1. 76.
    0
    struct group_info init_groups = { .usage = ATOMIC_INIT(2) };

    struct group_info *groups_alloc(int gidsetsize){

    struct group_info *group_info;

    int nblocks;

    int i;

    nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK;

    /* Make sure we always allocate at least one indirect block pointer */

    nblocks = nblocks ? : 1;

    group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER);

    if (!group_info)

    return NULL;

    group_info->ngroups = gidsetsize;

    group_info->nblocks = nblocks;

    atomic_set(&group_info->usage, 1);

    if (gidsetsize <= NGROUPS_SMALL)

    group_info->blocks[0] = group_info->small_block;

    else {

    for (i = 0; i < nblocks; i++) {

    gid_t *b;

    b = (void *)__get_free_page(GFP_USER);

    if (!b)

    goto out_undo_partial_alloc;

    group_info->blocks[i] = b;

    }

    }

    return group_info;

    out_undo_partial_alloc:

    while (--i >= 0) {

    free_page((unsigned long)group_info->blocks[i]);

    }

    kfree(group_info);

    return NULL;

    }

    EXPORT_SYMBOL(groups_alloc);

    void groups_free(struct group_info *group_info)

    {

    if (group_info->blocks[0] != group_info->small_block) {

    int i;

    for (i = 0; i < group_info->nblocks; i++)

    free_page((unsigned long)group_info->blocks[i]);

    }

    kfree(group_info);

    }

    EXPORT_SYMBOL(groups_free);

    /* export the group_info to a user-space array */

    static int groups_to_user(gid_t __user *grouplist,

    const struct group_info *group_info)

    {

    int i;

    unsigned int count = group_info->ngroups;

    for (i = 0; i < group_info->nblocks; i++) {

    unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);

    unsigned int len = cp_count * sizeof(*grouplist);

    if (copy_to_user(grouplist, group_info->blocks[i], len))

    return -EFAULT;

    grouplist += NGROUPS_PER_BLOCK;

    count -= cp_count;

    }

    return 0;

    }

    /* fill a group_info from a user-space array - it must be allocated already */

    static int groups_from_user(struct group_info *group_info,

    gid_t __user *grouplist)

    {

    int i;

    unsigned int count = group_info->ngroups;

    for (i = 0; i < group_info->nblocks; i++) {

    unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);

    unsigned int len = cp_count * sizeof(*grouplist);

    if (copy_from_user(group_info->blocks[i], grouplist, len))

    return -EFAULT;

    grouplist += NGROUPS_PER_BLOCK;

    count -= cp_count;

    }

    return 0;

    }

    /* a simple Shell sort */

    static void groups_sort(struct group_info *group_info)

    {

    int base, max, stride;

    int gidsetsize = group_info->ngroups;

    for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1)

    ; /* nothing */

    stride /= 3;

    while (stride) {

    max = gidsetsize - stride;

    for (base = 0; base < max; base++) {

    int left = base;

    int right = left + stride;

    gid_t tmp = GROUP_AT(group_info, right);

    while (left >= 0 && GROUP_AT(group_info, left) > tmp) {

    GROUP_AT(group_info, right) =

    GROUP_AT(group_info, left);

    right = left;

    left -= stride;

    }

    GROUP_AT(group_info, right) = tmp;

    }

    stride /= 3;

    }

    }

    /* a simple bsearch */

    int groups_search(const struct group_info *group_info, gid_t grp)

    {

    unsigned int left, right;

    if (!group_info)

    return 0;

    left = 0;

    right = group_info->ngroups;

    while (left < right) {

    unsigned int mid = (left+right)/2;

    if (grp > GROUP_AT(group_info, mid))

    left = mid + 1;

    else if (grp < GROUP_AT(group_info, mid))

    right = mid;

    else

    return 1;

    }

    return 0;

    }

    /**

    * set_groups - Change a group subscription in a set of credentials

    * @new: The newly prepared set of credentials to alter

    * @group_info: The group list to install

    *

    * Validate a group subscription and, if valid, insert it into a set

    * of credentials.

    */

    int set_groups(struct cred *new, struct group_info *group_info)

    {

    put_group_info(new->group_info);

    groups_sort(group_info);

    get_group_info(group_info);

    new->group_info = group_info;

    return 0;

    }

    EXPORT_SYMBOL(set_groups);

    /**

    * set_current_groups - Change current\\\'s group subscription

    * @group_info: The group list to impose

    *

    * Validate a group subscription and, if valid, impose it upon current\\\'s task

    * security record.

    */

    int set_current_groups(struct group_info *group_info)

    {

    struct cred *new;

    int ret;

    new = prepare_creds();

    if (!new)

    return -ENOMEM;

    ret = set_groups(new, group_info);

    if (ret < 0) {

    abort_creds(new);

    return ret;

    }

    return commit_creds(new);

    }

    EXPORT_SYMBOL(set_current_groups);

    SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)

    {

    const struct cred *cred = current_cred();

    int i;

    if (gidsetsize < 0)

    return -EINVAL;

    /* no need to grab task_lock here; it cannot change */

    i = cred->group_info->ngroups;

    if (gidsetsize) {

    if (i > gidsetsize) {

    i = -EINVAL;

    goto out;

    }

    if (groups_to_user(grouplist, cred->group_info)) {

    i = -EFAULT;

    goto out;

    }

    }

    out:

    return i;

    }

    /*

    * SMP: Our groups are copy-on-write. We can set them safely

    * without another task interfering.

    */

    SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)

    {

    struct group_info *group_info;

    int retval;

    if (!nsown_capable(CAP_SETGID))

    return -EPERM;

    if ((unsigned)gidsetsize > NGROUPS_MAX)

    return -EINVAL;

    group_info = groups_alloc(gidsetsize);

    if (!group_info)

    return -ENOMEM;

    retval = groups_from_user(group_info, grouplist);

    if (retval) {

    put_group_info(group_info);

    return retval;

    }

    retval = set_current_groups(group_info);

    put_group_info(group_info);

    return retval;

    }

    /*

    * Check whether we\\\'re fsgid/egid or in the supplemental group..

    */

    int in_group_p(gid_t grp)

    {

    const struct cred *cred = current_cred();

    int retval = 1;

    if (grp != cred->fsgid)

    retval = groups_search(cred->group_info, grp);

    return retval;

    }

    EXPORT_SYMBOL(in_group_p);

    int in_egroup_p(gid_t grp)

    {

    const struct cred *cred = current_cred();

    int retval = 1;

    if (grp != cred->egid)

    retval = groups_search(cred->group_info, grp);

    return retval;
    )
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