[PATCH v4 0/3] dm: audit event logging

dm integrity and also stacked dm crypt devices track integrity violations internally. Thus, integrity violations could be polled from user space, e.g., by 'integritysetup status'. a number of integrity violations, but not when and where the violation exactly was taking place. The current error log to the kernel ring buffer, contains those information, time stamp and sector on device. However, for auditing the audit subsystem provides a separate logging mechanism which meets certain criteria for secure audit logging. With this small series we make use of the kernel audit framework and extend the dm driver to log audit events in case of such integrity violations. Further, we also log construction and destruction of the device mappings. We focus on dm-integrity and stacked dm-crypt devices for now. However, the helper functions to log audit messages should be applicable to dm-verity too. The first patch introduce generic audit wrapper functions. The second patch makes use of the audit wrapper functions in the dm-integrity.c. The third patch uses the wrapper functions in dm-crypt.c. The audit logs look like this if executing the following simple test: # dd if=/dev/zero of=test.img bs=1M count=1024 # losetup -f test.img # integritysetup -vD format --integrity sha256 -t 32 /dev/loop0 # integritysetup open -D /dev/loop0 --integrity sha256 integritytest # integritysetup status integritytest # integritysetup close integritytest # integritysetup open -D /dev/loop0 --integrity sha256 integritytest # integritysetup status integritytest # dd if=/dev/urandom of=/dev/loop0 bs=512 count=1 seek=100000 # dd if=/dev/mapper/integritytest of=/dev/null ------------------------- audit.log from auditd type=UNKNOWN[1336] msg=audit(1630425039.363:184): module=integrity op=ctr ppid=3807 pid=3819 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts2 ses=3 comm="integritysetup" exe="/sbin/integritysetup" subj==unconfined dev=254:3 error_msg='success' res=1 type=UNKNOWN[1336] msg=audit(1630425039.471:185): module=integrity op=dtr ppid=3807 pid=3819 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts2 ses=3 comm="integritysetup" exe="/sbin/integritysetup" subj==unconfined dev=254:3 error_msg='success' res=1 type=UNKNOWN[1336] msg=audit(1630425039.611:186): module=integrity op=ctr ppid=3807 pid=3819 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts2 ses=3 comm="integritysetup" exe="/sbin/integritysetup" subj==unconfined dev=254:3 error_msg='success' res=1 type=UNKNOWN[1336] msg=audit(1630425054.475:187): module=integrity op=dtr ppid=3807 pid=3819 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts2 ses=3 comm="integritysetup" exe="/sbin/integritysetup" subj==unconfined dev=254:3 error_msg='success' res=1 type=UNKNOWN[1336] msg=audit(1630425073.171:191): module=integrity op=ctr ppid=3807 pid=3883 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts2 ses=3 comm="integritysetup" exe="/sbin/integritysetup" subj==unconfined dev=254:3 error_msg='success' res=1 type=UNKNOWN[1336] msg=audit(1630425087.239:192): module=integrity op=dtr ppid=3807 pid=3902 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts2 ses=3 comm="integritysetup" exe="/sbin/integritysetup" subj==unconfined dev=254:3 error_msg='success' res=1 type=UNKNOWN[1336] msg=audit(1630425093.755:193): module=integrity op=ctr ppid=3807 pid=3906 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts2 ses=3 comm="integritysetup" exe="/sbin/integritysetup" subj==unconfined dev=254:3 error_msg='success' res=1 type=UNKNOWN[1337] msg=audit(1630425112.119:194): module=integrity op=integrity-checksum dev=254:3 sector=77480 res=0 type=UNKNOWN[1337] msg=audit(1630425112.119:195): module=integrity op=integrity-checksum dev=254:3 sector=77480 res=0 type=UNKNOWN[1337] msg=audit(1630425112.119:196): module=integrity op=integrity-checksum dev=254:3 sector=77480 res=0 type=UNKNOWN[1337] msg=audit(1630425112.119:197): module=integrity op=integrity-checksum dev=254:3 sector=77480 res=0 type=UNKNOWN[1337] msg=audit(1630425112.119:198): module=integrity op=integrity-checksum dev=254:3 sector=77480 res=0 type=UNKNOWN[1337] msg=audit(1630425112.119:199): module=integrity op=integrity-checksum dev=254:3 sector=77480 res=0 type=UNKNOWN[1337] msg=audit(1630425112.119:200): module=integrity op=integrity-checksum dev=254:3 sector=77480 res=0 type=UNKNOWN[1337] msg=audit(1630425112.119:201): module=integrity op=integrity-checksum dev=254:3 sector=77480 res=0 type=UNKNOWN[1337] msg=audit(1630425112.119:202): module=integrity op=integrity-checksum dev=254:3 sector=77480 res=0 type=UNKNOWN[1337] msg=audit(1630425112.119:203): module=integrity op=integrity-checksum dev=254:3 sector=77480 res=0 v4 Changes: - Added comments on intended use of wrapper functions in dm-audit.h - dm_audit_log_bio(): Fixed missing '=' as spotted by Paul - dm_audit_log_ti(): Handle wrong audit_type as suggested by Paul v3 Changes: - Use of two audit event types AUDIT_DM_EVENT und AUDIT_DM_CTRL - Additionaly use audit_log_task_info in case of AUDIT_DM_CTRL messages - Provide consistent fields per message type as suggested by Paul - Added sample events to commit message of [1/3] as suggested by Paul - Rebased on v5.14 v2 Changes: - Fixed compile errors if CONFIG_DM_AUDIT is not set - Fixed formatting and typos as suggested by Casey Michael Weiß (3): dm: introduce audit event module for device mapper dm integrity: log audit events for dm-integrity target dm crypt: log aead integrity violations to audit subsystem drivers/md/Kconfig | 10 +++++ drivers/md/Makefile | 4 ++ drivers/md/dm-audit.c | 84 ++++++++++++++++++++++++++++++++++++++ drivers/md/dm-audit.h | 66 ++++++++++++++++++++++++++++++ drivers/md/dm-crypt.c | 22 ++++++++-- drivers/md/dm-integrity.c | 25 ++++++++++-- include/uapi/linux/audit.h | 2 + 7 files changed, 205 insertions(+), 8 deletions(-) create mode 100644 drivers/md/dm-audit.c create mode 100644 drivers/md/dm-audit.h -- 2.20.1