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 <[email protected]>
Acked-by: Serge Hallyn <[email protected]>
Acked-by: Neil Horman <[email protected]>
Reviewed-by: Ondrej Mosnacek <[email protected]>
---
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 89cf7c66abe6..15d0defc5193 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -330,6 +330,8 @@ static inline int audit_signal_info(int sig, struct task_struct *t)
/* These are defined in auditsc.c */
/* Public API */
+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);
@@ -592,6 +594,12 @@ 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)
+{
+ return NULL;
+}
+static inline void audit_free_context(struct audit_context *context)
+{ }
static inline void audit_syscall_entry(int major, unsigned long a0,
unsigned long a1, unsigned long a2,
unsigned long a3)
diff --git a/kernel/audit.h b/kernel/audit.h
index 0c9446f8d52c..a7f88d76163f 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -98,6 +98,7 @@ 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 9e79645e5c0e..935eb3d2cde9 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -908,11 +908,13 @@ 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;
@@ -948,7 +950,8 @@ int audit_alloc_syscall(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_syscall");
return -ENOMEM;
@@ -960,8 +963,27 @@ int audit_alloc_syscall(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);
@@ -972,6 +994,7 @@ 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, unsigned int sessionid,
@@ -2204,7 +2227,7 @@ void __audit_inode_child(struct inode *parent,
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();
--
1.8.3.1
On Sat, Jun 27, 2020 at 9:22 AM Richard Guy Briggs <[email protected]> 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.
We've had some good discussions on the list about why we can't reuse
the "in_syscall" field and need to add a "local" field, I think it
would be good to address that here in the commit description.
> Signed-off-by: Richard Guy Briggs <[email protected]>
> Acked-by: Serge Hallyn <[email protected]>
> Acked-by: Neil Horman <[email protected]>
> Reviewed-by: Ondrej Mosnacek <[email protected]>
> ---
> include/linux/audit.h | 8 ++++++++
> kernel/audit.h | 1 +
> kernel/auditsc.c | 33 ++++++++++++++++++++++++++++-----
> 3 files changed, 37 insertions(+), 5 deletions(-)
...
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 9e79645e5c0e..935eb3d2cde9 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -908,11 +908,13 @@ 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() */
At this point I think it's clear we need a respin so I'm not going to
preface all of my nitpick comments as such, although this definitely
would qualify ...
I don't believe audit_tg() doesn't exist yet, likely coming later in
this patchset, so please remove this comment as it doesn't make sense
in this context.
To be frank, don't re-add the comment later in the patchset either.
Comments like these tend to be fragile and don't really add any great
insight. The audit_tg() function can, and most likely will, be
modified at some point in the future such that the comment above no
longer applies, and there is a reasonable chance that when it does the
above comment will not be updated. Further, anyone modifying the
audit_alloc_context() is going to look at the callers (rather they
*should* look at the callers) and will notice the no-sleep
requirements.
> @@ -960,8 +963,27 @@ int audit_alloc_syscall(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;
You might as well just return NULL here, no need to jump and then return NULL.
> + }
> + context->serial = audit_serial();
> + ktime_get_coarse_real_ts64(&context->ctime);
> + context->local = true;
> +out:
> + return context;
> +}
> +EXPORT_SYMBOL(audit_alloc_local);
--
paul moore
http://www.paul-moore.com