073931017b
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>
137 lines
2.8 KiB
C
137 lines
2.8 KiB
C
/*
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* linux/fs/hfsplus/posix_acl.c
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*
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* Vyacheslav Dubeyko <slava@dubeyko.com>
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*
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* Handler for Posix Access Control Lists (ACLs) support.
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*/
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#include "hfsplus_fs.h"
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#include "xattr.h"
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#include "acl.h"
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struct posix_acl *hfsplus_get_posix_acl(struct inode *inode, int type)
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{
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struct posix_acl *acl;
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char *xattr_name;
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char *value = NULL;
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ssize_t size;
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hfs_dbg(ACL_MOD, "[%s]: ino %lu\n", __func__, inode->i_ino);
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switch (type) {
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case ACL_TYPE_ACCESS:
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xattr_name = XATTR_NAME_POSIX_ACL_ACCESS;
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break;
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case ACL_TYPE_DEFAULT:
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xattr_name = XATTR_NAME_POSIX_ACL_DEFAULT;
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break;
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default:
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return ERR_PTR(-EINVAL);
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}
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size = __hfsplus_getxattr(inode, xattr_name, NULL, 0);
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if (size > 0) {
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value = (char *)hfsplus_alloc_attr_entry();
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if (unlikely(!value))
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return ERR_PTR(-ENOMEM);
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size = __hfsplus_getxattr(inode, xattr_name, value, size);
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}
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if (size > 0)
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acl = posix_acl_from_xattr(&init_user_ns, value, size);
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else if (size == -ENODATA)
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acl = NULL;
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else
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acl = ERR_PTR(size);
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hfsplus_destroy_attr_entry((hfsplus_attr_entry *)value);
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return acl;
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}
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int hfsplus_set_posix_acl(struct inode *inode, struct posix_acl *acl,
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int type)
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{
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int err;
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char *xattr_name;
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size_t size = 0;
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char *value = NULL;
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hfs_dbg(ACL_MOD, "[%s]: ino %lu\n", __func__, inode->i_ino);
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switch (type) {
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case ACL_TYPE_ACCESS:
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xattr_name = XATTR_NAME_POSIX_ACL_ACCESS;
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if (acl) {
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err = posix_acl_update_mode(inode, &inode->i_mode, &acl);
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if (err)
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return err;
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}
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err = 0;
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break;
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case ACL_TYPE_DEFAULT:
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xattr_name = XATTR_NAME_POSIX_ACL_DEFAULT;
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if (!S_ISDIR(inode->i_mode))
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return acl ? -EACCES : 0;
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break;
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default:
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return -EINVAL;
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}
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if (acl) {
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size = posix_acl_xattr_size(acl->a_count);
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if (unlikely(size > HFSPLUS_MAX_INLINE_DATA_SIZE))
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return -ENOMEM;
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value = (char *)hfsplus_alloc_attr_entry();
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if (unlikely(!value))
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return -ENOMEM;
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err = posix_acl_to_xattr(&init_user_ns, acl, value, size);
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if (unlikely(err < 0))
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goto end_set_acl;
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}
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err = __hfsplus_setxattr(inode, xattr_name, value, size, 0);
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end_set_acl:
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hfsplus_destroy_attr_entry((hfsplus_attr_entry *)value);
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if (!err)
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set_cached_acl(inode, type, acl);
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return err;
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}
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int hfsplus_init_posix_acl(struct inode *inode, struct inode *dir)
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{
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int err = 0;
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struct posix_acl *default_acl, *acl;
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hfs_dbg(ACL_MOD,
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"[%s]: ino %lu, dir->ino %lu\n",
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__func__, inode->i_ino, dir->i_ino);
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if (S_ISLNK(inode->i_mode))
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return 0;
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err = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
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if (err)
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return err;
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if (default_acl) {
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err = hfsplus_set_posix_acl(inode, default_acl,
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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 (!err)
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err = hfsplus_set_posix_acl(inode, acl,
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ACL_TYPE_ACCESS);
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posix_acl_release(acl);
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}
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return err;
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}
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