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110 lines
2.9 KiB
110 lines
2.9 KiB
/* Key permission checking |
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* |
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* Copyright (C) 2005 Red Hat, Inc. All Rights Reserved. |
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* Written by David Howells (dhowells@redhat.com) |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU General Public License |
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* as published by the Free Software Foundation; either version |
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* 2 of the License, or (at your option) any later version. |
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*/ |
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#include <linux/module.h> |
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#include <linux/security.h> |
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#include "internal.h" |
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/** |
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* key_task_permission - Check a key can be used |
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* @key_ref: The key to check. |
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* @cred: The credentials to use. |
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* @perm: The permissions to check for. |
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* |
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* Check to see whether permission is granted to use a key in the desired way, |
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* but permit the security modules to override. |
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* |
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* The caller must hold either a ref on cred or must hold the RCU readlock. |
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* |
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* Returns 0 if successful, -EACCES if access is denied based on the |
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* permissions bits or the LSM check. |
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*/ |
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int key_task_permission(const key_ref_t key_ref, const struct cred *cred, |
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unsigned perm) |
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{ |
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struct key *key; |
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key_perm_t kperm; |
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int ret; |
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key = key_ref_to_ptr(key_ref); |
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/* use the second 8-bits of permissions for keys the caller owns */ |
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if (uid_eq(key->uid, cred->fsuid)) { |
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kperm = key->perm >> 16; |
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goto use_these_perms; |
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} |
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/* use the third 8-bits of permissions for keys the caller has a group |
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* membership in common with */ |
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if (gid_valid(key->gid) && key->perm & KEY_GRP_ALL) { |
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if (gid_eq(key->gid, cred->fsgid)) { |
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kperm = key->perm >> 8; |
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goto use_these_perms; |
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} |
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ret = groups_search(cred->group_info, key->gid); |
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if (ret) { |
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kperm = key->perm >> 8; |
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goto use_these_perms; |
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} |
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} |
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/* otherwise use the least-significant 8-bits */ |
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kperm = key->perm; |
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use_these_perms: |
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/* use the top 8-bits of permissions for keys the caller possesses |
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* - possessor permissions are additive with other permissions |
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*/ |
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if (is_key_possessed(key_ref)) |
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kperm |= key->perm >> 24; |
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kperm = kperm & perm & KEY_NEED_ALL; |
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if (kperm != perm) |
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return -EACCES; |
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/* let LSM be the final arbiter */ |
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return security_key_permission(key_ref, cred, perm); |
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} |
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EXPORT_SYMBOL(key_task_permission); |
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/** |
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* key_validate - Validate a key. |
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* @key: The key to be validated. |
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* |
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* Check that a key is valid, returning 0 if the key is okay, -ENOKEY if the |
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* key is invalidated, -EKEYREVOKED if the key's type has been removed or if |
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* the key has been revoked or -EKEYEXPIRED if the key has expired. |
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*/ |
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int key_validate(const struct key *key) |
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{ |
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unsigned long flags = key->flags; |
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if (flags & (1 << KEY_FLAG_INVALIDATED)) |
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return -ENOKEY; |
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/* check it's still accessible */ |
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if (flags & ((1 << KEY_FLAG_REVOKED) | |
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(1 << KEY_FLAG_DEAD))) |
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return -EKEYREVOKED; |
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/* check it hasn't expired */ |
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if (key->expiry) { |
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struct timespec now = current_kernel_time(); |
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if (now.tv_sec >= key->expiry) |
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return -EKEYEXPIRED; |
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} |
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return 0; |
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} |
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EXPORT_SYMBOL(key_validate);
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