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![Jan Kara](/assets/img/avatar_default.png)
When file permissions are modified via chmod(2) and the user is not in the owning group or capable of CAP_FSETID, the setgid bit is cleared in inode_change_ok(). Setting a POSIX ACL via setxattr(2) sets the file permissions as well as the new ACL, but doesn't clear the setgid bit in a similar way; this allows to bypass the check in chmod(2). Fix that. References: CVE-2016-7097 Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
167 lines
4.1 KiB
C
167 lines
4.1 KiB
C
/*
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* (C) 2001 Clemson University and The University of Chicago
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*
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* See COPYING in top-level directory.
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*/
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#include "protocol.h"
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#include "orangefs-kernel.h"
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#include "orangefs-bufmap.h"
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#include <linux/posix_acl_xattr.h>
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#include <linux/fs_struct.h>
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struct posix_acl *orangefs_get_acl(struct inode *inode, int type)
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{
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struct posix_acl *acl;
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int ret;
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char *key = NULL, *value = NULL;
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switch (type) {
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case ACL_TYPE_ACCESS:
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key = XATTR_NAME_POSIX_ACL_ACCESS;
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break;
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case ACL_TYPE_DEFAULT:
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key = XATTR_NAME_POSIX_ACL_DEFAULT;
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break;
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default:
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gossip_err("orangefs_get_acl: bogus value of type %d\n", type);
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return ERR_PTR(-EINVAL);
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}
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/*
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* Rather than incurring a network call just to determine the exact
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* length of the attribute, I just allocate a max length to save on
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* the network call. Conceivably, we could pass NULL to
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* orangefs_inode_getxattr() to probe the length of the value, but
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* I don't do that for now.
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*/
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value = kmalloc(ORANGEFS_MAX_XATTR_VALUELEN, GFP_KERNEL);
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if (value == NULL)
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return ERR_PTR(-ENOMEM);
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gossip_debug(GOSSIP_ACL_DEBUG,
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"inode %pU, key %s, type %d\n",
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get_khandle_from_ino(inode),
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key,
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type);
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ret = orangefs_inode_getxattr(inode, key, value,
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ORANGEFS_MAX_XATTR_VALUELEN);
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/* if the key exists, convert it to an in-memory rep */
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if (ret > 0) {
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acl = posix_acl_from_xattr(&init_user_ns, value, ret);
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} else if (ret == -ENODATA || ret == -ENOSYS) {
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acl = NULL;
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} else {
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gossip_err("inode %pU retrieving acl's failed with error %d\n",
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get_khandle_from_ino(inode),
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ret);
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acl = ERR_PTR(ret);
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}
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/* kfree(NULL) is safe, so don't worry if value ever got used */
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kfree(value);
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return acl;
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}
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int orangefs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
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{
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struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
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int error = 0;
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void *value = NULL;
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size_t size = 0;
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const char *name = NULL;
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switch (type) {
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case ACL_TYPE_ACCESS:
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name = XATTR_NAME_POSIX_ACL_ACCESS;
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if (acl) {
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umode_t mode;
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error = posix_acl_update_mode(inode, &mode, &acl);
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if (error) {
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gossip_err("%s: posix_acl_update_mode err: %d\n",
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__func__,
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error);
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return error;
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}
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if (inode->i_mode != mode)
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SetModeFlag(orangefs_inode);
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inode->i_mode = mode;
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mark_inode_dirty_sync(inode);
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}
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break;
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case ACL_TYPE_DEFAULT:
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name = XATTR_NAME_POSIX_ACL_DEFAULT;
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break;
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default:
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gossip_err("%s: invalid type %d!\n", __func__, type);
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return -EINVAL;
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}
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gossip_debug(GOSSIP_ACL_DEBUG,
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"%s: inode %pU, key %s type %d\n",
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__func__, get_khandle_from_ino(inode),
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name,
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type);
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if (acl) {
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size = posix_acl_xattr_size(acl->a_count);
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value = kmalloc(size, GFP_KERNEL);
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if (!value)
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return -ENOMEM;
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error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
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if (error < 0)
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goto out;
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}
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gossip_debug(GOSSIP_ACL_DEBUG,
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"%s: name %s, value %p, size %zd, acl %p\n",
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__func__, name, value, size, acl);
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/*
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* Go ahead and set the extended attribute now. NOTE: Suppose acl
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* was NULL, then value will be NULL and size will be 0 and that
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* will xlate to a removexattr. However, we don't want removexattr
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* complain if attributes does not exist.
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*/
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error = orangefs_inode_setxattr(inode, name, value, size, 0);
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out:
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kfree(value);
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if (!error)
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set_cached_acl(inode, type, acl);
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return error;
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}
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int orangefs_init_acl(struct inode *inode, struct inode *dir)
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{
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struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
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struct posix_acl *default_acl, *acl;
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umode_t mode = inode->i_mode;
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int error = 0;
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ClearModeFlag(orangefs_inode);
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error = posix_acl_create(dir, &mode, &default_acl, &acl);
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if (error)
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return error;
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if (default_acl) {
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error = orangefs_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
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posix_acl_release(default_acl);
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}
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if (acl) {
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if (!error)
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error = orangefs_set_acl(inode, acl, ACL_TYPE_ACCESS);
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posix_acl_release(acl);
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}
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/* If mode of the inode was changed, then do a forcible ->setattr */
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if (mode != inode->i_mode) {
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SetModeFlag(orangefs_inode);
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inode->i_mode = mode;
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orangefs_flush_inode(inode);
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}
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return error;
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}
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