| Message ID | 20201212180251.9943-6-tusharsu@linux.microsoft.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | IMA: support for measuring kernel integrity critical data | expand |
On 2020-12-12 10:02:48, Tushar Sugandhi wrote: > System administrators should be able to limit which kernel subsystems > they want to measure the critical data for. To enable that, an IMA policy > condition to choose specific kernel subsystems is needed. This policy > condition would constrain the measurement of the critical data based on > a label for the given subsystems. > > Add a new IMA policy condition - "data_source:=" to the IMA func > CRITICAL_DATA to allow measurement of various kernel subsystems. This > policy condition would enable the system administrators to restrict the > measurement to the labels listed in "data_source:=". > > Limit the measurement to the labels that are specified in the IMA > policy - CRITICAL_DATA+"data_source:=". If "data_sources:=" is not > provided with the func CRITICAL_DATA, the data from all the > supported kernel subsystems is measured. > > Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com> Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com> Tyler > --- > Documentation/ABI/testing/ima_policy | 2 ++ > security/integrity/ima/ima_policy.c | 37 +++++++++++++++++++++++++--- > 2 files changed, 36 insertions(+), 3 deletions(-) > > diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy > index 6ec7daa87cba..0f4ee9e0a455 100644 > --- a/Documentation/ABI/testing/ima_policy > +++ b/Documentation/ABI/testing/ima_policy > @@ -52,6 +52,8 @@ Description: > template:= name of a defined IMA template type > (eg, ima-ng). Only valid when action is "measure". > pcr:= decimal value > + data_source:= [label] > + label:= a unique string used for grouping and limiting critical data. > > default policy: > # PROC_SUPER_MAGIC > diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c > index d45c2dbb6d45..fea996a9e26c 100644 > --- a/security/integrity/ima/ima_policy.c > +++ b/security/integrity/ima/ima_policy.c > @@ -34,6 +34,7 @@ > #define IMA_PCR 0x0100 > #define IMA_FSNAME 0x0200 > #define IMA_KEYRINGS 0x0400 > +#define IMA_DATA_SOURCE 0x0800 > > #define UNKNOWN 0 > #define MEASURE 0x0001 /* same as IMA_MEASURE */ > @@ -85,6 +86,7 @@ struct ima_rule_entry { > } lsm[MAX_LSM_RULES]; > char *fsname; > struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */ > + struct ima_rule_opt_list *data_source; /* Measure data from this source */ > struct ima_template_desc *template; > }; > > @@ -480,7 +482,11 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule, > opt_list = rule->keyrings; > break; > case CRITICAL_DATA: > - return true; > + if (!rule->data_source) > + return true; > + > + opt_list = rule->data_source; > + break; > default: > return false; > } > @@ -925,7 +931,7 @@ enum { > Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt, > Opt_appraise_type, Opt_appraise_flag, > Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings, > - Opt_err > + Opt_data_source, Opt_err > }; > > static const match_table_t policy_tokens = { > @@ -962,6 +968,7 @@ static const match_table_t policy_tokens = { > {Opt_pcr, "pcr=%s"}, > {Opt_template, "template=%s"}, > {Opt_keyrings, "keyrings=%s"}, > + {Opt_data_source, "data_source=%s"}, > {Opt_err, NULL} > }; > > @@ -1129,7 +1136,8 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) > if (entry->action & ~(MEASURE | DONT_MEASURE)) > return false; > > - if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR)) > + if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR | > + IMA_DATA_SOURCE)) > return false; > > if (ima_rule_contains_lsm_cond(entry)) > @@ -1339,6 +1347,23 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) > > entry->flags |= IMA_KEYRINGS; > break; > + case Opt_data_source: > + ima_log_string(ab, "data_source", args[0].from); > + > + if (entry->data_source) { > + result = -EINVAL; > + break; > + } > + > + entry->data_source = ima_alloc_rule_opt_list(args); > + if (IS_ERR(entry->data_source)) { > + result = PTR_ERR(entry->data_source); > + entry->data_source = NULL; > + break; > + } > + > + entry->flags |= IMA_DATA_SOURCE; > + break; > case Opt_fsuuid: > ima_log_string(ab, "fsuuid", args[0].from); > > @@ -1719,6 +1744,12 @@ int ima_policy_show(struct seq_file *m, void *v) > seq_puts(m, " "); > } > > + if (entry->flags & IMA_DATA_SOURCE) { > + seq_puts(m, "data_source="); > + ima_show_rule_opt_list(m, entry->data_source); > + seq_puts(m, " "); > + } > + > if (entry->flags & IMA_PCR) { > snprintf(tbuf, sizeof(tbuf), "%d", entry->pcr); > seq_printf(m, pt(Opt_pcr), tbuf); > -- > 2.17.1 >
On 2020-12-12 11:20 a.m., Tyler Hicks wrote: > On 2020-12-12 10:02:48, Tushar Sugandhi wrote: >> System administrators should be able to limit which kernel subsystems >> they want to measure the critical data for. To enable that, an IMA policy >> condition to choose specific kernel subsystems is needed. This policy >> condition would constrain the measurement of the critical data based on >> a label for the given subsystems. >> >> Add a new IMA policy condition - "data_source:=" to the IMA func >> CRITICAL_DATA to allow measurement of various kernel subsystems. This >> policy condition would enable the system administrators to restrict the >> measurement to the labels listed in "data_source:=". >> >> Limit the measurement to the labels that are specified in the IMA >> policy - CRITICAL_DATA+"data_source:=". If "data_sources:=" is not >> provided with the func CRITICAL_DATA, the data from all the >> supported kernel subsystems is measured. >> >> Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com> > > Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com> > > Tyler > Thanks again Tyler. ~Tushar
Hi Tushar, On Sat, 2020-12-12 at 10:02 -0800, Tushar Sugandhi wrote: > System administrators should be able to limit which kernel subsystems > they want to measure the critical data for. To enable that, an IMA policy > condition to choose specific kernel subsystems is needed. This policy > condition would constrain the measurement of the critical data based on > a label for the given subsystems. Restricting which kernel integrity critical data is measured is not only of interest to system administrators. Why single them out? Limiting which critical data is measured is based on a label, making it flexible. In your use case scenario, you're grouping the label based on kernel subsystem, but is that really necessary? In the broader picture, there could be cross subsystem critical data being measured based on a single label. Please think about the broader picture and re-write the patch descirption more generically. > > Add a new IMA policy condition - "data_source:=" to the IMA func What is with "add"? You're "adding support for" or "defining" a new policy condition. Remove the single hyphen, as explained in 3/8. Please replace "data_source" with something more generic (e.g. label). thanks, Mimi > CRITICAL_DATA to allow measurement of various kernel subsystems. This > policy condition would enable the system administrators to restrict the > measurement to the labels listed in "data_source:=". > > Limit the measurement to the labels that are specified in the IMA > policy - CRITICAL_DATA+"data_source:=". If "data_sources:=" is not > provided with the func CRITICAL_DATA, the data from all the > supported kernel subsystems is measured. > > Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
On 2020-12-24 6:29 a.m., Mimi Zohar wrote: > Hi Tushar, > > On Sat, 2020-12-12 at 10:02 -0800, Tushar Sugandhi wrote: >> System administrators should be able to limit which kernel subsystems >> they want to measure the critical data for. To enable that, an IMA policy >> condition to choose specific kernel subsystems is needed. This policy >> condition would constrain the measurement of the critical data based on >> a label for the given subsystems. > > Restricting which kernel integrity critical data is measured is not > only of interest to system administrators. Why single them out? > system administrators are usually responsible for system policies/configurations.They own modifications in the config files like ima-policy. That's why we wanted to address them to begin with. But you are correct. This is not only of interest to sysadmins. I will make the description more generic. > Limiting which critical data is measured is based on a label, making it > flexible. In your use case scenario, you're grouping the label based > on kernel subsystem, but is that really necessary? In the broader > picture, there could be cross subsystem critical data being measured > based on a single label. > > Please think about the broader picture and re-write the patch > descirption more generically. > Makes sense. Will make the patch description more generic. >> >> Add a new IMA policy condition - "data_source:=" to the IMA func > > What is with "add"? You're "adding support for" or "defining" a new > policy condition. Remove the single hyphen, as explained in 3/8. > > Please replace "data_source" with something more generic (e.g. label). > Sounds good. Would you prefer "label" or something else like "data_label"? In the policy file the "label" looks logical and more generic than "data_label". measure func=CRITICAL_DATA label=selinux For the time being, I will stick with "label", please let me know if you prefer something else. Thanks, Tushar > thanks, > > Mimi > >> CRITICAL_DATA to allow measurement of various kernel subsystems. This >> policy condition would enable the system administrators to restrict the >> measurement to the labels listed in "data_source:=". >> >> Limit the measurement to the labels that are specified in the IMA >> policy - CRITICAL_DATA+"data_source:=". If "data_sources:=" is not >> provided with the func CRITICAL_DATA, the data from all the >> supported kernel subsystems is measured. >> >> Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index 6ec7daa87cba..0f4ee9e0a455 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -52,6 +52,8 @@ Description: template:= name of a defined IMA template type (eg, ima-ng). Only valid when action is "measure". pcr:= decimal value + data_source:= [label] + label:= a unique string used for grouping and limiting critical data. default policy: # PROC_SUPER_MAGIC diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index d45c2dbb6d45..fea996a9e26c 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -34,6 +34,7 @@ #define IMA_PCR 0x0100 #define IMA_FSNAME 0x0200 #define IMA_KEYRINGS 0x0400 +#define IMA_DATA_SOURCE 0x0800 #define UNKNOWN 0 #define MEASURE 0x0001 /* same as IMA_MEASURE */ @@ -85,6 +86,7 @@ struct ima_rule_entry { } lsm[MAX_LSM_RULES]; char *fsname; struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */ + struct ima_rule_opt_list *data_source; /* Measure data from this source */ struct ima_template_desc *template; }; @@ -480,7 +482,11 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule, opt_list = rule->keyrings; break; case CRITICAL_DATA: - return true; + if (!rule->data_source) + return true; + + opt_list = rule->data_source; + break; default: return false; } @@ -925,7 +931,7 @@ enum { Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt, Opt_appraise_type, Opt_appraise_flag, Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings, - Opt_err + Opt_data_source, Opt_err }; static const match_table_t policy_tokens = { @@ -962,6 +968,7 @@ static const match_table_t policy_tokens = { {Opt_pcr, "pcr=%s"}, {Opt_template, "template=%s"}, {Opt_keyrings, "keyrings=%s"}, + {Opt_data_source, "data_source=%s"}, {Opt_err, NULL} }; @@ -1129,7 +1136,8 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) if (entry->action & ~(MEASURE | DONT_MEASURE)) return false; - if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR)) + if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR | + IMA_DATA_SOURCE)) return false; if (ima_rule_contains_lsm_cond(entry)) @@ -1339,6 +1347,23 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) entry->flags |= IMA_KEYRINGS; break; + case Opt_data_source: + ima_log_string(ab, "data_source", args[0].from); + + if (entry->data_source) { + result = -EINVAL; + break; + } + + entry->data_source = ima_alloc_rule_opt_list(args); + if (IS_ERR(entry->data_source)) { + result = PTR_ERR(entry->data_source); + entry->data_source = NULL; + break; + } + + entry->flags |= IMA_DATA_SOURCE; + break; case Opt_fsuuid: ima_log_string(ab, "fsuuid", args[0].from); @@ -1719,6 +1744,12 @@ int ima_policy_show(struct seq_file *m, void *v) seq_puts(m, " "); } + if (entry->flags & IMA_DATA_SOURCE) { + seq_puts(m, "data_source="); + ima_show_rule_opt_list(m, entry->data_source); + seq_puts(m, " "); + } + if (entry->flags & IMA_PCR) { snprintf(tbuf, sizeof(tbuf), "%d", entry->pcr); seq_printf(m, pt(Opt_pcr), tbuf);
System administrators should be able to limit which kernel subsystems they want to measure the critical data for. To enable that, an IMA policy condition to choose specific kernel subsystems is needed. This policy condition would constrain the measurement of the critical data based on a label for the given subsystems. Add a new IMA policy condition - "data_source:=" to the IMA func CRITICAL_DATA to allow measurement of various kernel subsystems. This policy condition would enable the system administrators to restrict the measurement to the labels listed in "data_source:=". Limit the measurement to the labels that are specified in the IMA policy - CRITICAL_DATA+"data_source:=". If "data_sources:=" is not provided with the func CRITICAL_DATA, the data from all the supported kernel subsystems is measured. Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com> --- Documentation/ABI/testing/ima_policy | 2 ++ security/integrity/ima/ima_policy.c | 37 +++++++++++++++++++++++++--- 2 files changed, 36 insertions(+), 3 deletions(-)