[PATCH v38 33/39] Audit: Add record for multiple task security contexts

Create a new audit record AUDIT_MAC_TASK_CONTEXTS. An example of the MAC_TASK_CONTEXTS (1420) record is: type=MAC_TASK_CONTEXTS[1420] msg=audit(1600880931.832:113) subj_apparmor=unconfined subj_smack=_ When an audit event includes a AUDIT_MAC_TASK_CONTEXTS record the "subj=" field in other records in the event will be "subj=?". An AUDIT_MAC_TASK_CONTEXTS record is supplied when the system has multiple security modules that may make access decisions based on a subject security context. Acked-by: Paul Moore <paul(a)paul-moore.com&gt; Signed-off-by: Casey Schaufler <casey(a)schaufler-ca.com&gt; --- include/uapi/linux/audit.h | 1 + kernel/audit.c | 42 +++++++++++++++++++++++++++++++------- 2 files changed, 36 insertions(+), 7 deletions(-) diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index 7c1dc818b1d5..7a5966b46f38 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -143,6 +143,7 @@ #define AUDIT_MAC_UNLBL_STCDEL 1417 /* NetLabel: del a static label */ #define AUDIT_MAC_CALIPSO_ADD 1418 /* NetLabel: add CALIPSO DOI entry */ #define AUDIT_MAC_CALIPSO_DEL 1419 /* NetLabel: del CALIPSO DOI entry */ +#define AUDIT_MAC_TASK_CONTEXTS 1420 /* Multiple LSM task contexts */ #define AUDIT_FIRST_KERN_ANOM_MSG 1700 #define AUDIT_LAST_KERN_ANOM_MSG 1799 diff --git a/kernel/audit.c b/kernel/audit.c index ef6b2d38e38d..fb182f7e9d18 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -2228,6 +2228,7 @@ static void audit_buffer_aux_end(struct audit_buffer *ab) int audit_log_task_context(struct audit_buffer *ab) { + int i; int error; struct lsmblob blob; struct lsmcontext context; @@ -2236,16 +2237,43 @@ int audit_log_task_context(struct audit_buffer *ab) if (!lsmblob_is_set(&blob)) return 0; - error = security_secid_to_secctx(&blob, &context, LSMBLOB_FIRST); - - if (error) { - if (error != -EINVAL) + if (!lsm_multiple_contexts()) { + error = security_secid_to_secctx(&blob, &context, + LSMBLOB_FIRST); + if (error) { + if (error != -EINVAL) + goto error_path; + return 0; + } + audit_log_format(ab, " subj=%s", context.context); + security_release_secctx(&context); + } else { + /* Multiple LSMs provide contexts. Include an aux record. */ + audit_log_format(ab, " subj=?"); + error = audit_buffer_aux_new(ab, AUDIT_MAC_TASK_CONTEXTS); + if (error) goto error_path; - return 0; + for (i = 0; i < LSMBLOB_ENTRIES; i++) { + if (blob.secid[i] == 0) + continue; + error = security_secid_to_secctx(&blob, &context, i); + if (error) { + audit_log_format(ab, "%ssubj_%s=?", + i ? " " : "", + lsm_slot_to_name(i)); + if (error != -EINVAL) + audit_panic("error in audit_log_task_context"); + } else { + audit_log_format(ab, "%ssubj_%s=%s", + i ? " " : "", + lsm_slot_to_name(i), + context.context); + security_release_secctx(&context); + } + } + audit_buffer_aux_end(ab); } - audit_log_format(ab, " subj=%s", context.context); - security_release_secctx(&context); return 0; error_path: -- 2.37.3