Re: [PATCH ghak90 V5 05/10] audit: add containerid support for ptrace and signals

On 2019-03-27 22:17, Ondrej Mosnacek wrote: > On Fri, Mar 15, 2019 at 7:34 PM Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > > Add audit container identifier support to ptrace and signals. In > > particular, the "ref" field provides a way to label the auxiliary record > > to which it is associated. > > > > Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; > > Acked-by: Serge Hallyn <serge(a)hallyn.com&gt; > > Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; > > --- > > include/linux/audit.h | 1 + > > kernel/audit.c | 2 ++ > > kernel/audit.h | 2 ++ > > kernel/auditsc.c | 23 +++++++++++++++++------ > > 4 files changed, 22 insertions(+), 6 deletions(-) > > > > diff --git a/include/linux/audit.h b/include/linux/audit.h > > index 43438192ca2a..ebd6625ca80e 100644 > > --- a/include/linux/audit.h > > +++ b/include/linux/audit.h > > @@ -35,6 +35,7 @@ struct audit_sig_info { > > uid_t uid; > > pid_t pid; > > char ctx[0]; > > + u64 cid; > > }; > > It seems like this structure implicitly defines the format of some > message that is sent to userspace... If so, how will userspace detect > that a new format (including the cid) is being used? Even assuming the > fixed order as pointed out by Neil, the message still seems to be > variable-sized so userspace cannot even use the length to infer that. > Am I missing something here? (I hope I am :) How humble of you again. No, you're not missing something. This ends up being an api change... That can be fixed in userspace by checking for AUDIT_FEATURE_BITMAP_CONTAINERID, but how do we make a newer kernel not break an older userspace... I think this was the original rationale for adding it after the ctx but totally missing the fact that the latter is a variable-length field.

This patch really should be split into audit_sig_cid changes in a patch by itself and target_cid changes which could go with the second and fourth patches.

> > struct audit_buffer; > > diff --git a/kernel/audit.c b/kernel/audit.c > > index 8cc0e88d7f2a..cfa659b3f6c4 100644 > > --- a/kernel/audit.c > > +++ b/kernel/audit.c > > @@ -138,6 +138,7 @@ struct audit_net { > > kuid_t audit_sig_uid = INVALID_UID; > > pid_t audit_sig_pid = -1; > > u32 audit_sig_sid = 0; > > +u64 audit_sig_cid = AUDIT_CID_UNSET; > > > > /* Records can be lost in several ways: > > 0) [suppressed in audit_alloc] > > @@ -1515,6 +1516,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) > > memcpy(sig_data->ctx, ctx, len); > > security_release_secctx(ctx, len); > > } > > + sig_data->cid = audit_sig_cid; > > audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0, > > sig_data, sizeof(*sig_data) + len); > > kfree(sig_data); > > diff --git a/kernel/audit.h b/kernel/audit.h > > index c00e2ee3c6b3..c5ac6436317e 100644 > > --- a/kernel/audit.h > > +++ b/kernel/audit.h > > @@ -148,6 +148,7 @@ struct audit_context { > > kuid_t target_uid; > > unsigned int target_sessionid; > > u32 target_sid; > > + u64 target_cid; > > char target_comm[TASK_COMM_LEN]; > > > > struct audit_tree_refs *trees, *first_trees; > > @@ -344,6 +345,7 @@ extern void audit_filter_inodes(struct task_struct *tsk, > > extern pid_t audit_sig_pid; > > extern kuid_t audit_sig_uid; > > extern u32 audit_sig_sid; > > +extern u64 audit_sig_cid; > > > > extern int audit_filter(int msgtype, unsigned int listtype); > > > > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > > index a8c8b44b954d..f04e115df5dc 100644 > > --- a/kernel/auditsc.c > > +++ b/kernel/auditsc.c > > @@ -113,6 +113,7 @@ struct audit_aux_data_pids { > > kuid_t target_uid[AUDIT_AUX_PIDS]; > > unsigned int target_sessionid[AUDIT_AUX_PIDS]; > > u32 target_sid[AUDIT_AUX_PIDS]; > > + u64 target_cid[AUDIT_AUX_PIDS]; > > char target_comm[AUDIT_AUX_PIDS][TASK_COMM_LEN]; > > int pid_count; > > }; > > @@ -1514,7 +1515,7 @@ static void audit_log_exit(void) > > for (aux = context->aux_pids; aux; aux = aux->next) { > > struct audit_aux_data_pids *axs = (void *)aux; > > > > - for (i = 0; i < axs->pid_count; i++) > > + for (i = 0; i < axs->pid_count; i++) { > > if (audit_log_pid_context(context, axs->target_pid[i], > > axs->target_auid[i], > > axs->target_uid[i], > > @@ -1522,14 +1523,20 @@ static void audit_log_exit(void) > > axs->target_sid[i], > > axs->target_comm[i])) > > call_panic = 1; > > + audit_log_contid(context, axs->target_cid[i]); > > + } > > } > > > > - if (context->target_pid && > > - audit_log_pid_context(context, context->target_pid, > > - context->target_auid, context->target_uid, > > - context->target_sessionid, > > - context->target_sid, context->target_comm)) > > + if (context->target_pid) { > > + if (audit_log_pid_context(context, context->target_pid, > > + context->target_auid, > > + context->target_uid, > > + context->target_sessionid, > > + context->target_sid, > > + context->target_comm)) > > call_panic = 1; > > + audit_log_contid(context, context->target_cid); > > + } > > > > if (context->pwd.dentry && context->pwd.mnt) { > > ab = audit_log_start(context, GFP_KERNEL, AUDIT_CWD); > > @@ -2360,6 +2367,7 @@ void __audit_ptrace(struct task_struct *t) > > context->target_uid = task_uid(t); > > context->target_sessionid = audit_get_sessionid(t); > > security_task_getsecid(t, &context->target_sid); > > + context->target_cid = audit_get_contid(t); > > memcpy(context->target_comm, t->comm, TASK_COMM_LEN); > > } > > > > @@ -2387,6 +2395,7 @@ int audit_signal_info(int sig, struct task_struct *t) > > else > > audit_sig_uid = uid; > > security_task_getsecid(current, &audit_sig_sid); > > + audit_sig_cid = audit_get_contid(current); > > } > > > > if (!audit_signals || audit_dummy_context()) > > @@ -2400,6 +2409,7 @@ int audit_signal_info(int sig, struct task_struct *t) > > ctx->target_uid = t_uid; > > ctx->target_sessionid = audit_get_sessionid(t); > > security_task_getsecid(t, &ctx->target_sid); > > + ctx->target_cid = audit_get_contid(t); > > memcpy(ctx->target_comm, t->comm, TASK_COMM_LEN); > > return 0; > > } > > @@ -2421,6 +2431,7 @@ int audit_signal_info(int sig, struct task_struct *t) > > axp->target_uid[axp->pid_count] = t_uid; > > axp->target_sessionid[axp->pid_count] = audit_get_sessionid(t); > > security_task_getsecid(t, &axp->target_sid[axp->pid_count]); > > + axp->target_cid[axp->pid_count] = audit_get_contid(t); > > memcpy(axp->target_comm[axp->pid_count], t->comm, TASK_COMM_LEN); > > axp->pid_count++; > > > > Ondrej Mosnacek <omosnace at redhat dot com> - RGB