| Message ID | 20250203232033.64123-4-chenste@linux.microsoft.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | ima: kexec: measure events between kexec load and excute | expand |
On 2/3/25 6:20 PM, steven chen wrote: > kexec_calculate_store_digests() calculates and stores the digest of the > segment at kexec_file_load syscall where the IMA segment is also > allocated. With this series, the IMA segment will be updated with the > measurement log at kexec excute stage when soft reboot is initiated. s/excute/execute > Therefore, it may fail digest verification in verify_sha256_digest() > after kexec soft reboot into the new kernel. Therefore, the digest > calculation/verification of the IMA segment needs to be skipped. > > Skip IMA segment from calculating and storing digest in function Skip the calculation and storing of the digest of the IMA segment in kexec_calculate_store_digests() so that ... > kexec_calculate_store_digests() so that it is not added to the > 'purgatory_sha_regions'. > > Since verify_sha256_digest() only verifies 'purgatory_sha_regions', > no change is needed in verify_sha256_digest() in this context. > > With this change, the IMA segment is not included in the digest > calculation, storage, and verification. > > Author: Tushar Sugandhi <tusharsu@linux.microsoft.com> > Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com> > Signed-off-by: steven chen <chenste@linux.microsoft.com> > ---> include/linux/kexec.h | 3 +++ > kernel/kexec_file.c | 23 +++++++++++++++++++++++ > security/integrity/ima/ima_kexec.c | 3 +++ > 3 files changed, 29 insertions(+) > > diff --git a/include/linux/kexec.h b/include/linux/kexec.h > index f8413ea5c8c8..f3246e881ac8 100644 > --- a/include/linux/kexec.h > +++ b/include/linux/kexec.h > @@ -362,6 +362,9 @@ struct kimage { > > phys_addr_t ima_buffer_addr; > size_t ima_buffer_size; > + > + unsigned long ima_segment_index; > + bool is_ima_segment_index_set; > #endif > > /* Core ELF header buffer */ > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index 3eedb8c226ad..a3370a0dce20 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -38,6 +38,22 @@ void set_kexec_sig_enforced(void) > } > #endif > > +#ifdef CONFIG_IMA_KEXEC > +static bool check_ima_segment_index(struct kimage *image, int i) > +{ > + if (image->is_ima_segment_index_set && > + i == image->ima_segment_index) The 'i =' should be indented under 'image->'. With these nits fixed: Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > + return true; > + else > + return false; > +} > +#else > +static bool check_ima_segment_index(struct kimage *image, int i) > +{ > + return false; > +} > +#endif > + > static int kexec_calculate_store_digests(struct kimage *image); > > /* Maximum size in bytes for kernel/initrd files. */ > @@ -764,6 +780,13 @@ static int kexec_calculate_store_digests(struct kimage *image) > if (ksegment->kbuf == pi->purgatory_buf) > continue; > > + /* > + * Skip the segment if ima_segment_index is set and matches > + * the current index > + */ > + if (check_ima_segment_index(image, i)) > + continue; > + > ret = crypto_shash_update(desc, ksegment->kbuf, > ksegment->bufsz); > if (ret) > diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c > index b60a902460e2..283860d20521 100644 > --- a/security/integrity/ima/ima_kexec.c > +++ b/security/integrity/ima/ima_kexec.c > @@ -162,6 +162,7 @@ void ima_add_kexec_buffer(struct kimage *image) > kbuf.buffer = kexec_buffer; > kbuf.bufsz = kexec_buffer_size; > kbuf.memsz = kexec_segment_size; > + image->is_ima_segment_index_set = false; > ret = kexec_add_buffer(&kbuf); > if (ret) { > pr_err("Error passing over kexec measurement buffer.\n"); > @@ -172,6 +173,8 @@ void ima_add_kexec_buffer(struct kimage *image) > image->ima_buffer_addr = kbuf.mem; > image->ima_buffer_size = kexec_segment_size; > image->ima_buffer = kexec_buffer; > + 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
On 2/4/2025 11:39 AM, Stefan Berger wrote: > On 2/3/25 6:20 PM, steven chen wrote: >> kexec_calculate_store_digests() calculates and stores the digest of the >> segment at kexec_file_load syscall where the IMA segment is also >> allocated. With this series, the IMA segment will be updated with the >> measurement log at kexec excute stage when soft reboot is initiated. > > s/excute/execute > >> Therefore, it may fail digest verification in verify_sha256_digest() >> after kexec soft reboot into the new kernel. Therefore, the digest >> calculation/verification of the IMA segment needs to be skipped. >> >> Skip IMA segment from calculating and storing digest in function > > Skip the calculation and storing of the digest of the IMA segment in > kexec_calculate_store_digests() so that ... > > >> kexec_calculate_store_digests() so that it is not added to the >> 'purgatory_sha_regions'. >> >> Since verify_sha256_digest() only verifies 'purgatory_sha_regions', >> no change is needed in verify_sha256_digest() in this context. >> >> With this change, the IMA segment is not included in the digest >> calculation, storage, and verification. >> >> Author: Tushar Sugandhi <tusharsu@linux.microsoft.com> >> Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com> >> Signed-off-by: steven chen <chenste@linux.microsoft.com> > > ---> include/linux/kexec.h | 3 +++ >> kernel/kexec_file.c | 23 +++++++++++++++++++++++ >> security/integrity/ima/ima_kexec.c | 3 +++ >> 3 files changed, 29 insertions(+) >> >> diff --git a/include/linux/kexec.h b/include/linux/kexec.h >> index f8413ea5c8c8..f3246e881ac8 100644 >> --- a/include/linux/kexec.h >> +++ b/include/linux/kexec.h >> @@ -362,6 +362,9 @@ struct kimage { >> phys_addr_t ima_buffer_addr; >> size_t ima_buffer_size; >> + >> + unsigned long ima_segment_index; >> + bool is_ima_segment_index_set; >> #endif >> /* Core ELF header buffer */ >> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c >> index 3eedb8c226ad..a3370a0dce20 100644 >> --- a/kernel/kexec_file.c >> +++ b/kernel/kexec_file.c >> @@ -38,6 +38,22 @@ void set_kexec_sig_enforced(void) >> } >> #endif >> +#ifdef CONFIG_IMA_KEXEC >> +static bool check_ima_segment_index(struct kimage *image, int i) >> +{ >> + if (image->is_ima_segment_index_set && >> + i == image->ima_segment_index) > > The 'i =' should be indented under 'image->'. > > With these nits fixed: > > Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > >> + return true; >> + else >> + return false; >> +} >> +#else >> +static bool check_ima_segment_index(struct kimage *image, int i) >> +{ >> + return false; >> +} >> +#endif >> + >> static int kexec_calculate_store_digests(struct kimage *image); >> /* Maximum size in bytes for kernel/initrd files. */ >> @@ -764,6 +780,13 @@ static int kexec_calculate_store_digests(struct >> kimage *image) >> if (ksegment->kbuf == pi->purgatory_buf) >> continue; >> + /* >> + * Skip the segment if ima_segment_index is set and matches >> + * the current index >> + */ >> + if (check_ima_segment_index(image, i)) >> + continue; >> + >> ret = crypto_shash_update(desc, ksegment->kbuf, >> ksegment->bufsz); >> if (ret) >> diff --git a/security/integrity/ima/ima_kexec.c >> b/security/integrity/ima/ima_kexec.c >> index b60a902460e2..283860d20521 100644 >> --- a/security/integrity/ima/ima_kexec.c >> +++ b/security/integrity/ima/ima_kexec.c >> @@ -162,6 +162,7 @@ void ima_add_kexec_buffer(struct kimage *image) >> kbuf.buffer = kexec_buffer; >> kbuf.bufsz = kexec_buffer_size; >> kbuf.memsz = kexec_segment_size; >> + image->is_ima_segment_index_set = false; >> ret = kexec_add_buffer(&kbuf); >> if (ret) { >> pr_err("Error passing over kexec measurement buffer.\n"); >> @@ -172,6 +173,8 @@ void ima_add_kexec_buffer(struct kimage *image) >> image->ima_buffer_addr = kbuf.mem; >> image->ima_buffer_size = kexec_segment_size; >> image->ima_buffer = kexec_buffer; >> + 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 Hi Stefan, I will update in next release. Thanks!
On 2/4/25 3:28 PM, steven chen wrote: > On 2/4/2025 11:39 AM, Stefan Berger wrote: >> On 2/3/25 6:20 PM, steven chen wrote: > > > Hi Stefan, I will update in next release. Thanks! You should try to rebase it on 6.14-rc1. There were a few changes.
diff --git a/include/linux/kexec.h b/include/linux/kexec.h index f8413ea5c8c8..f3246e881ac8 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -362,6 +362,9 @@ struct kimage { phys_addr_t ima_buffer_addr; size_t ima_buffer_size; + + unsigned long ima_segment_index; + bool is_ima_segment_index_set; #endif /* Core ELF header buffer */ diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 3eedb8c226ad..a3370a0dce20 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -38,6 +38,22 @@ void set_kexec_sig_enforced(void) } #endif +#ifdef CONFIG_IMA_KEXEC +static bool check_ima_segment_index(struct kimage *image, int i) +{ + if (image->is_ima_segment_index_set && + i == image->ima_segment_index) + return true; + else + return false; +} +#else +static bool check_ima_segment_index(struct kimage *image, int i) +{ + return false; +} +#endif + static int kexec_calculate_store_digests(struct kimage *image); /* Maximum size in bytes for kernel/initrd files. */ @@ -764,6 +780,13 @@ static int kexec_calculate_store_digests(struct kimage *image) if (ksegment->kbuf == pi->purgatory_buf) continue; + /* + * Skip the segment if ima_segment_index is set and matches + * the current index + */ + if (check_ima_segment_index(image, i)) + continue; + ret = crypto_shash_update(desc, ksegment->kbuf, ksegment->bufsz); if (ret) diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c index b60a902460e2..283860d20521 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -162,6 +162,7 @@ void ima_add_kexec_buffer(struct kimage *image) kbuf.buffer = kexec_buffer; kbuf.bufsz = kexec_buffer_size; kbuf.memsz = kexec_segment_size; + image->is_ima_segment_index_set = false; ret = kexec_add_buffer(&kbuf); if (ret) { pr_err("Error passing over kexec measurement buffer.\n"); @@ -172,6 +173,8 @@ void ima_add_kexec_buffer(struct kimage *image) image->ima_buffer_addr = kbuf.mem; image->ima_buffer_size = kexec_segment_size; image->ima_buffer = kexec_buffer; + 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