#include <linux/export.h>
#include <linux/security.h>
+#include <linux/user_namespace.h>
+#include <linux/uaccess.h>
#include "internal.h"
+struct key_acl default_key_acl = {
+ .usage = REFCOUNT_INIT(1),
+ .nr_ace = 2,
+ .possessor_viewable = true,
+ .aces = {
+ KEY_POSSESSOR_ACE(KEY_ACE__PERMS & ~KEY_ACE_JOIN),
+ KEY_OWNER_ACE(KEY_ACE_VIEW),
+ }
+};
+EXPORT_SYMBOL(default_key_acl);
+
+struct key_acl joinable_keyring_acl = {
+ .usage = REFCOUNT_INIT(1),
+ .nr_ace = 2,
+ .possessor_viewable = true,
+ .aces = {
+ KEY_POSSESSOR_ACE(KEY_ACE__PERMS & ~KEY_ACE_JOIN),
+ KEY_OWNER_ACE(KEY_ACE_VIEW | KEY_ACE_READ | KEY_ACE_LINK | KEY_ACE_JOIN),
+ }
+};
+EXPORT_SYMBOL(joinable_keyring_acl);
+
+struct key_acl internal_key_acl = {
+ .usage = REFCOUNT_INIT(1),
+ .nr_ace = 2,
+ .aces = {
+ KEY_POSSESSOR_ACE(KEY_ACE_SEARCH),
+ KEY_OWNER_ACE(KEY_ACE_VIEW | KEY_ACE_READ | KEY_ACE_SEARCH),
+ }
+};
+EXPORT_SYMBOL(internal_key_acl);
+
+struct key_acl internal_keyring_acl = {
+ .usage = REFCOUNT_INIT(1),
+ .nr_ace = 2,
+ .aces = {
+ KEY_POSSESSOR_ACE(KEY_ACE_SEARCH),
+ KEY_OWNER_ACE(KEY_ACE_VIEW | KEY_ACE_READ | KEY_ACE_SEARCH),
+ }
+};
+EXPORT_SYMBOL(internal_keyring_acl);
+
+struct key_acl internal_writable_keyring_acl = {
+ .usage = REFCOUNT_INIT(1),
+ .nr_ace = 2,
+ .aces = {
+ KEY_POSSESSOR_ACE(KEY_ACE_SEARCH | KEY_ACE_WRITE),
+ KEY_OWNER_ACE(KEY_ACE_VIEW | KEY_ACE_READ | KEY_ACE_WRITE | KEY_ACE_SEARCH),
+ }
+};
+EXPORT_SYMBOL(internal_writable_keyring_acl);
+
/**
* key_task_permission - Check a key can be used
* @key_ref: The key to check.
* @cred: The credentials to use.
- * @perm: The permissions to check for.
+ * @desired_perm: The permission to check for.
*
* Check to see whether permission is granted to use a key in the desired way,
* but permit the security modules to override.
* permissions bits or the LSM check.
*/
int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
- unsigned perm)
+ unsigned int desired_perm)
{
- struct key *key;
- key_perm_t kperm;
- int ret;
+ const struct key_acl *acl;
+ const struct key *key;
+ unsigned int allow = 0;
+ int i;
+
+ BUILD_BUG_ON(KEY_NEED_VIEW != KEY_ACE_VIEW ||
+ KEY_NEED_READ != KEY_ACE_READ ||
+ KEY_NEED_WRITE != KEY_ACE_WRITE ||
+ KEY_NEED_SEARCH != KEY_ACE_SEARCH ||
+ KEY_NEED_LINK != KEY_ACE_LINK ||
+ KEY_NEED_SETSEC != KEY_ACE_SET_SECURITY ||
+ KEY_NEED_INVAL != KEY_ACE_INVAL ||
+ KEY_NEED_REVOKE != KEY_ACE_REVOKE ||
+ KEY_NEED_JOIN != KEY_ACE_JOIN ||
+ KEY_NEED_CLEAR != KEY_ACE_CLEAR);
key = key_ref_to_ptr(key_ref);
- /* use the second 8-bits of permissions for keys the caller owns */
- if (uid_eq(key->uid, cred->fsuid)) {
- kperm = key->perm >> 16;
- goto use_these_perms;
- }
+ rcu_read_lock();
- /* use the third 8-bits of permissions for keys the caller has a group
- * membership in common with */
- if (gid_valid(key->gid) && key->perm & KEY_GRP_ALL) {
- if (gid_eq(key->gid, cred->fsgid)) {
- kperm = key->perm >> 8;
- goto use_these_perms;
- }
+ acl = rcu_dereference(key->acl);
+ if (!acl || acl->nr_ace == 0)
+ goto no_access_rcu;
- ret = groups_search(cred->group_info, key->gid);
- if (ret) {
- kperm = key->perm >> 8;
- goto use_these_perms;
+ for (i = 0; i < acl->nr_ace; i++) {
+ const struct key_ace *ace = &acl->aces[i];
+
+ switch (ace->type) {
+ case KEY_ACE_SUBJ_STANDARD:
+ switch (ace->subject_id) {
+ case KEY_ACE_POSSESSOR:
+ if (is_key_possessed(key_ref))
+ allow |= ace->perm;
+ break;
+ case KEY_ACE_OWNER:
+ if (uid_eq(key->uid, cred->fsuid))
+ allow |= ace->perm;
+ break;
+ case KEY_ACE_GROUP:
+ if (gid_valid(key->gid)) {
+ if (gid_eq(key->gid, cred->fsgid))
+ allow |= ace->perm;
+ else if (groups_search(cred->group_info, key->gid))
+ allow |= ace->perm;
+ }
+ break;
+ case KEY_ACE_EVERYONE:
+ allow |= ace->perm;
+ break;
+ }
+ break;
}
}
- /* otherwise use the least-significant 8-bits */
- kperm = key->perm;
-
-use_these_perms:
+ rcu_read_unlock();
- /* use the top 8-bits of permissions for keys the caller possesses
- * - possessor permissions are additive with other permissions
- */
- if (is_key_possessed(key_ref))
- kperm |= key->perm >> 24;
+ if (!(allow & desired_perm))
+ goto no_access;
- kperm = kperm & perm & KEY_NEED_ALL;
+ return security_key_permission(key_ref, cred, desired_perm);
- if (kperm != perm)
- return -EACCES;
-
- /* let LSM be the final arbiter */
- return security_key_permission(key_ref, cred, perm);
+no_access_rcu:
+ rcu_read_unlock();
+no_access:
+ return -EACCES;
}
EXPORT_SYMBOL(key_task_permission);
return 0;
}
EXPORT_SYMBOL(key_validate);
+
+/*
+ * Roughly render an ACL to an old-style permissions mask. We cannot
+ * accurately render what the ACL, particularly if it has ACEs that represent
+ * subjects outside of { poss, user, group, other }.
+ */
+unsigned int key_acl_to_perm(const struct key_acl *acl)
+{
+ unsigned int perm = 0, tperm;
+ int i;
+
+ BUILD_BUG_ON(KEY_OTH_VIEW != KEY_ACE_VIEW ||
+ KEY_OTH_READ != KEY_ACE_READ ||
+ KEY_OTH_WRITE != KEY_ACE_WRITE ||
+ KEY_OTH_SEARCH != KEY_ACE_SEARCH ||
+ KEY_OTH_LINK != KEY_ACE_LINK ||
+ KEY_OTH_SETATTR != KEY_ACE_SET_SECURITY);
+
+ if (!acl || acl->nr_ace == 0)
+ return 0;
+
+ for (i = 0; i < acl->nr_ace; i++) {
+ const struct key_ace *ace = &acl->aces[i];
+
+ switch (ace->type) {
+ case KEY_ACE_SUBJ_STANDARD:
+ tperm = ace->perm & KEY_OTH_ALL;
+
+ /* Invalidation and joining were allowed by SEARCH */
+ if (ace->perm & (KEY_ACE_INVAL | KEY_ACE_JOIN))
+ tperm |= KEY_OTH_SEARCH;
+
+ /* Revocation was allowed by either SETATTR or WRITE */
+ if ((ace->perm & KEY_ACE_REVOKE) && !(tperm & KEY_OTH_SETATTR))
+ tperm |= KEY_OTH_WRITE;
+
+ /* Clearing was allowed by WRITE */
+ if (ace->perm & KEY_ACE_CLEAR)
+ tperm |= KEY_OTH_WRITE;
+
+ switch (ace->subject_id) {
+ case KEY_ACE_POSSESSOR:
+ perm |= tperm << 24;
+ break;
+ case KEY_ACE_OWNER:
+ perm |= tperm << 16;
+ break;
+ case KEY_ACE_GROUP:
+ perm |= tperm << 8;
+ break;
+ case KEY_ACE_EVERYONE:
+ perm |= tperm << 0;
+ break;
+ }
+ }
+ }
+
+ return perm;
+}
+
+/*
+ * Destroy a key's ACL.
+ */
+void key_put_acl(struct key_acl *acl)
+{
+ if (acl && refcount_dec_and_test(&acl->usage))
+ kfree_rcu(acl, rcu);
+}
+
+/*
+ * Try to set the ACL. This either attaches or discards the proposed ACL.
+ */
+long key_set_acl(struct key *key, struct key_acl *acl)
+{
+ int i;
+
+ /* If we're not the sysadmin, we can only change a key that we own. */
+ if (!capable(CAP_SYS_ADMIN) && !uid_eq(key->uid, current_fsuid())) {
+ key_put_acl(acl);
+ return -EACCES;
+ }
+
+ for (i = 0; i < acl->nr_ace; i++) {
+ const struct key_ace *ace = &acl->aces[i];
+ if (ace->type == KEY_ACE_SUBJ_STANDARD &&
+ ace->subject_id == KEY_ACE_POSSESSOR) {
+ if (ace->perm & KEY_ACE_VIEW)
+ acl->possessor_viewable = true;
+ break;
+ }
+ }
+
+ rcu_swap_protected(key->acl, acl, lockdep_is_held(&key->sem));
+ key_put_acl(acl);
+ return 0;
+}
+
+/*
+ * Allocate a new ACL with an extra ACE slot.
+ */
+static struct key_acl *key_alloc_acl(const struct key_acl *old_acl, int nr, int skip)
+{
+ struct key_acl *acl;
+ int nr_ace, i, j = 0;
+
+ nr_ace = old_acl->nr_ace + nr;
+ if (nr_ace > 16)
+ return ERR_PTR(-EINVAL);
+
+ acl = kzalloc(struct_size(acl, aces, nr_ace), GFP_KERNEL);
+ if (!acl)
+ return ERR_PTR(-ENOMEM);
+
+ refcount_set(&acl->usage, 1);
+ acl->nr_ace = nr_ace;
+ for (i = 0; i < old_acl->nr_ace; i++) {
+ if (i == skip)
+ continue;
+ acl->aces[j] = old_acl->aces[i];
+ j++;
+ }
+ return acl;
+}
+
+/*
+ * Generate the revised ACL.
+ */
+static long key_change_acl(struct key *key, struct key_ace *new_ace)
+{
+ struct key_acl *acl, *old;
+ int i;
+
+ old = rcu_dereference_protected(key->acl, lockdep_is_held(&key->sem));
+
+ for (i = 0; i < old->nr_ace; i++)
+ if (old->aces[i].type == new_ace->type &&
+ old->aces[i].subject_id == new_ace->subject_id)
+ goto found_match;
+
+ if (new_ace->perm == 0)
+ return 0; /* No permissions to remove. Add deny record? */
+
+ acl = key_alloc_acl(old, 1, -1);
+ if (IS_ERR(acl))
+ return PTR_ERR(acl);
+ acl->aces[i] = *new_ace;
+ goto change;
+
+found_match:
+ if (new_ace->perm == 0)
+ goto delete_ace;
+ if (new_ace->perm == old->aces[i].perm)
+ return 0;
+ acl = key_alloc_acl(old, 0, -1);
+ if (IS_ERR(acl))
+ return PTR_ERR(acl);
+ acl->aces[i].perm = new_ace->perm;
+ goto change;
+
+delete_ace:
+ acl = key_alloc_acl(old, -1, i);
+ if (IS_ERR(acl))
+ return PTR_ERR(acl);
+ goto change;
+
+change:
+ return key_set_acl(key, acl);
+}
+
+/*
+ * Add, alter or remove (if perm == 0) an ACE in a key's ACL.
+ */
+long keyctl_grant_permission(key_serial_t keyid,
+ enum key_ace_subject_type type,
+ unsigned int subject,
+ unsigned int perm)
+{
+ struct key_ace new_ace;
+ struct key *key;
+ key_ref_t key_ref;
+ long ret;
+
+ new_ace.type = type;
+ new_ace.perm = perm;
+
+ switch (type) {
+ case KEY_ACE_SUBJ_STANDARD:
+ if (subject >= nr__key_ace_standard_subject)
+ return -ENOENT;
+ new_ace.subject_id = subject;
+ break;
+
+ default:
+ return -ENOENT;
+ }
+
+ key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_SETSEC);
+ if (IS_ERR(key_ref)) {
+ ret = PTR_ERR(key_ref);
+ goto error;
+ }
+
+ key = key_ref_to_ptr(key_ref);
+
+ down_write(&key->sem);
+
+ /* If we're not the sysadmin, we can only change a key that we own */
+ ret = -EACCES;
+ if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid()))
+ ret = key_change_acl(key, &new_ace);
+ up_write(&key->sem);
+ key_put(key);
+error:
+ return ret;
+}
git.samba.org / sfrench / cifs-2.6.git / blobdiff