On 2/14/24 10:38, Tushar Sugandhi wrote:
ima_dump_measurement_list() is called during kexec 'load', which may
result in loss of IMA measurements during kexec soft reboot. It needs
to be called during kexec 'execute'.
This patch includes the following changes:
- Call kimage_file_post_load() from kexec_file_load() syscall only for
kexec soft reboot scenarios and not for KEXEC_FILE_ON_CRASH. It will
map the IMA segment, and register reboot notifier for the function
ima_update_kexec_buffer() which would copy the IMA log at kexec soft
reboot.
- Make kexec_segment_size variable local static to the file, for it to be
accessible both during kexec 'load' and 'execute'.
- Move ima_dump_measurement_list() call from ima_add_kexec_buffer()
to ima_update_kexec_buffer().
- Remove ima_reset_kexec_file() call from ima_add_kexec_buffer(), now
that the buffer is being copied at kexec 'execute', and resetting the
file at kexec 'load' will corrupt the buffer.
Signed-off-by: Tushar Sugandhi <tusharsu@xxxxxxxxxxxxxxxxxxx>
---
kernel/kexec_file.c | 3 ++
security/integrity/ima/ima_kexec.c | 45 +++++++++++++++++++-----------
2 files changed, 32 insertions(+), 16 deletions(-)
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index fe59cb7c179d..2d5df320c34f 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -410,6 +410,9 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
kimage_terminate(image);
+ if (!(flags & KEXEC_FILE_ON_CRASH))
+ kimage_file_post_load(image);
+
ret = machine_kexec_post_load(image);
if (ret)
goto out;
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 1d4d6c122d82..98fc9b9782a2 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -19,6 +19,7 @@
#ifdef CONFIG_IMA_KEXEC
static struct seq_file ima_kexec_file;
static void *ima_kexec_buffer;
+static size_t kexec_segment_size;
static bool ima_kexec_update_registered;
static void ima_reset_kexec_file(struct seq_file *sf)
@@ -129,7 +130,6 @@ void ima_add_kexec_buffer(struct kimage *image)
/* use more understandable variable names than defined in kbuf */
void *kexec_buffer = NULL;
size_t kexec_buffer_size;
- size_t kexec_segment_size;
int ret;
/*
@@ -154,14 +154,6 @@ void ima_add_kexec_buffer(struct kimage *image)
return;
}
- ret = ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
- kexec_segment_size);
- if (ret < 0) {
- pr_err("%s: Failed to dump IMA measurements. Error:%d.\n",
- __func__, ret);
- return;
- }
-
kbuf.buffer = kexec_buffer;
kbuf.bufsz = kexec_buffer_size;
kbuf.memsz = kexec_segment_size;
@@ -179,12 +171,6 @@ void ima_add_kexec_buffer(struct kimage *image)
image->ima_segment_index = image->nr_segments - 1;
image->is_ima_segment_index_set = true;
- /*
- * kexec owns kexec_buffer after kexec_add_buffer() is called
- * and it will vfree() that buffer.
- */
- ima_reset_kexec_file(&ima_kexec_file);
-
kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
kbuf.mem);
}
@@ -195,7 +181,34 @@ void ima_add_kexec_buffer(struct kimage *image)
static int ima_update_kexec_buffer(struct notifier_block *self,
unsigned long action, void *data)
{
- return NOTIFY_OK;
+ void *buf = NULL;
+ size_t buf_size;
+ int ret = NOTIFY_OK;
+
+ if (!kexec_in_progress) {
+ pr_info("%s: No kexec in progress.\n", __func__);
+ return ret;
+ }
+
+ if (!ima_kexec_buffer) {
+ pr_err("%s: Kexec buffer not set.\n", __func__);
+ return ret;
+ }
+
+ ret = ima_dump_measurement_list(&buf_size, &buf,
+ kexec_segment_size);
+
+ if (!buf) {
Use 'if (ret)' ? You're setting *buffer = NULL in case of error but ret
should be used to test for failure.
+ pr_err("%s: Dump measurements failed. Error:%d\n",
+ __func__, ret);
+ goto out;
+ }
+ memcpy(ima_kexec_buffer, buf, buf_size);
+out:
+ kimage_unmap_segment(ima_kexec_buffer);
+ ima_kexec_buffer = NULL;
+
+ return ret;
}
struct notifier_block update_buffer_nb = {
