s390/mcck: fix calculation of SIE critical section size
[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         atomic_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
138         new = prepare_creds();
139         if (!new)
140                 return -ENOMEM;
141
142         set_groups(new, group_info);
143         return commit_creds(new);
144 }
145
146 EXPORT_SYMBOL(set_current_groups);
147
148 SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
149 {
150         const struct cred *cred = current_cred();
151         int i;
152
153         if (gidsetsize < 0)
154                 return -EINVAL;
155
156         /* no need to grab task_lock here; it cannot change */
157         i = cred->group_info->ngroups;
158         if (gidsetsize) {
159                 if (i > gidsetsize) {
160                         i = -EINVAL;
161                         goto out;
162                 }
163                 if (groups_to_user(grouplist, cred->group_info)) {
164                         i = -EFAULT;
165                         goto out;
166                 }
167         }
168 out:
169         return i;
170 }
171
172 bool may_setgroups(void)
173 {
174         struct user_namespace *user_ns = current_user_ns();
175
176         return ns_capable_setid(user_ns, CAP_SETGID) &&
177                 userns_may_setgroups(user_ns);
178 }
179
180 /*
181  *      SMP: Our groups are copy-on-write. We can set them safely
182  *      without another task interfering.
183  */
184
185 SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
186 {
187         struct group_info *group_info;
188         int retval;
189
190         if (!may_setgroups())
191                 return -EPERM;
192         if ((unsigned)gidsetsize > NGROUPS_MAX)
193                 return -EINVAL;
194
195         group_info = groups_alloc(gidsetsize);
196         if (!group_info)
197                 return -ENOMEM;
198         retval = groups_from_user(group_info, grouplist);
199         if (retval) {
200                 put_group_info(group_info);
201                 return retval;
202         }
203
204         groups_sort(group_info);
205         retval = set_current_groups(group_info);
206         put_group_info(group_info);
207
208         return retval;
209 }
210
211 /*
212  * Check whether we're fsgid/egid or in the supplemental group..
213  */
214 int in_group_p(kgid_t grp)
215 {
216         const struct cred *cred = current_cred();
217         int retval = 1;
218
219         if (!gid_eq(grp, cred->fsgid))
220                 retval = groups_search(cred->group_info, grp);
221         return retval;
222 }
223
224 EXPORT_SYMBOL(in_group_p);
225
226 int in_egroup_p(kgid_t grp)
227 {
228         const struct cred *cred = current_cred();
229         int retval = 1;
230
231         if (!gid_eq(grp, cred->egid))
232                 retval = groups_search(cred->group_info, grp);
233         return retval;
234 }
235
236 EXPORT_SYMBOL(in_egroup_p);