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authorKees Cook <keescook@chromium.org>2020-10-02 10:38:20 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-10-05 13:37:03 +0200
commitb64fcae74b6d6940d14243c963ab0089e8f0d82d (patch)
tree301791490a1bce0d017a380cc37475510ecee286 /kernel/kexec.c
parent885352881f11f1f3113d8eb877786bcb6d720544 (diff)
downloadlinux-b64fcae74b6d6940d14243c963ab0089e8f0d82d.tar.bz2
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 'kernel/kexec.c')
-rw-r--r--kernel/kexec.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/kexec.c b/kernel/kexec.c
index f977786fe498..c82c6c06f051 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -205,7 +205,7 @@ static inline int kexec_load_check(unsigned long nr_segments,
return -EPERM;
/* Permit LSMs and IMA to fail the kexec */
- result = security_kernel_load_data(LOADING_KEXEC_IMAGE);
+ result = security_kernel_load_data(LOADING_KEXEC_IMAGE, false);
if (result < 0)
return result;