Otherwise a subsequent header could change the height and width
allowing future OOB writes.
Fixes: CVE-2024-45774
Reported-by: Nils Langius <nils@langius.de>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
An overly long filename can be passed to tftp_open() which would cause
grub_normalize_filename() to write out of bounds.
Fixed by adding an extra argument to grub_normalize_filename() for the
space available, making it act closer to a strlcpy(). As several fixed
strings are strcpy()'d after into the same buffer, their total length is
checked to see if they exceed the remaining space in the buffer. If so,
return an error.
On the occasion simplify code a bit by removing unneeded rrqlen zeroing.
Reported-by: B Horn <b@horn.uk>
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The function included a call to grub_strcpy() which copied data from an
environment variable to a buffer allocated in grub_cmd_normal(). The
grub_cmd_normal() didn't consider the length of the environment variable.
So, the copy operation could exceed the allocation and lead to an OOB
write. Fix the issue by replacing grub_strcpy() with grub_strlcpy() and
pass the underlying buffers size to the grub_net_search_config_file().
Fixes: CVE-2025-0624
Reported-by: B Horn <b@horn.uk>
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The grub_net_network_level_interface_unregister(), previously
implemented in a header, did not remove the variables hooks that
were registered in grub_net_network_level_interface_register().
Fix this by implementing the same logic used to register the
variables and move the function into the grub-core/net/net.c.
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The net module is a dependency of normal. So, it shouldn't be possible
to unload the net. Though unregister variables hooks as a precaution.
It also gets in line with unregistering the other net module hooks.
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
If unbounded recursion is allowed it becomes possible to collide the
stack with the heap. As UEFI firmware often lacks guard pages this
becomes an exploitable issue as it is possible in some cases to do
a controlled overwrite of a section of this heap region with
arbitrary data.
Reported-by: B Horn <b@horn.uk>
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The part_iterate() is used by grub_partition_iterate() as a callback in
the partition iterate functions. However, part_iterate() may also call
the partition iterate functions which may lead to recursion. Fix potential
issue by limiting the recursion depth.
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The grub_disk_read() may trigger other disk reads, e.g. via loopbacks.
This may lead to very deep recursion which can corrupt the heap. So, fix
the issue by limiting reads depth.
Reported-by: B Horn <b@horn.uk>
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
It was possible to delete a loopback while there were still references
to it. This led to an exploitable use-after-free.
Fixed by implementing a reference counting in the grub_loopback struct.
Reported-by: B Horn <b@horn.uk>
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The GRUB may use TPM to verify the integrity of boot components and the
result can determine whether a previously sealed key can be released. If
everything checks out, showing nothing has been tampered with, the key
is released and GRUB unlocks the encrypted root partition for the next
stage of booting.
However, the liberal Command Line Interface (CLI) can be misused by
anyone in this case to access files in the encrypted partition one way
or another. Despite efforts to keep the CLI secure by preventing utility
command output from leaking file content, many techniques in the wild
could still be used to exploit the CLI, enabling attacks or learning
methods to attack. It's nearly impossible to account for all scenarios
where a hack could be applied.
Therefore, to mitigate potential misuse of the CLI after the root device
has been successfully unlocked via TPM, the user should be required to
authenticate using the LUKS password. This added layer of security
ensures that only authorized users can access the CLI reducing the risk
of exploitation or unauthorized access to the encrypted partition.
Fixes: CVE-2024-49504
Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The grub_file_open() and grub_file_close() should be the only places
that allow a reference to a filesystem to stay open. So, add grub_dl_t
to grub_fs_t and set this in the GRUB_MOD_INIT() for each filesystem to
avoid issues when filesystems forget to do it themselves or do not track
their own references, e.g. squash4.
The fs_label(), fs_uuid(), fs_mtime() and fs_read() should all ref and
unref in the same function but it is essentially redundant in GRUB
single threaded model.
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This is to avoid a generic issue were some filesystems would not set
data and also not set a grub_errno. This meant it was possible for many
filesystems to grub_dl_unref() themselves multiple times resulting in
it being possible to unload the filesystems while there were still
references to them, e.g., via a loopback.
Reported-by: B Horn <b@horn.uk>
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
It was previously possible for grub_xfs_mount() to return NULL without
setting grub_errno if the XFS version was invalid. This resulted in it
being possible for grub_dl_unref() to be called twice allowing the XFS
module to be unloaded while there were still references to it.
Fixing this problem in general by ensuring a grub_errno is set if the
fail label is reached.
Reported-by: B Horn <b@horn.uk>
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The number of records in the root key array read from disk was not being
validated against the size of the root node. This could lead to an
out-of-bounds read.
This patch adds a check to ensure that the number of records in the root
key array does not exceed the expected size of a root node read from
disk. If this check detects an out-of-bounds condition the operation is
aborted to prevent random errors due to metadata corruption.
Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
It was possible to read OOB when an attribute had a size that exceeded
the allocated buffer. This resolves that by making sure all attributes
that get read are fully in the allocated space by implementing
a function to validate them.
Defining the offsets in include/grub/ntfs.h but they are only used in
the validation function and not across the rest of the NTFS code.
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Right now to access the next attribute the code reads the length of the
current attribute and adds that to the current pointer. This is error
prone as bounds checking needs to be performed all over the place. So,
implement a helper and ensure its used across find_attr() and read_attr().
This commit does *not* implement full bounds checking. It is just the
preparation work for this to be added into the helper.
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The end of the attribute buffer should be stored alongside the rest of
the attribute struct as right now it is not possible to implement bounds
checking when accessing attributes sequentially.
This is done via:
- updating init_attr() to set at->end and check is is not initially out of bounds,
- implementing checks as init_attr() had its type change in its callers,
- updating the value of at->end when needed.
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
When parsing NTFS file records the presence of the 0xFF marker indicates
the end of the attribute list. This value signifies that there are no
more attributes to process.
However, when the end marker is missing due to corrupted metadata the
loop continues to read beyond the attribute list resulting in out-of-bounds
reads and potentially entering an infinite loop.
This patch adds a check to provide a stop condition for the loop ensuring
it stops at the end of the attribute list or at the end of the Master File
Table. This guards against out-of-bounds reads and prevents infinite loops.
Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
When inline extents are used, i.e. the extent tree depth equals zero,
a maximum of four entries can fit into the inode's data block. If the
extent header states a number of entries greater than four the current
ext2 implementation causes an out-of-bounds read. Fix this issue by
capping the number of extents to four when reading inline extents.
Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The getblk() returns a value of type grub_int64_t which is assigned to
iagblk and inoblk, both of type grub_uint64_t, in grub_jfs_read_inode()
via grub_jfs_blkno(). This patch fixes the type mismatch in the
functions. Additionally, the getblk() will return 0 instead of -1 on
failure cases. This change is safe because grub_errno is always set in
getblk() to indicate errors and it is later checked in the callers.
Signed-off-by: Lidong Chen <lidong.chen@oracle.com>
Reviewed-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Ross Philipson <ross.philipson@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
An extent's logical offset and address are represented as a 40-bit value
split into two parts: the most significant 8 bits and the least
significant 32 bits. Currently the JFS code uses only the least
significant 32 bits value for offsets and addresses assuming the data
size will never exceed the 32-bit range. This approach ignores the most
significant 8 bits potentially leading to incorrect offsets and
addresses for larger values. The patch fixes it by incorporating the
most significant 8 bits into the calculation to get the full 40-bits
value for offsets and addresses.
https://jfs.sourceforge.net/project/pub/jfslayout.pdf
"off1,off2 is a 40-bit field, containing the logical offset of the first
block in the extent.
...
addr1,addr2 is a 40-bit field, containing the address of the extent."
Signed-off-by: Lidong Chen <lidong.chen@oracle.com>
Reviewed-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Ross Philipson <ross.philipson@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
While fuzz testing JFS with ASAN enabled an OOB read was detected in
grub_jfs_opendir(). The issue occurred due to an invalid directory slot
index in the first entry of the sorted directory slot array in the inode
directory header. The fix ensures the slot index is validated before
accessing it. Given that an internal or a leaf node in a directory B+
tree is a 4 KiB in size and each directory slot is always 32 bytes, the
max number of slots in a node is 128. The validation ensures that the
slot index doesn't exceed this limit.
[1] https://jfs.sourceforge.net/project/pub/jfslayout.pdf
JFS will allocate 4K of disk space for an internal node of the B+ tree.
An internal node looks the same as a leaf node.
- page 10
Fixed number of Directory Slots depending on the size of the node. These are
the slots to be used for storing the directory slot array and the directory
entries or router entries. A directory slot is always 32 bytes.
...
A Directory Slot Array which is a sorted array of indices to the directory
slots that are currently in use.
...
An internal or a leaf node in the directory B+ tree is a 4K page.
- page 25
Signed-off-by: Lidong Chen <lidong.chen@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Alec Brown <alec.r.brown@oracle.com>
The JFS fuzzing revealed an OOB read in grub_jfs_getent(). The crash
was caused by an invalid leaf nodes count, diro->dirpage->header.count,
which was larger than the maximum number of leaf nodes allowed in an
inode. This fix is to ensure that the leaf nodes count is validated in
grub_jfs_opendir() before calling grub_jfs_getent().
On the occasion replace existing raw numbers with newly defined constant.
Signed-off-by: Lidong Chen <lidong.chen@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Alec Brown <alec.r.brown@oracle.com>
The ctx->filename can point to either a string literal or a dynamically
allocated string. The ctx->filename_alloc field is used to indicate the
type of allocation.
An issue has been identified where ctx->filename is reassigned to
a string literal in susp_iterate_dir() but ctx->filename_alloc is not
correctly handled. This oversight causes a memory leak and an invalid
free operation later.
The fix involves checking ctx->filename_alloc, freeing the allocated
string if necessary and clearing ctx->filename_alloc for string literals.
Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
It was possible for a grub_errno to not be set if mount of an ISO 9660
filesystem failed when set_rockridge() returned 0.
This isn't known to be exploitable as the other filesystems due to
filesystem helper checking the requested file type. Though fixing
as a precaution.
Reported-by: B Horn <b@horn.uk>
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
It was possible for mount to fail but not set grub_errno. This led to
a possible double decrement of the module reference count if the NULL
page was mapped.
Fixing in general as a similar bug was fixed in commit 61b13c187
(fs/hfsplus: Set grub_errno to prevent NULL pointer access) and there
are likely more variants around.
Fixes: CVE-2024-45783
Reported-by: B Horn <b@horn.uk>
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
It was previously possible for grub_errno to not be set when
grub_f2fs_mount() failed if nat_bitmap_ptr() returned NULL.
This issue is solved by ensuring a grub_errno is set in the fail case.
Reported-by: B Horn <b@horn.uk>
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Both namesize and linksize are derived from hd.size, a 12-digit octal
number parsed by read_number(). Later direct arithmetic calculation like
"namesize + 1" and "linksize + 1" may exceed the maximum value of
grub_size_t leading to heap OOB write. This patch fixes the issue by
using grub_add() and checking for an overflow.
Fixes: CVE-2024-45780
Reported-by: Nils Langius <nils@langius.de>
Signed-off-by: Lidong Chen <lidong.chen@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Alec Brown <alec.r.brown@oracle.com>
It was possible to iterate through grub_cpio_find_file() without
allocating name and not setting mode to GRUB_ARCHELP_ATTR_END, which
would cause the uninitialized value for name to be used as an argument
for canonicalize() in grub_archelp_dir().
Reported-by: B Horn <b@horn.uk>
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
grub_strcpy() was used to copy a symlink name from the filesystem
image to a heap allocated buffer. This led to a OOB write to adjacent
heap allocations. Fix by using grub_strlcpy().
Fixes: CVE-2024-45781
Reported-by: B Horn <b@horn.uk>
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
grub_strlcpy() acts the same way as strlcpy() does on most *NIX,
returning the length of src and ensuring dest is always NUL
terminated except when size is 0.
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Follow recent extensions of EFI support providing a TCG2 driver with
a public API for getting the maximum TPM command size and passing a TPM
command through to the TPM 2. Implement this functionality using ieee1275
PowerPC firmware API calls. Move tcg2.c into the TCG2 driver.
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Move tpm_get_tpm_version() into grub_ieee1275_tpm_init() and invalidate
grub_ieee1275_tpm_ihandle in case no TPM 2 could be detected. Try the
initialization only once so that grub_tpm_present() will always return
the same result. Use the grub_ieee1275_tpm_ihandle as indicator for an
available TPM instead of grub_ieee1275_tpm_version, which can now be
removed.
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Move common initialization functions from the ibmvtpm driver module into
tcg2.c that will be moved into the new TCG2 driver in a subsequent patch.
Make the functions available to the ibmvtpm driver as public functions
and variables.
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Consolidate repeated definitions of IEEE1275_IHANDLE_INVALID that are cast
to the type grub_ieee1275_ihandle_t. On the occasion add "GRUB_" prefix to
the constant name.
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Cast 0 to proper type grub_ieee1275_ihandle_t. This type is
used for struct grub_serial_port's handle that assigns or
compares with IEEE1275_IHANDLE_INVALID.
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The TPM bit fields need to be in reverse order for big endian targets,
such as ieee1275 PowerPC platforms that run GRUB in big endian mode.
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Gary Lin <glin@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Update the user manual to address TPM2 key protector including the two
related commands, tpm2_key_protector_init and tpm2_key_protector_clear,
and the user-space utility: grub-protect.
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
For the tpm2_key_protector module, the TCG2 command submission function
is the only difference between a QEMU instance and grub-emu. To test
TPM2 key unsealing with a QEMU instance, it requires an extra OS image
to invoke grub-protect to seal the LUKS key, rather than a simple
grub-shell rescue CD image. On the other hand, grub-emu can share the
emulated TPM2 device with the host, so that we can seal the LUKS key on
host and test key unsealing with grub-emu.
This test script firstly creates a simple LUKS image to be loaded as a
loopback device in grub-emu. Then an emulated TPM2 device is created by
"swtpm chardev" and PCR 0 and 1 are extended.
There are several test cases in the script to test various settings. Each
test case uses grub-protect or tpm2-tools to seal the LUKS password
with PCR 0 and PCR 1. Then grub-emu is launched to load the LUKS image,
try to mount the image with tpm2_key_protector_init and cryptomount, and
verify the result.
Based on the idea from Michael Chang.
Cc: Michael Chang <mchang@suse.com>
Cc: Stefan Berger <stefanb@linux.ibm.com>
Cc: Glenn Washburn <development@efficientek.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
As a preparation to test tpm2_key_protector with grub-emu, the new
option, --tpm-device, is introduced to specify the TPM device for
grub-emu so that grub-emu can access an emulated TPM device from
the host.
Since grub-emu can directly access the device on host, it's easy to
implement the essential TCG2 command submission function with the
read/write functions and enable tpm2_key_protector module for grub-emu,
so that we can further test TPM2 key unsealing with grub-emu.
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
When using disk auto-unlocking with TPM 2.0, the typical grub.cfg may
look like this:
tpm2_key_protector_init --tpm2key=(hd0,gpt1)/boot/grub/sealed.tpm
cryptomount -u <PART-UUID> -P tpm2
search --fs-uuid --set=root <FS-UUID>
Since the disk search order is based on the order of module loading, the
attacker could insert a malicious disk with the same FS-UUID root to
trick GRUB to boot into the malicious root and further dump memory to
steal the unsealed key.
Do defend against such an attack, we can specify the hint provided by
"grub-probe" to search the encrypted partition first:
search --fs-uuid --set=root --hint='cryptouuid/<PART-UUID>' <FS-UUID>
However, for LVM on an encrypted partition, the search hint provided by
"grub-probe" is:
--hint='lvmid/<VG-UUID>/<LV-UUID>'
It doesn't guarantee to look up the logical volume from the encrypted
partition, so the attacker may have the chance to fool GRUB to boot
into the malicious disk.
To minimize the attack surface, this commit tweaks the disk device search
in diskfilter to look up cryptodisk devices first and then others, so
that the auto-unlocked disk will be found first, not the attacker's disk.
Cc: Fabian Vogt <fvogt@suse.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
An attacker may insert a malicious disk with the same crypto UUID and
trick GRUB to mount the fake root. Even though the key from the key
protector fails to unlock the fake root, it's not wiped out cleanly so
the attacker could dump the memory to retrieve the secret key. To defend
such attack, wipe out the cached key when we don't need it.
Cc: Fabian Vogt <fvogt@suse.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
If a protector is specified, but it fails to unlock the disk, fall back
to asking for the passphrase.
Before requesting the passphrase, the error from the key protector(s)
has to be cleared, or the later code, e.g., LUKS code, may stop as
grub_errno is set. This commit prints error from the key protector(s)
and sets grub_errno to GRUB_ERR_NONE to have a fresh start.
Signed-off-by: Patrick Colp <patrick.colp@oracle.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
Currently with the TPM2 protector, only SRK mode is supported and
NV index support is just a stub. Implement the NV index option.
Note: This only extends support on the unseal path. grub-protect
has not been updated. tpm2-tools can be used to insert a key into
the NV index.
An example of inserting a key using tpm2-tools:
# Get random key.
tpm2_getrandom 32 > key.dat
# Create primary object.
tpm2_createprimary -C o -g sha256 -G ecc -c primary.ctx
# Create policy object. `pcrs.dat` contains the PCR values to seal against.
tpm2_startauthsession -S session.dat
tpm2_policypcr -S session.dat -l sha256:7,11 -f pcrs.dat -L policy.dat
tpm2_flushcontext session.dat
# Seal key into TPM.
cat key.dat | tpm2_create -C primary.ctx -u key.pub -r key.priv -L policy.dat -i-
tpm2_load -C primary.ctx -u key.pub -r key.priv -n sealing.name -c sealing.ctx
tpm2_evictcontrol -C o -c sealing.ctx 0x81000000
Then to unseal the key in GRUB, add this to grub.cfg:
tpm2_key_protector_init --mode=nv --nvindex=0x81000000 --pcrs=7,11
cryptomount -u <UUID> --protector tpm2
Signed-off-by: Patrick Colp <patrick.colp@oracle.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
This commit handles the TPM2_PolicyAuthorize command from the key file
in TPM 2.0 Key File format.
TPM2_PolicyAuthorize is the essential command to support authorized
policy which allows the users to sign TPM policies with their own keys.
Per TPM 2.0 Key File [1], CommandPolicy for TPM2_PolicyAuthorize
comprises "TPM2B_PUBLIC pubkey", "TPM2B_DIGEST policy_ref", and
"TPMT_SIGNATURE signature". To verify the signature, the current policy
digest is hashed with the hash algorithm written in "signature", and then
"signature" is verified with the hashed policy digest and "pubkey". Once
TPM accepts "signature", TPM2_PolicyAuthorize is invoked to authorize the
signed policy.
To create the key file with authorized policy, here are the pcr-oracle [2]
commands:
# Generate the RSA key and create the authorized policy file
$ pcr-oracle \
--rsa-generate-key \
--private-key policy-key.pem \
--auth authorized.policy \
create-authorized-policy 0,2,4,7,9
# Seal the secret with the authorized policy
$ pcr-oracle \
--key-format tpm2.0 \
--auth authorized.policy \
--input disk-secret.txt \
--output sealed.key \
seal-secret
# Sign the predicted PCR policy
$ pcr-oracle \
--key-format tpm2.0 \
--private-key policy-key.pem \
--from eventlog \
--stop-event "grub-file=grub.cfg" \
--after \
--input sealed.key \
--output /boot/efi/efi/grub/sealed.tpm \
sign 0,2,4,7,9
Then specify the key file and the key protector to grub.cfg in the EFI
system partition:
tpm2_key_protector_init -a RSA --tpm2key=(hd0,gpt1)/efi/grub/sealed.tpm
cryptomount -u <PART_UUID> -P tpm2
For any change in the boot components, just run the "sign" command again
to update the signature in sealed.tpm, and TPM can unseal the key file
with the updated PCR policy.
[1] https://www.hansenpartnership.com/draft-bottomley-tpm2-keys.html
[2] https://github.com/okirch/pcr-oracle
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
To utilize the key protectors framework, there must be a way to protect
full-disk encryption keys in the first place. The grub-protect tool
includes support for the TPM2 key protector but other protectors that
require setup ahead of time can be supported in the future.
For the TPM2 key protector, the intended flow is for a user to have
a LUKS 1 or LUKS 2-protected fully-encrypted disk. The user then creates
a new LUKS key file, say by reading /dev/urandom into a file, and creates
a new LUKS key slot for this key. Then, the user invokes the grub-protect
tool to seal this key file to a set of PCRs using the system's TPM 2.0.
The resulting sealed key file is stored in an unencrypted partition such
as the EFI System Partition (ESP) so that GRUB may read it. The user also
has to ensure the cryptomount command is included in GRUB's boot script
and that it carries the requisite key protector (-P) parameter.
Sample usage:
$ dd if=/dev/urandom of=luks-key bs=1 count=32
$ sudo cryptsetup luksAddKey /dev/sdb1 luks-key --pbkdf=pbkdf2 --hash=sha512
To seal the key with TPM 2.0 Key File (recommended):
$ sudo grub-protect --action=add \
--protector=tpm2 \
--tpm2-pcrs=0,2,4,7,9 \
--tpm2key \
--tpm2-keyfile=luks-key \
--tpm2-outfile=/boot/efi/efi/grub/sealed.tpm
Or, to seal the key with the raw sealed key:
$ sudo grub-protect --action=add \
--protector=tpm2 \
--tpm2-pcrs=0,2,4,7,9 \
--tpm2-keyfile=luks-key \
--tpm2-outfile=/boot/efi/efi/grub/sealed.key
Then, in the boot script, for TPM 2.0 Key File:
tpm2_key_protector_init --tpm2key=(hd0,gpt1)/efi/grub/sealed.tpm
cryptomount -u <SDB1_UUID> -P tpm2
Or, for the raw sealed key:
tpm2_key_protector_init --keyfile=(hd0,gpt1)/efi/grub/sealed.key --pcrs=0,2,4,7,9
cryptomount -u <SDB1_UUID> -P tpm2
The benefit of using TPM 2.0 Key File is that the PCR set is already
written in the key file, so there is no need to specify PCRs when
invoking tpm2_key_protector_init.
Signed-off-by: Hernan Gatta <hegatta@linux.microsoft.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
Add a new parameter to cryptomount to support the key protectors framework: -P.
The parameter is used to automatically retrieve a key from specified key
protectors. The parameter may be repeated to specify any number of key
protectors. These are tried in order until one provides a usable key for any
given disk.
Signed-off-by: Hernan Gatta <hegatta@linux.microsoft.com>
Signed-off-by: Michael Chang <mchang@suse.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
The TPM2 key protector is a module that enables the automatic retrieval
of a fully-encrypted disk's unlocking key from a TPM 2.0.
The theory of operation is such that the module accepts various
arguments, most of which are optional and therefore possess reasonable
defaults. One of these arguments is the keyfile/tpm2key parameter, which
is mandatory. There are two supported key formats:
1. Raw Sealed Key (--keyfile)
When sealing a key with TPM2_Create, the public portion of the sealed
key is stored in TPM2B_PUBLIC, and the private portion is in
TPM2B_PRIVATE. The raw sealed key glues the fully marshalled
TPM2B_PUBLIC and TPM2B_PRIVATE into one file.
2. TPM 2.0 Key (--tpm2key)
The following is the ASN.1 definition of TPM 2.0 Key File:
TPMPolicy ::= SEQUENCE {
CommandCode [0] EXPLICIT INTEGER
CommandPolicy [1] EXPLICIT OCTET STRING
}
TPMAuthPolicy ::= SEQUENCE {
Name [0] EXPLICIT UTF8STRING OPTIONAL
Policy [1] EXPLICIT SEQUENCE OF TPMPolicy
}
TPMKey ::= SEQUENCE {
type OBJECT IDENTIFIER
emptyAuth [0] EXPLICIT BOOLEAN OPTIONAL
policy [1] EXPLICIT SEQUENCE OF TPMPolicy OPTIONAL
secret [2] EXPLICIT OCTET STRING OPTIONAL
authPolicy [3] EXPLICIT SEQUENCE OF TPMAuthPolicy OPTIONAL
description [4] EXPLICIT UTF8String OPTIONAL,
rsaParent [5] EXPLICIT BOOLEAN OPTIONAL,
parent INTEGER
pubkey OCTET STRING
privkey OCTET STRING
}
The TPM2 key protector only expects a "sealed" key in DER encoding,
so "type" is always 2.23.133.10.1.5, "emptyAuth" is "TRUE", and
"secret" is empty. "policy" and "authPolicy" are the possible policy
command sequences to construct the policy digest to unseal the key.
Similar to the raw sealed key, the public portion (TPM2B_PUBLIC) of
the sealed key is stored in "pubkey", and the private portion
(TPM2B_PRIVATE) is in "privkey".
For more details: https://www.hansenpartnership.com/draft-bottomley-tpm2-keys.html
This sealed key file is created via the grub-protect tool. The tool
utilizes the TPM's sealing functionality to seal (i.e., encrypt) an
unlocking key using a Storage Root Key (SRK) to the values of various
Platform Configuration Registers (PCRs). These PCRs reflect the state
of the system as it boots. If the values are as expected, the system
may be considered trustworthy, at which point the TPM allows for a
caller to utilize the private component of the SRK to unseal (i.e.,
decrypt) the sealed key file. The caller, in this case, is this key
protector.
The TPM2 key protector registers two commands:
- tpm2_key_protector_init: Initializes the state of the TPM2 key
protector for later usage, clearing any
previous state, too, if any.
- tpm2_key_protector_clear: Clears any state set by tpm2_key_protector_init.
The way this is expected to be used requires the user to, either
interactively or, normally, via a boot script, initialize/configure
the key protector and then specify that it be used by the "cryptomount"
command (modifications to this command are in a different patch).
For instance, to unseal the raw sealed key file:
tpm2_key_protector_init --keyfile=(hd0,gpt1)/efi/grub/sealed-1.key
cryptomount -u <PART1_UUID> -P tpm2
tpm2_key_protector_init --keyfile=(hd0,gpt1)/efi/grub/sealed-2.key --pcrs=7,11
cryptomount -u <PART2_UUID> -P tpm2
Or, to unseal the TPM 2.0 Key file:
tpm2_key_protector_init --tpm2key=(hd0,gpt1)/efi/grub/sealed-1.tpm
cryptomount -u <PART1_UUID> -P tpm2
tpm2_key_protector_init --tpm2key=(hd0,gpt1)/efi/grub/sealed-2.tpm --pcrs=7,11
cryptomount -u <PART2_UUID> -P tpm2
If a user does not initialize the key protector and attempts to use it
anyway, the protector returns an error.
Before unsealing the key, the TPM2 key protector follows the "TPMPolicy"
sequences to enforce the TPM policy commands to construct a valid policy
digest to unseal the key.
For the TPM 2.0 Key files, "authPolicy" may contain multiple "TPMPolicy"
sequences, the TPM2 key protector iterates "authPolicy" to find a valid
sequence to unseal key. If "authPolicy" is empty or all sequences in
"authPolicy" fail, the protector tries the one from "policy". In case
"policy" is also empty, the protector creates a "TPMPolicy" sequence
based on the given PCR selection.
For the raw sealed key, the TPM2 key protector treats the key file as a
TPM 2.0 Key file without "authPolicy" and "policy", so the "TPMPolicy"
sequence is always based on the PCR selection from the command
parameters.
This commit only supports one policy command: TPM2_PolicyPCR. The
command set will be extended to support advanced features, such as
authorized policy, in the later commits.
Cc: James Bottomley <jejb@linux.ibm.com>
Signed-off-by: Hernan Gatta <hegatta@linux.microsoft.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
