1 // SPDX-License-Identifier: GPL-2.0
2 /* XDP user-space packet buffer
3  * Copyright(c) 2018 Intel Corporation.
4  */
5 
6 #include <linux/init.h>
7 #include <linux/sched/mm.h>
8 #include <linux/sched/signal.h>
9 #include <linux/sched/task.h>
10 #include <linux/uaccess.h>
11 #include <linux/slab.h>
12 #include <linux/bpf.h>
13 #include <linux/mm.h>
14 #include <linux/netdevice.h>
15 #include <linux/rtnetlink.h>
16 #include <linux/idr.h>
17 #include <linux/vmalloc.h>
18 
19 #include "xdp_umem.h"
20 #include "xsk_queue.h"
21 
22 #define XDP_UMEM_MIN_CHUNK_SIZE 2048
23 
24 static DEFINE_IDA(umem_ida);
25 
xdp_umem_unpin_pages(struct xdp_umem * umem)26 static void xdp_umem_unpin_pages(struct xdp_umem *umem)
27 {
28 	unpin_user_pages_dirty_lock(umem->pgs, umem->npgs, true);
29 
30 	kvfree(umem->pgs);
31 	umem->pgs = NULL;
32 }
33 
xdp_umem_unaccount_pages(struct xdp_umem * umem)34 static void xdp_umem_unaccount_pages(struct xdp_umem *umem)
35 {
36 	if (umem->user) {
37 		atomic_long_sub(umem->npgs, &umem->user->locked_vm);
38 		free_uid(umem->user);
39 	}
40 }
41 
xdp_umem_addr_unmap(struct xdp_umem * umem)42 static void xdp_umem_addr_unmap(struct xdp_umem *umem)
43 {
44 	vunmap(umem->addrs);
45 	umem->addrs = NULL;
46 }
47 
xdp_umem_addr_map(struct xdp_umem * umem,struct page ** pages,u32 nr_pages)48 static int xdp_umem_addr_map(struct xdp_umem *umem, struct page **pages,
49 			     u32 nr_pages)
50 {
51 	umem->addrs = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
52 	if (!umem->addrs)
53 		return -ENOMEM;
54 	return 0;
55 }
56 
xdp_umem_release(struct xdp_umem * umem)57 static void xdp_umem_release(struct xdp_umem *umem)
58 {
59 	umem->zc = false;
60 	ida_simple_remove(&umem_ida, umem->id);
61 
62 	xdp_umem_addr_unmap(umem);
63 	xdp_umem_unpin_pages(umem);
64 
65 	xdp_umem_unaccount_pages(umem);
66 	kfree(umem);
67 }
68 
xdp_umem_release_deferred(struct work_struct * work)69 static void xdp_umem_release_deferred(struct work_struct *work)
70 {
71 	struct xdp_umem *umem = container_of(work, struct xdp_umem, work);
72 
73 	xdp_umem_release(umem);
74 }
75 
xdp_get_umem(struct xdp_umem * umem)76 void xdp_get_umem(struct xdp_umem *umem)
77 {
78 	refcount_inc(&umem->users);
79 }
80 
xdp_put_umem(struct xdp_umem * umem,bool defer_cleanup)81 void xdp_put_umem(struct xdp_umem *umem, bool defer_cleanup)
82 {
83 	if (!umem)
84 		return;
85 
86 	if (refcount_dec_and_test(&umem->users)) {
87 		if (defer_cleanup) {
88 			INIT_WORK(&umem->work, xdp_umem_release_deferred);
89 			schedule_work(&umem->work);
90 		} else {
91 			xdp_umem_release(umem);
92 		}
93 	}
94 }
95 
xdp_umem_pin_pages(struct xdp_umem * umem,unsigned long address)96 static int xdp_umem_pin_pages(struct xdp_umem *umem, unsigned long address)
97 {
98 	unsigned int gup_flags = FOLL_WRITE;
99 	long npgs;
100 	int err;
101 
102 	umem->pgs = kvcalloc(umem->npgs, sizeof(*umem->pgs), GFP_KERNEL | __GFP_NOWARN);
103 	if (!umem->pgs)
104 		return -ENOMEM;
105 
106 	mmap_read_lock(current->mm);
107 	npgs = pin_user_pages(address, umem->npgs,
108 			      gup_flags | FOLL_LONGTERM, &umem->pgs[0], NULL);
109 	mmap_read_unlock(current->mm);
110 
111 	if (npgs != umem->npgs) {
112 		if (npgs >= 0) {
113 			umem->npgs = npgs;
114 			err = -ENOMEM;
115 			goto out_pin;
116 		}
117 		err = npgs;
118 		goto out_pgs;
119 	}
120 	return 0;
121 
122 out_pin:
123 	xdp_umem_unpin_pages(umem);
124 out_pgs:
125 	kvfree(umem->pgs);
126 	umem->pgs = NULL;
127 	return err;
128 }
129 
xdp_umem_account_pages(struct xdp_umem * umem)130 static int xdp_umem_account_pages(struct xdp_umem *umem)
131 {
132 	unsigned long lock_limit, new_npgs, old_npgs;
133 
134 	if (capable(CAP_IPC_LOCK))
135 		return 0;
136 
137 	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
138 	umem->user = get_uid(current_user());
139 
140 	do {
141 		old_npgs = atomic_long_read(&umem->user->locked_vm);
142 		new_npgs = old_npgs + umem->npgs;
143 		if (new_npgs > lock_limit) {
144 			free_uid(umem->user);
145 			umem->user = NULL;
146 			return -ENOBUFS;
147 		}
148 	} while (atomic_long_cmpxchg(&umem->user->locked_vm, old_npgs,
149 				     new_npgs) != old_npgs);
150 	return 0;
151 }
152 
xdp_umem_reg(struct xdp_umem * umem,struct xdp_umem_reg * mr)153 static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
154 {
155 	u32 npgs_rem, chunk_size = mr->chunk_size, headroom = mr->headroom;
156 	bool unaligned_chunks = mr->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG;
157 	u64 npgs, addr = mr->addr, size = mr->len;
158 	unsigned int chunks, chunks_rem;
159 	int err;
160 
161 	if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) {
162 		/* Strictly speaking we could support this, if:
163 		 * - huge pages, or*
164 		 * - using an IOMMU, or
165 		 * - making sure the memory area is consecutive
166 		 * but for now, we simply say "computer says no".
167 		 */
168 		return -EINVAL;
169 	}
170 
171 	if (mr->flags & ~XDP_UMEM_UNALIGNED_CHUNK_FLAG)
172 		return -EINVAL;
173 
174 	if (!unaligned_chunks && !is_power_of_2(chunk_size))
175 		return -EINVAL;
176 
177 	if (!PAGE_ALIGNED(addr)) {
178 		/* Memory area has to be page size aligned. For
179 		 * simplicity, this might change.
180 		 */
181 		return -EINVAL;
182 	}
183 
184 	if ((addr + size) < addr)
185 		return -EINVAL;
186 
187 	npgs = div_u64_rem(size, PAGE_SIZE, &npgs_rem);
188 	if (npgs_rem)
189 		npgs++;
190 	if (npgs > U32_MAX)
191 		return -EINVAL;
192 
193 	chunks = (unsigned int)div_u64_rem(size, chunk_size, &chunks_rem);
194 	if (chunks == 0)
195 		return -EINVAL;
196 
197 	if (!unaligned_chunks && chunks_rem)
198 		return -EINVAL;
199 
200 	if (headroom >= chunk_size - XDP_PACKET_HEADROOM)
201 		return -EINVAL;
202 
203 	umem->size = size;
204 	umem->headroom = headroom;
205 	umem->chunk_size = chunk_size;
206 	umem->chunks = chunks;
207 	umem->npgs = (u32)npgs;
208 	umem->pgs = NULL;
209 	umem->user = NULL;
210 	umem->flags = mr->flags;
211 
212 	INIT_LIST_HEAD(&umem->xsk_dma_list);
213 	refcount_set(&umem->users, 1);
214 
215 	err = xdp_umem_account_pages(umem);
216 	if (err)
217 		return err;
218 
219 	err = xdp_umem_pin_pages(umem, (unsigned long)addr);
220 	if (err)
221 		goto out_account;
222 
223 	err = xdp_umem_addr_map(umem, umem->pgs, umem->npgs);
224 	if (err)
225 		goto out_unpin;
226 
227 	return 0;
228 
229 out_unpin:
230 	xdp_umem_unpin_pages(umem);
231 out_account:
232 	xdp_umem_unaccount_pages(umem);
233 	return err;
234 }
235 
xdp_umem_create(struct xdp_umem_reg * mr)236 struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr)
237 {
238 	struct xdp_umem *umem;
239 	int err;
240 
241 	umem = kzalloc(sizeof(*umem), GFP_KERNEL);
242 	if (!umem)
243 		return ERR_PTR(-ENOMEM);
244 
245 	err = ida_simple_get(&umem_ida, 0, 0, GFP_KERNEL);
246 	if (err < 0) {
247 		kfree(umem);
248 		return ERR_PTR(err);
249 	}
250 	umem->id = err;
251 
252 	err = xdp_umem_reg(umem, mr);
253 	if (err) {
254 		ida_simple_remove(&umem_ida, umem->id);
255 		kfree(umem);
256 		return ERR_PTR(err);
257 	}
258 
259 	return umem;
260 }
261