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b64fcae74b
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 <keescook@chromium.org> Reviewed-by: KP Singh <kpsingh@google.com> Link: https://lore.kernel.org/r/20201002173828.2099543-9-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
39 lines
852 B
C
39 lines
852 B
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/efi_embedded_fw.h>
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#include <linux/property.h>
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#include <linux/security.h>
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#include <linux/vmalloc.h>
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#include "fallback.h"
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#include "firmware.h"
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int firmware_fallback_platform(struct fw_priv *fw_priv, u32 opt_flags)
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{
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const u8 *data;
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size_t size;
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int rc;
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if (!(opt_flags & FW_OPT_FALLBACK_PLATFORM))
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return -ENOENT;
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rc = security_kernel_load_data(LOADING_FIRMWARE, false);
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if (rc)
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return rc;
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rc = efi_get_embedded_fw(fw_priv->fw_name, &data, &size);
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if (rc)
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return rc; /* rc == -ENOENT when the fw was not found */
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if (fw_priv->data && size > fw_priv->allocated_size)
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return -ENOMEM;
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if (!fw_priv->data)
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fw_priv->data = vmalloc(size);
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if (!fw_priv->data)
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return -ENOMEM;
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memcpy(fw_priv->data, data, size);
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fw_priv->size = size;
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fw_state_done(fw_priv);
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return 0;
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}
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