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authorKees Cook <keescook@chromium.org>2020-10-02 19:38:20 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-10-05 13:37:03 +0200
commitb64fcae74b6d6940d14243c963ab0089e8f0d82d (patch)
tree301791490a1bce0d017a380cc37475510ecee286 /drivers
parentfs/kernel_read_file: Add file_size output argument (diff)
downloadlinux-b64fcae74b6d6940d14243c963ab0089e8f0d82d.tar.xz
linux-b64fcae74b6d6940d14243c963ab0089e8f0d82d.zip
LSM: Introduce kernel_post_load_data() hook
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/base/firmware_loader/fallback.c2
-rw-r--r--drivers/base/firmware_loader/fallback_platform.c2
2 files changed, 2 insertions, 2 deletions
diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
index 283ca2de76d4..bff4717cc6b5 100644
--- a/drivers/base/firmware_loader/fallback.c
+++ b/drivers/base/firmware_loader/fallback.c
@@ -613,7 +613,7 @@ static bool fw_run_sysfs_fallback(u32 opt_flags)
return false;
/* Also permit LSMs and IMA to fail firmware sysfs fallback */
- ret = security_kernel_load_data(LOADING_FIRMWARE);
+ ret = security_kernel_load_data(LOADING_FIRMWARE, false);
if (ret < 0)
return false;
diff --git a/drivers/base/firmware_loader/fallback_platform.c b/drivers/base/firmware_loader/fallback_platform.c
index 6958ab1a8059..a12c79d47efc 100644
--- a/drivers/base/firmware_loader/fallback_platform.c
+++ b/drivers/base/firmware_loader/fallback_platform.c
@@ -17,7 +17,7 @@ int firmware_fallback_platform(struct fw_priv *fw_priv, u32 opt_flags)
if (!(opt_flags & FW_OPT_FALLBACK_PLATFORM))
return -ENOENT;
- rc = security_kernel_load_data(LOADING_FIRMWARE);
+ rc = security_kernel_load_data(LOADING_FIRMWARE, false);
if (rc)
return rc;