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author | Kees Cook <keescook@chromium.org> | 2020-10-02 19:38:20 +0200 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-10-05 13:37:03 +0200 |
commit | b64fcae74b6d6940d14243c963ab0089e8f0d82d (patch) | |
tree | 301791490a1bce0d017a380cc37475510ecee286 /kernel/kexec.c | |
parent | fs/kernel_read_file: Add file_size output argument (diff) | |
download | linux-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 'kernel/kexec.c')
-rw-r--r-- | kernel/kexec.c | 2 |
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; |