From 763dafc520add02a1f4639b500c509acc0ea8e5b Mon Sep 17 00:00:00 2001 From: Paul Moore Date: Mon, 20 Apr 2020 16:24:34 -0400 Subject: audit: check the length of userspace generated audit records Commit 756125289285 ("audit: always check the netlink payload length in audit_receive_msg()") fixed a number of missing message length checks, but forgot to check the length of userspace generated audit records. The good news is that you need CAP_AUDIT_WRITE to submit userspace audit records, which is generally only given to trusted processes, so the impact should be limited. Cc: stable@vger.kernel.org Fixes: 756125289285 ("audit: always check the netlink payload length in audit_receive_msg()") Reported-by: syzbot+49e69b4d71a420ceda3e@syzkaller.appspotmail.com Signed-off-by: Paul Moore --- kernel/audit.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel/audit.c') diff --git a/kernel/audit.c b/kernel/audit.c index b69c8b460341..87f31bf1f0a0 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -1326,6 +1326,9 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: if (!audit_enabled && msg_type != AUDIT_USER_AVC) return 0; + /* exit early if there isn't at least one character to print */ + if (data_len < 2) + return -EINVAL; err = audit_filter(msg_type, AUDIT_FILTER_USER); if (err == 1) { /* match or error */ -- cgit v1.2.3 From a48b284b403a4a073d8beb72d2bb33e54df67fb6 Mon Sep 17 00:00:00 2001 From: Paul Moore Date: Mon, 20 Apr 2020 10:09:29 -0400 Subject: audit: fix a net reference leak in audit_send_reply() If audit_send_reply() fails when trying to create a new thread to send the reply it also fails to cleanup properly, leaking a reference to a net structure. This patch fixes the error path and makes a handful of other cleanups that came up while fixing the code. Reported-by: teroincn@gmail.com Reviewed-by: Richard Guy Briggs Signed-off-by: Paul Moore --- kernel/audit.c | 50 +++++++++++++++++++++++++++++--------------------- 1 file changed, 29 insertions(+), 21 deletions(-) (limited to 'kernel/audit.c') diff --git a/kernel/audit.c b/kernel/audit.c index b69c8b460341..66b81358b64f 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -924,19 +924,30 @@ out_kfree_skb: return NULL; } +static void audit_free_reply(struct audit_reply *reply) +{ + if (!reply) + return; + + if (reply->skb) + kfree_skb(reply->skb); + if (reply->net) + put_net(reply->net); + kfree(reply); +} + static int audit_send_reply_thread(void *arg) { struct audit_reply *reply = (struct audit_reply *)arg; - struct sock *sk = audit_get_sk(reply->net); audit_ctl_lock(); audit_ctl_unlock(); /* Ignore failure. It'll only happen if the sender goes away, because our timeout is set to infinite. */ - netlink_unicast(sk, reply->skb, reply->portid, 0); - put_net(reply->net); - kfree(reply); + netlink_unicast(audit_get_sk(reply->net), reply->skb, reply->portid, 0); + reply->skb = NULL; + audit_free_reply(reply); return 0; } @@ -950,35 +961,32 @@ static int audit_send_reply_thread(void *arg) * @payload: payload data * @size: payload size * - * Allocates an skb, builds the netlink message, and sends it to the port id. - * No failure notifications. + * Allocates a skb, builds the netlink message, and sends it to the port id. */ static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done, int multi, const void *payload, int size) { - struct net *net = sock_net(NETLINK_CB(request_skb).sk); - struct sk_buff *skb; struct task_struct *tsk; - struct audit_reply *reply = kmalloc(sizeof(struct audit_reply), - GFP_KERNEL); + struct audit_reply *reply; + reply = kzalloc(sizeof(*reply), GFP_KERNEL); if (!reply) return; - skb = audit_make_reply(seq, type, done, multi, payload, size); - if (!skb) - goto out; - - reply->net = get_net(net); + reply->skb = audit_make_reply(seq, type, done, multi, payload, size); + if (!reply->skb) + goto err; + reply->net = get_net(sock_net(NETLINK_CB(request_skb).sk)); reply->portid = NETLINK_CB(request_skb).portid; - reply->skb = skb; tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply"); - if (!IS_ERR(tsk)) - return; - kfree_skb(skb); -out: - kfree(reply); + if (IS_ERR(tsk)) + goto err; + + return; + +err: + audit_free_reply(reply); } /* -- cgit v1.2.3 From 3054d06719079388a543de6adb812638675ad8f5 Mon Sep 17 00:00:00 2001 From: Paul Moore Date: Tue, 21 Apr 2020 09:10:56 -0400 Subject: audit: fix a net reference leak in audit_list_rules_send() If audit_list_rules_send() fails when trying to create a new thread to send the rules it also fails to cleanup properly, leaking a reference to a net structure. This patch fixes the error patch and renames audit_send_list() to audit_send_list_thread() to better match its cousin, audit_send_reply_thread(). Reported-by: teroincn@gmail.com Reviewed-by: Richard Guy Briggs Signed-off-by: Paul Moore --- kernel/audit.c | 2 +- kernel/audit.h | 2 +- kernel/auditfilter.c | 16 +++++++--------- 3 files changed, 9 insertions(+), 11 deletions(-) (limited to 'kernel/audit.c') diff --git a/kernel/audit.c b/kernel/audit.c index 66b81358b64f..622c30246d19 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -880,7 +880,7 @@ main_queue: return 0; } -int audit_send_list(void *_dest) +int audit_send_list_thread(void *_dest) { struct audit_netlink_list *dest = _dest; struct sk_buff *skb; diff --git a/kernel/audit.h b/kernel/audit.h index 2eed4d231624..f0233dc40b17 100644 --- a/kernel/audit.h +++ b/kernel/audit.h @@ -229,7 +229,7 @@ struct audit_netlink_list { struct sk_buff_head q; }; -int audit_send_list(void *_dest); +int audit_send_list_thread(void *_dest); extern int selinux_audit_rule_update(void); diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c index 026e34da4ace..a10e2997aa6c 100644 --- a/kernel/auditfilter.c +++ b/kernel/auditfilter.c @@ -1161,11 +1161,8 @@ int audit_rule_change(int type, int seq, void *data, size_t datasz) */ int audit_list_rules_send(struct sk_buff *request_skb, int seq) { - u32 portid = NETLINK_CB(request_skb).portid; - struct net *net = sock_net(NETLINK_CB(request_skb).sk); struct task_struct *tsk; struct audit_netlink_list *dest; - int err = 0; /* We can't just spew out the rules here because we might fill * the available socket buffer space and deadlock waiting for @@ -1173,25 +1170,26 @@ int audit_list_rules_send(struct sk_buff *request_skb, int seq) * happen if we're actually running in the context of auditctl * trying to _send_ the stuff */ - dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL); + dest = kmalloc(sizeof(*dest), GFP_KERNEL); if (!dest) return -ENOMEM; - dest->net = get_net(net); - dest->portid = portid; + dest->net = get_net(sock_net(NETLINK_CB(request_skb).sk)); + dest->portid = NETLINK_CB(request_skb).portid; skb_queue_head_init(&dest->q); mutex_lock(&audit_filter_mutex); audit_list_rules(seq, &dest->q); mutex_unlock(&audit_filter_mutex); - tsk = kthread_run(audit_send_list, dest, "audit_send_list"); + tsk = kthread_run(audit_send_list_thread, dest, "audit_send_list"); if (IS_ERR(tsk)) { skb_queue_purge(&dest->q); + put_net(dest->net); kfree(dest); - err = PTR_ERR(tsk); + return PTR_ERR(tsk); } - return err; + return 0; } int audit_comparator(u32 left, u32 op, u32 right) -- cgit v1.2.3 From 9d2161bed4e39ef7a5e5f18f69c4a57d001051b9 Mon Sep 17 00:00:00 2001 From: Richard Guy Briggs Date: Wed, 22 Apr 2020 17:37:04 -0400 Subject: audit: log audit netlink multicast bind and unbind Log information about programs connecting to and disconnecting from the audit netlink multicast socket. This is needed so that during investigations a security officer can tell who or what had access to the audit trail. This helps to meet the FAU_SAR.2 requirement for Common Criteria. Here is the systemd startup event: type=PROCTITLE msg=audit(2020-04-22 10:10:21.787:10) : proctitle=/init type=SYSCALL msg=audit(2020-04-22 10:10:21.787:10) : arch=x86_64 syscall=bind success=yes exit=0 a0=0x19 a1=0x555f4aac7e90 a2=0xc a3=0x7ffcb792ff44 items=0 ppid=0 pid=1 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=systemd exe=/usr/lib/systemd/systemd subj=kernel key=(null) type=UNKNOWN[1335] msg=audit(2020-04-22 10:10:21.787:10) : pid=1 uid=root auid=unset tty=(none) ses=unset subj=kernel comm=systemd exe=/usr/lib/systemd/systemd nl-mcgrp=1 op=connect res=yes And events from the test suite that just uses close(): type=PROCTITLE msg=audit(2020-04-22 11:47:08.501:442) : proctitle=/usr/bin/perl -w amcast_joinpart/test type=SYSCALL msg=audit(2020-04-22 11:47:08.501:442) : arch=x86_64 syscall=bind success=yes exit=0 a0=0x7 a1=0x563004378760 a2=0xc a3=0x0 items=0 ppid=815 pid=818 auid=root uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=ttyS0 ses=1 comm=perl exe=/usr/bin/perl subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null) type=UNKNOWN[1335] msg=audit(2020-04-22 11:47:08.501:442) : pid=818 uid=root auid=root tty=ttyS0 ses=1 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 comm=perl exe=/usr/bin/perl nl-mcgrp=1 op=connect res=yes type=UNKNOWN[1335] msg=audit(2020-04-22 11:47:08.501:443) : pid=818 uid=root auid=root tty=ttyS0 ses=1 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 comm=perl exe=/usr/bin/perl nl-mcgrp=1 op=disconnect res=yes And the events from the test suite using setsockopt with NETLINK_DROP_MEMBERSHIP: type=PROCTITLE msg=audit(2020-04-22 11:39:53.291:439) : proctitle=/usr/bin/perl -w amcast_joinpart/test type=SYSCALL msg=audit(2020-04-22 11:39:53.291:439) : arch=x86_64 syscall=bind success=yes exit=0 a0=0x7 a1=0x5560877c2d20 a2=0xc a3=0x0 items=0 ppid=772 pid=775 auid=root uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=ttyS0 ses=1 comm=perl exe=/usr/bin/perl subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null) type=UNKNOWN[1335] msg=audit(2020-04-22 11:39:53.291:439) : pid=775 uid=root auid=root tty=ttyS0 ses=1 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 comm=perl exe=/usr/bin/perl nl-mcgrp=1 op=connect res=yes type=PROCTITLE msg=audit(2020-04-22 11:39:53.292:440) : proctitle=/usr/bin/perl -w amcast_joinpart/test type=SYSCALL msg=audit(2020-04-22 11:39:53.292:440) : arch=x86_64 syscall=setsockopt success=yes exit=0 a0=0x7 a1=SOL_NETLINK a2=0x2 a3=0x7ffc8366f000 items=0 ppid=772 pid=775 auid=root uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=ttyS0 ses=1 comm=perl exe=/usr/bin/perl subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null) type=UNKNOWN[1335] msg=audit(2020-04-22 11:39:53.292:440) : pid=775 uid=root auid=root tty=ttyS0 ses=1 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 comm=perl exe=/usr/bin/perl nl-mcgrp=1 op=disconnect res=yes Please see the upstream issue tracker at https://github.com/linux-audit/audit-kernel/issues/28 With the feature description at https://github.com/linux-audit/audit-kernel/wiki/RFE-Audit-Multicast-Socket-Join-Part The testsuite support is at https://github.com/rgbriggs/audit-testsuite/compare/ghak28-mcast-part-join https://github.com/linux-audit/audit-testsuite/pull/93 And the userspace support patch is at https://github.com/linux-audit/audit-userspace/pull/114 Signed-off-by: Richard Guy Briggs Signed-off-by: Paul Moore --- include/uapi/linux/audit.h | 1 + kernel/audit.c | 48 ++++++++++++++++++++++++++++++++++++++++++---- 2 files changed, 45 insertions(+), 4 deletions(-) (limited to 'kernel/audit.c') diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index a534d71e689a..9b6a973f4cc3 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -117,6 +117,7 @@ #define AUDIT_TIME_INJOFFSET 1332 /* Timekeeping offset injected */ #define AUDIT_TIME_ADJNTPVAL 1333 /* NTP value adjustment */ #define AUDIT_BPF 1334 /* BPF subsystem */ +#define AUDIT_EVENT_LISTENER 1335 /* Task joined multicast read socket */ #define AUDIT_AVC 1400 /* SE Linux avc denial or grant */ #define AUDIT_SELINUX_ERR 1401 /* Internal SE Linux Errors */ diff --git a/kernel/audit.c b/kernel/audit.c index 622c30246d19..e33460e01b3b 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -1530,20 +1530,60 @@ static void audit_receive(struct sk_buff *skb) audit_ctl_unlock(); } +/* Log information about who is connecting to the audit multicast socket */ +static void audit_log_multicast(int group, const char *op, int err) +{ + const struct cred *cred; + struct tty_struct *tty; + char comm[sizeof(current->comm)]; + struct audit_buffer *ab; + + if (!audit_enabled) + return; + + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_EVENT_LISTENER); + if (!ab) + return; + + cred = current_cred(); + tty = audit_get_tty(); + audit_log_format(ab, "pid=%u uid=%u auid=%u tty=%s ses=%u", + task_pid_nr(current), + from_kuid(&init_user_ns, cred->uid), + from_kuid(&init_user_ns, audit_get_loginuid(current)), + tty ? tty_name(tty) : "(none)", + audit_get_sessionid(current)); + audit_put_tty(tty); + audit_log_task_context(ab); /* subj= */ + audit_log_format(ab, " comm="); + audit_log_untrustedstring(ab, get_task_comm(comm, current)); + audit_log_d_path_exe(ab, current->mm); /* exe= */ + audit_log_format(ab, " nl-mcgrp=%d op=%s res=%d", group, op, !err); + audit_log_end(ab); +} + /* Run custom bind function on netlink socket group connect or bind requests. */ -static int audit_bind(struct net *net, int group) +static int audit_multicast_bind(struct net *net, int group) { + int err = 0; + if (!capable(CAP_AUDIT_READ)) - return -EPERM; + err = -EPERM; + audit_log_multicast(group, "connect", err); + return err; +} - return 0; +static void audit_multicast_unbind(struct net *net, int group) +{ + audit_log_multicast(group, "disconnect", 0); } static int __net_init audit_net_init(struct net *net) { struct netlink_kernel_cfg cfg = { .input = audit_receive, - .bind = audit_bind, + .bind = audit_multicast_bind, + .unbind = audit_multicast_unbind, .flags = NL_CFG_F_NONROOT_RECV, .groups = AUDIT_NLGRP_MAX, }; -- cgit v1.2.3