Re: [RFC PATCH ghak32 V2 01/13] audit: add container id

From: Steve Grubb
Date: Mon Jun 04 2018 - 12:09:28 EST

On Friday, June 1, 2018 5:04:55 PM EDT Richard Guy Briggs wrote:
> Re: [RFC PATCH ghak32 V2 01/13] audit: add container id
>
> From: Richard Guy Briggs <rgb@xxxxxxxxxx>
> To: Me
> CC: linux-api@xxxxxxxxxxxxxxx, containers@xxxxxxxxxxxxxxxxxxxxxxxxxx, LKML
> <linux-kernel@xxxxxxxxxxxxxxx>, eparis@xxxxxxxxxxxxxx, ... Date: 6/1/18
> 5:04 PM
>
> On 2018-05-17 17:00, Steve Grubb wrote:
> > On Fri, 16 Mar 2018 05:00:28 -0400
> >
> > Richard Guy Briggs <rgb@xxxxxxxxxx> wrote:
> > > Implement the proc fs write to set the audit container ID of a
> > > process, emitting an AUDIT_CONTAINER record to document the event.
> > >
> > > This is a write from the container orchestrator task to a proc entry
> > > of the form /proc/PID/containerid where PID is the process ID of the
> > > newly created task that is to become the first task in a container,
> > > or an additional task added to a container.
> > >
> > > The write expects up to a u64 value (unset: 18446744073709551615).
> > >
> > > This will produce a record such as this:
> > > type=CONTAINER msg=audit(1519903238.968:261): op=set pid=596 uid=0
> > > subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 auid=0
> > > tty=pts0 ses=1 opid=596 old-contid=18446744073709551615 contid=123455
> > > res=0
> >
> > The was one thing I was wondering about. Currently when we set the
> > loginuid, the record is AUDIT_LOGINUID. The corollary is that when we
> > set the container id, the event should be AUDIT_CONTAINERID or
> > AUDIT_CONTAINER_ID.
> >
> > During syscall events, the path info is returned in a a record simply
> > called AUDIT_PATH, cwd info is returned in AUDIT_CWD. So, rather than
> > calling the record that gets attached to everything
> > AUDIT_CONTAINER_INFO, how about simply AUDIT_CONTAINER.
> >
> > > The "op" field indicates an initial set. The "pid" to "ses" fields
> > > are the orchestrator while the "opid" field is the object's PID, the
> > > process being "contained". Old and new container ID values are given
> > > in the "contid" fields, while res indicates its success.
> > >
> > > It is not permitted to self-set, unset or re-set the container ID. A
> > > child inherits its parent's container ID, but then can be set only
> > > once after.
> > >
> > > See: https://github.com/linux-audit/audit-kernel/issues/32
> > >
> > > Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
> > > ---
> > > fs/proc/base.c | 37 ++++++++++++++++++++
> > > include/linux/audit.h | 16 +++++++++
> > > include/linux/init_task.h | 4 ++-
> > > include/linux/sched.h | 1 +
> > > include/uapi/linux/audit.h | 2 ++
> > > kernel/auditsc.c | 84
> > > ++++++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 143
> > > insertions(+), 1 deletion(-)
> > >
> > > diff --git a/fs/proc/base.c b/fs/proc/base.c
> > > index 60316b5..6ce4fbe 100644
> > > --- a/fs/proc/base.c
> > > +++ b/fs/proc/base.c
> > > @@ -1299,6 +1299,41 @@ static ssize_t proc_sessionid_read(struct file
> > > * file, char __user * buf, .read = proc_sessionid_read,
> > > .llseek = generic_file_llseek,
> > > };
> > > +
> > > +static ssize_t proc_containerid_write(struct file *file, const char
> > > __user *buf,
> > > + size_t count, loff_t *ppos)
> > > +{
> > > + struct inode *inode = file_inode(file);
> > > + u64 containerid;
> > > + int rv;
> > > + struct task_struct *task = get_proc_task(inode);
> > > +
> > > + if (!task)
> > > + return -ESRCH;
> > > + if (*ppos != 0) {
> > > + /* No partial writes. */
> > > + put_task_struct(task);
> > > + return -EINVAL;
> > > + }
> > > +
> > > + rv = kstrtou64_from_user(buf, count, 10, &containerid);
> > > + if (rv < 0) {
> > > + put_task_struct(task);
> > > + return rv;
> > > + }
> > > +
> > > + rv = audit_set_containerid(task, containerid);
> > > + put_task_struct(task);
> > > + if (rv < 0)
> > > + return rv;
> > > + return count;
> > > +}
> > > +
> > > +static const struct file_operations proc_containerid_operations = {
> > > + .write = proc_containerid_write,
> > > + .llseek = generic_file_llseek,
> > > +};
> > > +
> > > #endif
> > >
> > > #ifdef CONFIG_FAULT_INJECTION
> > > @@ -2961,6 +2996,7 @@ static int proc_pid_patch_state(struct seq_file
> > > *m, struct pid_namespace *ns, #ifdef CONFIG_AUDITSYSCALL
> > > REG("loginuid", S_IWUSR|S_IRUGO, proc_loginuid_operations),
> > > REG("sessionid", S_IRUGO, proc_sessionid_operations),
> > > + REG("containerid", S_IWUSR, proc_containerid_operations),
> > > #endif
> > > #ifdef CONFIG_FAULT_INJECTION
> > > REG("make-it-fail", S_IRUGO|S_IWUSR,
> > > proc_fault_inject_operations), @@ -3355,6 +3391,7 @@ static int
> > > proc_tid_comm_permission(struct inode *inode, int mask) #ifdef
> > > CONFIG_AUDITSYSCALL REG("loginuid", S_IWUSR|S_IRUGO,
> > > proc_loginuid_operations), REG("sessionid", S_IRUGO,
> > > proc_sessionid_operations),
> > > + REG("containerid", S_IWUSR, proc_containerid_operations),
> > > #endif
> > > #ifdef CONFIG_FAULT_INJECTION
> > > REG("make-it-fail", S_IRUGO|S_IWUSR,
> > > proc_fault_inject_operations), diff --git a/include/linux/audit.h
> > > b/include/linux/audit.h index af410d9..fe4ba3f 100644
> > > --- a/include/linux/audit.h
> > > +++ b/include/linux/audit.h
> > > @@ -29,6 +29,7 @@
> > >
> > > #define AUDIT_INO_UNSET ((unsigned long)-1)
> > > #define AUDIT_DEV_UNSET ((dev_t)-1)
> > > +#define INVALID_CID AUDIT_CID_UNSET
> > >
> > > struct audit_sig_info {
> > > uid_t uid;
> > > @@ -321,6 +322,7 @@ static inline void audit_ptrace(struct
> > > task_struct *t) extern int auditsc_get_stamp(struct audit_context
> > > *ctx, struct timespec64 *t, unsigned int *serial);
> > > extern int audit_set_loginuid(kuid_t loginuid);
> > > +extern int audit_set_containerid(struct task_struct *tsk, u64
> > > containerid);
> > > static inline kuid_t audit_get_loginuid(struct task_struct *tsk)
> > > {
> > > @@ -332,6 +334,11 @@ static inline unsigned int
> > > audit_get_sessionid(struct task_struct *tsk) return tsk->sessionid;
> > > }
> > >
> > > +static inline u64 audit_get_containerid(struct task_struct *tsk)
> > > +{
> > > + return tsk->containerid;
> > > +}
> > > +
> > > extern void __audit_ipc_obj(struct kern_ipc_perm *ipcp);
> > > extern void __audit_ipc_set_perm(unsigned long qbytes, uid_t uid,
> > > gid_t gid, umode_t mode); extern void __audit_bprm(struct
> > > linux_binprm *bprm); @@ -517,6 +524,10 @@ static inline unsigned int
> > > audit_get_sessionid(struct task_struct *tsk) {
> > > return -1;
> > > }
> > > +static inline kuid_t audit_get_containerid(struct task_struct *tsk)
> > > +{
> > > + return INVALID_CID;
> > > +}
> > > static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp)
> > > { }
> > > static inline void audit_ipc_set_perm(unsigned long qbytes, uid_t
> > > uid, @@ -581,6 +592,11 @@ static inline bool
> > > audit_loginuid_set(struct task_struct *tsk) return
> > > uid_valid(audit_get_loginuid(tsk)); }
> > >
> > > +static inline bool audit_containerid_set(struct task_struct *tsk)
> > > +{
> > > + return audit_get_containerid(tsk) != INVALID_CID;
> > > +}
> > > +
> > > static inline void audit_log_string(struct audit_buffer *ab, const
> > > char *buf) {
> > > audit_log_n_string(ab, buf, strlen(buf));
> > > diff --git a/include/linux/init_task.h b/include/linux/init_task.h
> > > index 6a53262..046bd0a 100644
> > > --- a/include/linux/init_task.h
> > > +++ b/include/linux/init_task.h
> > > @@ -18,6 +18,7 @@
> > > #include <linux/sched/rt.h>
> > > #include <linux/livepatch.h>
> > > #include <linux/mm_types.h>
> > > +#include <linux/audit.h>
> > >
> > > #include <asm/thread_info.h>
> > >
> > > @@ -120,7 +121,8 @@
> > > #ifdef CONFIG_AUDITSYSCALL
> > > #define INIT_IDS \
> > > .loginuid = INVALID_UID, \
> > > - .sessionid = (unsigned int)-1,
> > > + .sessionid = (unsigned int)-1, \
> > > + .containerid = INVALID_CID,
> > > #else
> > > #define INIT_IDS
> > > #endif
> > > diff --git a/include/linux/sched.h b/include/linux/sched.h
> > > index d258826..1b82191 100644
> > > --- a/include/linux/sched.h
> > > +++ b/include/linux/sched.h
> > > @@ -796,6 +796,7 @@ struct task_struct {
> > > #ifdef CONFIG_AUDITSYSCALL
> > > kuid_t loginuid;
> > > unsigned int sessionid;
> > > + u64 containerid;
> > > #endif
> > > struct seccomp seccomp;
> > >
> > > diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> > > index 4e61a9e..921a71f 100644
> > > --- a/include/uapi/linux/audit.h
> > > +++ b/include/uapi/linux/audit.h
> > > @@ -71,6 +71,7 @@
> > > #define AUDIT_TTY_SET 1017 /* Set TTY auditing
> > > status */ #define AUDIT_SET_FEATURE 1018 /* Turn an
> > > audit feature on or off */ #define AUDIT_GET_FEATURE
> > > 1019 /* Get which features are enabled */ +#define
> > > AUDIT_CONTAINER 1020 /* Define the container id
> > > and information */ #define AUDIT_FIRST_USER_MSG 1100 /*
> > > Userspace messages mostly uninteresting to kernel */ #define
> > > AUDIT_USER_AVC 1107 /* We filter this
> > > differently */ @@ -465,6 +466,7 @@ struct audit_tty_status { };
> > >
> > > #define AUDIT_UID_UNSET (unsigned int)-1
> > > +#define AUDIT_CID_UNSET ((u64)-1)
> > >
> > > /* audit_rule_data supports filter rules with both integer and string
> > > * fields. It corresponds with AUDIT_ADD_RULE, AUDIT_DEL_RULE and
> > > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > > index 4e0a4ac..29c8482 100644
> > > --- a/kernel/auditsc.c
> > > +++ b/kernel/auditsc.c
> > > @@ -2073,6 +2073,90 @@ int audit_set_loginuid(kuid_t loginuid)
> > > return rc;
> > > }
> > >
> > > +static int audit_set_containerid_perm(struct task_struct *task, u64
> > > containerid) +{
> > > + struct task_struct *parent;
> > > + u64 pcontainerid, ccontainerid;
> > > +
> > > + /* Don't allow to set our own containerid */
> > > + if (current == task)
> > > + return -EPERM;
> > > + /* Don't allow the containerid to be unset */
> > > + if (!cid_valid(containerid))
> > > + return -EINVAL;
> > > + /* if we don't have caps, reject */
> > > + if (!capable(CAP_AUDIT_CONTROL))
> > > + return -EPERM;
> > > + /* if containerid is unset, allow */
> > > + if (!audit_containerid_set(task))
> > > + return 0;
> > > + /* it is already set, and not inherited from the parent,
> > > reject */
> > > + ccontainerid = audit_get_containerid(task);
> > > + rcu_read_lock();
> > > + parent = rcu_dereference(task->real_parent);
> > > + rcu_read_unlock();
> > > + task_lock(parent);
> > > + pcontainerid = audit_get_containerid(parent);
> > > + task_unlock(parent);
> > > + if (ccontainerid != pcontainerid)
> > > + return -EPERM;
> > > + return 0;
> > > +}
> > > +
> > > +static void audit_log_set_containerid(struct task_struct *task, u64
> > > oldcontainerid,
> > > + u64 containerid, int rc)
> > > +{
> > > + struct audit_buffer *ab;
> > > + uid_t uid;
> > > + struct tty_struct *tty;
> > > +
> > > + if (!audit_enabled)
> > > + return;
> > > +
> > > + ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONTAINER);
> > > + if (!ab)
> > > + return;
> > > +
> > > + uid = from_kuid(&init_user_ns, task_uid(current));
> > > + tty = audit_get_tty(current);
> > > +
> > > + audit_log_format(ab, "op=set pid=%d uid=%u",
> > > task_tgid_nr(current), uid);
> > > + audit_log_task_context(ab);
> > > + audit_log_format(ab, " auid=%u tty=%s ses=%u opid=%d
> > > old-contid=%llu contid=%llu res=%d",
> >
> > The preferred ordering would be: op, opid, old-contid, contid, pid, uid,
> > tty, ses, subj, comm, exe, res. This groups the searchable fields
> > together using the most common ordering so that parsing is simple.
>
> Where would you like auid? It appears that just before uid would be the
> right place, if not in place of uid, but this is just a guess since it
> isn't consistent.


Just after the uid is the proper place. The most common sequence is:
pid, uid, auid, tty, session, subject context, comm, exe.

Thanks,
-Steve