Mark all files used in a standard build of bin-x86_64-efi/snponly.efi
as permitted for UEFI Secure Boot. These files represent the core
functionality of iPXE that is guaranteed to have been included in
every binary that was previously subject to a security review and
signed by Microsoft. It is therefore legitimate to assume that at
least these files have already been reviewed to the required standard
multiple times.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add a fault-injection mechanism that allows an arbitrary delay
(configured via config/fault.h) to be added to any packets transmitted
via the neighbour resolution mechanism, as a way of reproducing
symptoms that occur only on high-latency connections such as a
satellite uplink.
The neighbour discovery mechanism is not a natural conceptual fit for
this artficial delay, since neighbour discovery has nothing to do with
transmit latency. However, the neighbour discovery mechanism happens
to already include a deferred transmission queue that can be (ab)used
to implement this artifical delay in a minimally intrusive way. In
particular, there is zero code size impact on a standard build with no
artificial delay configured.
Implementing the delay only for packets transmitted via neighbour
resolution has the side effect that broadcast packets (such as DHCP
and ARP) are unaffected. This is likely in practice to produce a
better emulation of a high-latency uplink scenario, where local
network traffic such as DHCP and ARP will complete quickly and only
the subsequent TCP/UDP traffic will experience delays.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
On startup, we may be running from read-only memory, and therefore
cannot zero the .bss section (or write to the .data section) until we
have parsed the system memory map and relocated ourselves to somewhere
suitable in RAM. The code that runs during this early initialisation
stage must be carefully written to avoid writing to the .data section
and to avoid reading from or writing to the .bss section.
Detecting code that erroneously writes to the .data or .bss sections
is relatively easy since running from read-only memory (e.g. via
QEMU's -pflash option) will immediately reveal the bug. Detecting
code that erroneously reads from the .bss section is harder, since in
a freshly powered-on machine (or in a virtual machine) there is a high
probability that the contents of the memory will be zero even before
we explicitly zero out the section.
Add the ability to fill the .bss section with an invalid non-zero
value to expose bugs in early initialisation code that erroneously
relies upon variables in .bss before the section has been zeroed. We
use the value 0xeb55eb55eb55eb55 ("EBSS") since this is immediately
recognisable as a value in a crash dump, and will trigger a page fault
if dereferenced since the address is in a non-canonical form.
Poisoning the .bss can be done only when the image is known to already
reside in writable memory. It will overwrite the relocation records,
and so can be done only on a system where relocation is known to be
unnecessary (e.g. because paging is supported). We therefore do not
enable this behaviour by default, but leave it as a configurable
option via the config/fault.h header.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The Google Virtual Ethernet NIC (GVE or gVNIC) is found only in Google
Cloud instances. There is essentially zero documentation available
beyond the mostly uncommented source code in the Linux kernel.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Provide a generic inject_fault() function that can be used to inject
random faults with configurable probabilities.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
