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    Subject[PATCH ghak90 (was ghak32) V4 01/10] audit: collect audit task parameters
    Date
    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.

    See: https://github.com/linux-audit/audit-kernel/issues/81

    Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
    ---
    include/linux/audit.h | 34 ++++++++++++++++++++++++----------
    include/linux/sched.h | 5 +----
    init/init_task.c | 3 +--
    init/main.c | 2 ++
    kernel/auditsc.c | 51 ++++++++++++++++++++++++++++++++++++++++++---------
    kernel/fork.c | 4 +++-
    6 files changed, 73 insertions(+), 26 deletions(-)

    diff --git a/include/linux/audit.h b/include/linux/audit.h
    index 9334fbe..8964332 100644
    --- a/include/linux/audit.h
    +++ b/include/linux/audit.h
    @@ -219,8 +219,15 @@ static inline void audit_log_task_info(struct audit_buffer *ab,

    /* These are defined in auditsc.c */
    /* Public API */
    +struct audit_task_info {
    + kuid_t loginuid;
    + unsigned int sessionid;
    + struct audit_context *ctx;
    +};
    +extern struct audit_task_info init_struct_audit;
    +extern void __init audit_task_init(void);
    extern int audit_alloc(struct task_struct *task);
    -extern void __audit_free(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);
    @@ -242,12 +249,15 @@ 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 current->audit->ctx;
    + else
    + return NULL;
    }

    static inline bool audit_dummy_context(void)
    @@ -255,11 +265,7 @@ 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)
    @@ -331,12 +337,18 @@ extern int auditsc_get_stamp(struct audit_context *ctx,

    static inline kuid_t audit_get_loginuid(struct task_struct *tsk)
    {
    - return tsk->loginuid;
    + if (tsk->audit)
    + return tsk->audit->loginuid;
    + else
    + return INVALID_UID;
    }

    static inline unsigned int audit_get_sessionid(struct task_struct *tsk)
    {
    - return tsk->sessionid;
    + if (tsk->audit)
    + return tsk->audit->sessionid;
    + else
    + return AUDIT_SID_UNSET;
    }

    extern void __audit_ipc_obj(struct kern_ipc_perm *ipcp);
    @@ -461,6 +473,8 @@ static inline void audit_fanotify(unsigned int response)
    extern int audit_n_rules;
    extern int audit_signals;
    #else /* CONFIG_AUDITSYSCALL */
    +static inline void __init audit_task_init(void)
    +{ }
    static inline int audit_alloc(struct task_struct *task)
    {
    return 0;
    diff --git a/include/linux/sched.h b/include/linux/sched.h
    index 87bf02d..e117272 100644
    --- a/include/linux/sched.h
    +++ b/include/linux/sched.h
    @@ -30,7 +30,6 @@
    #include <linux/rseq.h>

    /* task_struct member predeclarations (sorted alphabetically): */
    -struct audit_context;
    struct backing_dev_info;
    struct bio_list;
    struct blk_plug;
    @@ -873,10 +872,8 @@ struct task_struct {

    struct callback_head *task_works;

    - struct audit_context *audit_context;
    #ifdef CONFIG_AUDITSYSCALL
    - 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 74f60ba..4058840 100644
    --- a/init/init_task.c
    +++ b/init/init_task.c
    @@ -119,8 +119,7 @@ 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_AUDITSYSCALL
    - .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 3b4ada1..6aba171 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>
    @@ -721,6 +722,7 @@ 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/auditsc.c b/kernel/auditsc.c
    index fb20746..88779a7 100644
    --- a/kernel/auditsc.c
    +++ b/kernel/auditsc.c
    @@ -841,7 +841,7 @@ static inline struct audit_context *audit_take_context(struct task_struct *tsk,
    int return_valid,
    long return_code)
    {
    - struct audit_context *context = tsk->audit_context;
    + struct audit_context *context = tsk->audit->ctx;

    if (!context)
    return NULL;
    @@ -926,6 +926,15 @@ static inline struct audit_context *audit_alloc_context(enum audit_state state)
    return context;
    }

    +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 context block for a task
    * @tsk: task
    @@ -940,17 +949,28 @@ int audit_alloc(struct task_struct *tsk)
    struct audit_context *context;
    enum audit_state state;
    char *key = NULL;
    + struct audit_task_info *info;
    +
    + info = kmem_cache_zalloc(audit_task_cache, GFP_KERNEL);
    + if (!info)
    + return -ENOMEM;
    + info->loginuid = audit_get_loginuid(current);
    + info->sessionid = audit_get_sessionid(current);
    + tsk->audit = info;

    if (likely(!audit_ever_enabled))
    return 0; /* Return if not auditing. */

    state = audit_filter_task(tsk, &key);
    if (state == AUDIT_DISABLED) {
    + audit_set_context(tsk, NULL);
    clear_tsk_thread_flag(tsk, TIF_SYSCALL_AUDIT);
    return 0;
    }

    if (!(context = audit_alloc_context(state))) {
    + tsk->audit = NULL;
    + kmem_cache_free(audit_task_cache, info);
    kfree(key);
    audit_log_lost("out of memory in audit_alloc");
    return -ENOMEM;
    @@ -962,6 +982,12 @@ int audit_alloc(struct task_struct *tsk)
    return 0;
    }

    +struct audit_task_info init_struct_audit = {
    + .loginuid = INVALID_UID,
    + .sessionid = AUDIT_SID_UNSET,
    + .ctx = NULL,
    +};
    +
    static inline void audit_free_context(struct audit_context *context)
    {
    audit_free_names(context);
    @@ -1469,26 +1495,33 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
    }

    /**
    - * __audit_free - free a per-task audit context
    + * audit_free - free a per-task audit context
    * @tsk: task whose audit context block to free
    *
    * Called from copy_process and do_exit
    */
    -void __audit_free(struct task_struct *tsk)
    +void audit_free(struct task_struct *tsk)
    {
    struct audit_context *context;
    + struct audit_task_info *info;

    context = audit_take_context(tsk, 0, 0);
    - if (!context)
    - return;
    -
    /* Check for system calls that do not go through the exit
    * function (e.g., exit_group), then free context block.
    * We use GFP_ATOMIC here because we might be doing this
    * in the context of the idle thread */
    /* that can happen only if we are called from do_exit() */
    - if (context->in_syscall && context->current_state == AUDIT_RECORD_CONTEXT)
    + if (context && context->in_syscall &&
    + context->current_state == AUDIT_RECORD_CONTEXT)
    audit_log_exit(context, 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);
    + if (!context)
    + return;
    if (!list_empty(&context->killed_trees))
    audit_kill_trees(&context->killed_trees);

    @@ -2071,8 +2104,8 @@ int audit_set_loginuid(kuid_t loginuid)
    sessionid = (unsigned int)atomic_inc_return(&session_id);
    }

    - task->sessionid = sessionid;
    - task->loginuid = loginuid;
    + task->audit->sessionid = sessionid;
    + task->audit->loginuid = loginuid;
    out:
    audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
    return rc;
    diff --git a/kernel/fork.c b/kernel/fork.c
    index 9440d61..1bfb0ff 100644
    --- a/kernel/fork.c
    +++ b/kernel/fork.c
    @@ -1721,7 +1721,9 @@ 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);
    +#ifdef CONFIG_AUDITSYSCALL
    + p->audit = NULL;
    +#endif /* CONFIG_AUDITSYSCALL */
    cgroup_fork(p);
    #ifdef CONFIG_NUMA
    p->mempolicy = mpol_dup(p->mempolicy);
    --
    1.8.3.1
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