Message ID | 20250318010448.954-7-chenste@linux.microsoft.com (mailing list archive) |
---|---|
State | New |
Headers | show |
Series | ima: kexec: measure events between kexec load and execute | expand |
On Mon, 2025-03-17 at 18:04 -0700, steven chen wrote: > ima_dump_measurement_list() is called during kexec 'load', which may > result in loss of IMA measurements during kexec soft reboot. Due to > missed measurements that only occurred after kexec 'load', this function > needs to be called during kexec 'execute'. -> , defer calling ima_dump_measurement_list() to kexec 'execute'. > > This patch includes the following changes: > - Implement kimage_file_post_load() function to be invoked after the new > kernel image has been loaded for kexec. > - 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 so that it > becomes accessible both during kexec 'load' and 'execute'. > - Move ima_dump_measurement_list() call from ima_add_kexec_buffer() > to ima_update_kexec_buffer(). > - Copy the measurement list as much as possible. Let's summarize the above changes, as below, and then remove the list. Define and call the new kimage_file_post_load() to call ima_kexec_post_load(), which registers the reboot notifier (ima_update_kexec_buffer). Finally, move ima_dump_measurement_list() from ima_add_kexec_buffer() to ima_update_kexec_buffer() to defer copying the measurement list. > - 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' would corrupt the buffer. Instead of adding and then removing the ima_reset_kexec_file() call from ima_add_kexec_buffer(), defer adding the test in ima_alloc_kexec_file_buf() to see if the segment size has changed. That should be a subsequent patch, after this one. ima_reset_kexec_file() is then ever called from only one place. Combine ima_reset_kexec_file() with ima_free_kexec_file_buf(). thanks, Mimi > > Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com> > Cc: Eric Biederman <ebiederm@xmission.com> > Cc: Baoquan He <bhe@redhat.com> > Cc: Vivek Goyal <vgoyal@redhat.com> > Cc: Dave Young <dyoung@redhat.com> > Signed-off-by: steven chen <chenste@linux.microsoft.com> > Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > --- > kernel/kexec_file.c | 10 ++++++ > security/integrity/ima/ima_kexec.c | 51 ++++++++++++++++++------------ > 2 files changed, 40 insertions(+), 21 deletions(-) > > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index 606132253c79..ab449b43aaee 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -201,6 +201,13 @@ kimage_validate_signature(struct kimage *image) > } > #endif > > +static void kimage_file_post_load(struct kimage *image) > +{ > +#ifdef CONFIG_IMA_KEXEC > + ima_kexec_post_load(image); > +#endif > +} > + > /* > * In file mode list of segments is prepared by kernel. Copy relevant > * data from user space, do error checking, prepare segment list > @@ -428,6 +435,9 @@ 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 9336c4f60650..c390c745f882 100644 > --- a/security/integrity/ima/ima_kexec.c > +++ b/security/integrity/ima/ima_kexec.c > @@ -19,6 +19,7 @@ > #ifdef CONFIG_IMA_KEXEC > static bool ima_kexec_update_registered; > static struct seq_file ima_kexec_file; > +static size_t kexec_segment_size; > static void *ima_kexec_buffer; > > static void ima_reset_kexec_file(struct seq_file *sf) > @@ -67,7 +68,7 @@ static int ima_alloc_kexec_file_buf(size_t segment_size) > * if the size of the allocated memory is not less than the size of IMA measurement list > * copy the measurement list to the allocated memory. > * else > - * return error > + * copy the measurement list as much as possible. > */ > static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, > unsigned long segment_size) > @@ -95,9 +96,6 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, > } > } > > - if (ret < 0) > - goto out; > - > /* > * fill in reserved space with some buffer details > * (eg. version, buffer size, number of measurements) > @@ -117,7 +115,7 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, > > *buffer_size = ima_kexec_file.count; > *buffer = ima_kexec_file.buf; > -out: > + > return ret; > } > > @@ -135,9 +133,8 @@ void ima_add_kexec_buffer(struct kimage *image) > unsigned long binary_runtime_size; > > /* use more understandable variable names than defined in kbuf */ > + size_t kexec_buffer_size = 0; > void *kexec_buffer = NULL; > - size_t kexec_buffer_size; > - size_t kexec_segment_size; > int ret; > > /* > @@ -162,13 +159,6 @@ void ima_add_kexec_buffer(struct kimage *image) > return; > } > > - ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer, > - kexec_segment_size); > - if (!kexec_buffer) { > - pr_err("Not enough memory for the kexec measurement buffer.\n"); > - return; > - } > - > kbuf.buffer = kexec_buffer; > kbuf.bufsz = kexec_buffer_size; > kbuf.memsz = kexec_segment_size; > @@ -186,12 +176,6 @@ 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); > } > @@ -202,7 +186,32 @@ 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; > + size_t buf_size = 0; > + int ret = NOTIFY_OK; > + void *buf = NULL; > + > + if (!kexec_in_progress) { > + pr_info("No kexec in progress.\n"); > + return ret; > + } > + > + if (!ima_kexec_buffer) { > + pr_err("Kexec buffer not set.\n"); > + return ret; > + } > + > + ret = ima_dump_measurement_list(&buf_size, &buf, kexec_segment_size); > + > + if (ret) > + pr_err("Dump measurements failed. Error:%d\n", ret); > + > + if (buf_size != 0) > + memcpy(ima_kexec_buffer, buf, buf_size); > + > + kimage_unmap_segment(ima_kexec_buffer); > + ima_kexec_buffer = NULL; > + > + return ret; > } > > static struct notifier_block update_buffer_nb = {
On 03/17/25 at 06:04pm, steven chen wrote: ...snip... > --- > kernel/kexec_file.c | 10 ++++++ > security/integrity/ima/ima_kexec.c | 51 ++++++++++++++++++------------ > 2 files changed, 40 insertions(+), 21 deletions(-) > > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index 606132253c79..ab449b43aaee 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -201,6 +201,13 @@ kimage_validate_signature(struct kimage *image) > } > #endif > > +static void kimage_file_post_load(struct kimage *image) > +{ > +#ifdef CONFIG_IMA_KEXEC > + ima_kexec_post_load(image); > +#endif > +} > + > /* > * In file mode list of segments is prepared by kernel. Copy relevant > * data from user space, do error checking, prepare segment list > @@ -428,6 +435,9 @@ 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); machine_kexec_post_load() is called by both kexec_load and kexec_file_load, we should use it to do things post load, but not introducing another kimage_file_post_load(). > + > ret = machine_kexec_post_load(image); > if (ret) > goto out; ...snip...
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 606132253c79..ab449b43aaee 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -201,6 +201,13 @@ kimage_validate_signature(struct kimage *image) } #endif +static void kimage_file_post_load(struct kimage *image) +{ +#ifdef CONFIG_IMA_KEXEC + ima_kexec_post_load(image); +#endif +} + /* * In file mode list of segments is prepared by kernel. Copy relevant * data from user space, do error checking, prepare segment list @@ -428,6 +435,9 @@ 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 9336c4f60650..c390c745f882 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -19,6 +19,7 @@ #ifdef CONFIG_IMA_KEXEC static bool ima_kexec_update_registered; static struct seq_file ima_kexec_file; +static size_t kexec_segment_size; static void *ima_kexec_buffer; static void ima_reset_kexec_file(struct seq_file *sf) @@ -67,7 +68,7 @@ static int ima_alloc_kexec_file_buf(size_t segment_size) * if the size of the allocated memory is not less than the size of IMA measurement list * copy the measurement list to the allocated memory. * else - * return error + * copy the measurement list as much as possible. */ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, unsigned long segment_size) @@ -95,9 +96,6 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, } } - if (ret < 0) - goto out; - /* * fill in reserved space with some buffer details * (eg. version, buffer size, number of measurements) @@ -117,7 +115,7 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, *buffer_size = ima_kexec_file.count; *buffer = ima_kexec_file.buf; -out: + return ret; } @@ -135,9 +133,8 @@ void ima_add_kexec_buffer(struct kimage *image) unsigned long binary_runtime_size; /* use more understandable variable names than defined in kbuf */ + size_t kexec_buffer_size = 0; void *kexec_buffer = NULL; - size_t kexec_buffer_size; - size_t kexec_segment_size; int ret; /* @@ -162,13 +159,6 @@ void ima_add_kexec_buffer(struct kimage *image) return; } - ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer, - kexec_segment_size); - if (!kexec_buffer) { - pr_err("Not enough memory for the kexec measurement buffer.\n"); - return; - } - kbuf.buffer = kexec_buffer; kbuf.bufsz = kexec_buffer_size; kbuf.memsz = kexec_segment_size; @@ -186,12 +176,6 @@ 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); } @@ -202,7 +186,32 @@ 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; + size_t buf_size = 0; + int ret = NOTIFY_OK; + void *buf = NULL; + + if (!kexec_in_progress) { + pr_info("No kexec in progress.\n"); + return ret; + } + + if (!ima_kexec_buffer) { + pr_err("Kexec buffer not set.\n"); + return ret; + } + + ret = ima_dump_measurement_list(&buf_size, &buf, kexec_segment_size); + + if (ret) + pr_err("Dump measurements failed. Error:%d\n", ret); + + if (buf_size != 0) + memcpy(ima_kexec_buffer, buf, buf_size); + + kimage_unmap_segment(ima_kexec_buffer); + ima_kexec_buffer = NULL; + + return ret; } static struct notifier_block update_buffer_nb = {