct xdp_buff_xsk, xdp); + + list_del(&xskb->xskb_list_node); +} + +static inline struct xdp_buff *xsk_buff_get_tail(struct xdp_buff *first) +{ + struct xdp_buff_xsk *xskb = container_of(first, struct xdp_buff_xsk, xdp); + struct xdp_buff_xsk *frag; + + frag = list_last_entry(&xskb->pool->xskb_list, struct xdp_buff_xsk, + xskb_list_node); + return &frag->xdp; +} + static inline void xsk_buff_set_size(struct xdp_buff *xdp, u32 size) { xdp->data = xdp->data_hard_start + XDP_PACKET_HEADROOM; diff --git a/net/core/filter.c b/net/core/filter.c index 0adaa4afa35f..5409254eb3f5 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -83,6 +83,7 @@ #include #include #include +#include #include "dev.h" @@ -4075,6 +4076,35 @@ static int bpf_xdp_frags_increase_tail(struct xdp_buff *xdp, int offset) return 0; } +static void __shrink_data(struct xdp_buff *xdp, struct xdp_mem_info *mem_info, + skb_frag_t *frag, int shrink) +{ + if (mem_info->type == MEM_TYPE_XSK_BUFF_POOL) + xsk_buff_get_tail(xdp)->data_end -= shrink; + skb_frag_size_sub(frag, shrink); +} + +static bool shrink_data(struct xdp_buff *xdp, skb_frag_t *frag, int shrink) +{ + struct xdp_mem_info *mem_info = &xdp->rxq->mem; + + if (skb_frag_size(frag) == shrink) { + struct page *page = skb_frag_page(frag); + struct xdp_buff *zc_frag = NULL; + + if (mem_info->type == MEM_TYPE_XSK_BUFF_POOL) { + zc_frag = xsk_buff_get_tail(xdp); + xdp_buff_clear_frags_flag(zc_frag); + xsk_buff_tail_del(zc_frag); + } + + __xdp_return(page_address(page), mem_info, false, zc_frag); + return true; + } + __shrink_data(xdp, mem_info, frag, shrink); + return false; +} + static int bpf_xdp_frags_shrink_tail(struct xdp_buff *xdp, int offset) { struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp); @@ -4089,17 +4119,10 @@ static int bpf_xdp_frags_shrink_tail(struct xdp_buff *xdp, int offset) len_free += shrink; offset -= shrink; - - if (skb_frag_size(frag) == shrink) { - struct page *page = skb_frag_page(frag); - - __xdp_return(page_address(page), &xdp->rxq->mem, - false, NULL); + if (shrink_data(xdp, frag, shrink)) n_frags_free++; - } else { - skb_frag_size_sub(frag, shrink); + else break; - } } sinfo->nr_frags -= n_frags_free; sinfo->xdp_frags_size -= len_free;