1 // SPDX-License-Identifier: GPL-2.0-only 1 // SPDX-License-Identifier: GPL-2.0-only
2 2
3 #include <linux/stat.h> 3 #include <linux/stat.h>
4 #include <linux/sysctl.h> 4 #include <linux/sysctl.h>
5 #include <linux/slab.h> 5 #include <linux/slab.h>
6 #include <linux/cred.h> 6 #include <linux/cred.h>
7 #include <linux/hash.h> 7 #include <linux/hash.h>
8 #include <linux/kmemleak.h> 8 #include <linux/kmemleak.h>
9 #include <linux/user_namespace.h> 9 #include <linux/user_namespace.h>
10 10
11 struct ucounts init_ucounts = { 11 struct ucounts init_ucounts = {
12 .ns = &init_user_ns, 12 .ns = &init_user_ns,
13 .uid = GLOBAL_ROOT_UID, 13 .uid = GLOBAL_ROOT_UID,
14 .count = ATOMIC_INIT(1), !! 14 .count = 1,
15 }; 15 };
16 16
17 #define UCOUNTS_HASHTABLE_BITS 10 17 #define UCOUNTS_HASHTABLE_BITS 10
18 static struct hlist_head ucounts_hashtable[(1 18 static struct hlist_head ucounts_hashtable[(1 << UCOUNTS_HASHTABLE_BITS)];
19 static DEFINE_SPINLOCK(ucounts_lock); 19 static DEFINE_SPINLOCK(ucounts_lock);
20 20
21 #define ucounts_hashfn(ns, uid) 21 #define ucounts_hashfn(ns, uid) \
22 hash_long((unsigned long)__kuid_val(ui 22 hash_long((unsigned long)__kuid_val(uid) + (unsigned long)(ns), \
23 UCOUNTS_HASHTABLE_BITS) 23 UCOUNTS_HASHTABLE_BITS)
24 #define ucounts_hashentry(ns, uid) \ 24 #define ucounts_hashentry(ns, uid) \
25 (ucounts_hashtable + ucounts_hashfn(ns 25 (ucounts_hashtable + ucounts_hashfn(ns, uid))
26 26
27 27
28 #ifdef CONFIG_SYSCTL 28 #ifdef CONFIG_SYSCTL
29 static struct ctl_table_set * 29 static struct ctl_table_set *
30 set_lookup(struct ctl_table_root *root) 30 set_lookup(struct ctl_table_root *root)
31 { 31 {
32 return ¤t_user_ns()->set; 32 return ¤t_user_ns()->set;
33 } 33 }
34 34
35 static int set_is_seen(struct ctl_table_set *s 35 static int set_is_seen(struct ctl_table_set *set)
36 { 36 {
37 return ¤t_user_ns()->set == set; 37 return ¤t_user_ns()->set == set;
38 } 38 }
39 39
40 static int set_permissions(struct ctl_table_he 40 static int set_permissions(struct ctl_table_header *head,
41 const struct ctl_ta !! 41 struct ctl_table *table)
42 { 42 {
43 struct user_namespace *user_ns = 43 struct user_namespace *user_ns =
44 container_of(head->set, struct 44 container_of(head->set, struct user_namespace, set);
45 int mode; 45 int mode;
46 46
47 /* Allow users with CAP_SYS_RESOURCE u 47 /* Allow users with CAP_SYS_RESOURCE unrestrained access */
48 if (ns_capable(user_ns, CAP_SYS_RESOUR 48 if (ns_capable(user_ns, CAP_SYS_RESOURCE))
49 mode = (table->mode & S_IRWXU) 49 mode = (table->mode & S_IRWXU) >> 6;
50 else 50 else
51 /* Allow all others at most read-only 51 /* Allow all others at most read-only access */
52 mode = table->mode & S_IROTH; 52 mode = table->mode & S_IROTH;
53 return (mode << 6) | (mode << 3) | mod 53 return (mode << 6) | (mode << 3) | mode;
54 } 54 }
55 55
56 static struct ctl_table_root set_root = { 56 static struct ctl_table_root set_root = {
57 .lookup = set_lookup, 57 .lookup = set_lookup,
58 .permissions = set_permissions, 58 .permissions = set_permissions,
59 }; 59 };
60 60
61 static long ue_zero = 0; !! 61 #define UCOUNT_ENTRY(name) \
62 static long ue_int_max = INT_MAX; !! 62 { \
63 !! 63 .procname = name, \
64 #define UCOUNT_ENTRY(name) !! 64 .maxlen = sizeof(int), \
65 { !! 65 .mode = 0644, \
66 .procname = name, !! 66 .proc_handler = proc_dointvec_minmax, \
67 .maxlen = sizeof(long) !! 67 .extra1 = SYSCTL_ZERO, \
68 .mode = 0644, !! 68 .extra2 = SYSCTL_INT_MAX, \
69 .proc_handler = proc_doulong <<
70 .extra1 = &ue_zero, <<
71 .extra2 = &ue_int_max, <<
72 } 69 }
73 static struct ctl_table user_table[] = { 70 static struct ctl_table user_table[] = {
74 UCOUNT_ENTRY("max_user_namespaces"), 71 UCOUNT_ENTRY("max_user_namespaces"),
75 UCOUNT_ENTRY("max_pid_namespaces"), 72 UCOUNT_ENTRY("max_pid_namespaces"),
76 UCOUNT_ENTRY("max_uts_namespaces"), 73 UCOUNT_ENTRY("max_uts_namespaces"),
77 UCOUNT_ENTRY("max_ipc_namespaces"), 74 UCOUNT_ENTRY("max_ipc_namespaces"),
78 UCOUNT_ENTRY("max_net_namespaces"), 75 UCOUNT_ENTRY("max_net_namespaces"),
79 UCOUNT_ENTRY("max_mnt_namespaces"), 76 UCOUNT_ENTRY("max_mnt_namespaces"),
80 UCOUNT_ENTRY("max_cgroup_namespaces"), 77 UCOUNT_ENTRY("max_cgroup_namespaces"),
81 UCOUNT_ENTRY("max_time_namespaces"), 78 UCOUNT_ENTRY("max_time_namespaces"),
82 #ifdef CONFIG_INOTIFY_USER 79 #ifdef CONFIG_INOTIFY_USER
83 UCOUNT_ENTRY("max_inotify_instances"), 80 UCOUNT_ENTRY("max_inotify_instances"),
84 UCOUNT_ENTRY("max_inotify_watches"), 81 UCOUNT_ENTRY("max_inotify_watches"),
85 #endif 82 #endif
86 #ifdef CONFIG_FANOTIFY 83 #ifdef CONFIG_FANOTIFY
87 UCOUNT_ENTRY("max_fanotify_groups"), 84 UCOUNT_ENTRY("max_fanotify_groups"),
88 UCOUNT_ENTRY("max_fanotify_marks"), 85 UCOUNT_ENTRY("max_fanotify_marks"),
89 #endif 86 #endif
>> 87 { }
90 }; 88 };
91 #endif /* CONFIG_SYSCTL */ 89 #endif /* CONFIG_SYSCTL */
92 90
93 bool setup_userns_sysctls(struct user_namespac 91 bool setup_userns_sysctls(struct user_namespace *ns)
94 { 92 {
95 #ifdef CONFIG_SYSCTL 93 #ifdef CONFIG_SYSCTL
96 struct ctl_table *tbl; 94 struct ctl_table *tbl;
97 95
98 BUILD_BUG_ON(ARRAY_SIZE(user_table) != !! 96 BUILD_BUG_ON(ARRAY_SIZE(user_table) != UCOUNT_COUNTS + 1);
99 setup_sysctl_set(&ns->set, &set_root, 97 setup_sysctl_set(&ns->set, &set_root, set_is_seen);
100 tbl = kmemdup(user_table, sizeof(user_ 98 tbl = kmemdup(user_table, sizeof(user_table), GFP_KERNEL);
101 if (tbl) { 99 if (tbl) {
102 int i; 100 int i;
103 for (i = 0; i < UCOUNT_COUNTS; 101 for (i = 0; i < UCOUNT_COUNTS; i++) {
104 tbl[i].data = &ns->uco 102 tbl[i].data = &ns->ucount_max[i];
105 } 103 }
106 ns->sysctls = __register_sysct !! 104 ns->sysctls = __register_sysctl_table(&ns->set, "user", tbl);
107 <<
108 } 105 }
109 if (!ns->sysctls) { 106 if (!ns->sysctls) {
110 kfree(tbl); 107 kfree(tbl);
111 retire_sysctl_set(&ns->set); 108 retire_sysctl_set(&ns->set);
112 return false; 109 return false;
113 } 110 }
114 #endif 111 #endif
115 return true; 112 return true;
116 } 113 }
117 114
118 void retire_userns_sysctls(struct user_namespa 115 void retire_userns_sysctls(struct user_namespace *ns)
119 { 116 {
120 #ifdef CONFIG_SYSCTL 117 #ifdef CONFIG_SYSCTL
121 const struct ctl_table *tbl; !! 118 struct ctl_table *tbl;
122 119
123 tbl = ns->sysctls->ctl_table_arg; 120 tbl = ns->sysctls->ctl_table_arg;
124 unregister_sysctl_table(ns->sysctls); 121 unregister_sysctl_table(ns->sysctls);
125 retire_sysctl_set(&ns->set); 122 retire_sysctl_set(&ns->set);
126 kfree(tbl); 123 kfree(tbl);
127 #endif 124 #endif
128 } 125 }
129 126
130 static struct ucounts *find_ucounts(struct use 127 static struct ucounts *find_ucounts(struct user_namespace *ns, kuid_t uid, struct hlist_head *hashent)
131 { 128 {
132 struct ucounts *ucounts; 129 struct ucounts *ucounts;
133 130
134 hlist_for_each_entry(ucounts, hashent, 131 hlist_for_each_entry(ucounts, hashent, node) {
135 if (uid_eq(ucounts->uid, uid) 132 if (uid_eq(ucounts->uid, uid) && (ucounts->ns == ns))
136 return ucounts; 133 return ucounts;
137 } 134 }
138 return NULL; 135 return NULL;
139 } 136 }
140 137
141 static void hlist_add_ucounts(struct ucounts * 138 static void hlist_add_ucounts(struct ucounts *ucounts)
142 { 139 {
143 struct hlist_head *hashent = ucounts_h 140 struct hlist_head *hashent = ucounts_hashentry(ucounts->ns, ucounts->uid);
144 spin_lock_irq(&ucounts_lock); 141 spin_lock_irq(&ucounts_lock);
145 hlist_add_head(&ucounts->node, hashent 142 hlist_add_head(&ucounts->node, hashent);
146 spin_unlock_irq(&ucounts_lock); 143 spin_unlock_irq(&ucounts_lock);
147 } 144 }
148 145
149 static inline bool get_ucounts_or_wrap(struct <<
150 { <<
151 /* Returns true on a successful get, f <<
152 return !atomic_add_negative(1, &ucount <<
153 } <<
154 <<
155 struct ucounts *get_ucounts(struct ucounts *uc <<
156 { <<
157 if (!get_ucounts_or_wrap(ucounts)) { <<
158 put_ucounts(ucounts); <<
159 ucounts = NULL; <<
160 } <<
161 return ucounts; <<
162 } <<
163 <<
164 struct ucounts *alloc_ucounts(struct user_name 146 struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid)
165 { 147 {
166 struct hlist_head *hashent = ucounts_h 148 struct hlist_head *hashent = ucounts_hashentry(ns, uid);
167 struct ucounts *ucounts, *new; 149 struct ucounts *ucounts, *new;
168 bool wrapped; <<
169 150
170 spin_lock_irq(&ucounts_lock); 151 spin_lock_irq(&ucounts_lock);
171 ucounts = find_ucounts(ns, uid, hashen 152 ucounts = find_ucounts(ns, uid, hashent);
172 if (!ucounts) { 153 if (!ucounts) {
173 spin_unlock_irq(&ucounts_lock) 154 spin_unlock_irq(&ucounts_lock);
174 155
175 new = kzalloc(sizeof(*new), GF 156 new = kzalloc(sizeof(*new), GFP_KERNEL);
176 if (!new) 157 if (!new)
177 return NULL; 158 return NULL;
178 159
179 new->ns = ns; 160 new->ns = ns;
180 new->uid = uid; 161 new->uid = uid;
181 atomic_set(&new->count, 1); !! 162 new->count = 0;
182 163
183 spin_lock_irq(&ucounts_lock); 164 spin_lock_irq(&ucounts_lock);
184 ucounts = find_ucounts(ns, uid 165 ucounts = find_ucounts(ns, uid, hashent);
185 if (ucounts) { 166 if (ucounts) {
186 kfree(new); 167 kfree(new);
187 } else { 168 } else {
188 hlist_add_head(&new->n 169 hlist_add_head(&new->node, hashent);
189 get_user_ns(new->ns); !! 170 ucounts = new;
190 spin_unlock_irq(&ucoun <<
191 return new; <<
192 } 171 }
193 } 172 }
194 wrapped = !get_ucounts_or_wrap(ucounts !! 173 if (ucounts->count == INT_MAX)
>> 174 ucounts = NULL;
>> 175 else
>> 176 ucounts->count += 1;
195 spin_unlock_irq(&ucounts_lock); 177 spin_unlock_irq(&ucounts_lock);
196 if (wrapped) { !! 178 return ucounts;
197 put_ucounts(ucounts); !! 179 }
>> 180
>> 181 struct ucounts *get_ucounts(struct ucounts *ucounts)
>> 182 {
>> 183 unsigned long flags;
>> 184
>> 185 if (!ucounts)
198 return NULL; 186 return NULL;
>> 187
>> 188 spin_lock_irqsave(&ucounts_lock, flags);
>> 189 if (ucounts->count == INT_MAX) {
>> 190 WARN_ONCE(1, "ucounts: counter has reached its maximum value");
>> 191 ucounts = NULL;
>> 192 } else {
>> 193 ucounts->count += 1;
199 } 194 }
>> 195 spin_unlock_irqrestore(&ucounts_lock, flags);
>> 196
200 return ucounts; 197 return ucounts;
201 } 198 }
202 199
203 void put_ucounts(struct ucounts *ucounts) 200 void put_ucounts(struct ucounts *ucounts)
204 { 201 {
205 unsigned long flags; 202 unsigned long flags;
206 203
207 if (atomic_dec_and_lock_irqsave(&ucoun !! 204 spin_lock_irqsave(&ucounts_lock, flags);
>> 205 ucounts->count -= 1;
>> 206 if (!ucounts->count)
208 hlist_del_init(&ucounts->node) 207 hlist_del_init(&ucounts->node);
209 spin_unlock_irqrestore(&ucount !! 208 else
210 put_user_ns(ucounts->ns); !! 209 ucounts = NULL;
211 kfree(ucounts); !! 210 spin_unlock_irqrestore(&ucounts_lock, flags);
212 } !! 211
>> 212 kfree(ucounts);
213 } 213 }
214 214
215 static inline bool atomic_long_inc_below(atomi !! 215 static inline bool atomic_inc_below(atomic_t *v, int u)
216 { 216 {
217 long c, old; !! 217 int c, old;
218 c = atomic_long_read(v); !! 218 c = atomic_read(v);
219 for (;;) { 219 for (;;) {
220 if (unlikely(c >= u)) 220 if (unlikely(c >= u))
221 return false; 221 return false;
222 old = atomic_long_cmpxchg(v, c !! 222 old = atomic_cmpxchg(v, c, c+1);
223 if (likely(old == c)) 223 if (likely(old == c))
224 return true; 224 return true;
225 c = old; 225 c = old;
226 } 226 }
227 } 227 }
228 228
229 struct ucounts *inc_ucount(struct user_namespa 229 struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid,
230 enum ucount_type ty 230 enum ucount_type type)
231 { 231 {
232 struct ucounts *ucounts, *iter, *bad; 232 struct ucounts *ucounts, *iter, *bad;
233 struct user_namespace *tns; 233 struct user_namespace *tns;
234 ucounts = alloc_ucounts(ns, uid); 234 ucounts = alloc_ucounts(ns, uid);
235 for (iter = ucounts; iter; iter = tns- 235 for (iter = ucounts; iter; iter = tns->ucounts) {
236 long max; !! 236 int max;
237 tns = iter->ns; 237 tns = iter->ns;
238 max = READ_ONCE(tns->ucount_ma 238 max = READ_ONCE(tns->ucount_max[type]);
239 if (!atomic_long_inc_below(&it !! 239 if (!atomic_inc_below(&iter->ucount[type], max))
240 goto fail; 240 goto fail;
241 } 241 }
242 return ucounts; 242 return ucounts;
243 fail: 243 fail:
244 bad = iter; 244 bad = iter;
245 for (iter = ucounts; iter != bad; iter 245 for (iter = ucounts; iter != bad; iter = iter->ns->ucounts)
246 atomic_long_dec(&iter->ucount[ !! 246 atomic_dec(&iter->ucount[type]);
247 247
248 put_ucounts(ucounts); 248 put_ucounts(ucounts);
249 return NULL; 249 return NULL;
250 } 250 }
251 251
252 void dec_ucount(struct ucounts *ucounts, enum 252 void dec_ucount(struct ucounts *ucounts, enum ucount_type type)
253 { 253 {
254 struct ucounts *iter; 254 struct ucounts *iter;
255 for (iter = ucounts; iter; iter = iter 255 for (iter = ucounts; iter; iter = iter->ns->ucounts) {
256 long dec = atomic_long_dec_if_ !! 256 int dec = atomic_dec_if_positive(&iter->ucount[type]);
257 WARN_ON_ONCE(dec < 0); 257 WARN_ON_ONCE(dec < 0);
258 } 258 }
259 put_ucounts(ucounts); 259 put_ucounts(ucounts);
260 } 260 }
261 261
262 long inc_rlimit_ucounts(struct ucounts *ucount <<
263 { <<
264 struct ucounts *iter; <<
265 long max = LONG_MAX; <<
266 long ret = 0; <<
267 <<
268 for (iter = ucounts; iter; iter = iter <<
269 long new = atomic_long_add_ret <<
270 if (new < 0 || new > max) <<
271 ret = LONG_MAX; <<
272 else if (iter == ucounts) <<
273 ret = new; <<
274 max = get_userns_rlimit_max(it <<
275 } <<
276 return ret; <<
277 } <<
278 <<
279 bool dec_rlimit_ucounts(struct ucounts *ucount <<
280 { <<
281 struct ucounts *iter; <<
282 long new = -1; /* Silence compiler war <<
283 for (iter = ucounts; iter; iter = iter <<
284 long dec = atomic_long_sub_ret <<
285 WARN_ON_ONCE(dec < 0); <<
286 if (iter == ucounts) <<
287 new = dec; <<
288 } <<
289 return (new == 0); <<
290 } <<
291 <<
292 static void do_dec_rlimit_put_ucounts(struct u <<
293 struct ucounts <<
294 { <<
295 struct ucounts *iter, *next; <<
296 for (iter = ucounts; iter != last; ite <<
297 long dec = atomic_long_sub_ret <<
298 WARN_ON_ONCE(dec < 0); <<
299 next = iter->ns->ucounts; <<
300 if (dec == 0) <<
301 put_ucounts(iter); <<
302 } <<
303 } <<
304 <<
305 void dec_rlimit_put_ucounts(struct ucounts *uc <<
306 { <<
307 do_dec_rlimit_put_ucounts(ucounts, NUL <<
308 } <<
309 <<
310 long inc_rlimit_get_ucounts(struct ucounts *uc <<
311 { <<
312 /* Caller must hold a reference to uco <<
313 struct ucounts *iter; <<
314 long max = LONG_MAX; <<
315 long dec, ret = 0; <<
316 <<
317 for (iter = ucounts; iter; iter = iter <<
318 long new = atomic_long_add_ret <<
319 if (new < 0 || new > max) <<
320 goto unwind; <<
321 if (iter == ucounts) <<
322 ret = new; <<
323 max = get_userns_rlimit_max(it <<
324 /* <<
325 * Grab an extra ucount refere <<
326 * the rlimit count was previo <<
327 */ <<
328 if (new != 1) <<
329 continue; <<
330 if (!get_ucounts(iter)) <<
331 goto dec_unwind; <<
332 } <<
333 return ret; <<
334 dec_unwind: <<
335 dec = atomic_long_sub_return(1, &iter- <<
336 WARN_ON_ONCE(dec < 0); <<
337 unwind: <<
338 do_dec_rlimit_put_ucounts(ucounts, ite <<
339 return 0; <<
340 } <<
341 <<
342 bool is_rlimit_overlimit(struct ucounts *ucoun <<
343 { <<
344 struct ucounts *iter; <<
345 long max = rlimit; <<
346 if (rlimit > LONG_MAX) <<
347 max = LONG_MAX; <<
348 for (iter = ucounts; iter; iter = iter <<
349 long val = get_rlimit_value(it <<
350 if (val < 0 || val > max) <<
351 return true; <<
352 max = get_userns_rlimit_max(it <<
353 } <<
354 return false; <<
355 } <<
356 <<
357 static __init int user_namespace_sysctl_init(v 262 static __init int user_namespace_sysctl_init(void)
358 { 263 {
359 #ifdef CONFIG_SYSCTL 264 #ifdef CONFIG_SYSCTL
360 static struct ctl_table_header *user_h 265 static struct ctl_table_header *user_header;
361 static struct ctl_table empty[1]; 266 static struct ctl_table empty[1];
362 /* 267 /*
363 * It is necessary to register the use 268 * It is necessary to register the user directory in the
364 * default set so that registrations i 269 * default set so that registrations in the child sets work
365 * properly. 270 * properly.
366 */ 271 */
367 user_header = register_sysctl_sz("user !! 272 user_header = register_sysctl("user", empty);
368 kmemleak_ignore(user_header); 273 kmemleak_ignore(user_header);
369 BUG_ON(!user_header); 274 BUG_ON(!user_header);
370 BUG_ON(!setup_userns_sysctls(&init_use 275 BUG_ON(!setup_userns_sysctls(&init_user_ns));
371 #endif 276 #endif
372 hlist_add_ucounts(&init_ucounts); 277 hlist_add_ucounts(&init_ucounts);
373 inc_rlimit_ucounts(&init_ucounts, UCOU <<
374 return 0; 278 return 0;
375 } 279 }
376 subsys_initcall(user_namespace_sysctl_init); 280 subsys_initcall(user_namespace_sysctl_init);
377 281
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