kernel/linux.git/security/integrity/ima, branch v5.10.5

ima: Don't modify file descriptor mode on the fly

2020-12-30T10:54:17+00:00

commit 207cdd565dfc95a0a5185263a567817b7ebf5467 upstream. Commit a408e4a86b36b ("ima: open a new file instance if no read permissions") already introduced a second open to measure a file when the original file descriptor does not allow it. However, it didn't remove the existing method of changing the mode of the original file descriptor, which is still necessary if the current process does not have enough privileges to open a new one. Changing the mode isn't really an option, as the filesystem might need to do preliminary steps to make the read possible. Thus, this patch removes the code and keeps the second open as the only option to measure a file when it is unreadable with the original file descriptor. Cc: # 4.20.x: 0014cc04e8ec0 ima: Set file->f_mode Fixes: 2fe5d6def1672 ("ima: integrity appraisal extension") Signed-off-by: Roberto Sassu Reviewed-by: Christoph Hellwig Signed-off-by: Mimi Zohar Signed-off-by: Greg Kroah-Hartman

ima: Replace zero-length array with flexible-array member

2020-10-29T22:22:59+00:00

There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2]. [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arrays Signed-off-by: Gustavo A. R. Silva

Merge tag 'integrity-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

2020-10-15T22:58:18+00:00

Pull integrity updates from Mimi Zohar: "Continuing IMA policy rule cleanup and validation in particular for measuring keys, adding/removing/updating informational and error messages (e.g. "ima_appraise" boot command line option), and other bug fixes (e.g. minimal data size validation before use, return code and NULL pointer checking)" * tag 'integrity-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity: ima: Fix NULL pointer dereference in ima_file_hash evm: Check size of security.evm before using it ima: Remove semicolon at the end of ima_get_binary_runtime_size() ima: Don't ignore errors from crypto_shash_update() ima: Use kmemdup rather than kmalloc+memcpy integrity: include keyring name for unknown key request ima: limit secure boot feedback scope for appraise integrity: invalid kernel parameters feedback ima: add check for enforced appraise option integrity: Use current_uid() in integrity_audit_message() ima: Fail rule parsing when asymmetric key measurement isn't supportable ima: Pre-parse the list of keyrings in a KEY_CHECK rule

fs/kernel_file_read: Add "offset" arg for partial reads

2020-10-05T11:37:04+00:00

To perform partial reads, callers of kernel_read_file*() must have a non-NULL file_size argument and a preallocated buffer. The new "offset" argument can then be used to seek to specific locations in the file to fill the buffer to, at most, "buf_size" per call. Where possible, the LSM hooks can report whether a full file has been read or not so that the contents can be reasoned about. Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20201002173828.2099543-14-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman

IMA: Add support for file reads without contents

2020-10-05T11:37:04+00:00

When the kernel_read_file LSM hook is called with contents=false, IMA can appraise the file directly, without requiring a filled buffer. When such a buffer is available, though, IMA can continue to use it instead of forcing a double read here. Signed-off-by: Scott Branden Link: https://lore.kernel.org/lkml/20200706232309.12010-10-scott.branden@broadcom.com/ Signed-off-by: Kees Cook Reviewed-by: Mimi Zohar Link: https://lore.kernel.org/r/20201002173828.2099543-13-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman

LSM: Add "contents" flag to kernel_read_file hook

2020-10-05T11:37:03+00:00

As with the kernel_load_data LSM hook, add a "contents" flag to the kernel_read_file LSM hook that indicates whether the LSM can expect a matching call to the kernel_post_read_file LSM hook with the full contents of the file. With the coming addition of partial file read support for kernel_read_file*() API, the LSM will no longer be able to always see the entire contents of a file during the read calls. For cases where the LSM must read examine the complete file contents, it will need to do so on its own every time the kernel_read_file hook is called with contents=false (or reject such cases). Adjust all existing LSMs to retain existing behavior. Signed-off-by: Kees Cook Reviewed-by: Mimi Zohar Link: https://lore.kernel.org/r/20201002173828.2099543-12-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman

firmware_loader: Use security_post_load_data()

2020-10-05T11:37:03+00:00

Now that security_post_load_data() is wired up, use it instead of the NULL file argument style of security_post_read_file(), and update the security_kernel_load_data() call to indicate that a security_kernel_post_load_data() call is expected. Wire up the IMA check to match earlier logic. Perhaps a generalized change to ima_post_load_data() might look something like this: return process_buffer_measurement(buf, size, kernel_load_data_id_str(load_id), read_idmap[load_id] ?: FILE_CHECK, 0, NULL); Signed-off-by: Kees Cook Reviewed-by: Mimi Zohar Link: https://lore.kernel.org/r/20201002173828.2099543-10-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman

LSM: Introduce kernel_post_load_data() hook

2020-10-05T11:37:03+00:00

There are a few places in the kernel where LSMs would like to have visibility into the contents of a kernel buffer that has been loaded or read. While security_kernel_post_read_file() (which includes the buffer) exists as a pairing for security_kernel_read_file(), no such hook exists to pair with security_kernel_load_data(). Earlier proposals for just using security_kernel_post_read_file() with a NULL file argument were rejected (i.e. "file" should always be valid for the security_..._file hooks, but it appears at least one case was left in the kernel during earlier refactoring. (This will be fixed in a subsequent patch.) Since not all cases of security_kernel_load_data() can have a single contiguous buffer made available to the LSM hook (e.g. kexec image segments are separately loaded), there needs to be a way for the LSM to reason about its expectations of the hook coverage. In order to handle this, add a "contents" argument to the "kernel_load_data" hook that indicates if the newly added "kernel_post_load_data" hook will be called with the full contents once loaded. That way, LSMs requiring full contents can choose to unilaterally reject "kernel_load_data" with contents=false (which is effectively the existing hook coverage), but when contents=true they can allow it and later evaluate the "kernel_post_load_data" hook once the buffer is loaded. With this change, LSMs can gain coverage over non-file-backed data loads (e.g. init_module(2) and firmware userspace helper), which will happen in subsequent patches. Additionally prepare IMA to start processing these cases. Signed-off-by: Kees Cook Reviewed-by: KP Singh Link: https://lore.kernel.org/r/20201002173828.2099543-9-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman

fs/kernel_read_file: Add file_size output argument

2020-10-05T11:37:03+00:00

In preparation for adding partial read support, add an optional output argument to kernel_read_file*() that reports the file size so callers can reason more easily about their reading progress. Signed-off-by: Kees Cook Reviewed-by: Mimi Zohar Reviewed-by: Luis Chamberlain Reviewed-by: James Morris Acked-by: Scott Branden Link: https://lore.kernel.org/r/20201002173828.2099543-8-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman

fs/kernel_read_file: Switch buffer size arg to size_t

2020-10-05T11:34:19+00:00

In preparation for further refactoring of kernel_read_file*(), rename the "max_size" argument to the more accurate "buf_size", and correct its type to size_t. Add kerndoc to explain the specifics of how the arguments will be used. Note that with buf_size now size_t, it can no longer be negative (and was never called with a negative value). Adjust callers to use it as a "maximum size" when *buf is NULL. Signed-off-by: Kees Cook Reviewed-by: Mimi Zohar Reviewed-by: Luis Chamberlain Reviewed-by: James Morris Acked-by: Scott Branden Link: https://lore.kernel.org/r/20201002173828.2099543-7-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman