On Sun, Aug 5, 2018 at 4:32 AM Richard Guy Briggs <rgb@xxxxxxxxxx> 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. > > See: https://github.com/linux-audit/audit-kernel/issues/81 > > Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx> > --- > 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; > +}; ... > 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 > @@ -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; Prior to this patch audit_context was available regardless of CONFIG_AUDITSYSCALL, after this patch the corresponding audit_context is only available when CONFIG_AUDITSYSCALL is defined. > 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(); It seems like we would need either init_struct_audit or audit_task_init(), but not both, yes? > 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); > +} This is somewhat related to the CONFIG_AUDITSYSCALL comment above, but since the audit_task_info contains generic audit state (not just syscall related state), it seems like this, and the audit_task_info accessors/helpers, should live in kernel/audit.c. There are probably a few other things that should move to kernel/audit.c too, e.g. audit_alloc(). Have you verified that this builds/runs correctly on architectures that define CONFIG_AUDIT but not CONFIG_AUDITSYSCALL? > /** > * 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. */ I don't view this as necessary for initial acceptance, and synchronization/locking might render this undesirable, but it would be curious to see if we could do something clever with refcnts and copy-on-write to minimize the number of kmem_cache objects in use in the !audit_ever_enabled (and possibly the AUDIT_DISABLED) case. > state = audit_filter_task(tsk, &key); > if (state == AUDIT_DISABLED) { > + audit_set_context(tsk, NULL); It's already NULL, isn't it? > 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); -- paul moore www.paul-moore.com
