Re: [PATCH v24 21/25] audit: add support for non-syscall auxiliary records

[Richard Guy Briggs]

On 2021-01-26 10:58, Casey Schaufler wrote:
> On 1/26/2021 10:42 AM, Richard Guy Briggs wrote:
> > On 2021-01-26 08:41, Casey Schaufler wrote:
> >> Standalone audit records have the timestamp and serial number generated
> >> on the fly and as such are unique, making them standalone.  This new
> >> function audit_alloc_local() generates a local audit context that will
> >> be used only for a standalone record and its auxiliary record(s).  The
> >> context is discarded immediately after the local associated records are
> >> produced.
> >>
> >> Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
> >> Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
> >> Cc: linux-audit@xxxxxxxxxx
> >> To: Richard Guy Briggs <rgb@xxxxxxxxxx>
> > This has been minorly bothering me for several revisions...  Is there a
> > way for the development/authorship to be accurately reflected
> > if/when this patch is merged before the contid patch set?
> 
> I don't know the right way to do that because I had to pull
> some of what was in the original patch out. Any way you would
> like it done is fine with me.

Other than diff context, it appears to be identical to the patch in the
v9 contid patchset (with one tiny cut/paste below, I don't know how it
compiles...).  There are minor updates to bring it up to v11.

> >> ---
> >>  include/linux/audit.h |  8 ++++++++
> >>  kernel/audit.h        |  1 +
> >>  kernel/auditsc.c      | 33 ++++++++++++++++++++++++++++-----
> >>  3 files changed, 37 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/include/linux/audit.h b/include/linux/audit.h
> >> index 418a485af114..97cd7471e572 100644
> >> --- a/include/linux/audit.h
> >> +++ b/include/linux/audit.h
> >> @@ -289,6 +289,8 @@ static inline int audit_signal_info(int sig, struct task_struct *t)
> >>  				/* Public API */
> >>  extern int  audit_alloc(struct task_struct *task);
> >>  extern void __audit_free(struct task_struct *task);
> >> +extern struct audit_context *audit_alloc_local(gfp_t gfpflags);
> >> +extern void audit_free_context(struct audit_context *context);
> >>  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);
> >> @@ -552,6 +554,12 @@ static inline void audit_log_nfcfg(const char *name, u8 af,
> >>  extern int audit_n_rules;
> >>  extern int audit_signals;
> >>  #else /* CONFIG_AUDITSYSCALL */
> >> ++static inline struct audit_context *audit_alloc_local(gfp_t gfpflags)

This extra "+" that ends up at the beginning of the line looks
unintentional and I'd have expected the compiler to complain.

> >> +{
> >> +	return NULL;
> >> +}
> >> +static inline void audit_free_context(struct audit_context *context)
> >> +{ }
> >>  static inline int audit_alloc(struct task_struct *task)
> >>  {
> >>  	return 0;
> >> diff --git a/kernel/audit.h b/kernel/audit.h
> >> index ce41886807bb..3f2285e1c6e0 100644
> >> --- a/kernel/audit.h
> >> +++ b/kernel/audit.h
> >> @@ -99,6 +99,7 @@ struct audit_proctitle {
> >>  struct audit_context {
> >>  	int		    dummy;	/* must be the first element */
> >>  	int		    in_syscall;	/* 1 if task is in a syscall */
> >> +	bool		    local;	/* local context needed */
> >>  	enum audit_state    state, current_state;
> >>  	unsigned int	    serial;     /* serial number for record */
> >>  	int		    major;      /* syscall number */
> >> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> >> index de2b2ecb3aea..479b3933d788 100644
> >> --- a/kernel/auditsc.c
> >> +++ b/kernel/auditsc.c
> >> @@ -927,11 +927,13 @@ static inline void audit_free_aux(struct audit_context *context)
> >>  	}
> >>  }
> >>  
> >> -static inline struct audit_context *audit_alloc_context(enum audit_state state)
> >> +static inline struct audit_context *audit_alloc_context(enum audit_state state,
> >> +							gfp_t gfpflags)
> >>  {
> >>  	struct audit_context *context;
> >>  
> >> -	context = kzalloc(sizeof(*context), GFP_KERNEL);
> >> +	/* We can be called in atomic context via audit_tg() */
> >> +	context = kzalloc(sizeof(*context), gfpflags);
> >>  	if (!context)
> >>  		return NULL;
> >>  	context->state = state;
> >> @@ -967,7 +969,8 @@ int audit_alloc(struct task_struct *tsk)
> >>  		return 0;
> >>  	}
> >>  
> >> -	if (!(context = audit_alloc_context(state))) {
> >> +	context = audit_alloc_context(state, GFP_KERNEL);
> >> +	if (!context) {
> >>  		kfree(key);
> >>  		audit_log_lost("out of memory in audit_alloc");
> >>  		return -ENOMEM;
> >> @@ -979,8 +982,27 @@ int audit_alloc(struct task_struct *tsk)
> >>  	return 0;
> >>  }
> >>  
> >> -static inline void audit_free_context(struct audit_context *context)
> >> +struct audit_context *audit_alloc_local(gfp_t gfpflags)
> >>  {
> >> +	struct audit_context *context = NULL;
> >> +
> >> +	context = audit_alloc_context(AUDIT_RECORD_CONTEXT, gfpflags);
> >> +	if (!context) {
> >> +		audit_log_lost("out of memory in audit_alloc_local");
> >> +		goto out;
> >> +	}
> >> +	context->serial = audit_serial();
> >> +	ktime_get_coarse_real_ts64(&context->ctime);
> >> +	context->local = true;
> >> +out:
> >> +	return context;
> >> +}
> >> +EXPORT_SYMBOL(audit_alloc_local);
> >> +
> >> +void audit_free_context(struct audit_context *context)
> >> +{
> >> +	if (!context)
> >> +		return;
> >>  	audit_free_module(context);
> >>  	audit_free_names(context);
> >>  	unroll_tree_refs(context, NULL, 0);
> >> @@ -991,6 +1013,7 @@ static inline void audit_free_context(struct audit_context *context)
> >>  	audit_proctitle_free(context);
> >>  	kfree(context);
> >>  }
> >> +EXPORT_SYMBOL(audit_free_context);
> >>  
> >>  static int audit_log_pid_context(struct audit_context *context, pid_t pid,
> >>  				 kuid_t auid, kuid_t uid,
> >> @@ -2214,7 +2237,7 @@ EXPORT_SYMBOL_GPL(__audit_inode_child);
> >>  int auditsc_get_stamp(struct audit_context *ctx,
> >>  		       struct timespec64 *t, unsigned int *serial)
> >>  {
> >> -	if (!ctx->in_syscall)
> >> +	if (!ctx->in_syscall && !ctx->local)
> >>  		return 0;
> >>  	if (!ctx->serial)
> >>  		ctx->serial = audit_serial();
> >> -- 
> >> 2.25.4
> >>
> > - RGB

- RGB

--
Richard Guy Briggs <rgb@xxxxxxxxxx>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635