Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8445A44AB62; Tue, 21 Jul 2026 21:53:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784670837; cv=none; b=CEcXIt/vRerGT14yaCHRofTo/qWEO5vecwF2ZkFIdr6NqyOLb4iloGyXsv1bvjLIjnKUyJ4Boz4+HvRZc+tnYhd3sfp6shRzpT+tjUthMTkkI4N7WKXicDxga8I6DaENAhdi+gshl3vRGveuzn22jjqxoN1Vh+XP1dKG/ERXkCY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784670837; c=relaxed/simple; bh=aKCP6Y3vdN9NVQeTr/MuTjMQU/rhChB/T2paTatvzSA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aJLMFrJxIKydVGGg0uaRWnkZbj+9ozvQ+bd2E889Dk86SKy7lp1iqiBvOs6/F8mzAdHHrExxgLElv2Wt+9qCMh7xACUR61zxnxC/J3fJ0FfQxRBnyb2xkbtF1NhyaeYqlX9KJNfYx1irmhAHSKd1mKPM2JJmbF0SboNdzt9Fvc8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2bX7hHYh; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="2bX7hHYh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E9AEE1F000E9; Tue, 21 Jul 2026 21:53:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784670836; bh=yst1mx70upBYkJ/M7YOcyBD8gmGQeo0GEl5YlyQq8/g=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=2bX7hHYhF+aaDQf+BFoi48qgJR4rUfpFZWPgbwCOtwLJ0ItRxxL9Updjycfy+7JH1 +kPR/5xz8O/jKv8JMbxaV9eScb0ia9feonPt2SIxB4teK5gY1OKdjuhqzWoxWN5eNd gJ/m8S4ueREd8qBJo9Ue26UflNc+05o5rutnTyYA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yiming Qian , Keenan Dong , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15 020/843] net: skmsg: preserve sg.copy across SG transforms Date: Tue, 21 Jul 2026 17:14:15 +0200 Message-ID: <20260721152406.415046357@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152405.946368001@linuxfoundation.org> References: <20260721152405.946368001@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yiming Qian [ Upstream commit 406e8a651a7b854c41fecd5117bb282b3a6c2c6b ] The sk_msg sg.copy bitmap is part of the scatterlist entry ownership state. A set bit tells sk_msg_compute_data_pointers() not to expose the entry through writable BPF ctx->data. This protects entries backed by pages that are not private to the sk_msg, such as splice-backed file page-cache pages. Several sk_msg transform paths move, copy, split, or compact msg->sg.data[] entries without moving the matching sg.copy bit. This can make an externally backed entry arrive at a new slot with a clear copy bit. A later SK_MSG verdict can then expose sg_virt(sge) as writable ctx->data and BPF stores can modify the original page cache. Keep sg.copy synchronized with sg.data[] whenever entries are transferred, shifted, split, or copied into a new sk_msg. Clear the bit when an entry is replaced by a newly allocated private page or freed. This covers the BPF pull/push/pop helpers, sk_msg_shift_left/right(), sk_msg_xfer(), and tls_split_open_record(), including the partial tail entry created during TLS open-record splitting. Fixes: d3b18ad31f93 ("tls: add bpf support to sk_msg handling") Cc: stable@vger.kernel.org Reported-by: Yiming Qian Reported-by: Keenan Dong Signed-off-by: Yiming Qian Link: https://patch.msgid.link/20260610062137.49075-1-yimingqian591@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- include/linux/skmsg.h | 15 +++++++++++---- net/core/filter.c | 27 +++++++++++++++++++++++++++ net/core/skmsg.c | 2 ++ net/tls/tls_sw.c | 4 ++++ 4 files changed, 44 insertions(+), 4 deletions(-) --- a/include/linux/skmsg.h +++ b/include/linux/skmsg.h @@ -4,6 +4,7 @@ #ifndef _LINUX_SKMSG_H #define _LINUX_SKMSG_H +#include #include #include #include @@ -188,11 +189,14 @@ static inline void sk_msg_xfer(struct sk int which, u32 size) { dst->sg.data[which] = src->sg.data[which]; + __assign_bit(which, dst->sg.copy, test_bit(which, src->sg.copy)); dst->sg.data[which].length = size; dst->sg.size += size; src->sg.size -= size; src->sg.data[which].length -= size; src->sg.data[which].offset += size; + if (!src->sg.data[which].length) + __clear_bit(which, src->sg.copy); } static inline void sk_msg_xfer_full(struct sk_msg *dst, struct sk_msg *src) @@ -262,16 +266,19 @@ static inline void sk_msg_page_add(struc static inline void sk_msg_sg_copy(struct sk_msg *msg, u32 i, bool copy_state) { do { - if (copy_state) - __set_bit(i, msg->sg.copy); - else - __clear_bit(i, msg->sg.copy); + __assign_bit(i, msg->sg.copy, copy_state); sk_msg_iter_var_next(i); if (i == msg->sg.end) break; } while (1); } +static inline void sk_msg_sg_copy_assign(struct sk_msg *dst, u32 dst_i, + const struct sk_msg *src, u32 src_i) +{ + __assign_bit(dst_i, dst->sg.copy, test_bit(src_i, src->sg.copy)); +} + static inline void sk_msg_sg_copy_set(struct sk_msg *msg, u32 start) { sk_msg_sg_copy(msg, start, true); --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2701,11 +2701,13 @@ BPF_CALL_4(bpf_msg_pull_data, struct sk_ poffset += len; sge->length = 0; put_page(sg_page(sge)); + __clear_bit(i, msg->sg.copy); sk_msg_iter_var_next(i); } while (i != last_sge); sg_set_page(&msg->sg.data[first_sge], page, copy, 0); + __clear_bit(first_sge, msg->sg.copy); /* To repair sg ring we need to shift entries. If we only * had a single entry though we can just replace it and @@ -2731,9 +2733,11 @@ BPF_CALL_4(bpf_msg_pull_data, struct sk_ break; msg->sg.data[i] = msg->sg.data[move_from]; + sk_msg_sg_copy_assign(msg, i, msg, move_from); msg->sg.data[move_from].length = 0; msg->sg.data[move_from].page_link = 0; msg->sg.data[move_from].offset = 0; + __clear_bit(move_from, msg->sg.copy); sk_msg_iter_var_next(i); } while (1); @@ -2762,6 +2766,7 @@ BPF_CALL_4(bpf_msg_push_data, struct sk_ { struct scatterlist sge, nsge, nnsge, rsge = {0}, *psge; u32 new, i = 0, l = 0, space, copy = 0, offset = 0; + bool sge_copy, nsge_copy, nnsge_copy, rsge_copy = false; u8 *raw, *to, *from; struct page *page; @@ -2834,6 +2839,7 @@ BPF_CALL_4(bpf_msg_push_data, struct sk_ sk_msg_iter_var_prev(i); psge = sk_msg_elem(msg, i); rsge = sk_msg_elem_cpy(msg, i); + rsge_copy = test_bit(i, msg->sg.copy); psge->length = start - offset; rsge.length -= psge->length; @@ -2858,24 +2864,32 @@ BPF_CALL_4(bpf_msg_push_data, struct sk_ /* Shift one or two slots as needed */ sge = sk_msg_elem_cpy(msg, new); + sge_copy = test_bit(new, msg->sg.copy); sg_unmark_end(&sge); nsge = sk_msg_elem_cpy(msg, i); + nsge_copy = test_bit(i, msg->sg.copy); if (rsge.length) { sk_msg_iter_var_next(i); nnsge = sk_msg_elem_cpy(msg, i); + nnsge_copy = test_bit(i, msg->sg.copy); sk_msg_iter_next(msg, end); } while (i != msg->sg.end) { msg->sg.data[i] = sge; + __assign_bit(i, msg->sg.copy, sge_copy); sge = nsge; + sge_copy = nsge_copy; sk_msg_iter_var_next(i); if (rsge.length) { nsge = nnsge; + nsge_copy = nnsge_copy; nnsge = sk_msg_elem_cpy(msg, i); + nnsge_copy = test_bit(i, msg->sg.copy); } else { nsge = sk_msg_elem_cpy(msg, i); + nsge_copy = test_bit(i, msg->sg.copy); } } @@ -2889,6 +2903,7 @@ place_new: get_page(sg_page(&rsge)); sk_msg_iter_var_next(new); msg->sg.data[new] = rsge; + __assign_bit(new, msg->sg.copy, rsge_copy); } sk_msg_reset_curr(msg); @@ -2916,25 +2931,33 @@ static void sk_msg_shift_left(struct sk_ prev = i; sk_msg_iter_var_next(i); msg->sg.data[prev] = msg->sg.data[i]; + sk_msg_sg_copy_assign(msg, prev, msg, i); } while (i != msg->sg.end); sk_msg_iter_prev(msg, end); + __clear_bit(msg->sg.end, msg->sg.copy); } static void sk_msg_shift_right(struct sk_msg *msg, int i) { struct scatterlist tmp, sge; + bool tmp_copy, sge_copy; sk_msg_iter_next(msg, end); sge = sk_msg_elem_cpy(msg, i); + sge_copy = test_bit(i, msg->sg.copy); sk_msg_iter_var_next(i); tmp = sk_msg_elem_cpy(msg, i); + tmp_copy = test_bit(i, msg->sg.copy); while (i != msg->sg.end) { msg->sg.data[i] = sge; + __assign_bit(i, msg->sg.copy, sge_copy); sk_msg_iter_var_next(i); sge = tmp; + sge_copy = tmp_copy; tmp = sk_msg_elem_cpy(msg, i); + tmp_copy = test_bit(i, msg->sg.copy); } } @@ -2994,6 +3017,8 @@ BPF_CALL_4(bpf_msg_pop_data, struct sk_m struct scatterlist *nsge, *sge = sk_msg_elem(msg, i); int a = start - offset; int b = sge->length - pop - a; + u32 sge_i = i; + bool sge_copy = test_bit(i, msg->sg.copy); sk_msg_iter_var_next(i); @@ -3006,6 +3031,7 @@ BPF_CALL_4(bpf_msg_pop_data, struct sk_m sg_set_page(nsge, sg_page(sge), b, sge->offset + pop + a); + __assign_bit(i, msg->sg.copy, sge_copy); } else { struct page *page, *orig; u8 *to, *from; @@ -3022,6 +3048,7 @@ BPF_CALL_4(bpf_msg_pop_data, struct sk_m memcpy(to, from, a); memcpy(to + a, from + a + pop, b); sg_set_page(sge, page, a + b, 0); + __clear_bit(sge_i, msg->sg.copy); put_page(orig); } pop = 0; --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -65,6 +65,7 @@ int sk_msg_alloc(struct sock *sk, struct sge = &msg->sg.data[msg->sg.end]; sg_unmark_end(sge); sg_set_page(sge, pfrag->page, use, orig_offset); + __clear_bit(msg->sg.end, msg->sg.copy); get_page(pfrag->page); sk_msg_iter_next(msg, end); } @@ -185,6 +186,7 @@ static int sk_msg_free_elem(struct sock sk_mem_uncharge(sk, len); put_page(sg_page(sge)); } + __clear_bit(i, msg->sg.copy); memset(sge, 0, sizeof(*sge)); return len; } --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -607,6 +607,7 @@ static int tls_split_open_record(struct struct scatterlist *sge, *osge, *nsge; u32 orig_size = msg_opl->sg.size; struct scatterlist tmp = { }; + u32 tmp_i = 0; struct sk_msg *msg_npl; struct tls_rec *new; int ret; @@ -628,6 +629,7 @@ static int tls_split_open_record(struct if (sge->length > apply) { u32 len = sge->length - apply; + tmp_i = i; get_page(sg_page(sge)); sg_set_page(&tmp, sg_page(sge), len, sge->offset + apply); @@ -659,6 +661,7 @@ static int tls_split_open_record(struct nsge = sk_msg_elem(msg_npl, j); if (tmp.length) { memcpy(nsge, &tmp, sizeof(*nsge)); + sk_msg_sg_copy_assign(msg_npl, j, msg_opl, tmp_i); sk_msg_iter_var_next(j); nsge = sk_msg_elem(msg_npl, j); } @@ -666,6 +669,7 @@ static int tls_split_open_record(struct osge = sk_msg_elem(msg_opl, i); while (osge->length) { memcpy(nsge, osge, sizeof(*nsge)); + sk_msg_sg_copy_assign(msg_npl, j, msg_opl, i); sg_unmark_end(nsge); sk_msg_iter_var_next(i); sk_msg_iter_var_next(j);