Re: [PATCH ghak90 V9 06/13] audit: add contid support for signalling the audit daemon

Add audit container identifier support to the action of signalling the audit daemon. Since this would need to add an element to the audit_sig_info struct, a new record type AUDIT_SIGNAL_INFO2 was created with a new audit_sig_info2 struct. Corresponding support is required in the userspace code to reflect the new record request and reply type. An older userspace won't break since it won't know to request this record type. Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; --- include/linux/audit.h | 8 ++++ include/uapi/linux/audit.h | 1 + kernel/audit.c | 95 ++++++++++++++++++++++++++++++++++++++++++++- security/selinux/nlmsgtab.c | 1 + 4 files changed, 104 insertions(+), 1 deletion(-) diff --git a/include/linux/audit.h b/include/linux/audit.h index 5eeba0efffc2..89cf7c66abe6 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -22,6 +22,13 @@ struct audit_sig_info { char ctx[]; }; +struct audit_sig_info2 { + uid_t uid; + pid_t pid; + u32 cid_len; + char data[]; +}; + struct audit_buffer; struct audit_context; struct inode; @@ -105,6 +112,7 @@ struct audit_contobj { u64 id; struct task_struct *owner; refcount_t refcount; + refcount_t sigflag; struct rcu_head rcu; };

diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index fd98460c983f..a56ad77069b9 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -72,6 +72,7 @@ #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_OP 1020 /* Define the container id and info */ +#define AUDIT_SIGNAL_INFO2 1021 /* Get info auditd signal sender */ #define AUDIT_FIRST_USER_MSG 1100 /* Userspace messages mostly uninteresting to kernel */ #define AUDIT_USER_AVC 1107 /* We filter this differently */ diff --git a/kernel/audit.c b/kernel/audit.c index a09f8f661234..54dd2cb69402 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -126,6 +126,8 @@ struct auditd_connection { kuid_t audit_sig_uid = INVALID_UID; pid_t audit_sig_pid = -1; u32 audit_sig_sid = 0; +static struct audit_contobj *audit_sig_cid; +static struct task_struct *audit_sig_atsk;

/* Records can be lost in several ways: 0) [suppressed in audit_alloc] @@ -239,7 +241,33 @@ void _audit_contobj_put(struct audit_contobj *cont) { if (!cont) return; - if (refcount_dec_and_test(&cont->refcount)) { + if (refcount_dec_and_test(&cont->refcount) && !refcount_read(&cont->sigflag)) { + put_task_struct(cont->owner); + list_del_rcu(&cont->list); + kfree_rcu(cont, rcu); + } +}

+/* rcu_read_lock must be held by caller unless new */ +static struct audit_contobj *_audit_contobj_get_sig(struct task_struct *tsk) +{ + struct audit_contobj *cont; + + if (!tsk->audit) + return NULL; + cont = tsk->audit->cont; + if (cont) + refcount_set(&cont->sigflag, 1); + return cont; +}

+/* rcu_read_lock must be held by caller */ +static void _audit_contobj_put_sig(struct audit_contobj *cont) +{ + if (!cont) + return; + refcount_set(&cont->sigflag, 0); + if (!refcount_read(&cont->refcount)) { put_task_struct(cont->owner); list_del_rcu(&cont->list); kfree_rcu(cont, rcu); @@ -309,6 +337,13 @@ void audit_free(struct task_struct *tsk) info = tsk->audit; tsk->audit = NULL; kmem_cache_free(audit_task_cache, info); + rcu_read_lock(); + if (audit_sig_atsk == tsk) { + _audit_contobj_put_sig(audit_sig_cid); + audit_sig_cid = NULL; + audit_sig_atsk = NULL; + } + rcu_read_unlock(); } /** @@ -1132,6 +1167,7 @@ static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type) case AUDIT_ADD_RULE: case AUDIT_DEL_RULE: case AUDIT_SIGNAL_INFO: + case AUDIT_SIGNAL_INFO2: case AUDIT_TTY_GET: case AUDIT_TTY_SET: case AUDIT_TRIM: @@ -1294,6 +1330,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) struct audit_buffer *ab; u16 msg_type = nlh->nlmsg_type; struct audit_sig_info *sig_data; + struct audit_sig_info2 *sig_data2; char *ctx = NULL; u32 len; @@ -1559,6 +1596,52 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) sig_data, sizeof(*sig_data) + len); kfree(sig_data); break; + case AUDIT_SIGNAL_INFO2: { + unsigned int contidstrlen = 0; + + len = 0; + if (audit_sig_sid) { + err = security_secid_to_secctx(audit_sig_sid, &ctx, + &len); + if (err) + return err; + } + if (audit_sig_cid) { + contidstr = kmalloc(21, GFP_KERNEL); + if (!contidstr) { + if (audit_sig_sid) + security_release_secctx(ctx, len); + return -ENOMEM; + } + contidstrlen = scnprintf(contidstr, 20, "%llu", audit_sig_cid->id); + } + sig_data2 = kmalloc(sizeof(*sig_data2) + contidstrlen + len, GFP_KERNEL); + if (!sig_data2) { + if (audit_sig_sid) + security_release_secctx(ctx, len); + kfree(contidstr); + return -ENOMEM; + } + sig_data2->uid = from_kuid(&init_user_ns, audit_sig_uid); + sig_data2->pid = audit_sig_pid; + if (audit_sig_cid) { + memcpy(sig_data2->data, contidstr, contidstrlen); + sig_data2->cid_len = contidstrlen; + kfree(contidstr); + } + if (audit_sig_sid) { + memcpy(sig_data2->data + contidstrlen, ctx, len); + security_release_secctx(ctx, len); + } + rcu_read_lock(); + _audit_contobj_put_sig(audit_sig_cid); + rcu_read_unlock();

+ audit_sig_cid = NULL; + audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO2, 0, 0, + sig_data2, sizeof(*sig_data2) + contidstrlen + len); + kfree(sig_data2); + break; + } case AUDIT_TTY_GET: { struct audit_tty_status s; unsigned int t; @@ -2470,6 +2553,11 @@ int audit_signal_info(int sig, struct task_struct *t) else audit_sig_uid = uid; security_task_getsecid(current, &audit_sig_sid); + rcu_read_lock(); + _audit_contobj_put_sig(audit_sig_cid); + audit_sig_cid = _audit_contobj_get_sig(current); + rcu_read_unlock(); + audit_sig_atsk = t; } return audit_signal_info_syscall(t); @@ -2532,6 +2620,11 @@ int audit_set_contid(struct task_struct *task, u64 contid) if (cont->id == contid) { /* task injection to existing container */ if (current == cont->owner) { + if (!refcount_read(&cont->refcount)) { + rc = -ESHUTDOWN;

+ spin_unlock(&audit_contobj_list_lock); + goto conterror; + } _audit_contobj_hold(cont); newcont = cont; } else { diff --git a/security/selinux/nlmsgtab.c b/security/selinux/nlmsgtab.c index b69231918686..8303bb7a63d0 100644 --- a/security/selinux/nlmsgtab.c +++ b/security/selinux/nlmsgtab.c @@ -137,6 +137,7 @@ struct nlmsg_perm { { AUDIT_DEL_RULE, NETLINK_AUDIT_SOCKET__NLMSG_WRITE }, { AUDIT_USER, NETLINK_AUDIT_SOCKET__NLMSG_RELAY }, { AUDIT_SIGNAL_INFO, NETLINK_AUDIT_SOCKET__NLMSG_READ }, + { AUDIT_SIGNAL_INFO2, NETLINK_AUDIT_SOCKET__NLMSG_READ }, { AUDIT_TRIM, NETLINK_AUDIT_SOCKET__NLMSG_WRITE }, { AUDIT_MAKE_EQUIV, NETLINK_AUDIT_SOCKET__NLMSG_WRITE }, { AUDIT_TTY_GET, NETLINK_AUDIT_SOCKET__NLMSG_READ },