| Message ID | 20250218225502.747963-8-chenste@linux.microsoft.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | ima: kexec: measure events between kexec load and execute | expand |
On 2/18/25 5:55 PM, steven chen wrote: > The amount of memory allocated at kexec load, even with the extra memory > allocated, might not be large enough for the entire measurement list. The > indeterminate interval between kexec 'load' and 'execute' could exacerbate > this problem. > > Define two new IMA events, 'kexec_load' and 'kexec_execute', to be > measured as critical data at kexec 'load' and 'execute' respectively. > Report the allocated kexec segment size, IMA binary log size and the > runtime measurements count as part of those events. > > These events, and the values reported through them, serve as markers in > the IMA log to verify the IMA events are captured during kexec soft > reboot. The presence of a 'kexec_load' event in between the last two > 'boot_aggregate' events in the IMA log implies this is a kexec soft > reboot, and not a cold-boot. And the absence of 'kexec_execute' event > after kexec soft reboot implies missing events in that window which > results in inconsistency with TPM PCR quotes, necessitating a cold boot > for a successful remote attestation. > > The 'kexec_load' event IMA log can be found using the following command: > sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | > grep kexec_load > > The 'kexec_load' event IMA log can be found using the following command: > sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | > grep kexec_execute > > Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com> > Signed-off-by: steven chen <chenste@linux.microsoft.com> > --- > security/integrity/ima/ima.h | 6 ++++++ > security/integrity/ima/ima_kexec.c | 21 +++++++++++++++++++++ > security/integrity/ima/ima_queue.c | 5 +++++ > 3 files changed, 32 insertions(+) > > diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h > index 4428fcf42167..1452c98242a4 100644 > --- a/security/integrity/ima/ima.h > +++ b/security/integrity/ima/ima.h > @@ -240,6 +240,12 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key, > unsigned long flags, bool create); > #endif > > +#ifdef CONFIG_IMA_KEXEC > +void ima_measure_kexec_event(const char *event_name); > +#else > +static inline void ima_measure_kexec_event(const char *event_name) {} > +#endif > + > /* > * The default binary_runtime_measurements list format is defined as the > * platform native format. The canonical format is defined as little-endian. > diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c > index 6c8c203ad81e..8d0782e51ffa 100644 > --- a/security/integrity/ima/ima_kexec.c > +++ b/security/integrity/ima/ima_kexec.c > @@ -17,6 +17,8 @@ > #include "ima.h" > > #ifdef CONFIG_IMA_KEXEC > +#define IMA_KEXEC_EVENT_LEN 256 > + > static struct seq_file ima_kexec_file; > static void *ima_kexec_buffer; > static size_t kexec_segment_size; > @@ -36,6 +38,24 @@ static void ima_free_kexec_file_buf(struct seq_file *sf) > ima_reset_kexec_file(sf); > } > > +void ima_measure_kexec_event(const char *event_name) > +{ > + char ima_kexec_event[IMA_KEXEC_EVENT_LEN]; > + size_t buf_size = 0; > + long len; > + > + buf_size = ima_get_binary_runtime_size(); > + len = atomic_long_read(&ima_htable.len); > + > + scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN, > + "kexec_segment_size=%lu;ima_binary_runtime_size=%lu;" > + "ima_runtime_measurements_count=%ld;", > + kexec_segment_size, buf_size, len); Indentation and n = scnprintf(...), as Mimi mentioned in v7. > + > + ima_measure_critical_data("ima_kexec", event_name, ima_kexec_event, > + strlen(ima_kexec_event), false, NULL, 0); Replace strlen(ima_kexec_event) with 'n'. With these fixes: Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > +} > + > static int ima_alloc_kexec_file_buf(size_t segment_size) > { > /* > @@ -58,6 +78,7 @@ static int ima_alloc_kexec_file_buf(size_t segment_size) > out: > ima_kexec_file.read_pos = 0; > ima_kexec_file.count = sizeof(struct ima_kexec_hdr); /* reserved space */ > + ima_measure_kexec_event("kexec_load"); > > return 0; > } > diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c > index 3dfd178d4292..6afb46989cf6 100644 > --- a/security/integrity/ima/ima_queue.c > +++ b/security/integrity/ima/ima_queue.c > @@ -241,6 +241,11 @@ static int ima_reboot_notifier(struct notifier_block *nb, > unsigned long action, > void *data) > { > +#ifdef CONFIG_IMA_KEXEC > + if (action == SYS_RESTART && data && !strcmp(data, "kexec reboot")) > + ima_measure_kexec_event("kexec_execute"); > +#endif > + > ima_measurements_suspend(); > > return NOTIFY_DONE;
On 2/19/2025 8:23 AM, Stefan Berger wrote: > > > On 2/18/25 5:55 PM, steven chen wrote: >> The amount of memory allocated at kexec load, even with the extra memory >> allocated, might not be large enough for the entire measurement >> list. The >> indeterminate interval between kexec 'load' and 'execute' could >> exacerbate >> this problem. >> >> Define two new IMA events, 'kexec_load' and 'kexec_execute', to be >> measured as critical data at kexec 'load' and 'execute' respectively. >> Report the allocated kexec segment size, IMA binary log size and the >> runtime measurements count as part of those events. >> >> These events, and the values reported through them, serve as markers in >> the IMA log to verify the IMA events are captured during kexec soft >> reboot. The presence of a 'kexec_load' event in between the last two >> 'boot_aggregate' events in the IMA log implies this is a kexec soft >> reboot, and not a cold-boot. And the absence of 'kexec_execute' event >> after kexec soft reboot implies missing events in that window which >> results in inconsistency with TPM PCR quotes, necessitating a cold boot >> for a successful remote attestation. >> >> The 'kexec_load' event IMA log can be found using the following command: >> sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | >> grep kexec_load >> >> The 'kexec_load' event IMA log can be found using the following command: >> sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | >> grep kexec_execute >> >> Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com> >> Signed-off-by: steven chen <chenste@linux.microsoft.com> >> --- >> security/integrity/ima/ima.h | 6 ++++++ >> security/integrity/ima/ima_kexec.c | 21 +++++++++++++++++++++ >> security/integrity/ima/ima_queue.c | 5 +++++ >> 3 files changed, 32 insertions(+) >> >> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h >> index 4428fcf42167..1452c98242a4 100644 >> --- a/security/integrity/ima/ima.h >> +++ b/security/integrity/ima/ima.h >> @@ -240,6 +240,12 @@ void ima_post_key_create_or_update(struct key >> *keyring, struct key *key, >> unsigned long flags, bool create); >> #endif >> +#ifdef CONFIG_IMA_KEXEC >> +void ima_measure_kexec_event(const char *event_name); >> +#else >> +static inline void ima_measure_kexec_event(const char *event_name) {} >> +#endif >> + >> /* >> * The default binary_runtime_measurements list format is defined >> as the >> * platform native format. The canonical format is defined as >> little-endian. >> diff --git a/security/integrity/ima/ima_kexec.c >> b/security/integrity/ima/ima_kexec.c >> index 6c8c203ad81e..8d0782e51ffa 100644 >> --- a/security/integrity/ima/ima_kexec.c >> +++ b/security/integrity/ima/ima_kexec.c >> @@ -17,6 +17,8 @@ >> #include "ima.h" >> #ifdef CONFIG_IMA_KEXEC >> +#define IMA_KEXEC_EVENT_LEN 256 >> + >> static struct seq_file ima_kexec_file; >> static void *ima_kexec_buffer; >> static size_t kexec_segment_size; >> @@ -36,6 +38,24 @@ static void ima_free_kexec_file_buf(struct >> seq_file *sf) >> ima_reset_kexec_file(sf); >> } >> +void ima_measure_kexec_event(const char *event_name) >> +{ >> + char ima_kexec_event[IMA_KEXEC_EVENT_LEN]; >> + size_t buf_size = 0; >> + long len; >> + >> + buf_size = ima_get_binary_runtime_size(); >> + len = atomic_long_read(&ima_htable.len); >> + >> + scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN, >> + "kexec_segment_size=%lu;ima_binary_runtime_size=%lu;" >> + "ima_runtime_measurements_count=%ld;", >> + kexec_segment_size, buf_size, len); > > Indentation and n = scnprintf(...), as Mimi mentioned in v7. > >> + >> + ima_measure_critical_data("ima_kexec", event_name, ima_kexec_event, >> + strlen(ima_kexec_event), false, NULL, 0); > > Replace strlen(ima_kexec_event) with 'n'. > > With these fixes: > > Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > >> +} >> + >> static int ima_alloc_kexec_file_buf(size_t segment_size) >> { >> /* >> @@ -58,6 +78,7 @@ static int ima_alloc_kexec_file_buf(size_t >> segment_size) >> out: >> ima_kexec_file.read_pos = 0; >> ima_kexec_file.count = sizeof(struct ima_kexec_hdr); /* >> reserved space */ >> + ima_measure_kexec_event("kexec_load"); >> return 0; >> } >> diff --git a/security/integrity/ima/ima_queue.c >> b/security/integrity/ima/ima_queue.c >> index 3dfd178d4292..6afb46989cf6 100644 >> --- a/security/integrity/ima/ima_queue.c >> +++ b/security/integrity/ima/ima_queue.c >> @@ -241,6 +241,11 @@ static int ima_reboot_notifier(struct >> notifier_block *nb, >> unsigned long action, >> void *data) >> { >> +#ifdef CONFIG_IMA_KEXEC >> + if (action == SYS_RESTART && data && !strcmp(data, "kexec reboot")) >> + ima_measure_kexec_event("kexec_execute"); >> +#endif >> + >> ima_measurements_suspend(); >> return NOTIFY_DONE; Hi Stefan, thanks for your comments. I will update in next version.
On Tue, 2025-02-18 at 14:55 -0800, steven chen wrote: > The amount of memory allocated at kexec load, even with the extra memory > allocated, might not be large enough for the entire measurement list. The > indeterminate interval between kexec 'load' and 'execute' could exacerbate > this problem. > > Define two new IMA events, 'kexec_load' and 'kexec_execute', to be > measured as critical data at kexec 'load' and 'execute' respectively. > Report the allocated kexec segment size, IMA binary log size and the > runtime measurements count as part of those events. > > These events, and the values reported through them, serve as markers in > the IMA log to verify the IMA events are captured during kexec soft > reboot. The presence of a 'kexec_load' event in between the last two > 'boot_aggregate' events in the IMA log implies this is a kexec soft > reboot, and not a cold-boot. And the absence of 'kexec_execute' event > after kexec soft reboot implies missing events in that window which > results in inconsistency with TPM PCR quotes, necessitating a cold boot > for a successful remote attestation. > > The 'kexec_load' event IMA log can be found using the following command: > sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | > grep kexec_load > > The 'kexec_load' event IMA log can be found using the following command: -> kexec_execute > sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | > grep kexec_execute These critical data events are displayed as hex encoded ascii in the ascii_runtime_measurement_list. Verifying the critical data hash requires calculating the hash of the decoded ascii string. For example: sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | grep kexec_load | cut -d' ' -f 6 | xxd -r -p | sha256sum > > Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com> > Signed-off-by: steven chen <chenste@linux.microsoft.com> > --- > security/integrity/ima/ima.h | 6 ++++++ > security/integrity/ima/ima_kexec.c | 21 +++++++++++++++++++++ > security/integrity/ima/ima_queue.c | 5 +++++ > 3 files changed, 32 insertions(+) > > diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h > index 4428fcf42167..1452c98242a4 100644 > --- a/security/integrity/ima/ima.h > +++ b/security/integrity/ima/ima.h > @@ -240,6 +240,12 @@ void ima_post_key_create_or_update(struct key *keyring, struct key > *key, > unsigned long flags, bool create); > #endif > > +#ifdef CONFIG_IMA_KEXEC > +void ima_measure_kexec_event(const char *event_name); > +#else > +static inline void ima_measure_kexec_event(const char *event_name) {} > +#endif > + > /* > * The default binary_runtime_measurements list format is defined as the > * platform native format. The canonical format is defined as little-endian. > diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c > index 6c8c203ad81e..8d0782e51ffa 100644 > --- a/security/integrity/ima/ima_kexec.c > +++ b/security/integrity/ima/ima_kexec.c > @@ -17,6 +17,8 @@ > #include "ima.h" > > #ifdef CONFIG_IMA_KEXEC > +#define IMA_KEXEC_EVENT_LEN 256 > + > static struct seq_file ima_kexec_file; > static void *ima_kexec_buffer; > static size_t kexec_segment_size; > @@ -36,6 +38,24 @@ static void ima_free_kexec_file_buf(struct seq_file *sf) > ima_reset_kexec_file(sf); > } > > +void ima_measure_kexec_event(const char *event_name) > +{ > + char ima_kexec_event[IMA_KEXEC_EVENT_LEN]; > + size_t buf_size = 0; > + long len; > + > + buf_size = ima_get_binary_runtime_size(); > + len = atomic_long_read(&ima_htable.len); > + > + scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN, > + "kexec_segment_size=%lu;ima_binary_runtime_size=%lu;" > + "ima_runtime_measurements_count=%ld;", > + kexec_segment_size, buf_size, len); > + > + ima_measure_critical_data("ima_kexec", event_name, ima_kexec_event, > + strlen(ima_kexec_event), false, NULL, 0); As previously mentioned, scnprintf() returns the length. No need to use strlen() here. Mimi > +} > + > static int ima_alloc_kexec_file_buf(size_t segment_size) > { > /* > @@ -58,6 +78,7 @@ static int ima_alloc_kexec_file_buf(size_t segment_size) > out: > ima_kexec_file.read_pos = 0; > ima_kexec_file.count = sizeof(struct ima_kexec_hdr); /* reserved space */ > + ima_measure_kexec_event("kexec_load"); > > return 0; > } > diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c > index 3dfd178d4292..6afb46989cf6 100644 > --- a/security/integrity/ima/ima_queue.c > +++ b/security/integrity/ima/ima_queue.c > @@ -241,6 +241,11 @@ static int ima_reboot_notifier(struct notifier_block *nb, > unsigned long action, > void *data) > { > +#ifdef CONFIG_IMA_KEXEC > + if (action == SYS_RESTART && data && !strcmp(data, "kexec reboot")) > + ima_measure_kexec_event("kexec_execute"); > +#endif > + > ima_measurements_suspend(); > > return NOTIFY_DONE;
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 4428fcf42167..1452c98242a4 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -240,6 +240,12 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key, unsigned long flags, bool create); #endif +#ifdef CONFIG_IMA_KEXEC +void ima_measure_kexec_event(const char *event_name); +#else +static inline void ima_measure_kexec_event(const char *event_name) {} +#endif + /* * The default binary_runtime_measurements list format is defined as the * platform native format. The canonical format is defined as little-endian. diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c index 6c8c203ad81e..8d0782e51ffa 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -17,6 +17,8 @@ #include "ima.h" #ifdef CONFIG_IMA_KEXEC +#define IMA_KEXEC_EVENT_LEN 256 + static struct seq_file ima_kexec_file; static void *ima_kexec_buffer; static size_t kexec_segment_size; @@ -36,6 +38,24 @@ static void ima_free_kexec_file_buf(struct seq_file *sf) ima_reset_kexec_file(sf); } +void ima_measure_kexec_event(const char *event_name) +{ + char ima_kexec_event[IMA_KEXEC_EVENT_LEN]; + size_t buf_size = 0; + long len; + + buf_size = ima_get_binary_runtime_size(); + len = atomic_long_read(&ima_htable.len); + + scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN, + "kexec_segment_size=%lu;ima_binary_runtime_size=%lu;" + "ima_runtime_measurements_count=%ld;", + kexec_segment_size, buf_size, len); + + ima_measure_critical_data("ima_kexec", event_name, ima_kexec_event, + strlen(ima_kexec_event), false, NULL, 0); +} + static int ima_alloc_kexec_file_buf(size_t segment_size) { /* @@ -58,6 +78,7 @@ static int ima_alloc_kexec_file_buf(size_t segment_size) out: ima_kexec_file.read_pos = 0; ima_kexec_file.count = sizeof(struct ima_kexec_hdr); /* reserved space */ + ima_measure_kexec_event("kexec_load"); return 0; } diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c index 3dfd178d4292..6afb46989cf6 100644 --- a/security/integrity/ima/ima_queue.c +++ b/security/integrity/ima/ima_queue.c @@ -241,6 +241,11 @@ static int ima_reboot_notifier(struct notifier_block *nb, unsigned long action, void *data) { +#ifdef CONFIG_IMA_KEXEC + if (action == SYS_RESTART && data && !strcmp(data, "kexec reboot")) + ima_measure_kexec_event("kexec_execute"); +#endif + ima_measurements_suspend(); return NOTIFY_DONE;