userns: Convert group_info values from gid_t to kgid_t.

As a first step to converting struct cred to be all kuid_t and kgid_t
values convert the group values stored in group_info to always be
kgid_t values.   Unless user namespaces are used this change should
have no effect.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 25 insertions, 23 deletions

diff --git a/kernel/groups.c b/kernel/groups.c
index 99b53d1eb7ea..84156f2d4c8c 100644
--- a/kernel/groups.c
+++ b/kernel/groups.c
@@ -31,7 +31,7 @@ struct group_info *groups_alloc(int gidsetsize)
                 group_info->blocks[0] = group_info->small_block;
         else {
                 for (i = 0; i < nblocks; i++) {
-                        gid_t *b;
+                        kgid_t *b;
                         b = (void *)__get_free_page(GFP_USER);
                         if (!b)
                                 goto out_undo_partial_alloc;
@@ -66,18 +66,15 @@ EXPORT_SYMBOL(groups_free);
 static int groups_to_user(gid_t __user *grouplist,
                           const struct group_info *group_info)
 {
+        struct user_namespace *user_ns = current_user_ns();
         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))
+        for (i = 0; i < count; i++) {
+                gid_t gid;
+                gid = from_kgid_munged(user_ns, GROUP_AT(group_info, i));
+                if (put_user(gid, grouplist+i))
                         return -EFAULT;
-
-                grouplist += NGROUPS_PER_BLOCK;
-                count -= cp_count;
         }
         return 0;
 }
@@ -86,18 +83,21 @@ static int groups_to_user(gid_t __user *grouplist,
 static int groups_from_user(struct group_info *group_info,
     gid_t __user *grouplist)
 {
+        struct user_namespace *user_ns = current_user_ns();
         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))
+        for (i = 0; i < count; i++) {
+                gid_t gid;
+                kgid_t kgid;
+                if (get_user(gid, grouplist+i))
                         return -EFAULT;
 
-                grouplist += NGROUPS_PER_BLOCK;
-                count -= cp_count;
+                kgid = make_kgid(user_ns, gid);
+                if (!gid_valid(kgid))
+                        return -EINVAL;
+
+                GROUP_AT(group_info, i) = kgid;
         }
         return 0;
 }
@@ -117,9 +117,9 @@ static void groups_sort(struct group_info *group_info)
                 for (base = 0; base < max; base++) {
                         int left = base;
                         int right = left + stride;
-                        gid_t tmp = GROUP_AT(group_info, right);
+                        kgid_t tmp = GROUP_AT(group_info, right);
 
-                        while (left >= 0 && GROUP_AT(group_info, left) > tmp) {
+                        while (left >= 0 && gid_gt(GROUP_AT(group_info, left), tmp)) {
                                 GROUP_AT(group_info, right) =
                                     GROUP_AT(group_info, left);
                                 right = left;
@@ -132,7 +132,7 @@ static void groups_sort(struct group_info *group_info)
 }
 
 /* a simple bsearch */
-int groups_search(const struct group_info *group_info, gid_t grp)
+int groups_search(const struct group_info *group_info, kgid_t grp)
 {
         unsigned int left, right;
 
@@ -143,9 +143,9 @@ int groups_search(const struct group_info *group_info, gid_t grp)
         right = group_info->ngroups;
         while (left < right) {
                 unsigned int mid = (left+right)/2;
-                if (grp > GROUP_AT(group_info, mid))
+                if (gid_gt(grp, GROUP_AT(group_info, mid)))
                         left = mid + 1;
-                else if (grp < GROUP_AT(group_info, mid))
+                else if (gid_lt(grp, GROUP_AT(group_info, mid)))
                         right = mid;
                 else
                         return 1;
@@ -262,7 +262,8 @@ int in_group_p(gid_t grp)
         int retval = 1;
 
         if (grp != cred->fsgid)
-                retval = groups_search(cred->group_info, grp);
+                retval = groups_search(cred->group_info,
+                                       make_kgid(cred->user_ns, grp));
         return retval;
 }
 
@@ -274,7 +275,8 @@ int in_egroup_p(gid_t grp)
         int retval = 1;
 
         if (grp != cred->egid)
-                retval = groups_search(cred->group_info, grp);
+                retval = groups_search(cred->group_info,
+                                       make_kgid(cred->user_ns, grp));
         return retval;
 }