veriexec(4) - NetBSD Manual Pages

VERIEXEC(4)             NetBSD Kernel Interfaces Manual            VERIEXEC(4)


NAME

     veriexec -- Veriexec pseudo-device


SYNOPSIS

     pseudo-device veriexec


DESCRIPTION

     The veriexec pseudo-device is used to interface the kernel's Veriexec
     data-structures.  It is used to size the kernel data structures and load
     the Veriexec fingerprints into kernel memory.

   Veriexec file operations
     All the following operations are invoked using the ioctl(2) system call.
     Refer to that man page for the description of the request and argp param-
     eters.  The following section lists the requests that can be made via
     ioctl(2).

   Veriexec file request descriptions
     VERIEXEC_TABLESIZE struct veriexec_sizing_params
                         Sizes the in kernel hash tables to accommodate the
                         fingerprint entries.  This request must be made prior
                         to loading the fingerprints into the kernel.  The
                         argument structure contains the device to which the
                         hash table relates and the number of fingerprint
                         entries that will be loaded into the kernel for the
                         device.

     VERIEXEC_LOAD struct veriexec_params
                         Inserts a fingerprint into the in-kernel tables.
                         These tables must have been previously sized using
                         the VERIEXEC_TABLESIZE request.  The argument struc-
                         ture is, as defined in
                         /usr/include/sys/verified_exec.h:

                         struct veriexec_params  {
                                 unsigned char type;
                                 unsigned char fp_type[VERIEXEC_TYPE_MAXLEN];
                                 char file[MAXPATHLEN];
                                 unsigned int size;
                                 unsigned char *fingerprint;
                         };

                         Where type is a bitfield that can be binary-OR'd with
                         one or more of:

                         VERIEXEC_DIRECT    Allow execution of the file if
                                            fingerprint matches.

                         VERIEXEC_INDIRECT  Allow execution of the file as a
                                            script interpreter only, direct
                                            command line invocation is disal-
                                            lowed.

                         VERIEXEC_FILE      The file is a plain file, not an
                                            executable.

                         Followed by fp_type, which is the fingerprint type.
                         This is a case-insensitive character string that must
                         match one of the fingerprint types supported by the
                         running kernel.  Next the path to the file to which
                         the fingerprint applies.  The field size is the num-
                         ber of bytes contained in the fingerprint, this is
                         used by the kernel to provide a simple sanity check
                         on the fingerprint passed.  Lastly, the fingerprint
                         is a pointer to an array of characters that comprise
                         the fingerprint for the file.

     Note that the requests VERIEXEC_TABLESIZE and VERIEXEC_LOAD are not per-
     mitted once the veriexec strict level has been raised past 0 by setting
     kern.veriexec.strict using sysctl(8).


SEE ALSO

     sysctl(3), sysctl(8), veriexecctl(8)


NOTES

     The size field in the VERIEXEC_LOAD structure is only used to validate
     that the size of the fingerprint being passed is the expected size for
     that fingerprint hash type; it is not used for any other purpose.  A
     malicious person could deliberately mismatch the size of the fingerprint
     array and, possibly, cause a kernel page fault panic when the kernel
     reads the input fingerprint array memory.  Due to this, it is recommended
     only the root user be allowed to access this device.

NetBSD 3.0                      August 2, 2005                      NetBSD 3.0