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8f6c5ffc89
After commit 6307f8fee2
("security: remove dead hook task_setgroups"),
set_groups will always return zero, so we could just remove return value
of set_groups.
This patch reduces code size, and simplfies code to use set_groups,
because we don't need to check its return value any more.
[akpm@linux-foundation.org: remove obsolete claims from set_groups() comment]
Signed-off-by: Wang YanQing <udknight@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
272 lines
5.8 KiB
C
272 lines
5.8 KiB
C
/*
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* Supplementary group IDs
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*/
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#include <linux/cred.h>
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#include <linux/export.h>
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#include <linux/slab.h>
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#include <linux/security.h>
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#include <linux/syscalls.h>
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#include <asm/uaccess.h>
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/* init to 2 - one for init_task, one to ensure it is never freed */
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struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
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struct group_info *groups_alloc(int gidsetsize)
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{
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struct group_info *group_info;
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int nblocks;
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int i;
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nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK;
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/* Make sure we always allocate at least one indirect block pointer */
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nblocks = nblocks ? : 1;
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group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER);
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if (!group_info)
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return NULL;
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group_info->ngroups = gidsetsize;
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group_info->nblocks = nblocks;
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atomic_set(&group_info->usage, 1);
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if (gidsetsize <= NGROUPS_SMALL)
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group_info->blocks[0] = group_info->small_block;
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else {
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for (i = 0; i < nblocks; i++) {
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kgid_t *b;
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b = (void *)__get_free_page(GFP_USER);
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if (!b)
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goto out_undo_partial_alloc;
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group_info->blocks[i] = b;
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}
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}
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return group_info;
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out_undo_partial_alloc:
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while (--i >= 0) {
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free_page((unsigned long)group_info->blocks[i]);
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}
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kfree(group_info);
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return NULL;
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}
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EXPORT_SYMBOL(groups_alloc);
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void groups_free(struct group_info *group_info)
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{
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if (group_info->blocks[0] != group_info->small_block) {
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int i;
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for (i = 0; i < group_info->nblocks; i++)
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free_page((unsigned long)group_info->blocks[i]);
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}
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kfree(group_info);
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}
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EXPORT_SYMBOL(groups_free);
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/* export the group_info to a user-space array */
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static int groups_to_user(gid_t __user *grouplist,
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const struct group_info *group_info)
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{
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struct user_namespace *user_ns = current_user_ns();
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int i;
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unsigned int count = group_info->ngroups;
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for (i = 0; i < count; i++) {
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gid_t gid;
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gid = from_kgid_munged(user_ns, GROUP_AT(group_info, i));
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if (put_user(gid, grouplist+i))
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return -EFAULT;
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}
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return 0;
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}
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/* fill a group_info from a user-space array - it must be allocated already */
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static int groups_from_user(struct group_info *group_info,
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gid_t __user *grouplist)
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{
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struct user_namespace *user_ns = current_user_ns();
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int i;
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unsigned int count = group_info->ngroups;
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for (i = 0; i < count; i++) {
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gid_t gid;
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kgid_t kgid;
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if (get_user(gid, grouplist+i))
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return -EFAULT;
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kgid = make_kgid(user_ns, gid);
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if (!gid_valid(kgid))
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return -EINVAL;
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GROUP_AT(group_info, i) = kgid;
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}
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return 0;
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}
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/* a simple Shell sort */
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static void groups_sort(struct group_info *group_info)
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{
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int base, max, stride;
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int gidsetsize = group_info->ngroups;
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for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1)
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; /* nothing */
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stride /= 3;
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while (stride) {
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max = gidsetsize - stride;
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for (base = 0; base < max; base++) {
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int left = base;
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int right = left + stride;
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kgid_t tmp = GROUP_AT(group_info, right);
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while (left >= 0 && gid_gt(GROUP_AT(group_info, left), tmp)) {
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GROUP_AT(group_info, right) =
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GROUP_AT(group_info, left);
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right = left;
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left -= stride;
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}
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GROUP_AT(group_info, right) = tmp;
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}
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stride /= 3;
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}
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}
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/* a simple bsearch */
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int groups_search(const struct group_info *group_info, kgid_t grp)
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{
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unsigned int left, right;
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if (!group_info)
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return 0;
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left = 0;
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right = group_info->ngroups;
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while (left < right) {
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unsigned int mid = (left+right)/2;
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if (gid_gt(grp, GROUP_AT(group_info, mid)))
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left = mid + 1;
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else if (gid_lt(grp, GROUP_AT(group_info, mid)))
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right = mid;
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else
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return 1;
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}
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return 0;
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}
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/**
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* set_groups - Change a group subscription in a set of credentials
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* @new: The newly prepared set of credentials to alter
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* @group_info: The group list to install
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*/
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void set_groups(struct cred *new, struct group_info *group_info)
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{
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put_group_info(new->group_info);
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groups_sort(group_info);
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get_group_info(group_info);
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new->group_info = group_info;
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}
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EXPORT_SYMBOL(set_groups);
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/**
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* set_current_groups - Change current's group subscription
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* @group_info: The group list to impose
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*
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* Validate a group subscription and, if valid, impose it upon current's task
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* security record.
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*/
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int set_current_groups(struct group_info *group_info)
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{
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struct cred *new;
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new = prepare_creds();
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if (!new)
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return -ENOMEM;
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set_groups(new, group_info);
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return commit_creds(new);
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}
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EXPORT_SYMBOL(set_current_groups);
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SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
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{
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const struct cred *cred = current_cred();
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int i;
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if (gidsetsize < 0)
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return -EINVAL;
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/* no need to grab task_lock here; it cannot change */
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i = cred->group_info->ngroups;
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if (gidsetsize) {
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if (i > gidsetsize) {
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i = -EINVAL;
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goto out;
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}
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if (groups_to_user(grouplist, cred->group_info)) {
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i = -EFAULT;
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goto out;
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}
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}
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out:
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return i;
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}
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/*
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* SMP: Our groups are copy-on-write. We can set them safely
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* without another task interfering.
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*/
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SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
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{
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struct group_info *group_info;
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int retval;
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if (!ns_capable(current_user_ns(), CAP_SETGID))
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return -EPERM;
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if ((unsigned)gidsetsize > NGROUPS_MAX)
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return -EINVAL;
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group_info = groups_alloc(gidsetsize);
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if (!group_info)
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return -ENOMEM;
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retval = groups_from_user(group_info, grouplist);
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if (retval) {
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put_group_info(group_info);
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return retval;
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}
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retval = set_current_groups(group_info);
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put_group_info(group_info);
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return retval;
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}
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/*
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* Check whether we're fsgid/egid or in the supplemental group..
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*/
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int in_group_p(kgid_t grp)
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{
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const struct cred *cred = current_cred();
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int retval = 1;
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if (!gid_eq(grp, cred->fsgid))
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retval = groups_search(cred->group_info, grp);
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return retval;
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}
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EXPORT_SYMBOL(in_group_p);
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int in_egroup_p(kgid_t grp)
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{
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const struct cred *cred = current_cred();
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int retval = 1;
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if (!gid_eq(grp, cred->egid))
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retval = groups_search(cred->group_info, grp);
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return retval;
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}
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EXPORT_SYMBOL(in_egroup_p);
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