[PATCH] audit: fix a net reference leak in audit_list_rules_send()
by Paul Moore
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(a)gmail.com
Signed-off-by: Paul Moore <paul(a)paul-moore.com>
---
kernel/audit.c | 2 +-
kernel/audit.h | 2 +-
kernel/auditfilter.c | 16 +++++++---------
3 files changed, 9 insertions(+), 11 deletions(-)
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 @@ static int kauditd_thread(void *dummy)
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)
4 years, 8 months
[PATCH] audit: allow audit_reusename to check kernel path
by Yiwen Gu
Currently, audit_reusename check file path only by comparing
userspace pointer "uptr", without checking the situation where
the file name is different with the same uptr.
Add kname into audit_reusename function to check file names
from the audit_names list.
Signed-off-by: Yiwen Gu <guyiwen(a)huawei.com>
---
fs/namei.c | 9 +++++----
include/linux/audit.h | 11 +++++++----
kernel/auditsc.c | 7 ++++---
3 files changed, 16 insertions(+), 11 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index db6565c99825..d5fb4bd12aec 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -128,13 +128,10 @@ struct filename *
getname_flags(const char __user *filename, int flags, int *empty)
{
struct filename *result;
+ struct filename *result_audit;
char *kname;
int len;
- result = audit_reusename(filename);
- if (result)
- return result;
-
result = __getname();
if (unlikely(!result))
return ERR_PTR(-ENOMEM);
@@ -197,6 +194,10 @@ getname_flags(const char __user *filename, int flags, int *empty)
}
}
+ result_audit = audit_reusename(filename, kname);
+ if (result_audit)
+ return result_audit;
+
result->uptr = filename;
result->aname = NULL;
audit_getname(result);
diff --git a/include/linux/audit.h b/include/linux/audit.h
index f9ceae57ca8d..71fb783f14c4 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -266,7 +266,8 @@ extern void __audit_free(struct task_struct *task);
extern void __audit_syscall_entry(int major, unsigned long a0, unsigned long a1,
unsigned long a2, unsigned long a3);
extern void __audit_syscall_exit(int ret_success, long ret_value);
-extern struct filename *__audit_reusename(const __user char *uptr);
+extern struct filename *__audit_reusename(const __user char *uptr,
+ const char *kname);
extern void __audit_getname(struct filename *name);
extern void __audit_inode(struct filename *name, const struct dentry *dentry,
@@ -316,10 +317,11 @@ static inline void audit_syscall_exit(void *pt_regs)
__audit_syscall_exit(success, return_code);
}
}
-static inline struct filename *audit_reusename(const __user char *name)
+static inline struct filename *audit_reusename(const __user char *name,
+ const char *kname)
{
if (unlikely(!audit_dummy_context()))
- return __audit_reusename(name);
+ return __audit_reusename(name, kname);
return NULL;
}
static inline void audit_getname(struct filename *name)
@@ -539,7 +541,8 @@ static inline struct audit_context *audit_context(void)
{
return NULL;
}
-static inline struct filename *audit_reusename(const __user char *name)
+static inline struct filename *audit_reusename(const __user char *name,
+ const char *kname)
{
return NULL;
}
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 4effe01ebbe2..62ffc02abb98 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1843,13 +1843,14 @@ static struct audit_names *audit_alloc_name(struct audit_context *context,
/**
* __audit_reusename - fill out filename with info from existing entry
* @uptr: userland ptr to pathname
+ * @kname: kernel pathname string
*
* Search the audit_names list for the current audit context. If there is an
- * existing entry with a matching "uptr" then return the filename
+ * existing entry with matching "uptr" and "kname" then return the filename
* associated with that audit_name. If not, return NULL.
*/
struct filename *
-__audit_reusename(const __user char *uptr)
+__audit_reusename(const __user char *uptr, const char *kname)
{
struct audit_context *context = audit_context();
struct audit_names *n;
@@ -1857,7 +1858,7 @@ __audit_reusename(const __user char *uptr)
list_for_each_entry(n, &context->names_list, list) {
if (!n->name)
continue;
- if (n->name->uptr == uptr) {
+ if (n->name->uptr == uptr && !strcmp(kname, n->name->name)) {
n->name->refcnt++;
return n->name;
}
--
2.17.1
4 years, 8 months
[PATCH] audit: check the length of userspace generated audit records
by Paul Moore
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(a)vger.kernel.org
Fixes: 756125289285 ("audit: always check the netlink payload length in audit_receive_msg()")
Reported-by: syzbot+49e69b4d71a420ceda3e(a)syzkaller.appspotmail.com
Signed-off-by: Paul Moore <paul(a)paul-moore.com>
---
kernel/audit.c | 3 +++
1 file changed, 3 insertions(+)
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 */
4 years, 8 months
[PATCH ghak28 V7] audit: log audit netlink multicast bind and unbind events
by Richard Guy Briggs
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(2020-02-18 15:26:50.775:10) : proctitle=/init
type=SYSCALL msg=audit(2020-02-18 15:26:50.775:10) : arch=x86_64 syscall=bind success=yes exit=0 a0=0x19 a1=0x55645c369b70 a2=0xc a3=0x7fff9fedec24 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(2020-02-18 15:26:50.775:10) : 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 the events from the test suite:
type=PROCTITLE msg=audit(2020-02-18 15:28:01.594:307) : proctitle=/usr/bin/perl -w amcast_joinpart/test
type=SYSCALL msg=audit(2020-02-18 15:28:01.594:307) : arch=x86_64 syscall=bind success=yes exit=0 a0=0x7 a1=0x558ebc428be0 a2=0xc a3=0x0 items=0 ppid=642 pid=645 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(2020-02-18 15:28:01.594:307) : pid=645 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(2020-03-17 11:35:31.474:344) : proctitle=/usr/bin/perl -w amcast_joinpart/test
type=SYSCALL msg=audit(2020-03-17 11:35:31.474:344) : arch=x86_64 syscall=setsockopt success=yes exit=0 a0=0x7 a1=SOL_NETLINK a2=0x2 a3=0x7ffee21ca5f0 items=0 ppid=686 pid=689 auid=root uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=ttyS0 ses=3 comm=perl exe=/usr/bin/perl subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)
type=UNKNOWN[1335] msg=audit(2020-03-17 11:35:31.474:344) : pid=689 uid=root auid=root tty=ttyS0 ses=3 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 comm=perl exe=/usr/bin/perl nl-mcgrp=1 op=disconnect res=yes
type=UNKNOWN[1335] msg=audit(2020-01-17 10:36:24.051:295) : pid=674 uid=root auid=root tty=ttyS0 ses=3 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-Sock...
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 <rgb(a)redhat.com>
---
Note: subj attrs included due to missing syscall record for disconnect on close
Note: tried refactor of subj attrs, but this is yet another new order.
Changelog:
v7:
- rename audit_log_multicast_bind to audit_log_multicast
v6:
- rebased on 5.6-rc1 audit/next and audit log BPF
- updated patch description sample records
v5:
- rebased on 5.5-rc1 audit/next
- group bind/unbind ops
- add audit context
- justify message number skip
- check audit_enabled
- change field name from nlnk-grp to nl-mcgrp
- fix whitespace issues
v4:
- 2017-10-13 sgrubb
- squash to 1 patch
- rebase on KERN_MODULE event
- open code subj attrs
v3:
- 2016-11-30 sgrubb
- rebase on REPLACE event
- minimize audit_log_format calls
- rename audit_log_bind to audit_log_multicast_bind
v2:
- 2015-07-23 sgrubb
- spin off audit_log_task_simple in seperate patch
v1:
- 2014-10-07 rgb
---
include/uapi/linux/audit.h | 1 +
kernel/audit.c | 48 ++++++++++++++++++++++++++++++++++++++++++----
2 files changed, 45 insertions(+), 4 deletions(-)
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 b96331e1976d..612bd818f6d7 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1520,20 +1520,60 @@ 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,
};
--
1.8.3.1
4 years, 8 months
[PATCH ghak25 v3 0/3] Address NETFILTER_CFG issues
by Richard Guy Briggs
There were questions about the presence and cause of unsolicited syscall events
in the logs containing NETFILTER_CFG records and sometimes unaccompanied
NETFILTER_CFG records.
During testing at least the following list of events trigger NETFILTER_CFG
records and the syscalls related (There may be more events that will trigger
this message type.):
init_module, finit_module: modprobe
delete_module: rmmod
setsockopt: iptables-restore, ip6tables-restore, ebtables-restore
unshare: (h?)ostnamed, updatedb
clone: libvirtd
kernel threads garbage collecting empty ebtables
The syscall events unsolicited by any audit rule were found to be caused by a
missing !audit_dummy_context() check before issuing a NETFILTER_CFG
record. In fact, since this is a configuration change it is required,
and we always want the accompanying syscall record even with no rules
present, so this has been addressed by ghak120.
The vast majority of unaccompanied records are caused by the fedora default
rule: "-a never,task" and the occasional early startup one is I believe caused
by the iptables filter table module hard linked into the kernel rather than a
loadable module.
A couple of other factors should help eliminate unaccompanied records
which include commit cb74ed278f80 ("audit: always enable syscall
auditing when supported and audit is enabled") which makes sure that
when audit is enabled, so automatically is syscall auditing, and ghak66
which addressed initializing audit before PID 1.
Ebtables module initialization to register tables doesn't generate records
because it was never hooked in to audit. Recommend adding audit hooks to log
this covered by ghak43 covered by patch 1.
Table unregistration was never logged, which is now covered by ghak44 in
patch 2. Unaccompanied records were caused by kernel threads
automatically unregistering empty ebtables, which necessitates adding
subject credentials covered in patch 3.
Seemingly duplicate records are not actually exact duplicates that are caused
by netfilter table initialization in different network namespaces from the same
syscall. Recommend adding the network namespace ID (proc inode and dev)
to the record to make this obvious (address later with ghak79 after nsid
patches).
See: https://github.com/linux-audit/audit-kernel/issues/25
See: https://github.com/linux-audit/audit-kernel/issues/35
See: https://github.com/linux-audit/audit-kernel/issues/43
See: https://github.com/linux-audit/audit-kernel/issues/44
Changelog:
v3
- rebase on v5.6-rc1 audit/next
- change audit_nf_cfg to audit_log_nfcfg
- squash 2,3,4,5 to 1 and update patch descriptions
- add subject credentials to cover garbage collecting kernel threads
v2
- Rebase (audit/next 5.5-rc1) to get audit_context access and ebt_register_table ret code
- Split x_tables and ebtables updates
- Check audit_dummy_context
- Store struct audit_nfcfg params in audit_context, abstract to audit_nf_cfg() call
- Restore back to "table, family, entries" from "family, table, entries"
- Log unregistration of tables
- Add "op=" at the end of the AUDIT_NETFILTER_CFG record
- Defer nsid patch (ghak79) to once nsid patchset upstreamed (ghak32)
- Add ghak refs
- Ditch NETFILTER_CFGSOLO record
Richard Guy Briggs (3):
audit: tidy and extend netfilter_cfg x_tables and ebtables logging
netfilter: add audit table unregister actions
audit: add subj creds to NETFILTER_CFG record to cover async
unregister
include/linux/audit.h | 20 +++++++++++++++++++
kernel/auditsc.c | 43 +++++++++++++++++++++++++++++++++++++++++
net/bridge/netfilter/ebtables.c | 14 ++++++--------
net/netfilter/x_tables.c | 14 +++++---------
4 files changed, 74 insertions(+), 17 deletions(-)
--
1.8.3.1
4 years, 8 months
[PATCH] audit: fix a net reference leak in audit_send_reply()
by Paul Moore
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(a)gmail.com
Signed-off-by: Paul Moore <paul(a)paul-moore.com>
---
kernel/audit.c | 50 +++++++++++++++++++++++++++++---------------------
1 file changed, 29 insertions(+), 21 deletions(-)
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 @@ struct sk_buff *audit_make_reply(int seq, int type, int done,
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);
}
/*
4 years, 8 months
KMSAN: uninit-value in audit_log_vformat (2)
by syzbot
Hello,
syzbot found the following crash on:
HEAD commit: 5356842d [EXPERIMENTAL] kmsan: eagerly allocate shadow at ..
git tree: https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=12f06720100000
kernel config: https://syzkaller.appspot.com/x/.config?x=a5915107b3106aaa
dashboard link: https://syzkaller.appspot.com/bug?extid=49e69b4d71a420ceda3e
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
userspace arch: i386
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=133b5dabe00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=143e1610100000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+49e69b4d71a420ceda3e(a)syzkaller.appspotmail.com
=====================================================
BUG: KMSAN: uninit-value in string_nocheck lib/vsprintf.c:608 [inline]
BUG: KMSAN: uninit-value in string+0x522/0x690 lib/vsprintf.c:689
CPU: 1 PID: 8854 Comm: syz-executor694 Not tainted 5.6.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1c9/0x220 lib/dump_stack.c:118
kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
__msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
string_nocheck lib/vsprintf.c:608 [inline]
string+0x522/0x690 lib/vsprintf.c:689
vsnprintf+0x207d/0x31b0 lib/vsprintf.c:2574
audit_log_vformat+0x583/0xcd0 kernel/audit.c:1858
audit_log_format+0x220/0x260 kernel/audit.c:1892
audit_receive_msg kernel/audit.c:1344 [inline]
audit_receive+0x18a4/0x6d50 kernel/audit.c:1515
netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
netlink_unicast+0xf9e/0x1100 net/netlink/af_netlink.c:1329
netlink_sendmsg+0x1246/0x14d0 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg net/socket.c:672 [inline]
____sys_sendmsg+0x12b6/0x1350 net/socket.c:2345
___sys_sendmsg net/socket.c:2399 [inline]
__sys_sendmsg+0x451/0x5f0 net/socket.c:2432
__compat_sys_sendmsg net/compat.c:642 [inline]
__do_compat_sys_sendmsg net/compat.c:649 [inline]
__se_compat_sys_sendmsg net/compat.c:646 [inline]
__ia32_compat_sys_sendmsg+0xed/0x130 net/compat.c:646
do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7fa0d99
Code: 90 e8 0b 00 00 00 f3 90 0f ae e8 eb f9 8d 74 26 00 89 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000ffb27c7c EFLAGS: 00000246 ORIG_RAX: 0000000000000172
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000200002c0
RDX: 0000000000000000 RSI: 00000000080ea078 RDI: 00000000ffb27cd0
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Uninit was created at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:82
slab_alloc_node mm/slub.c:2801 [inline]
__kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4420
__kmalloc_reserve net/core/skbuff.c:142 [inline]
__alloc_skb+0x2fd/0xac0 net/core/skbuff.c:210
alloc_skb include/linux/skbuff.h:1081 [inline]
netlink_alloc_large_skb net/netlink/af_netlink.c:1175 [inline]
netlink_sendmsg+0x7d3/0x14d0 net/netlink/af_netlink.c:1893
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg net/socket.c:672 [inline]
____sys_sendmsg+0x12b6/0x1350 net/socket.c:2345
___sys_sendmsg net/socket.c:2399 [inline]
__sys_sendmsg+0x451/0x5f0 net/socket.c:2432
__compat_sys_sendmsg net/compat.c:642 [inline]
__do_compat_sys_sendmsg net/compat.c:649 [inline]
__se_compat_sys_sendmsg net/compat.c:646 [inline]
__ia32_compat_sys_sendmsg+0xed/0x130 net/compat.c:646
do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
=====================================================
---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller(a)googlegroups.com.
syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches
4 years, 8 months
kernel: audit.c: is it a memleak of net in function audit_send_reply
by 亿一
Hi, all:
when reviewing code in function audit_send_reply, I notice that if
kthread_run return failure, the net reference would not be released
because reply has been kfree directly.
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);
if (!reply)
return;
skb = audit_make_reply(seq, type, done, multi, payload, size);
if (!skb)
goto out;
reply->net = get_net(net); // hold a reference of net here
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); // kfree reply without release the net reference.
}
4 years, 8 months
[PATCH ghak96] audit: set cwd in audit context for file-related LSM audit records
by Vladis Dronov
Set a current working directory in an audit context for the following record
types in dump_common_audit_data(): LSM_AUDIT_DATA_PATH, LSM_AUDIT_DATA_FILE,
LSM_AUDIT_DATA_IOCTL_OP, LSM_AUDIT_DATA_DENTRY, LSM_AUDIT_DATA_INODE so a
separate CWD record is emitted later.
Link: https://github.com/linux-audit/audit-kernel/issues/96
Signed-off-by: Vladis Dronov <vdronov(a)redhat.com>
---
out-of-commit-message-note:
Hello,
Honestly, I'm not sure about "if (!context->in_syscall)" check in
__audit_getcwd(). It was copied from __audit_getname() and I do
not quite understand why it is there and if __audit_getcwd() needs
it. If you have an idea on this, could you please, tell?
include/linux/audit.h | 9 ++++++++-
kernel/auditsc.c | 17 +++++++++++++++++
security/lsm_audit.c | 5 +++++
3 files changed, 30 insertions(+), 1 deletion(-)
diff --git a/include/linux/audit.h b/include/linux/audit.h
index f9ceae57ca8d..b4306abc5891 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -268,7 +268,7 @@ extern void __audit_syscall_entry(int major, unsigned long a0, unsigned long a1,
extern void __audit_syscall_exit(int ret_success, long ret_value);
extern struct filename *__audit_reusename(const __user char *uptr);
extern void __audit_getname(struct filename *name);
-
+extern void __audit_getcwd(void);
extern void __audit_inode(struct filename *name, const struct dentry *dentry,
unsigned int flags);
extern void __audit_file(const struct file *);
@@ -327,6 +327,11 @@ static inline void audit_getname(struct filename *name)
if (unlikely(!audit_dummy_context()))
__audit_getname(name);
}
+static inline void audit_getcwd(void)
+{
+ if (unlikely(!audit_dummy_context()))
+ __audit_getcwd();
+}
static inline void audit_inode(struct filename *name,
const struct dentry *dentry,
unsigned int aflags) {
@@ -545,6 +550,8 @@ static inline struct filename *audit_reusename(const __user char *name)
}
static inline void audit_getname(struct filename *name)
{ }
+static inline void audit_getcwd(void)
+{ }
static inline void __audit_inode(struct filename *name,
const struct dentry *dentry,
unsigned int flags)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 814406a35db1..16316032ef9f 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1890,6 +1890,23 @@ void __audit_getname(struct filename *name)
get_fs_pwd(current->fs, &context->pwd);
}
+/**
+ * __audit_getcwd - set a current working directory
+ *
+ * Set a current working directory of an audited process for this context.
+ * Called from security/lsm_audit.c:dump_common_audit_data().
+ */
+void __audit_getcwd(void)
+{
+ struct audit_context *context = audit_context();
+
+ if (!context->in_syscall)
+ return;
+
+ if (!context->pwd.dentry)
+ get_fs_pwd(current->fs, &context->pwd);
+}
+
static inline int audit_copy_fcaps(struct audit_names *name,
const struct dentry *dentry)
{
diff --git a/security/lsm_audit.c b/security/lsm_audit.c
index 2d2bf49016f4..7c555621c2bd 100644
--- a/security/lsm_audit.c
+++ b/security/lsm_audit.c
@@ -241,6 +241,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
audit_log_untrustedstring(ab, inode->i_sb->s_id);
audit_log_format(ab, " ino=%lu", inode->i_ino);
}
+ audit_getcwd();
break;
}
case LSM_AUDIT_DATA_FILE: {
@@ -254,6 +255,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
audit_log_untrustedstring(ab, inode->i_sb->s_id);
audit_log_format(ab, " ino=%lu", inode->i_ino);
}
+ audit_getcwd();
break;
}
case LSM_AUDIT_DATA_IOCTL_OP: {
@@ -269,6 +271,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
}
audit_log_format(ab, " ioctlcmd=0x%hx", a->u.op->cmd);
+ audit_getcwd();
break;
}
case LSM_AUDIT_DATA_DENTRY: {
@@ -283,6 +286,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
audit_log_untrustedstring(ab, inode->i_sb->s_id);
audit_log_format(ab, " ino=%lu", inode->i_ino);
}
+ audit_getcwd();
break;
}
case LSM_AUDIT_DATA_INODE: {
@@ -300,6 +304,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
audit_log_format(ab, " dev=");
audit_log_untrustedstring(ab, inode->i_sb->s_id);
audit_log_format(ab, " ino=%lu", inode->i_ino);
+ audit_getcwd();
break;
}
case LSM_AUDIT_DATA_TASK: {
--
2.20.1
4 years, 8 months
Fwd: [oss-security] CVE-2020-10708 kernel: race condition in kernel/audit.c may allow low privilege users trigger kernel panic
by Steve Grubb
Hello,
Since this is public...no harm dropping a copy over here. My thoughts are
that there is a race here. But since starting/stopping the audit daemon
requires root privs and as root you can do worse things. I don't know if this
is fixable or working per design.
-Steve
---------- Forwarded Message ----------
Subject: [oss-security] CVE-2020-10708 kernel: race condition in kernel/
audit.c may allow low privilege users trigger kernel panic
Date: Friday, April 17, 2020, 12:40:10 AM EDT
From: 陈伟宸(田各) <splendidsky.cwc(a)alibaba-inc.com>
To: oss-security <oss-security(a)lists.openwall.com>
"A race condition was found in the Linux kernel audit subsystem. When the
system is configured to panic on events being dropped, an attacker who is able
to trigger an audit event that starts while auditd is in the process of
starting may be able to cause the system to panic by exploiting a race
condition in audit event handling. This creates a denial of service by
causing a panic."
https://bugzilla.redhat.com/show_bug.cgi?id=1822593
Env:
Red Hat Enterprise Linux Server release 7.7 (Maipo)
3.10.0-1062.12.1.el7.x86_64
Details:
Function audit_log_end and audit_panic may have race conditions when auditd
is restarting because audit_pid can be NULL in audit_log_end and then become
not NULL in audit_panic, which may allow attackers to trigger kernel panic.
Here is panic call stack:
void audit_log_end(struct audit_buffer *ab)
{
if (!ab)
return;
if (!audit_rate_check()) {
audit_log_lost("rate limit exceeded");
} else {
struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
nlh->nlmsg_len = ab->skb->len - NLMSG_HDRLEN;
if (audit_pid) {
skb_queue_tail(&audit_skb_queue, ab->skb);
wake_up_interruptible(&kauditd_wait);
} else {
audit_printk_skb(ab->skb); // <- audit_pid == NULL when auditd is
killed
}
ab->skb = NULL;
}
audit_buffer_free(ab);
}
-> audit_printk_skb -> audit_log_lost ->
void audit_panic(const char *message)
{
switch (audit_failure)
{
case AUDIT_FAIL_SILENT:
break;
case AUDIT_FAIL_PRINTK:
if (printk_ratelimit())
printk(KERN_ERR "audit: %s\n", message);
break;
case AUDIT_FAIL_PANIC:
/* test audit_pid since printk is always losey, why bother? */
if (audit_pid) // <- audit_pid not NULL because auditd is restarting
panic("audit: %s\n", message);
break;
}
}
How to reproduce：
1. set audit-failure to AUDIT_FAIL_PANIC(2) and add a random audit rule like:
[root@test ~]# cat /etc/audit/rules.d/audit.rules
-D
-b 8192
-f 2
-w /etc/hosts -p rwa -k hosts
2. keep killing auditd and then starting auditd, for example:
while true; do ps aux | grep "/sbin/auditd" | grep -v "grep" | awk '{print
$2}' | xargs kill; service auditd start; systemctl reset-failed
auditd.service; done
3. log in a low privilege user and keep reading /etc/hosts, for example:
while true; do cat /etc/hosts > /dev/null; done
4. kernel panic will happen within several minutes
Thanks.
-----------------------------------------
4 years, 8 months
