On Thursday, May 3, 2018 4:51:36 PM EDT Tyler Hicks wrote: > On 05/03/2018 03:48 PM, Paul Moore wrote: > > On Thu, May 3, 2018 at 4:42 PM, Steve Grubb <sgrubb@xxxxxxxxxx> wrote: > >> On Thursday, May 3, 2018 4:18:26 PM EDT Paul Moore wrote: > >>> On Wed, May 2, 2018 at 2:18 PM, Steve Grubb <sgrubb@xxxxxxxxxx> wrote: > >>>> On Wednesday, May 2, 2018 11:53:19 AM EDT Tyler Hicks wrote: > >>>>> The decision to log a seccomp action will always be subject to the > >>>>> value of the kernel.seccomp.actions_logged sysctl, even for processes > >>>>> that are being inspected via the audit subsystem, in an upcoming > >>>>> patch. > >>>>> Therefore, we need to emit an audit record on attempts at writing to > >>>>> the > >>>>> actions_logged sysctl when auditing is enabled. > >>>>> > >>>>> This patch updates the write handler for the actions_logged sysctl to > >>>>> emit an audit record on attempts to write to the sysctl. Successful > >>>>> writes to the sysctl will result in a record that includes a > >>>>> normalized > >>>>> list of logged actions in the "actions" field and a "res" field equal > >>>>> to > >>>>> 0. Unsuccessful writes to the sysctl will result in a record that > >>>>> doesn't include the "actions" field and has a "res" field equal to 1. > >>>>> > >>>>> Not all unsuccessful writes to the sysctl are audited. For example, > >>>>> an > >>>>> audit record will not be emitted if an unprivileged process attempts > >>>>> to > >>>>> open the sysctl file for reading since that access control check is > >>>>> not > >>>>> part of the sysctl's write handler. > >>>>> > >>>>> Below are some example audit records when writing various strings to > >>>>> the > >>>>> actions_logged sysctl. > >>>>> > >>>>> Writing "not-a-real-action", when the kernel.seccomp.actions_logged > >>>>> sysctl previously was "kill_process kill_thread trap errno trace > >>>>> log", > >>>>> > >>>>> emits this audit record: > >>>>> type=CONFIG_CHANGE msg=audit(1525275273.537:130): op=seccomp-logging > >>>>> old-actions=kill_process,kill_thread,trap,errno,trace,log res=0 > >>>>> > >>>>> If you then write "kill_process kill_thread errno trace log", this > >>>>> audit > >>>>> > >>>>> record is emitted: > >>>>> type=CONFIG_CHANGE msg=audit(1525275310.208:136): op=seccomp-logging > >>>>> actions=kill_process,kill_thread,errno,trace,log > >>>>> old-actions=kill_process,kill_thread,trap,errno,trace,log res=1 > >>>>> > >>>>> If you then write the string "log log errno trace kill_process > >>>>> kill_thread", which is unordered and contains the log action twice, > >>>>> > >>>>> it results in the same actions value as the previous record: > >>>>> type=CONFIG_CHANGE msg=audit(1525275325.613:142): op=seccomp-logging > >>>>> actions=kill_process,kill_thread,errno,trace,log > >>>>> old-actions=kill_process,kill_thread,errno,trace,log res=1 > >>>>> > >>>>> No audit records are generated when reading the actions_logged > >>>>> sysctl. > >>>> > >>>> ACK for the format of the records. > >>> > >>> I just wanted to clarify the record format with you Steve ... the > >>> "actions" and "old-actions" fields may not be included in the record > >>> in cases where there is an error building the action value string, are > >>> you okay with that or would you prefer the fields to always be > >>> included but with a "?" for the value? > >> > >> A ? would be more in line with how other things are handled. > > > > That's what I thought. > > > > Would you mind putting together a v3 Tyler? :) > > To be clear, "?" is only to be used when the call to > seccomp_names_from_actions_logged() fails, right? Yes and that is a question mark with no quotes in the audit record. > If the sysctl write fails for some other reason, such as when an invalid > action name is specified, can you confirm that you still want *no* > "actions" field, Its best that fields do not disappear. In the case of invalid input, you can just leave the new value as ? so that nothing malicious can be injected into the logs > the "old-actions" field to be the value prior to attempting the update to > the sysctl, and res to be 0? Yes -Steve -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
