From patchwork Thu Mar 27 08:34:47 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hou Tao X-Patchwork-Id: 14030851 X-Patchwork-Delegate: bpf@iogearbox.net Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (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 BFBD5204F7F for ; Thu, 27 Mar 2025 08:23:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743063786; cv=none; b=WenKj9HEGoJdikBg0lSXB9ctbldM4ak81Ay7IobhvJq9symrqBGiJE46u/KJmyKhQjtinEz+cvvH4MIi57bywGbEOSebsShaNXF1W4H6f35+Xr8t1LAgFbTLJnonp2EaI8pi9MhKqss/BFBqr3GvAiicKyg++wu5bbvzYVwb0BM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743063786; c=relaxed/simple; bh=6NmuHmprQGQyMyd6DhwXoJJEJPrriVBTKeim9p4R4E0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=eOg3sM7t9XpKsovgv6R6CiUwTx1Fsb+p07Kggjy3PXAHcZDmMqmOqmRUAJix/32Tex5rPWQzhOw8MHPC6ewGhZrgkeJ6a+aAEtsWA+wmhhHwQ8TPO4fj74UVMeBLC+fM5XddXJFnOcH0iDfKF7XEplbsH3a9Ji7dXcLuPicq5NQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4ZNc8m5DQTz4f3jXm for ; Thu, 27 Mar 2025 16:22:32 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id AD7EE1A0AD5 for ; Thu, 27 Mar 2025 16:22:55 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.124.27]) by APP4 (Coremail) with SMTP id gCh0CgAXe1_XCuVnluzSHg--.7420S12; Thu, 27 Mar 2025 16:22:55 +0800 (CST) From: Hou Tao To: bpf@vger.kernel.org Cc: Martin KaFai Lau , Alexei Starovoitov , Andrii Nakryiko , Eduard Zingerman , Song Liu , Hao Luo , Yonghong Song , Daniel Borkmann , KP Singh , Stanislav Fomichev , Jiri Olsa , John Fastabend , houtao1@huawei.com Subject: [PATCH bpf-next v3 08/16] bpf: Handle bpf_dynptr in bpf syscall when it is used as output Date: Thu, 27 Mar 2025 16:34:47 +0800 Message-Id: <20250327083455.848708-9-houtao@huaweicloud.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20250327083455.848708-1-houtao@huaweicloud.com> References: <20250327083455.848708-1-houtao@huaweicloud.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: gCh0CgAXe1_XCuVnluzSHg--.7420S12 X-Coremail-Antispam: 1UD129KBjvJXoW3WF1fuF1DAr4fAF1rJw1fWFg_yoW7KF15pF 48G3sxZr4Fqr43JFZ8X3Wjv3yrtrn7Ww1UGas3Ka4rWF9xWr90vr1xKFW09ryYvFyDCr12 vws2qr98ZrWxJrJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPvb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E 14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7 xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Y z7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc7CjxVAaw2 AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAq x4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r 43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_JFI_Gr1lIxAIcVC0I7IYx2IY6xkF 7I0E14v26r4UJVWxJr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14 v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr1j6F4UJbIYCTnIWIevJa73UjIFyTuY vjxUF9NVUUUUU X-CM-SenderInfo: xkrx3t3r6k3tpzhluzxrxghudrp/ X-Patchwork-Delegate: bpf@iogearbox.net From: Hou Tao For get_next_key operation, unext_key is used as an output argument. When there is dynptr in map key, unext_key will also be used as an input argument, because the userspace application needs to pre-allocate a buffer for each variable-length part in the map key and save the length and the address of these buffers in bpf_dynptr objects. To support get_next_key op for map with dynptr key, map_get_next_key() first calls bpf_copy_from_dynptr_ukey() to construct a map key in which each bpf_dynptr_kern object has the same size as the corresponding bpf_dynptr object. It then calls ->map_get_next_key() to get the next_key, and finally calls bpf_copy_to_dynptr_ukey() to copy both the non-dynptr part and dynptr part in the map key to unext_key. Signed-off-by: Hou Tao --- kernel/bpf/syscall.c | 89 ++++++++++++++++++++++++++++++++++++-------- 1 file changed, 74 insertions(+), 15 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index d6dbcea3c30cb..40c3d85b06bae 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1664,7 +1664,7 @@ int __weak bpf_stackmap_copy(struct bpf_map *map, void *key, void *value) return -ENOTSUPP; } -static void *bpf_copy_from_dynptr_ukey(const struct bpf_map *map, bpfptr_t ukey) +static void *bpf_copy_from_dynptr_ukey(const struct bpf_map *map, bpfptr_t ukey, bool copy_data) { const struct btf_record *record; const struct btf_field *field; @@ -1672,7 +1672,6 @@ static void *bpf_copy_from_dynptr_ukey(const struct bpf_map *map, bpfptr_t ukey) void *key, *new_key, *kdata; unsigned int key_size, size; struct bpf_dynptr *uptr; - bpfptr_t udata; unsigned int i; int err; @@ -1687,6 +1686,7 @@ static void *bpf_copy_from_dynptr_ukey(const struct bpf_map *map, bpfptr_t ukey) field = &record->fields[i]; if (field->type != BPF_DYNPTR) continue; + uptr = key + field->offset; if (!uptr->size || uptr->reserved) { err = -EINVAL; @@ -1717,10 +1717,14 @@ static void *bpf_copy_from_dynptr_ukey(const struct bpf_map *map, bpfptr_t ukey) uptr = key + field->offset; size = uptr->size; - udata = make_bpfptr((u64)(uintptr_t)uptr->data, bpfptr_is_kernel(ukey)); - if (copy_from_bpfptr(kdata, udata, size)) { - err = -EFAULT; - goto free_key; + if (copy_data) { + bpfptr_t udata = make_bpfptr((u64)(uintptr_t)uptr->data, + bpfptr_is_kernel(ukey)); + + if (copy_from_bpfptr(kdata, udata, size)) { + err = -EFAULT; + goto free_key; + } } kptr = (struct bpf_dynptr_kern *)uptr; bpf_dynptr_init(kptr, kdata, BPF_DYNPTR_TYPE_LOCAL, 0, size); @@ -1737,7 +1741,7 @@ static void *bpf_copy_from_dynptr_ukey(const struct bpf_map *map, bpfptr_t ukey) static void *__bpf_copy_key(const struct bpf_map *map, void __user *ukey) { if (bpf_map_has_dynptr_key(map)) - return bpf_copy_from_dynptr_ukey(map, USER_BPFPTR(ukey)); + return bpf_copy_from_dynptr_ukey(map, USER_BPFPTR(ukey), true); if (map->key_size) return vmemdup_user(ukey, map->key_size); @@ -1751,7 +1755,7 @@ static void *__bpf_copy_key(const struct bpf_map *map, void __user *ukey) static void *___bpf_copy_key(const struct bpf_map *map, bpfptr_t ukey) { if (bpf_map_has_dynptr_key(map)) - return bpf_copy_from_dynptr_ukey(map, ukey); + return bpf_copy_from_dynptr_ukey(map, ukey, true); if (map->key_size) return kvmemdup_bpfptr(ukey, map->key_size); @@ -1762,6 +1766,51 @@ static void *___bpf_copy_key(const struct bpf_map *map, bpfptr_t ukey) return NULL; } +static int bpf_copy_to_dynptr_ukey(const struct bpf_map *map, + void __user *ukey, void *key) +{ + struct bpf_dynptr __user *uptr; + struct bpf_dynptr_kern *kptr; + struct btf_record *record; + unsigned int i, offset; + + offset = 0; + record = map->key_record; + for (i = 0; i < record->cnt; i++) { + struct btf_field *field; + unsigned int size; + void *udata; + + field = &record->fields[i]; + if (field->type != BPF_DYNPTR) + continue; + + /* Any no-dynptr part before the dynptr ? */ + if (offset < field->offset && + copy_to_user(ukey + offset, key + offset, field->offset - offset)) + return -EFAULT; + + /* dynptr part */ + uptr = ukey + field->offset; + if (copy_from_user(&udata, &uptr->data, sizeof(udata))) + return -EFAULT; + + kptr = key + field->offset; + size = __bpf_dynptr_size(kptr); + if (copy_to_user((void __user *)udata, __bpf_dynptr_data(kptr, size), size) || + put_user(size, &uptr->size) || put_user(0, &uptr->reserved)) + return -EFAULT; + + offset = field->offset + field->size; + } + + if (offset < map->key_size && + copy_to_user(ukey + offset, key + offset, map->key_size - offset)) + return -EFAULT; + + return 0; +} + /* last field in 'union bpf_attr' used by this command */ #define BPF_MAP_LOOKUP_ELEM_LAST_FIELD flags @@ -1964,10 +2013,19 @@ static int map_get_next_key(union bpf_attr *attr) key = NULL; } - err = -ENOMEM; - next_key = kvmalloc(map->key_size, GFP_USER); - if (!next_key) + if (bpf_map_has_dynptr_key(map)) + next_key = bpf_copy_from_dynptr_ukey(map, USER_BPFPTR(unext_key), false); + else + next_key = kvmalloc(map->key_size, GFP_USER); + if (IS_ERR_OR_NULL(next_key)) { + if (!next_key) { + err = -ENOMEM; + } else { + err = PTR_ERR(next_key); + next_key = NULL; + } goto free_key; + } if (bpf_map_is_offloaded(map)) { err = bpf_map_offload_get_next_key(map, key, next_key); @@ -1981,12 +2039,13 @@ static int map_get_next_key(union bpf_attr *attr) if (err) goto free_next_key; - err = -EFAULT; - if (copy_to_user(unext_key, next_key, map->key_size) != 0) + if (bpf_map_has_dynptr_key(map)) + err = bpf_copy_to_dynptr_ukey(map, unext_key, next_key); + else + err = copy_to_user(unext_key, next_key, map->key_size) ? -EFAULT : 0; + if (err) goto free_next_key; - err = 0; - free_next_key: kvfree(next_key); free_key: