Alexey Dobriyan | 30639b6a | 2009-06-16 15:33:40 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Supplementary group IDs |
| 3 | */ |
| 4 | #include <linux/cred.h> |
| 5 | #include <linux/module.h> |
| 6 | #include <linux/slab.h> |
| 7 | #include <linux/security.h> |
| 8 | #include <linux/syscalls.h> |
| 9 | #include <asm/uaccess.h> |
| 10 | |
| 11 | /* init to 2 - one for init_task, one to ensure it is never freed */ |
| 12 | struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; |
| 13 | |
| 14 | struct group_info *groups_alloc(int gidsetsize) |
| 15 | { |
| 16 | struct group_info *group_info; |
| 17 | int nblocks; |
| 18 | int i; |
| 19 | |
| 20 | nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK; |
| 21 | /* Make sure we always allocate at least one indirect block pointer */ |
| 22 | nblocks = nblocks ? : 1; |
| 23 | group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER); |
| 24 | if (!group_info) |
| 25 | return NULL; |
| 26 | group_info->ngroups = gidsetsize; |
| 27 | group_info->nblocks = nblocks; |
| 28 | atomic_set(&group_info->usage, 1); |
| 29 | |
| 30 | if (gidsetsize <= NGROUPS_SMALL) |
| 31 | group_info->blocks[0] = group_info->small_block; |
| 32 | else { |
| 33 | for (i = 0; i < nblocks; i++) { |
| 34 | gid_t *b; |
| 35 | b = (void *)__get_free_page(GFP_USER); |
| 36 | if (!b) |
| 37 | goto out_undo_partial_alloc; |
| 38 | group_info->blocks[i] = b; |
| 39 | } |
| 40 | } |
| 41 | return group_info; |
| 42 | |
| 43 | out_undo_partial_alloc: |
| 44 | while (--i >= 0) { |
| 45 | free_page((unsigned long)group_info->blocks[i]); |
| 46 | } |
| 47 | kfree(group_info); |
| 48 | return NULL; |
| 49 | } |
| 50 | |
| 51 | EXPORT_SYMBOL(groups_alloc); |
| 52 | |
| 53 | void groups_free(struct group_info *group_info) |
| 54 | { |
| 55 | if (group_info->blocks[0] != group_info->small_block) { |
| 56 | int i; |
| 57 | for (i = 0; i < group_info->nblocks; i++) |
| 58 | free_page((unsigned long)group_info->blocks[i]); |
| 59 | } |
| 60 | kfree(group_info); |
| 61 | } |
| 62 | |
| 63 | EXPORT_SYMBOL(groups_free); |
| 64 | |
| 65 | /* export the group_info to a user-space array */ |
| 66 | static int groups_to_user(gid_t __user *grouplist, |
| 67 | const struct group_info *group_info) |
| 68 | { |
| 69 | int i; |
| 70 | unsigned int count = group_info->ngroups; |
| 71 | |
| 72 | for (i = 0; i < group_info->nblocks; i++) { |
| 73 | unsigned int cp_count = min(NGROUPS_PER_BLOCK, count); |
| 74 | unsigned int len = cp_count * sizeof(*grouplist); |
| 75 | |
| 76 | if (copy_to_user(grouplist, group_info->blocks[i], len)) |
| 77 | return -EFAULT; |
| 78 | |
| 79 | grouplist += NGROUPS_PER_BLOCK; |
| 80 | count -= cp_count; |
| 81 | } |
| 82 | return 0; |
| 83 | } |
| 84 | |
| 85 | /* fill a group_info from a user-space array - it must be allocated already */ |
| 86 | static int groups_from_user(struct group_info *group_info, |
| 87 | gid_t __user *grouplist) |
| 88 | { |
| 89 | int i; |
| 90 | unsigned int count = group_info->ngroups; |
| 91 | |
| 92 | for (i = 0; i < group_info->nblocks; i++) { |
| 93 | unsigned int cp_count = min(NGROUPS_PER_BLOCK, count); |
| 94 | unsigned int len = cp_count * sizeof(*grouplist); |
| 95 | |
| 96 | if (copy_from_user(group_info->blocks[i], grouplist, len)) |
| 97 | return -EFAULT; |
| 98 | |
| 99 | grouplist += NGROUPS_PER_BLOCK; |
| 100 | count -= cp_count; |
| 101 | } |
| 102 | return 0; |
| 103 | } |
| 104 | |
| 105 | /* a simple Shell sort */ |
| 106 | static void groups_sort(struct group_info *group_info) |
| 107 | { |
| 108 | int base, max, stride; |
| 109 | int gidsetsize = group_info->ngroups; |
| 110 | |
| 111 | for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1) |
| 112 | ; /* nothing */ |
| 113 | stride /= 3; |
| 114 | |
| 115 | while (stride) { |
| 116 | max = gidsetsize - stride; |
| 117 | for (base = 0; base < max; base++) { |
| 118 | int left = base; |
| 119 | int right = left + stride; |
| 120 | gid_t tmp = GROUP_AT(group_info, right); |
| 121 | |
| 122 | while (left >= 0 && GROUP_AT(group_info, left) > tmp) { |
| 123 | GROUP_AT(group_info, right) = |
| 124 | GROUP_AT(group_info, left); |
| 125 | right = left; |
| 126 | left -= stride; |
| 127 | } |
| 128 | GROUP_AT(group_info, right) = tmp; |
| 129 | } |
| 130 | stride /= 3; |
| 131 | } |
| 132 | } |
| 133 | |
| 134 | /* a simple bsearch */ |
| 135 | int groups_search(const struct group_info *group_info, gid_t grp) |
| 136 | { |
| 137 | unsigned int left, right; |
| 138 | |
| 139 | if (!group_info) |
| 140 | return 0; |
| 141 | |
| 142 | left = 0; |
| 143 | right = group_info->ngroups; |
| 144 | while (left < right) { |
| 145 | unsigned int mid = (left+right)/2; |
Jerome Marchand | 1c24de6 | 2010-09-09 16:37:59 -0700 | [diff] [blame] | 146 | if (grp > GROUP_AT(group_info, mid)) |
Alexey Dobriyan | 30639b6a | 2009-06-16 15:33:40 -0700 | [diff] [blame] | 147 | left = mid + 1; |
Jerome Marchand | 1c24de6 | 2010-09-09 16:37:59 -0700 | [diff] [blame] | 148 | else if (grp < GROUP_AT(group_info, mid)) |
Alexey Dobriyan | 30639b6a | 2009-06-16 15:33:40 -0700 | [diff] [blame] | 149 | right = mid; |
| 150 | else |
| 151 | return 1; |
| 152 | } |
| 153 | return 0; |
| 154 | } |
| 155 | |
| 156 | /** |
| 157 | * set_groups - Change a group subscription in a set of credentials |
| 158 | * @new: The newly prepared set of credentials to alter |
| 159 | * @group_info: The group list to install |
| 160 | * |
| 161 | * Validate a group subscription and, if valid, insert it into a set |
| 162 | * of credentials. |
| 163 | */ |
| 164 | int set_groups(struct cred *new, struct group_info *group_info) |
| 165 | { |
Alexey Dobriyan | 30639b6a | 2009-06-16 15:33:40 -0700 | [diff] [blame] | 166 | put_group_info(new->group_info); |
| 167 | groups_sort(group_info); |
| 168 | get_group_info(group_info); |
| 169 | new->group_info = group_info; |
| 170 | return 0; |
| 171 | } |
| 172 | |
| 173 | EXPORT_SYMBOL(set_groups); |
| 174 | |
| 175 | /** |
| 176 | * set_current_groups - Change current's group subscription |
| 177 | * @group_info: The group list to impose |
| 178 | * |
| 179 | * Validate a group subscription and, if valid, impose it upon current's task |
| 180 | * security record. |
| 181 | */ |
| 182 | int set_current_groups(struct group_info *group_info) |
| 183 | { |
| 184 | struct cred *new; |
| 185 | int ret; |
| 186 | |
| 187 | new = prepare_creds(); |
| 188 | if (!new) |
| 189 | return -ENOMEM; |
| 190 | |
| 191 | ret = set_groups(new, group_info); |
| 192 | if (ret < 0) { |
| 193 | abort_creds(new); |
| 194 | return ret; |
| 195 | } |
| 196 | |
| 197 | return commit_creds(new); |
| 198 | } |
| 199 | |
| 200 | EXPORT_SYMBOL(set_current_groups); |
| 201 | |
| 202 | SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist) |
| 203 | { |
| 204 | const struct cred *cred = current_cred(); |
| 205 | int i; |
| 206 | |
| 207 | if (gidsetsize < 0) |
| 208 | return -EINVAL; |
| 209 | |
| 210 | /* no need to grab task_lock here; it cannot change */ |
| 211 | i = cred->group_info->ngroups; |
| 212 | if (gidsetsize) { |
| 213 | if (i > gidsetsize) { |
| 214 | i = -EINVAL; |
| 215 | goto out; |
| 216 | } |
| 217 | if (groups_to_user(grouplist, cred->group_info)) { |
| 218 | i = -EFAULT; |
| 219 | goto out; |
| 220 | } |
| 221 | } |
| 222 | out: |
| 223 | return i; |
| 224 | } |
| 225 | |
| 226 | /* |
| 227 | * SMP: Our groups are copy-on-write. We can set them safely |
| 228 | * without another task interfering. |
| 229 | */ |
| 230 | |
| 231 | SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) |
| 232 | { |
| 233 | struct group_info *group_info; |
| 234 | int retval; |
| 235 | |
| 236 | if (!capable(CAP_SETGID)) |
| 237 | return -EPERM; |
| 238 | if ((unsigned)gidsetsize > NGROUPS_MAX) |
| 239 | return -EINVAL; |
| 240 | |
| 241 | group_info = groups_alloc(gidsetsize); |
| 242 | if (!group_info) |
| 243 | return -ENOMEM; |
| 244 | retval = groups_from_user(group_info, grouplist); |
| 245 | if (retval) { |
| 246 | put_group_info(group_info); |
| 247 | return retval; |
| 248 | } |
| 249 | |
| 250 | retval = set_current_groups(group_info); |
| 251 | put_group_info(group_info); |
| 252 | |
| 253 | return retval; |
| 254 | } |
| 255 | |
| 256 | /* |
| 257 | * Check whether we're fsgid/egid or in the supplemental group.. |
| 258 | */ |
| 259 | int in_group_p(gid_t grp) |
| 260 | { |
| 261 | const struct cred *cred = current_cred(); |
| 262 | int retval = 1; |
| 263 | |
| 264 | if (grp != cred->fsgid) |
| 265 | retval = groups_search(cred->group_info, grp); |
| 266 | return retval; |
| 267 | } |
| 268 | |
| 269 | EXPORT_SYMBOL(in_group_p); |
| 270 | |
| 271 | int in_egroup_p(gid_t grp) |
| 272 | { |
| 273 | const struct cred *cred = current_cred(); |
| 274 | int retval = 1; |
| 275 | |
| 276 | if (grp != cred->egid) |
| 277 | retval = groups_search(cred->group_info, grp); |
| 278 | return retval; |
| 279 | } |
| 280 | |
| 281 | EXPORT_SYMBOL(in_egroup_p); |