For the stage2 of zipl's boot loaders only 3 heap pages are available
[0x6000, 0x6000 + 0x3000]. Therefore, stage2 code needs to be very careful
when and for how long it allocates a heap page.
The heap OOM problem in stage2 was hidden until the commit 252be376
("zipl/boot: fix potential heap overflow in stage2"). Before this commit,
stage2 assumed that heap is 4 pages large which is apparently very wrong
but get_zeroed_page() still allowed allocating an extra 4th page by
overriding the memory segment following the heap area of stage2 (stage3
parameter area).
Try to avoid allocating a heap page and keeping it allocated over a long
period of time in the DASD dumpers. Free a heap page as soon as possible
if not required anymore.
And be extra careful with printf() because it always tries to allocate
a free heap page.
Fixes: 252be376 ("zipl/boot: fix potential heap overflow in stage2")
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Install libasan first, e.g. on Fedora 32:
dnf install -y libasan libasan-static.
To compile with address sanitizer, pass ASAN=1 to make.
AdressSanitizer helps to catch various memory bugs for which C/C++ is
infamous.
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Current heap size in stage2 is three pages long [0x6000-0x9000] but
get_zeroed_page() assumes it is one page more which might lead to
a heap overflow which will corrupt data located at 0x9000 (stage3
parameters). Calculate the heap size of a stage at run-time
by using the symbols provided by linker.
Furthermore, validate the given address in free_page() to stop illegal
memory accesses.
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Prevent access to freed memory still pointed to by entry.
entry still points into load_page that has been released with free_page.
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Commit 86856f98db ("zipl: Make use of __noreturn macro") moved the
'noreturn' attribute from declaration to definition. With this the
compiler can no longer optimize when the function is called in a
separate source file. Move the attribute back to the declaration
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Printing the number zero (e.g. printf("%u", 0)) currently only gives you
an empty string. This is because the while-do loop to map the number to a
string is only entered when the value is 'true', i.e. non-zero. Fix this
by using do-while instead.
Fixes: 6fe9e6c ("zipl/libc: Introduce vsnprintf")
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Reported-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Let's assume the original `command_line` is 'aaaaaaaaaaaaaaaaaa' and
`cextra` is ' =blub'. With the old code this would result in the
following new command line:
'blubaaaaaaaaaaaaa' instead of the expected result 'blub\0aaaaaaaaaaaa'
Let's fix this by setting the NULL-termination for the new command
line. While at it, use the `command_line` variable instead of casting
an address.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
The inserted blank must also be taken into account for the calculation
of `cmdline_len`. In general it's only possible to insert a blank if
the command line length is not already the maximum.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
`src` parameter for `memcpy` is set to `cextra + begin` but the offset
begin is not taken into account for the calculation of the length that
should be copied.
Fix this by increment the cextra pointer for each skipped whitespace
of the extra parameter.
While at it, rename `end` variable to `cmdline_len`, `command_line`
variable to `cmdline`, remove useless void pointer cast, and use
strlen instead of a while loop to determine the cmdline string length.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
1. `begin` is used as array index and should therefore never be greater
than COMMAND_LINE_SIZE - 1. Therefore let's fix the while condition.
2. `length` describes the string length and should therefore also never
be greater than COMMAND_LINE_SIZE - 1.
The 1. off-by-two error can lead to a out-of-bounds read and the 2.
to a buffer overflow.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Use STAGE2_ENTRY and PSW_LOAD instead of hard-coded values. While at
it, also move the libc.h to the top in tape2dump.c.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
While at it, rename PSW_SHORT_ADDR_MASK and PSW_ADDRESS_MASK to
PSW32_ADDR_MASK. As a side effect this removes the zipl.h dependency
of the boot loaders. While at it,
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Use C pre-processor for linker script generation and refactor some
constants. This allows the usage of the constants in our "linker
scripts" `*.lds.S` (actually, these are assembler files, so we can
make us of the C pre-processor and its capabilities).
While at it, enforce the described memory layout in the generated
linker script.
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Move COMMAND_LINE_EXTRA to `boot/loaders_layout.h` so it can be reused
by `menu.c`and `stage3.c`. Additionally, reuse COMMAND_LINE_SIZE from
`linux_layout.h` in `menu.c`.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Introduce a struct definition for the stage3 parameters used by
stage3.c. This makes it easier to maintain the stage3 linker script
and it allows us to consolidate the stage3_params structs defined in
`stage3.h` and `include/boot.h` as well as the stage3 flag macros.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This allows the usage of stage3.h in files where other libc
implementations than our minimal libc is used, e.g. glibc.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
In case secure boot is enabled but no components in the IPL report
are found it ends up in an endless loop in the component verification.
To prevent this check if components are found and exit if not.
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
The lowcore parmblock pointer is not valid in every case. For example
it is invalid for CCW type IPL.
To have an indication if the pointer is valid do a diag308 to store the
parmblock and check if secure boot is enabled.
If it is enabled the lowcore pointer is valid and the ipl report that is
needed for secure boot can be found right behind the ipl parmblock.
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Add a boot loader for protected virtualization (PV) that can be
combined with a kernel/initrd/parmfile to form a single bootable file.
This file must be constructed in a way that it can be used (1) for a
QEMU direct kernel boot and (2) it can be zipl'ed by the normal,
unmodified zipl program.
This new boot loader consists of two parts:
1. stage3a boot loader (cleartext), this loader is responsible for
the transition into the protected mode by doing diag308 subcode 8
and 10 calls.
2. stage3b boot loader (encrypted), this loader is very similar to the
normal zipl stage3 boot loader. It will be loaded by the Ultravisor
after the successful transition into protected mode. Like the zipl
stage3 boot loader it moves the kernel and patches in the values
for initrd and parmline.
The requirements for (1) and (2) result in the following constraints:
1. It must be possible to place stage3a and stage3b at a location >=
0x10000 because the zipl stage3 loader zeroes out everything at
addresses lower than 0x10000 of the image.
2. As the stage3 loader of zipl assumes that the passed kernel image
looks like a normal kernel image, the zipl stage3 loader modifies the
content at the memory area 0x10400 - 0x10800, therefore we leave this
area unused in our stage3a loader.
3. The default entry address used by the zipl stage3 loader is 0x10000
so we add a simple branch to 0x11000 at 0x10000 so the zipl stage3
loader can modify the area 0x10400 - 0x10800 without affecting the
stage3a loader.
The stage3b loader is linked at address 0x9000, therefore it will not
work at another address. The relocation support for the stage3b
loader, so that it can be placed at addresses != 0x9000, is added in
the next patch. This loader with relocation support has the name
'stage3b_reloc'.
The memory layout of the single bootable file looks like:
+-----------------------+-----------+------------------------+
|Start |End |Use |
+=======================+===========+========================+
|0 |0x7 |Short PSW, starting |
| | |instruction at 0x11000 |
+-----------------------+-----------+------------------------+
|0x10000 |0x10012 |Branch to 0x11000 |
+-----------------------+-----------+------------------------+
|0x10013 |0x10fff |Left intentionally |
| | |unused |
+-----------------------+-----------+------------------------+
|0x11000 |0x12fff |Stage3a |
+-----------------------+-----------+------------------------+
|0x13000 |0x13fff |IPIB used as argument |
| | |for the diag308 call |
+-----------------------+-----------+------------------------+
|0x14000 |0x1[45]fff |UV header used for the |
| | |diag308 call (size can |
| | |be either 1 or 2 pages) |
+-----------------------+-----------+------------------------+
|NEXT_PAGE_ALIGNED_ADDR | |Encrypted Kernel |
+-----------------------+-----------+------------------------+
|NEXT_PAGE_ALIGNED_ADDR | |Encrypted Cmdline |
+-----------------------+-----------+------------------------+
|NEXT_PAGE_ALIGNED_ADDR | |Encrypted Initrd |
+-----------------------+-----------+------------------------+
|NEXT_PAGE_ALIGNED_ADDR | |Encrypted Stage3b_reloc |
+-----------------------+-----------+------------------------+
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Add `sclp_print_ascii` function that can be used to print output on
the SCLP ASCII console. This would increase the size of the
loaders (e.g. eckd2.bin and fba2.bin) and therefore might break the
compilation. In order to avoid that add a macro 'ENABLE_SCLP_ASCII'
which must be defined by the users of the `sclp_print_ascii` function.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This allows the reuse of the code later in sclp.c. While at it, also
declare @source parameter of `ebcdic_to_ascii` function as `const` and
rename all `ebc_` function name prefixes into `ebcdic_`. Move
conversion tables to separate file so it only gets linked into loaders
that need it.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Now that we made sure that s390.h can be used with our minimal libc
implementation and glibc move s390.h to `include/boot/s390.h`. While
at it, make sure that s390.h is assembler compatible as it will be
used later in the PV boot loader and include s390.h in ipl.h as
PAGE_SIZE is used there.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This allows the use of s390.h in combination with other libc
implementations than our minimal libc, e.g. with glibc.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Rename `inline` macro into `__always_inline` so one can differentiate
between the macro and the C keyword. While at it, undefine the
previous `__always_inline` macro so s390.h can be used in combination
with glibc.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Use the constants defined in `linux_layout.h`. Therefore move the
`PARMAREA` address offset to `linux_layout.h` and include the header.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Move the Linux layout values to `include/boot/linux_layout.h`. This
allows the reuse of the definitions, e.g. in assembler files, and
later for the creation of linker scripts.
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Make `IPL_DEVICE` definition consistent with the kernel definition and
the definition in tape0.S. This allows us to refactor the code later.
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Move the IPL related definitions into `include/boot/ipl.h`. This
allows the reuse of the definitions, e.g. in the boot loader for
protected guests.
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
The use of sprintf can easily result in buffer overflows as it assumes
that the buffer it writes to is large enough to contain the formatted
string. Thus replace sprintf by snprintf and update its users.
This removes the last user of vsprintf. Thus also remove vsprintf and
its dependencies.
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Per definition vsprint assumes that the provided buffer it writes to is
large enough to contain the formatted string. As printf uses a fixed
sized buffer (81 bytes) and has no size checks the use of vsprintf can
easily cause buffer overflows. Protect against these buffer overflows by
using vsnprintf instead.
While at it fix a typo in the comment.
Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
The zipl boot loaders have their own minimalistic libc implementation.
In it printf and sprintf use vsprintf for string formatting. Per
definition vsprintf assumes that the buffer it writes to is large enough
to contain the formatted string and performs no size checks. This is
problematic for the boot loaders because the buffer they use are often
allocated on the stack. Thus even small changes to the string format can
potentially cause buffer overflows on the stack with the well known
consequences. Protect against such errors by implementing vsnprintf.
Later patches will make use of it.
This implementation of vsnprintf only supports a small subset of format
options defined in the C standard. In particular it allows the
specifiers:
* %s (strings)
* %o (unsigned int octal)
* %u (unsigned int decimal)
* %x (unsigned int hexadecimal)
Integer specifiers (o, u, and x) always use the long form, i.e. assume the
argument to be of type 'unsigned long int'. The length modified 'l' can
be given but is ignored.
Furthermore, it is possible to provide the optional field width (aligned
to the right only) and precision as decimal integer (i.e. not via '*')
as well as the flag for zero padding integers (i.e. '0').
The implementation was heavily inspired by the implementation in
lib/vsprintf.c from the Linux kernel tree.
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
