1 // SPDX-License-Identifier: GPL-2.0 <<
2 /* 1 /*
3 * Supplementary group IDs 2 * Supplementary group IDs
4 */ 3 */
5 #include <linux/cred.h> 4 #include <linux/cred.h>
6 #include <linux/export.h> 5 #include <linux/export.h>
7 #include <linux/slab.h> 6 #include <linux/slab.h>
8 #include <linux/security.h> 7 #include <linux/security.h>
9 #include <linux/sort.h> <<
10 #include <linux/syscalls.h> 8 #include <linux/syscalls.h>
11 #include <linux/user_namespace.h> 9 #include <linux/user_namespace.h>
12 #include <linux/vmalloc.h> 10 #include <linux/vmalloc.h>
13 #include <linux/uaccess.h> 11 #include <linux/uaccess.h>
14 12
15 struct group_info *groups_alloc(int gidsetsize 13 struct group_info *groups_alloc(int gidsetsize)
16 { 14 {
17 struct group_info *gi; 15 struct group_info *gi;
18 gi = kvmalloc(struct_size(gi, gid, gid !! 16 unsigned int len;
>> 17
>> 18 len = sizeof(struct group_info) + sizeof(kgid_t) * gidsetsize;
>> 19 gi = kmalloc(len, GFP_KERNEL_ACCOUNT|__GFP_NOWARN|__GFP_NORETRY);
>> 20 if (!gi)
>> 21 gi = __vmalloc(len, GFP_KERNEL_ACCOUNT, PAGE_KERNEL);
19 if (!gi) 22 if (!gi)
20 return NULL; 23 return NULL;
21 24
22 refcount_set(&gi->usage, 1); !! 25 atomic_set(&gi->usage, 1);
23 gi->ngroups = gidsetsize; 26 gi->ngroups = gidsetsize;
24 return gi; 27 return gi;
25 } 28 }
26 29
27 EXPORT_SYMBOL(groups_alloc); 30 EXPORT_SYMBOL(groups_alloc);
28 31
29 void groups_free(struct group_info *group_info 32 void groups_free(struct group_info *group_info)
30 { 33 {
31 kvfree(group_info); 34 kvfree(group_info);
32 } 35 }
33 36
34 EXPORT_SYMBOL(groups_free); 37 EXPORT_SYMBOL(groups_free);
35 38
36 /* export the group_info to a user-space array 39 /* export the group_info to a user-space array */
37 static int groups_to_user(gid_t __user *groupl 40 static int groups_to_user(gid_t __user *grouplist,
38 const struct group_i 41 const struct group_info *group_info)
39 { 42 {
40 struct user_namespace *user_ns = curre 43 struct user_namespace *user_ns = current_user_ns();
41 int i; 44 int i;
42 unsigned int count = group_info->ngrou 45 unsigned int count = group_info->ngroups;
43 46
44 for (i = 0; i < count; i++) { 47 for (i = 0; i < count; i++) {
45 gid_t gid; 48 gid_t gid;
46 gid = from_kgid_munged(user_ns 49 gid = from_kgid_munged(user_ns, group_info->gid[i]);
47 if (put_user(gid, grouplist+i) 50 if (put_user(gid, grouplist+i))
48 return -EFAULT; 51 return -EFAULT;
49 } 52 }
50 return 0; 53 return 0;
51 } 54 }
52 55
53 /* fill a group_info from a user-space array - 56 /* fill a group_info from a user-space array - it must be allocated already */
54 static int groups_from_user(struct group_info 57 static int groups_from_user(struct group_info *group_info,
55 gid_t __user *grouplist) 58 gid_t __user *grouplist)
56 { 59 {
57 struct user_namespace *user_ns = curre 60 struct user_namespace *user_ns = current_user_ns();
58 int i; 61 int i;
59 unsigned int count = group_info->ngrou 62 unsigned int count = group_info->ngroups;
60 63
61 for (i = 0; i < count; i++) { 64 for (i = 0; i < count; i++) {
62 gid_t gid; 65 gid_t gid;
63 kgid_t kgid; 66 kgid_t kgid;
64 if (get_user(gid, grouplist+i) 67 if (get_user(gid, grouplist+i))
65 return -EFAULT; 68 return -EFAULT;
66 69
67 kgid = make_kgid(user_ns, gid) 70 kgid = make_kgid(user_ns, gid);
68 if (!gid_valid(kgid)) 71 if (!gid_valid(kgid))
69 return -EINVAL; 72 return -EINVAL;
70 73
71 group_info->gid[i] = kgid; 74 group_info->gid[i] = kgid;
72 } 75 }
73 return 0; 76 return 0;
74 } 77 }
75 78
76 static int gid_cmp(const void *_a, const void !! 79 /* a simple Shell sort */
>> 80 static void groups_sort(struct group_info *group_info)
77 { 81 {
78 kgid_t a = *(kgid_t *)_a; !! 82 int base, max, stride;
79 kgid_t b = *(kgid_t *)_b; !! 83 int gidsetsize = group_info->ngroups;
80 <<
81 return gid_gt(a, b) - gid_lt(a, b); <<
82 } <<
83 84
84 void groups_sort(struct group_info *group_info !! 85 for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1)
85 { !! 86 ; /* nothing */
86 sort(group_info->gid, group_info->ngro !! 87 stride /= 3;
87 gid_cmp, NULL); !! 88
>> 89 while (stride) {
>> 90 max = gidsetsize - stride;
>> 91 for (base = 0; base < max; base++) {
>> 92 int left = base;
>> 93 int right = left + stride;
>> 94 kgid_t tmp = group_info->gid[right];
>> 95
>> 96 while (left >= 0 && gid_gt(group_info->gid[left], tmp)) {
>> 97 group_info->gid[right] = group_info->gid[left];
>> 98 right = left;
>> 99 left -= stride;
>> 100 }
>> 101 group_info->gid[right] = tmp;
>> 102 }
>> 103 stride /= 3;
>> 104 }
88 } 105 }
89 EXPORT_SYMBOL(groups_sort); <<
90 106
91 /* a simple bsearch */ 107 /* a simple bsearch */
92 int groups_search(const struct group_info *gro 108 int groups_search(const struct group_info *group_info, kgid_t grp)
93 { 109 {
94 unsigned int left, right; 110 unsigned int left, right;
95 111
96 if (!group_info) 112 if (!group_info)
97 return 0; 113 return 0;
98 114
99 left = 0; 115 left = 0;
100 right = group_info->ngroups; 116 right = group_info->ngroups;
101 while (left < right) { 117 while (left < right) {
102 unsigned int mid = (left+right 118 unsigned int mid = (left+right)/2;
103 if (gid_gt(grp, group_info->gi 119 if (gid_gt(grp, group_info->gid[mid]))
104 left = mid + 1; 120 left = mid + 1;
105 else if (gid_lt(grp, group_inf 121 else if (gid_lt(grp, group_info->gid[mid]))
106 right = mid; 122 right = mid;
107 else 123 else
108 return 1; 124 return 1;
109 } 125 }
110 return 0; 126 return 0;
111 } 127 }
112 128
113 /** 129 /**
114 * set_groups - Change a group subscription in 130 * set_groups - Change a group subscription in a set of credentials
115 * @new: The newly prepared set of credentials 131 * @new: The newly prepared set of credentials to alter
116 * @group_info: The group list to install 132 * @group_info: The group list to install
117 */ 133 */
118 void set_groups(struct cred *new, struct group 134 void set_groups(struct cred *new, struct group_info *group_info)
119 { 135 {
120 put_group_info(new->group_info); 136 put_group_info(new->group_info);
>> 137 groups_sort(group_info);
121 get_group_info(group_info); 138 get_group_info(group_info);
122 new->group_info = group_info; 139 new->group_info = group_info;
123 } 140 }
124 141
125 EXPORT_SYMBOL(set_groups); 142 EXPORT_SYMBOL(set_groups);
126 143
127 /** 144 /**
128 * set_current_groups - Change current's group 145 * set_current_groups - Change current's group subscription
129 * @group_info: The group list to impose 146 * @group_info: The group list to impose
130 * 147 *
131 * Validate a group subscription and, if valid 148 * Validate a group subscription and, if valid, impose it upon current's task
132 * security record. 149 * security record.
133 */ 150 */
134 int set_current_groups(struct group_info *grou 151 int set_current_groups(struct group_info *group_info)
135 { 152 {
136 struct cred *new; 153 struct cred *new;
137 const struct cred *old; <<
138 int retval; <<
139 154
140 new = prepare_creds(); 155 new = prepare_creds();
141 if (!new) 156 if (!new)
142 return -ENOMEM; 157 return -ENOMEM;
143 158
144 old = current_cred(); <<
145 <<
146 set_groups(new, group_info); 159 set_groups(new, group_info);
147 <<
148 retval = security_task_fix_setgroups(n <<
149 if (retval < 0) <<
150 goto error; <<
151 <<
152 return commit_creds(new); 160 return commit_creds(new);
153 <<
154 error: <<
155 abort_creds(new); <<
156 return retval; <<
157 } 161 }
158 162
159 EXPORT_SYMBOL(set_current_groups); 163 EXPORT_SYMBOL(set_current_groups);
160 164
161 SYSCALL_DEFINE2(getgroups, int, gidsetsize, gi 165 SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
162 { 166 {
163 const struct cred *cred = current_cred 167 const struct cred *cred = current_cred();
164 int i; 168 int i;
165 169
166 if (gidsetsize < 0) 170 if (gidsetsize < 0)
167 return -EINVAL; 171 return -EINVAL;
168 172
169 /* no need to grab task_lock here; it 173 /* no need to grab task_lock here; it cannot change */
170 i = cred->group_info->ngroups; 174 i = cred->group_info->ngroups;
171 if (gidsetsize) { 175 if (gidsetsize) {
172 if (i > gidsetsize) { 176 if (i > gidsetsize) {
173 i = -EINVAL; 177 i = -EINVAL;
174 goto out; 178 goto out;
175 } 179 }
176 if (groups_to_user(grouplist, 180 if (groups_to_user(grouplist, cred->group_info)) {
177 i = -EFAULT; 181 i = -EFAULT;
178 goto out; 182 goto out;
179 } 183 }
180 } 184 }
181 out: 185 out:
182 return i; 186 return i;
183 } 187 }
184 188
185 bool may_setgroups(void) 189 bool may_setgroups(void)
186 { 190 {
187 struct user_namespace *user_ns = curre 191 struct user_namespace *user_ns = current_user_ns();
188 192
189 return ns_capable_setid(user_ns, CAP_S !! 193 return ns_capable(user_ns, CAP_SETGID) &&
190 userns_may_setgroups(user_ns); 194 userns_may_setgroups(user_ns);
191 } 195 }
192 196
193 /* 197 /*
194 * SMP: Our groups are copy-on-write. We 198 * SMP: Our groups are copy-on-write. We can set them safely
195 * without another task interfering. 199 * without another task interfering.
196 */ 200 */
197 201
198 SYSCALL_DEFINE2(setgroups, int, gidsetsize, gi 202 SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
199 { 203 {
200 struct group_info *group_info; 204 struct group_info *group_info;
201 int retval; 205 int retval;
202 206
203 if (!may_setgroups()) 207 if (!may_setgroups())
204 return -EPERM; 208 return -EPERM;
205 if ((unsigned)gidsetsize > NGROUPS_MAX 209 if ((unsigned)gidsetsize > NGROUPS_MAX)
206 return -EINVAL; 210 return -EINVAL;
207 211
208 group_info = groups_alloc(gidsetsize); 212 group_info = groups_alloc(gidsetsize);
209 if (!group_info) 213 if (!group_info)
210 return -ENOMEM; 214 return -ENOMEM;
211 retval = groups_from_user(group_info, 215 retval = groups_from_user(group_info, grouplist);
212 if (retval) { 216 if (retval) {
213 put_group_info(group_info); 217 put_group_info(group_info);
214 return retval; 218 return retval;
215 } 219 }
216 220
217 groups_sort(group_info); <<
218 retval = set_current_groups(group_info 221 retval = set_current_groups(group_info);
219 put_group_info(group_info); 222 put_group_info(group_info);
220 223
221 return retval; 224 return retval;
222 } 225 }
223 226
224 /* 227 /*
225 * Check whether we're fsgid/egid or in the su 228 * Check whether we're fsgid/egid or in the supplemental group..
226 */ 229 */
227 int in_group_p(kgid_t grp) 230 int in_group_p(kgid_t grp)
228 { 231 {
229 const struct cred *cred = current_cred 232 const struct cred *cred = current_cred();
230 int retval = 1; 233 int retval = 1;
231 234
232 if (!gid_eq(grp, cred->fsgid)) 235 if (!gid_eq(grp, cred->fsgid))
233 retval = groups_search(cred->g 236 retval = groups_search(cred->group_info, grp);
234 return retval; 237 return retval;
235 } 238 }
236 239
237 EXPORT_SYMBOL(in_group_p); 240 EXPORT_SYMBOL(in_group_p);
238 241
239 int in_egroup_p(kgid_t grp) 242 int in_egroup_p(kgid_t grp)
240 { 243 {
241 const struct cred *cred = current_cred 244 const struct cred *cred = current_cred();
242 int retval = 1; 245 int retval = 1;
243 246
244 if (!gid_eq(grp, cred->egid)) 247 if (!gid_eq(grp, cred->egid))
245 retval = groups_search(cred->g 248 retval = groups_search(cred->group_info, grp);
246 return retval; 249 return retval;
247 } 250 }
248 251
249 EXPORT_SYMBOL(in_egroup_p); 252 EXPORT_SYMBOL(in_egroup_p);
250 253
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