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Message-ID: <CAFqZXNsct8yLwHSyAK5rdaOPLLJJS=1R+WyNsWKj0DKiT9_wGQ@mail.gmail.com>
Date: Wed, 27 Mar 2019 21:33:44 +0100
From: Ondrej Mosnacek <omosnace@...hat.com>
To: Richard Guy Briggs <rgb@...hat.com>
Cc: containers@...ts.linux-foundation.org, linux-api@...r.kernel.org,
Linux-Audit Mailing List <linux-audit@...hat.com>,
linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
netdev@...r.kernel.org, netfilter-devel@...r.kernel.org,
Paul Moore <paul@...l-moore.com>,
Steve Grubb <sgrubb@...hat.com>,
David Howells <dhowells@...hat.com>,
Simo Sorce <simo@...hat.com>,
Eric Paris <eparis@...isplace.org>,
"Serge E. Hallyn" <serge@...lyn.com>,
"Eric W . Biederman" <ebiederm@...ssion.com>, nhorman@...driver.com
Subject: Re: [PATCH ghak90 V5 01/10] audit: collect audit task parameters
On Fri, Mar 15, 2019 at 7:33 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> The audit-related parameters in struct task_struct should ideally be
> collected together and accessed through a standard audit API.
>
> Collect the existing loginuid, sessionid and audit_context together in a
> new struct audit_task_info called "audit" in struct task_struct.
>
> Use kmem_cache to manage this pool of memory.
> Un-inline audit_free() to be able to always recover that memory.
>
> Please see the upstream github issue
> https://github.com/linux-audit/audit-kernel/issues/81
> but that issue has been closed with this patch included with
> https://github.com/linux-audit/audit-kernel/issues/90
>
> Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
Reviewed-by: Ondrej Mosnacek <omosnace@...hat.com>
> ---
> include/linux/audit.h | 49 +++++++++++++++++++++++------------
> include/linux/sched.h | 7 +----
> init/init_task.c | 3 +--
> init/main.c | 2 ++
> kernel/audit.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++--
> kernel/audit.h | 5 ++++
> kernel/auditsc.c | 26 ++++++++++---------
> kernel/fork.c | 1 -
> 8 files changed, 124 insertions(+), 40 deletions(-)
>
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index 1e69d9fe16da..bde346e73f0c 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -86,6 +86,16 @@ struct audit_field {
> u32 op;
> };
>
> +struct audit_task_info {
> + kuid_t loginuid;
> + unsigned int sessionid;
> +#ifdef CONFIG_AUDITSYSCALL
> + struct audit_context *ctx;
> +#endif
> +};
> +
> +extern struct audit_task_info init_struct_audit;
> +
> extern int is_audit_feature_set(int which);
>
> extern int __init audit_register_class(int class, unsigned *list);
> @@ -122,6 +132,9 @@ struct audit_field {
> #ifdef CONFIG_AUDIT
> /* These are defined in audit.c */
> /* Public API */
> +extern int audit_alloc(struct task_struct *task);
> +extern void audit_free(struct task_struct *task);
> +extern void __init audit_task_init(void);
> extern __printf(4, 5)
> void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
> const char *fmt, ...);
> @@ -164,16 +177,28 @@ extern void audit_log_key(struct audit_buffer *ab,
>
> static inline kuid_t audit_get_loginuid(struct task_struct *tsk)
> {
> - return tsk->loginuid;
> + if (!tsk->audit)
> + return INVALID_UID;
> + return tsk->audit->loginuid;
> }
>
> static inline unsigned int audit_get_sessionid(struct task_struct *tsk)
> {
> - return tsk->sessionid;
> + if (!tsk->audit)
> + return AUDIT_SID_UNSET;
> + return tsk->audit->sessionid;
> }
>
> extern u32 audit_enabled;
> #else /* CONFIG_AUDIT */
> +static inline int audit_alloc(struct task_struct *task)
> +{
> + return 0;
> +}
> +static inline void audit_free(struct task_struct *task)
> +{ }
> +static inline void __init audit_task_init(void)
> +{ }
> static inline __printf(4, 5)
> void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
> const char *fmt, ...)
> @@ -239,8 +264,6 @@ static inline unsigned int audit_get_sessionid(struct task_struct *tsk)
>
> /* These are defined in auditsc.c */
> /* Public API */
> -extern int audit_alloc(struct task_struct *task);
> -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);
> @@ -263,12 +286,14 @@ extern void audit_seccomp_actions_logged(const char *names,
>
> static inline void audit_set_context(struct task_struct *task, struct audit_context *ctx)
> {
> - task->audit_context = ctx;
> + task->audit->ctx = ctx;
> }
>
> static inline struct audit_context *audit_context(void)
> {
> - return current->audit_context;
> + if (!current->audit)
> + return NULL;
> + return current->audit->ctx;
> }
>
> static inline bool audit_dummy_context(void)
> @@ -276,11 +301,7 @@ static inline bool audit_dummy_context(void)
> void *p = audit_context();
> return !p || *(int *)p;
> }
> -static inline void audit_free(struct task_struct *task)
> -{
> - if (unlikely(task->audit_context))
> - __audit_free(task);
> -}
> +
> static inline void audit_syscall_entry(int major, unsigned long a0,
> unsigned long a1, unsigned long a2,
> unsigned long a3)
> @@ -470,12 +491,6 @@ static inline void audit_fanotify(unsigned int response)
> extern int audit_n_rules;
> extern int audit_signals;
> #else /* CONFIG_AUDITSYSCALL */
> -static inline int audit_alloc(struct task_struct *task)
> -{
> - return 0;
> -}
> -static inline void audit_free(struct task_struct *task)
> -{ }
> static inline void audit_syscall_entry(int major, unsigned long a0,
> unsigned long a1, unsigned long a2,
> unsigned long a3)
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 765119df759a..6850d1e48ace 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -31,7 +31,6 @@
> #include <linux/rseq.h>
>
> /* task_struct member predeclarations (sorted alphabetically): */
> -struct audit_context;
> struct backing_dev_info;
> struct bio_list;
> struct blk_plug;
> @@ -886,11 +885,7 @@ struct task_struct {
> struct callback_head *task_works;
>
> #ifdef CONFIG_AUDIT
> -#ifdef CONFIG_AUDITSYSCALL
> - struct audit_context *audit_context;
> -#endif
> - kuid_t loginuid;
> - unsigned int sessionid;
> + struct audit_task_info *audit;
> #endif
> struct seccomp seccomp;
>
> diff --git a/init/init_task.c b/init/init_task.c
> index 39c3109acc1a..f9685e1edda1 100644
> --- a/init/init_task.c
> +++ b/init/init_task.c
> @@ -122,8 +122,7 @@ struct task_struct init_task
> .thread_group = LIST_HEAD_INIT(init_task.thread_group),
> .thread_node = LIST_HEAD_INIT(init_signals.thread_head),
> #ifdef CONFIG_AUDIT
> - .loginuid = INVALID_UID,
> - .sessionid = AUDIT_SID_UNSET,
> + .audit = &init_struct_audit,
> #endif
> #ifdef CONFIG_PERF_EVENTS
> .perf_event_mutex = __MUTEX_INITIALIZER(init_task.perf_event_mutex),
> diff --git a/init/main.c b/init/main.c
> index e2e80ca3165a..8a1c36625d12 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -92,6 +92,7 @@
> #include <linux/rodata_test.h>
> #include <linux/jump_label.h>
> #include <linux/mem_encrypt.h>
> +#include <linux/audit.h>
>
> #include <asm/io.h>
> #include <asm/bugs.h>
> @@ -727,6 +728,7 @@ asmlinkage __visible void __init start_kernel(void)
> nsfs_init();
> cpuset_init();
> cgroup_init();
> + audit_task_init();
> taskstats_init_early();
> delayacct_init();
>
> diff --git a/kernel/audit.c b/kernel/audit.c
> index c89ea48c70a6..67498c5690bb 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -215,6 +215,73 @@ struct audit_reply {
> struct sk_buff *skb;
> };
>
> +static struct kmem_cache *audit_task_cache;
> +
> +void __init audit_task_init(void)
> +{
> + audit_task_cache = kmem_cache_create("audit_task",
> + sizeof(struct audit_task_info),
> + 0, SLAB_PANIC, NULL);
> +}
> +
> +/**
> + * audit_alloc - allocate an audit info block for a task
> + * @tsk: task
> + *
> + * Call audit_alloc_syscall to filter on the task information and
> + * allocate a per-task audit context if necessary. This is called from
> + * copy_process, so no lock is needed.
> + */
> +int audit_alloc(struct task_struct *tsk)
> +{
> + int ret = 0;
> + struct audit_task_info *info;
> +
> + info = kmem_cache_alloc(audit_task_cache, GFP_KERNEL);
> + if (!info) {
> + ret = -ENOMEM;
> + goto out;
> + }
> + info->loginuid = audit_get_loginuid(current);
> + info->sessionid = audit_get_sessionid(current);
> + tsk->audit = info;
> +
> + ret = audit_alloc_syscall(tsk);
> + if (ret) {
> + tsk->audit = NULL;
> + kmem_cache_free(audit_task_cache, info);
> + }
> +out:
> + return ret;
> +}
> +
> +struct audit_task_info init_struct_audit = {
> + .loginuid = INVALID_UID,
> + .sessionid = AUDIT_SID_UNSET,
> +#ifdef CONFIG_AUDITSYSCALL
> + .ctx = NULL,
> +#endif
> +};
> +
> +/**
> + * audit_free - free per-task audit info
> + * @tsk: task whose audit info block to free
> + *
> + * Called from copy_process and do_exit
> + */
> +void audit_free(struct task_struct *tsk)
> +{
> + struct audit_task_info *info = tsk->audit;
> +
> + audit_free_syscall(tsk);
> + /* Freeing the audit_task_info struct must be performed after
> + * audit_log_exit() due to need for loginuid and sessionid.
> + */
> + info = tsk->audit;
> + tsk->audit = NULL;
> + kmem_cache_free(audit_task_cache, info);
> +}
> +
> /**
> * auditd_test_task - Check to see if a given task is an audit daemon
> * @task: the task to check
> @@ -2266,8 +2333,8 @@ int audit_set_loginuid(kuid_t loginuid)
> sessionid = (unsigned int)atomic_inc_return(&session_id);
> }
>
> - current->sessionid = sessionid;
> - current->loginuid = loginuid;
> + current->audit->sessionid = sessionid;
> + current->audit->loginuid = loginuid;
> out:
> audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
> return rc;
> diff --git a/kernel/audit.h b/kernel/audit.h
> index 958d5b8fc1b3..c00e2ee3c6b3 100644
> --- a/kernel/audit.h
> +++ b/kernel/audit.h
> @@ -264,6 +264,8 @@ extern void audit_log_d_path_exe(struct audit_buffer *ab,
> extern unsigned int audit_serial(void);
> extern int auditsc_get_stamp(struct audit_context *ctx,
> struct timespec64 *t, unsigned int *serial);
> +extern int audit_alloc_syscall(struct task_struct *tsk);
> +extern void audit_free_syscall(struct task_struct *tsk);
>
> extern void audit_put_watch(struct audit_watch *watch);
> extern void audit_get_watch(struct audit_watch *watch);
> @@ -305,6 +307,9 @@ extern void audit_filter_inodes(struct task_struct *tsk,
> extern struct list_head *audit_killed_trees(void);
> #else /* CONFIG_AUDITSYSCALL */
> #define auditsc_get_stamp(c, t, s) 0
> +#define audit_alloc_syscall(t) 0
> +#define audit_free_syscall(t) {}
> +
> #define audit_put_watch(w) {}
> #define audit_get_watch(w) {}
> #define audit_to_watch(k, p, l, o) (-EINVAL)
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index d1eab1d4a930..8090eff7868d 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -885,23 +885,25 @@ static inline struct audit_context *audit_alloc_context(enum audit_state state)
> return context;
> }
>
> -/**
> - * audit_alloc - allocate an audit context block for a task
> +/*
> + * audit_alloc_syscall - allocate an audit context block for a task
> * @tsk: task
> *
> * Filter on the task information and allocate a per-task audit context
> * if necessary. Doing so turns on system call auditing for the
> - * specified task. This is called from copy_process, so no lock is
> - * needed.
> + * specified task. This is called from copy_process via audit_alloc, so
> + * no lock is needed.
> */
> -int audit_alloc(struct task_struct *tsk)
> +int audit_alloc_syscall(struct task_struct *tsk)
> {
> struct audit_context *context;
> enum audit_state state;
> char *key = NULL;
>
> - if (likely(!audit_ever_enabled))
> + if (likely(!audit_ever_enabled)) {
> + audit_set_context(tsk, NULL);
> return 0; /* Return if not auditing. */
> + }
>
> state = audit_filter_task(tsk, &key);
> if (state == AUDIT_DISABLED) {
> @@ -911,7 +913,7 @@ int audit_alloc(struct task_struct *tsk)
>
> if (!(context = audit_alloc_context(state))) {
> kfree(key);
> - audit_log_lost("out of memory in audit_alloc");
> + audit_log_lost("out of memory in audit_alloc_syscall");
> return -ENOMEM;
> }
> context->filterkey = key;
> @@ -1555,14 +1557,15 @@ static void audit_log_exit(void)
> }
>
> /**
> - * __audit_free - free a per-task audit context
> + * audit_free_syscall - free per-task audit context info
> * @tsk: task whose audit context block to free
> *
> - * Called from copy_process and do_exit
> + * Called from audit_free
> */
> -void __audit_free(struct task_struct *tsk)
> +void audit_free_syscall(struct task_struct *tsk)
> {
> - struct audit_context *context = tsk->audit_context;
> + struct audit_task_info *info = tsk->audit;
> + struct audit_context *context = info->ctx;
>
> if (!context)
> return;
> @@ -1585,7 +1588,6 @@ void __audit_free(struct task_struct *tsk)
> if (context->current_state == AUDIT_RECORD_CONTEXT)
> audit_log_exit();
> }
> -
> audit_set_context(tsk, NULL);
> audit_free_context(context);
> }
> diff --git a/kernel/fork.c b/kernel/fork.c
> index a60459947f18..1107bd8b8ad8 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1836,7 +1836,6 @@ static __latent_entropy struct task_struct *copy_process(
> p->start_time = ktime_get_ns();
> p->real_start_time = ktime_get_boot_ns();
> p->io_context = NULL;
> - audit_set_context(p, NULL);
> cgroup_fork(p);
> #ifdef CONFIG_NUMA
> p->mempolicy = mpol_dup(p->mempolicy);
> --
> 1.8.3.1
>
--
Ondrej Mosnacek <omosnace at redhat dot com>
Software Engineer, Security Technologies
Red Hat, Inc.
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