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SubjectRe: [RFC PATCH ghak90 (was ghak32) V3 01/10] audit: add container id
On 2018-06-06 13:56, Steve Grubb wrote:
> On Wednesday, June 6, 2018 12:58:28 PM EDT Richard Guy Briggs wrote:
> > Implement the proc fs write to set the audit container identifier of a
> > process, emitting an AUDIT_CONTAINER_ID record to document the event.
> >
> > This is a write from the container orchestrator task to a proc entry of
> > the form /proc/PID/audit_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).
> >
> > The writer must have capability CAP_AUDIT_CONTROL.
> >
> > This will produce a record such as this:
> > type=CONTAINER_ID msg=audit(2018-06-06 12:39:29.636:26949) : op=set
> > opid=2209 old-contid=18446744073709551615 contid=123456 pid=628 auid=root
> > uid=root tty=ttyS0 ses=1
> > subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 comm=bash
> > exe=/usr/bin/bash res=yes
> >
> > 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 audit container identifier values are
> > given in the "contid" fields, while res indicates its success.
> >
> > It is not permitted to unset or re-set the audit container identifier.
> > A child inherits its parent's audit container identifier, but then can
> > be set only once after.
> >
> > See: https://github.com/linux-audit/audit-kernel/issues/90
> > See: https://github.com/linux-audit/audit-userspace/issues/51
> > See: https://github.com/linux-audit/audit-testsuite/issues/64
> > See:
> > https://github.com/linux-audit/audit-kernel/wiki/RFE-Audit-Container-ID
> >
> > Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> > ---
> > fs/proc/base.c | 37 ++++++++++++++++++++++++
> > include/linux/audit.h | 25 ++++++++++++++++
> > include/uapi/linux/audit.h | 2 ++
> > kernel/auditsc.c | 71
> > ++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 135
> > insertions(+)
> >
> > diff --git a/fs/proc/base.c b/fs/proc/base.c
> > index eafa39a..318dff4 100644
> > --- a/fs/proc/base.c
> > +++ b/fs/proc/base.c
> > @@ -1302,6 +1302,41 @@ static ssize_t proc_sessionid_read(struct file *
> > file, char __user * buf, .read = proc_sessionid_read,
> > .llseek = generic_file_llseek,
> > };
> > +
> > +static ssize_t proc_contid_write(struct file *file, const char __user
> > *buf, + size_t count, loff_t *ppos)
> > +{
> > + struct inode *inode = file_inode(file);
> > + u64 contid;
> > + 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, &contid);
> > + if (rv < 0) {
> > + put_task_struct(task);
> > + return rv;
> > + }
> > +
> > + rv = audit_set_contid(task, contid);
> > + put_task_struct(task);
> > + if (rv < 0)
> > + return rv;
> > + return count;
> > +}
> > +
> > +static const struct file_operations proc_contid_operations = {
> > + .write = proc_contid_write,
> > + .llseek = generic_file_llseek,
> > +};
> > +
> > #endif
> >
> > #ifdef CONFIG_FAULT_INJECTION
> > @@ -2995,6 +3030,7 @@ 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("audit_containerid", S_IWUSR, proc_contid_operations),
> > #endif
> > #ifdef CONFIG_FAULT_INJECTION
> > REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
> > @@ -3386,6 +3422,7 @@ 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("audit_containerid", S_IWUSR, proc_contid_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 4f824c4..497cd81 100644
> > --- a/include/linux/audit.h
> > +++ b/include/linux/audit.h
> > @@ -219,6 +219,8 @@ static inline void audit_log_task_info(struct
> > audit_buffer *ab, struct audit_task_info {
> > kuid_t loginuid;
> > unsigned int sessionid;
> > + u64 contid;
> > + bool inherited; /* containerid inheritance */
> > struct audit_context *ctx;
> > };
> > extern struct audit_task_info init_struct_audit;
> > @@ -331,6 +333,7 @@ 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_contid(struct task_struct *tsk, u64 contid);
> >
> > static inline kuid_t audit_get_loginuid(struct task_struct *tsk)
> > {
> > @@ -348,6 +351,14 @@ static inline unsigned int audit_get_sessionid(struct
> > task_struct *tsk) return AUDIT_SID_UNSET;
> > }
> >
> > +static inline u64 audit_get_contid(struct task_struct *tsk)
> > +{
> > + if (!tsk->audit)
> > + return AUDIT_CID_UNSET;
> > + else
> > + return tsk->audit->contid;
> > +}
> > +
> > 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);
> > @@ -542,6 +553,10 @@ static inline unsigned int audit_get_sessionid(struct
> > task_struct *tsk) {
> > return AUDIT_SID_UNSET;
> > }
> > +static inline kuid_t audit_get_contid(struct task_struct *tsk)
> > +{
> > + return AUDIT_CID_UNSET;
> > +}
> > static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp)
> > { }
> > static inline void audit_ipc_set_perm(unsigned long qbytes, uid_t uid,
> > @@ -606,6 +621,16 @@ static inline bool audit_loginuid_set(struct
> > task_struct *tsk) return uid_valid(audit_get_loginuid(tsk));
> > }
> >
> > +static inline bool cid_valid(u64 contid)
> > +{
> > + return contid != AUDIT_CID_UNSET;
> > +}
> > +
> > +static inline bool audit_contid_set(struct task_struct *tsk)
> > +{
> > + return cid_valid(audit_get_contid(tsk));
> > +}
> > +
> > 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/uapi/linux/audit.h b/include/uapi/linux/audit.h
> > index 04f9bd2..c3b1aca 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_ID 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 */
> > @@ -466,6 +467,7 @@ struct audit_tty_status {
> >
> > #define AUDIT_UID_UNSET (unsigned int)-1
> > #define AUDIT_SID_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 59ef7a81..611e926 100644
> > --- a/kernel/auditsc.c
> > +++ b/kernel/auditsc.c
> > @@ -956,6 +956,8 @@ int audit_alloc(struct task_struct *tsk)
> > return -ENOMEM;
> > info->loginuid = audit_get_loginuid(current);
> > info->sessionid = audit_get_sessionid(current);
> > + info->contid = audit_get_contid(current);
> > + info->inherited = true;
> > tsk->audit = info;
> >
> > if (likely(!audit_ever_enabled))
> > @@ -985,6 +987,8 @@ int audit_alloc(struct task_struct *tsk)
> > struct audit_task_info init_struct_audit = {
> > .loginuid = INVALID_UID,
> > .sessionid = AUDIT_SID_UNSET,
> > + .contid = AUDIT_CID_UNSET,
> > + .inherited = true,
> > .ctx = NULL,
> > };
> >
> > @@ -2112,6 +2116,73 @@ int audit_set_loginuid(kuid_t loginuid)
> > }
> >
> > /**
> > + * audit_set_contid - set current task's audit_context contid
> > + * @contid: contid value
> > + *
> > + * Returns 0 on success, -EPERM on permission failure.
> > + *
> > + * Called (set) from fs/proc/base.c::proc_contid_write().
> > + */
> > +int audit_set_contid(struct task_struct *task, u64 contid)
> > +{
> > + u64 oldcontid;
> > + int rc = 0;
> > + struct audit_buffer *ab;
> > + uid_t uid;
> > + struct tty_struct *tty;
> > + char comm[sizeof(current->comm)];
> > +
> > + /* Can't set if audit disabled */
> > + if (!task->audit)
> > + return -ENOPROTOOPT;
> > + oldcontid = audit_get_contid(task);
> > + /* Don't allow the audit containerid to be unset */
> > + if (!cid_valid(contid))
> > + rc = -EINVAL;
> > + /* if we don't have caps, reject */
> > + else if (!capable(CAP_AUDIT_CONTROL))
> > + rc = -EPERM;
> > + /* if task has children or is not single-threaded, deny */
> > + else if (!list_empty(&task->children))
> > + rc = -EBUSY;
> > + else if (!(thread_group_leader(task) && thread_group_empty(task)))
> > + rc = -EALREADY;
> > + /* it is already set, and not inherited from the parent, reject */
> > + else if (cid_valid(oldcontid) && !task->audit->inherited)
> > + rc = -EEXIST;
> > + if (!rc) {
> > + task_lock(task);
> > + task->audit->contid = contid;
> > + task->audit->inherited = false;
> > + task_unlock(task);
> > + }
> > +
> > + if (!audit_enabled)
> > + return rc;
> > +
> > + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONTAINER_ID);
> > + if (!ab)
> > + return rc;
> > +
> > + uid = from_kuid(&init_user_ns, task_uid(current));
> > + tty = audit_get_tty(current);
> > + audit_log_format(ab, "op=set opid=%d old-contid=%llu contid=%llu pid=%d
> > uid=%u auid=%u tty=%s ses=%u", + task_tgid_nr(task), oldcontid,
> contid,
> > + task_tgid_nr(current), uid
> > + from_kuid(&init_user_ns, audit_get_loginuid(current)),
> > + tty ? tty_name(tty) : "(none)",
> > + audit_get_sessionid(current));
>
> The event code doesn't match the example event at the top. (uid and auid are
> transposed.) But the code looks right.

Hmmm, I thought I checked that explicitly... That event sample must
have come from the previous compile before I fixed that.

> Ack for the event format.

Thanks!

> -Steve
>
> > + audit_put_tty(tty);
> > + audit_log_task_context(ab);
> > + audit_log_format(ab, " comm=");
> > + audit_log_untrustedstring(ab, get_task_comm(comm, current));
> > + audit_log_d_path_exe(ab, current->mm);
> > + audit_log_format(ab, " res=%d", !rc);
> > + audit_log_end(ab);
> > + return rc;
> > +}
> > +
> > +/**
> > * __audit_mq_open - record audit data for a POSIX MQ open
> > * @oflag: open flag
> > * @mode: mode bits

- RGB

--
Richard Guy Briggs <rgb@redhat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635

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