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 = { <<
12 .ns = &init_user_ns, <<
13 .uid = GLOBAL_ROOT_UID, <<
14 .count = ATOMIC_INIT(1), <<
15 }; <<
16 <<
17 #define UCOUNTS_HASHTABLE_BITS 10 11 #define UCOUNTS_HASHTABLE_BITS 10
18 static struct hlist_head ucounts_hashtable[(1 12 static struct hlist_head ucounts_hashtable[(1 << UCOUNTS_HASHTABLE_BITS)];
19 static DEFINE_SPINLOCK(ucounts_lock); 13 static DEFINE_SPINLOCK(ucounts_lock);
20 14
21 #define ucounts_hashfn(ns, uid) 15 #define ucounts_hashfn(ns, uid) \
22 hash_long((unsigned long)__kuid_val(ui 16 hash_long((unsigned long)__kuid_val(uid) + (unsigned long)(ns), \
23 UCOUNTS_HASHTABLE_BITS) 17 UCOUNTS_HASHTABLE_BITS)
24 #define ucounts_hashentry(ns, uid) \ 18 #define ucounts_hashentry(ns, uid) \
25 (ucounts_hashtable + ucounts_hashfn(ns 19 (ucounts_hashtable + ucounts_hashfn(ns, uid))
26 20
27 21
28 #ifdef CONFIG_SYSCTL 22 #ifdef CONFIG_SYSCTL
29 static struct ctl_table_set * 23 static struct ctl_table_set *
30 set_lookup(struct ctl_table_root *root) 24 set_lookup(struct ctl_table_root *root)
31 { 25 {
32 return ¤t_user_ns()->set; 26 return ¤t_user_ns()->set;
33 } 27 }
34 28
35 static int set_is_seen(struct ctl_table_set *s 29 static int set_is_seen(struct ctl_table_set *set)
36 { 30 {
37 return ¤t_user_ns()->set == set; 31 return ¤t_user_ns()->set == set;
38 } 32 }
39 33
40 static int set_permissions(struct ctl_table_he 34 static int set_permissions(struct ctl_table_header *head,
41 const struct ctl_ta !! 35 struct ctl_table *table)
42 { 36 {
43 struct user_namespace *user_ns = 37 struct user_namespace *user_ns =
44 container_of(head->set, struct 38 container_of(head->set, struct user_namespace, set);
45 int mode; 39 int mode;
46 40
47 /* Allow users with CAP_SYS_RESOURCE u 41 /* Allow users with CAP_SYS_RESOURCE unrestrained access */
48 if (ns_capable(user_ns, CAP_SYS_RESOUR 42 if (ns_capable(user_ns, CAP_SYS_RESOURCE))
49 mode = (table->mode & S_IRWXU) 43 mode = (table->mode & S_IRWXU) >> 6;
50 else 44 else
51 /* Allow all others at most read-only 45 /* Allow all others at most read-only access */
52 mode = table->mode & S_IROTH; 46 mode = table->mode & S_IROTH;
53 return (mode << 6) | (mode << 3) | mod 47 return (mode << 6) | (mode << 3) | mode;
54 } 48 }
55 49
56 static struct ctl_table_root set_root = { 50 static struct ctl_table_root set_root = {
57 .lookup = set_lookup, 51 .lookup = set_lookup,
58 .permissions = set_permissions, 52 .permissions = set_permissions,
59 }; 53 };
60 54
61 static long ue_zero = 0; !! 55 #define UCOUNT_ENTRY(name) \
62 static long ue_int_max = INT_MAX; !! 56 { \
63 !! 57 .procname = name, \
64 #define UCOUNT_ENTRY(name) !! 58 .maxlen = sizeof(int), \
65 { !! 59 .mode = 0644, \
66 .procname = name, !! 60 .proc_handler = proc_dointvec_minmax, \
67 .maxlen = sizeof(long) !! 61 .extra1 = SYSCTL_ZERO, \
68 .mode = 0644, !! 62 .extra2 = SYSCTL_INT_MAX, \
69 .proc_handler = proc_doulong <<
70 .extra1 = &ue_zero, <<
71 .extra2 = &ue_int_max, <<
72 } 63 }
73 static struct ctl_table user_table[] = { 64 static struct ctl_table user_table[] = {
74 UCOUNT_ENTRY("max_user_namespaces"), 65 UCOUNT_ENTRY("max_user_namespaces"),
75 UCOUNT_ENTRY("max_pid_namespaces"), 66 UCOUNT_ENTRY("max_pid_namespaces"),
76 UCOUNT_ENTRY("max_uts_namespaces"), 67 UCOUNT_ENTRY("max_uts_namespaces"),
77 UCOUNT_ENTRY("max_ipc_namespaces"), 68 UCOUNT_ENTRY("max_ipc_namespaces"),
78 UCOUNT_ENTRY("max_net_namespaces"), 69 UCOUNT_ENTRY("max_net_namespaces"),
79 UCOUNT_ENTRY("max_mnt_namespaces"), 70 UCOUNT_ENTRY("max_mnt_namespaces"),
80 UCOUNT_ENTRY("max_cgroup_namespaces"), 71 UCOUNT_ENTRY("max_cgroup_namespaces"),
81 UCOUNT_ENTRY("max_time_namespaces"), 72 UCOUNT_ENTRY("max_time_namespaces"),
82 #ifdef CONFIG_INOTIFY_USER 73 #ifdef CONFIG_INOTIFY_USER
83 UCOUNT_ENTRY("max_inotify_instances"), 74 UCOUNT_ENTRY("max_inotify_instances"),
84 UCOUNT_ENTRY("max_inotify_watches"), 75 UCOUNT_ENTRY("max_inotify_watches"),
85 #endif 76 #endif
86 #ifdef CONFIG_FANOTIFY !! 77 { }
87 UCOUNT_ENTRY("max_fanotify_groups"), <<
88 UCOUNT_ENTRY("max_fanotify_marks"), <<
89 #endif <<
90 }; 78 };
91 #endif /* CONFIG_SYSCTL */ 79 #endif /* CONFIG_SYSCTL */
92 80
93 bool setup_userns_sysctls(struct user_namespac 81 bool setup_userns_sysctls(struct user_namespace *ns)
94 { 82 {
95 #ifdef CONFIG_SYSCTL 83 #ifdef CONFIG_SYSCTL
96 struct ctl_table *tbl; 84 struct ctl_table *tbl;
97 85
98 BUILD_BUG_ON(ARRAY_SIZE(user_table) != !! 86 BUILD_BUG_ON(ARRAY_SIZE(user_table) != UCOUNT_COUNTS + 1);
99 setup_sysctl_set(&ns->set, &set_root, 87 setup_sysctl_set(&ns->set, &set_root, set_is_seen);
100 tbl = kmemdup(user_table, sizeof(user_ 88 tbl = kmemdup(user_table, sizeof(user_table), GFP_KERNEL);
101 if (tbl) { 89 if (tbl) {
102 int i; 90 int i;
103 for (i = 0; i < UCOUNT_COUNTS; 91 for (i = 0; i < UCOUNT_COUNTS; i++) {
104 tbl[i].data = &ns->uco 92 tbl[i].data = &ns->ucount_max[i];
105 } 93 }
106 ns->sysctls = __register_sysct !! 94 ns->sysctls = __register_sysctl_table(&ns->set, "user", tbl);
107 <<
108 } 95 }
109 if (!ns->sysctls) { 96 if (!ns->sysctls) {
110 kfree(tbl); 97 kfree(tbl);
111 retire_sysctl_set(&ns->set); 98 retire_sysctl_set(&ns->set);
112 return false; 99 return false;
113 } 100 }
114 #endif 101 #endif
115 return true; 102 return true;
116 } 103 }
117 104
118 void retire_userns_sysctls(struct user_namespa 105 void retire_userns_sysctls(struct user_namespace *ns)
119 { 106 {
120 #ifdef CONFIG_SYSCTL 107 #ifdef CONFIG_SYSCTL
121 const struct ctl_table *tbl; !! 108 struct ctl_table *tbl;
122 109
123 tbl = ns->sysctls->ctl_table_arg; 110 tbl = ns->sysctls->ctl_table_arg;
124 unregister_sysctl_table(ns->sysctls); 111 unregister_sysctl_table(ns->sysctls);
125 retire_sysctl_set(&ns->set); 112 retire_sysctl_set(&ns->set);
126 kfree(tbl); 113 kfree(tbl);
127 #endif 114 #endif
128 } 115 }
129 116
130 static struct ucounts *find_ucounts(struct use 117 static struct ucounts *find_ucounts(struct user_namespace *ns, kuid_t uid, struct hlist_head *hashent)
131 { 118 {
132 struct ucounts *ucounts; 119 struct ucounts *ucounts;
133 120
134 hlist_for_each_entry(ucounts, hashent, 121 hlist_for_each_entry(ucounts, hashent, node) {
135 if (uid_eq(ucounts->uid, uid) 122 if (uid_eq(ucounts->uid, uid) && (ucounts->ns == ns))
136 return ucounts; 123 return ucounts;
137 } 124 }
138 return NULL; 125 return NULL;
139 } 126 }
140 127
141 static void hlist_add_ucounts(struct ucounts * !! 128 static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid)
142 { <<
143 struct hlist_head *hashent = ucounts_h <<
144 spin_lock_irq(&ucounts_lock); <<
145 hlist_add_head(&ucounts->node, hashent <<
146 spin_unlock_irq(&ucounts_lock); <<
147 } <<
148 <<
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 <<
165 { 129 {
166 struct hlist_head *hashent = ucounts_h 130 struct hlist_head *hashent = ucounts_hashentry(ns, uid);
167 struct ucounts *ucounts, *new; 131 struct ucounts *ucounts, *new;
168 bool wrapped; <<
169 132
170 spin_lock_irq(&ucounts_lock); 133 spin_lock_irq(&ucounts_lock);
171 ucounts = find_ucounts(ns, uid, hashen 134 ucounts = find_ucounts(ns, uid, hashent);
172 if (!ucounts) { 135 if (!ucounts) {
173 spin_unlock_irq(&ucounts_lock) 136 spin_unlock_irq(&ucounts_lock);
174 137
175 new = kzalloc(sizeof(*new), GF 138 new = kzalloc(sizeof(*new), GFP_KERNEL);
176 if (!new) 139 if (!new)
177 return NULL; 140 return NULL;
178 141
179 new->ns = ns; 142 new->ns = ns;
180 new->uid = uid; 143 new->uid = uid;
181 atomic_set(&new->count, 1); !! 144 new->count = 0;
182 145
183 spin_lock_irq(&ucounts_lock); 146 spin_lock_irq(&ucounts_lock);
184 ucounts = find_ucounts(ns, uid 147 ucounts = find_ucounts(ns, uid, hashent);
185 if (ucounts) { 148 if (ucounts) {
186 kfree(new); 149 kfree(new);
187 } else { 150 } else {
188 hlist_add_head(&new->n 151 hlist_add_head(&new->node, hashent);
189 get_user_ns(new->ns); !! 152 ucounts = new;
190 spin_unlock_irq(&ucoun <<
191 return new; <<
192 } 153 }
193 } 154 }
194 wrapped = !get_ucounts_or_wrap(ucounts !! 155 if (ucounts->count == INT_MAX)
>> 156 ucounts = NULL;
>> 157 else
>> 158 ucounts->count += 1;
195 spin_unlock_irq(&ucounts_lock); 159 spin_unlock_irq(&ucounts_lock);
196 if (wrapped) { <<
197 put_ucounts(ucounts); <<
198 return NULL; <<
199 } <<
200 return ucounts; 160 return ucounts;
201 } 161 }
202 162
203 void put_ucounts(struct ucounts *ucounts) !! 163 static void put_ucounts(struct ucounts *ucounts)
204 { 164 {
205 unsigned long flags; 165 unsigned long flags;
206 166
207 if (atomic_dec_and_lock_irqsave(&ucoun !! 167 spin_lock_irqsave(&ucounts_lock, flags);
>> 168 ucounts->count -= 1;
>> 169 if (!ucounts->count)
208 hlist_del_init(&ucounts->node) 170 hlist_del_init(&ucounts->node);
209 spin_unlock_irqrestore(&ucount !! 171 else
210 put_user_ns(ucounts->ns); !! 172 ucounts = NULL;
211 kfree(ucounts); !! 173 spin_unlock_irqrestore(&ucounts_lock, flags);
212 } !! 174
>> 175 kfree(ucounts);
213 } 176 }
214 177
215 static inline bool atomic_long_inc_below(atomi !! 178 static inline bool atomic_inc_below(atomic_t *v, int u)
216 { 179 {
217 long c, old; !! 180 int c, old;
218 c = atomic_long_read(v); !! 181 c = atomic_read(v);
219 for (;;) { 182 for (;;) {
220 if (unlikely(c >= u)) 183 if (unlikely(c >= u))
221 return false; 184 return false;
222 old = atomic_long_cmpxchg(v, c !! 185 old = atomic_cmpxchg(v, c, c+1);
223 if (likely(old == c)) 186 if (likely(old == c))
224 return true; 187 return true;
225 c = old; 188 c = old;
226 } 189 }
227 } 190 }
228 191
229 struct ucounts *inc_ucount(struct user_namespa 192 struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid,
230 enum ucount_type ty 193 enum ucount_type type)
231 { 194 {
232 struct ucounts *ucounts, *iter, *bad; 195 struct ucounts *ucounts, *iter, *bad;
233 struct user_namespace *tns; 196 struct user_namespace *tns;
234 ucounts = alloc_ucounts(ns, uid); !! 197 ucounts = get_ucounts(ns, uid);
235 for (iter = ucounts; iter; iter = tns- 198 for (iter = ucounts; iter; iter = tns->ucounts) {
236 long max; !! 199 int max;
237 tns = iter->ns; 200 tns = iter->ns;
238 max = READ_ONCE(tns->ucount_ma 201 max = READ_ONCE(tns->ucount_max[type]);
239 if (!atomic_long_inc_below(&it !! 202 if (!atomic_inc_below(&iter->ucount[type], max))
240 goto fail; 203 goto fail;
241 } 204 }
242 return ucounts; 205 return ucounts;
243 fail: 206 fail:
244 bad = iter; 207 bad = iter;
245 for (iter = ucounts; iter != bad; iter 208 for (iter = ucounts; iter != bad; iter = iter->ns->ucounts)
246 atomic_long_dec(&iter->ucount[ !! 209 atomic_dec(&iter->ucount[type]);
247 210
248 put_ucounts(ucounts); 211 put_ucounts(ucounts);
249 return NULL; 212 return NULL;
250 } 213 }
251 214
252 void dec_ucount(struct ucounts *ucounts, enum 215 void dec_ucount(struct ucounts *ucounts, enum ucount_type type)
253 { 216 {
254 struct ucounts *iter; 217 struct ucounts *iter;
255 for (iter = ucounts; iter; iter = iter 218 for (iter = ucounts; iter; iter = iter->ns->ucounts) {
256 long dec = atomic_long_dec_if_ !! 219 int dec = atomic_dec_if_positive(&iter->ucount[type]);
257 WARN_ON_ONCE(dec < 0); 220 WARN_ON_ONCE(dec < 0);
258 } 221 }
259 put_ucounts(ucounts); 222 put_ucounts(ucounts);
260 } 223 }
261 224
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 225 static __init int user_namespace_sysctl_init(void)
358 { 226 {
359 #ifdef CONFIG_SYSCTL 227 #ifdef CONFIG_SYSCTL
360 static struct ctl_table_header *user_h 228 static struct ctl_table_header *user_header;
361 static struct ctl_table empty[1]; 229 static struct ctl_table empty[1];
362 /* 230 /*
363 * It is necessary to register the use 231 * It is necessary to register the user directory in the
364 * default set so that registrations i 232 * default set so that registrations in the child sets work
365 * properly. 233 * properly.
366 */ 234 */
367 user_header = register_sysctl_sz("user !! 235 user_header = register_sysctl("user", empty);
368 kmemleak_ignore(user_header); 236 kmemleak_ignore(user_header);
369 BUG_ON(!user_header); 237 BUG_ON(!user_header);
370 BUG_ON(!setup_userns_sysctls(&init_use 238 BUG_ON(!setup_userns_sysctls(&init_user_ns));
371 #endif 239 #endif
372 hlist_add_ucounts(&init_ucounts); <<
373 inc_rlimit_ucounts(&init_ucounts, UCOU <<
374 return 0; 240 return 0;
375 } 241 }
376 subsys_initcall(user_namespace_sysctl_init); 242 subsys_initcall(user_namespace_sysctl_init);
377 243
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