Merge tag 'tag-chrome-platform-firmware-for-v6.8' of git://git.kernel.org/pub/scm...
[linux-2.6-microblaze.git] / kernel / groups.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Supplementary group IDs
4  */
5 #include <linux/cred.h>
6 #include <linux/export.h>
7 #include <linux/slab.h>
8 #include <linux/security.h>
9 #include <linux/sort.h>
10 #include <linux/syscalls.h>
11 #include <linux/user_namespace.h>
12 #include <linux/vmalloc.h>
13 #include <linux/uaccess.h>
14
15 struct group_info *groups_alloc(int gidsetsize)
16 {
17         struct group_info *gi;
18         gi = kvmalloc(struct_size(gi, gid, gidsetsize), GFP_KERNEL_ACCOUNT);
19         if (!gi)
20                 return NULL;
21
22         refcount_set(&gi->usage, 1);
23         gi->ngroups = gidsetsize;
24         return gi;
25 }
26
27 EXPORT_SYMBOL(groups_alloc);
28
29 void groups_free(struct group_info *group_info)
30 {
31         kvfree(group_info);
32 }
33
34 EXPORT_SYMBOL(groups_free);
35
36 /* export the group_info to a user-space array */
37 static int groups_to_user(gid_t __user *grouplist,
38                           const struct group_info *group_info)
39 {
40         struct user_namespace *user_ns = current_user_ns();
41         int i;
42         unsigned int count = group_info->ngroups;
43
44         for (i = 0; i < count; i++) {
45                 gid_t gid;
46                 gid = from_kgid_munged(user_ns, group_info->gid[i]);
47                 if (put_user(gid, grouplist+i))
48                         return -EFAULT;
49         }
50         return 0;
51 }
52
53 /* fill a group_info from a user-space array - it must be allocated already */
54 static int groups_from_user(struct group_info *group_info,
55     gid_t __user *grouplist)
56 {
57         struct user_namespace *user_ns = current_user_ns();
58         int i;
59         unsigned int count = group_info->ngroups;
60
61         for (i = 0; i < count; i++) {
62                 gid_t gid;
63                 kgid_t kgid;
64                 if (get_user(gid, grouplist+i))
65                         return -EFAULT;
66
67                 kgid = make_kgid(user_ns, gid);
68                 if (!gid_valid(kgid))
69                         return -EINVAL;
70
71                 group_info->gid[i] = kgid;
72         }
73         return 0;
74 }
75
76 static int gid_cmp(const void *_a, const void *_b)
77 {
78         kgid_t a = *(kgid_t *)_a;
79         kgid_t b = *(kgid_t *)_b;
80
81         return gid_gt(a, b) - gid_lt(a, b);
82 }
83
84 void groups_sort(struct group_info *group_info)
85 {
86         sort(group_info->gid, group_info->ngroups, sizeof(*group_info->gid),
87              gid_cmp, NULL);
88 }
89 EXPORT_SYMBOL(groups_sort);
90
91 /* a simple bsearch */
92 int groups_search(const struct group_info *group_info, kgid_t grp)
93 {
94         unsigned int left, right;
95
96         if (!group_info)
97                 return 0;
98
99         left = 0;
100         right = group_info->ngroups;
101         while (left < right) {
102                 unsigned int mid = (left+right)/2;
103                 if (gid_gt(grp, group_info->gid[mid]))
104                         left = mid + 1;
105                 else if (gid_lt(grp, group_info->gid[mid]))
106                         right = mid;
107                 else
108                         return 1;
109         }
110         return 0;
111 }
112
113 /**
114  * set_groups - Change a group subscription in a set of credentials
115  * @new: The newly prepared set of credentials to alter
116  * @group_info: The group list to install
117  */
118 void set_groups(struct cred *new, struct group_info *group_info)
119 {
120         put_group_info(new->group_info);
121         get_group_info(group_info);
122         new->group_info = group_info;
123 }
124
125 EXPORT_SYMBOL(set_groups);
126
127 /**
128  * set_current_groups - Change current's group subscription
129  * @group_info: The group list to impose
130  *
131  * Validate a group subscription and, if valid, impose it upon current's task
132  * security record.
133  */
134 int set_current_groups(struct group_info *group_info)
135 {
136         struct cred *new;
137         const struct cred *old;
138         int retval;
139
140         new = prepare_creds();
141         if (!new)
142                 return -ENOMEM;
143
144         old = current_cred();
145
146         set_groups(new, group_info);
147
148         retval = security_task_fix_setgroups(new, old);
149         if (retval < 0)
150                 goto error;
151
152         return commit_creds(new);
153
154 error:
155         abort_creds(new);
156         return retval;
157 }
158
159 EXPORT_SYMBOL(set_current_groups);
160
161 SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
162 {
163         const struct cred *cred = current_cred();
164         int i;
165
166         if (gidsetsize < 0)
167                 return -EINVAL;
168
169         /* no need to grab task_lock here; it cannot change */
170         i = cred->group_info->ngroups;
171         if (gidsetsize) {
172                 if (i > gidsetsize) {
173                         i = -EINVAL;
174                         goto out;
175                 }
176                 if (groups_to_user(grouplist, cred->group_info)) {
177                         i = -EFAULT;
178                         goto out;
179                 }
180         }
181 out:
182         return i;
183 }
184
185 bool may_setgroups(void)
186 {
187         struct user_namespace *user_ns = current_user_ns();
188
189         return ns_capable_setid(user_ns, CAP_SETGID) &&
190                 userns_may_setgroups(user_ns);
191 }
192
193 /*
194  *      SMP: Our groups are copy-on-write. We can set them safely
195  *      without another task interfering.
196  */
197
198 SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
199 {
200         struct group_info *group_info;
201         int retval;
202
203         if (!may_setgroups())
204                 return -EPERM;
205         if ((unsigned)gidsetsize > NGROUPS_MAX)
206                 return -EINVAL;
207
208         group_info = groups_alloc(gidsetsize);
209         if (!group_info)
210                 return -ENOMEM;
211         retval = groups_from_user(group_info, grouplist);
212         if (retval) {
213                 put_group_info(group_info);
214                 return retval;
215         }
216
217         groups_sort(group_info);
218         retval = set_current_groups(group_info);
219         put_group_info(group_info);
220
221         return retval;
222 }
223
224 /*
225  * Check whether we're fsgid/egid or in the supplemental group..
226  */
227 int in_group_p(kgid_t grp)
228 {
229         const struct cred *cred = current_cred();
230         int retval = 1;
231
232         if (!gid_eq(grp, cred->fsgid))
233                 retval = groups_search(cred->group_info, grp);
234         return retval;
235 }
236
237 EXPORT_SYMBOL(in_group_p);
238
239 int in_egroup_p(kgid_t grp)
240 {
241         const struct cred *cred = current_cred();
242         int retval = 1;
243
244         if (!gid_eq(grp, cred->egid))
245                 retval = groups_search(cred->group_info, grp);
246         return retval;
247 }
248
249 EXPORT_SYMBOL(in_egroup_p);