linux-kernel - Re: [RFC] [PATCH] audit: log module name on init

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Date:   Mon, 30 Jan 2017 11:54:03 +0100
From:   Steve Grubb <sgrubb@...hat.com>
To:     Richard Guy Briggs <rgb@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-audit@...hat.com,
        Eric Paris <eparis@...hat.com>, Paul Moore <pmoore@...hat.com>,
        Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: [RFC] [PATCH] audit: log module name on init_module

On Thu, 26 Jan 2017 14:50:07 -0500
Richard Guy Briggs <rgb@...hat.com> wrote:

> This adds a new auxiliary record MODULE_INIT to the SYSCALL event.

Thanks, this is definitely needed. Can you provide an example event
generated by this?

-Steve

> We get finit_module for free since it made most sense to hook this in
> to load_module().
> 
> https://github.com/linux-audit/audit-kernel/issues/7
> https://github.com/linux-audit/audit-kernel/wiki/RFE-Module-load-record-format
> 
> Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
> ---
>  include/linux/audit.h      |   12 ++++++++++++
>  include/uapi/linux/audit.h |    1 +
>  kernel/audit.h             |    3 +++
>  kernel/auditsc.c           |   20 ++++++++++++++++++++
>  kernel/module.c            |    5 ++++-
>  5 files changed, 40 insertions(+), 1 deletions(-)
> 
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index 476bc12..6222042 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -358,6 +358,7 @@ extern int __audit_log_bprm_fcaps(struct
> linux_binprm *bprm, const struct cred *old);
>  extern void __audit_log_capset(const struct cred *new, const struct
> cred *old); extern void __audit_mmap_fd(int fd, int flags);
> +extern void __audit_module_init(char *name);
>  
>  static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp)
>  {
> @@ -434,6 +435,12 @@ static inline void audit_mmap_fd(int fd, int
> flags) __audit_mmap_fd(fd, flags);
>  }
>  
> +static inline void audit_module_init(char *name)
> +{
> +	if (!audit_dummy_context())
> +		__audit_module_init(name);
> +}
> +
>  extern int audit_n_rules;
>  extern int audit_signals;
>  #else /* CONFIG_AUDITSYSCALL */
> @@ -539,6 +546,11 @@ static inline void audit_log_capset(const struct
> cred *new, { }
>  static inline void audit_mmap_fd(int fd, int flags)
>  { }
> +
> +static inline void audit_module_init(char *name)
> +{
> +}
> +
>  static inline void audit_ptrace(struct task_struct *t)
>  { }
>  #define audit_n_rules 0
> diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> index 843540c..513c930 100644
> --- a/include/uapi/linux/audit.h
> +++ b/include/uapi/linux/audit.h
> @@ -110,6 +110,7 @@
>  #define AUDIT_SECCOMP		1326	/* Secure Computing
> event */ #define AUDIT_PROCTITLE		1327	/*
> Proctitle emit event */ #define AUDIT_FEATURE_CHANGE
> 1328	/* audit log listing feature changes */ +#define
> AUDIT_MODULE_INIT	1329	/* Module init event */ 
>  #define AUDIT_AVC		1400	/* SE Linux avc denial
> or grant */ #define AUDIT_SELINUX_ERR	1401	/* Internal
> SE Linux Errors */ diff --git a/kernel/audit.h b/kernel/audit.h
> index de6cbb7..cf86486 100644
> --- a/kernel/audit.h
> +++ b/kernel/audit.h
> @@ -198,6 +198,9 @@ struct audit_context {
>  		struct {
>  			int			argc;
>  		} execve;
> +		struct {
> +			char			*name;
> +		} module;
>  	};
>  	int fds[2];
>  	struct audit_proctitle proctitle;
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index b86cc04..93967b8 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -1168,6 +1168,14 @@ static void audit_log_execve_info(struct
> audit_context *context, kfree(buf);
>  }
>  
> +static void audit_log_kern_module(struct audit_context *context,
> +				  struct audit_buffer **ab)
> +{
> +	audit_log_format(*ab, " name=");
> +	audit_log_untrustedstring(*ab, context->module.name);
> +	kfree(context->module.name);
> +}
> +
>  static void show_special(struct audit_context *context, int
> *call_panic) {
>  	struct audit_buffer *ab;
> @@ -1264,6 +1272,9 @@ static void show_special(struct audit_context
> *context, int *call_panic) case AUDIT_EXECVE: {
>  		audit_log_execve_info(context, &ab);
>  		break; }
> +	case AUDIT_MODULE_INIT:
> +		audit_log_kern_module(context, &ab);
> +		break;
>  	}
>  	audit_log_end(ab);
>  }
> @@ -2356,6 +2367,15 @@ void __audit_mmap_fd(int fd, int flags)
>  	context->type = AUDIT_MMAP;
>  }
>  
> +void __audit_module_init(char *name)
> +{
> +	struct audit_context *context = current->audit_context;
> +
> +	context->module.name = kmalloc(strlen(name) + 1, GFP_KERNEL);
> +	strcpy(context->module.name, name);
> +	context->type = AUDIT_MODULE_INIT;
> +}
> +
>  static void audit_log_task(struct audit_buffer *ab)
>  {
>  	kuid_t auid, uid;
> diff --git a/kernel/module.c b/kernel/module.c
> index 8f051a1..214ba85 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -59,6 +59,7 @@
>  #include <linux/jump_label.h>
>  #include <linux/pfn.h>
>  #include <linux/bsearch.h>
> +#include <linux/audit.h>
>  #include <uapi/linux/module.h>
>  #include "module-internal.h"
>  
> @@ -3441,6 +3442,8 @@ static int load_module(struct load_info *info,
> const char __user *uargs, goto free_copy;
>  	}
>  
> +	audit_module_init(mod->name);
> +
>  	/* Reserve our place in the list. */
>  	err = add_unformed_module(mod);
>  	if (err)
> @@ -3525,7 +3528,7 @@ static int load_module(struct load_info *info,
> const char __user *uargs, mod->name, after_dashes);
>  	}
>  
> -	/* Link in to syfs. */
> +	/* Link in to sysfs. */
>  	err = mod_sysfs_setup(mod, info, mod->kp, mod->num_kp);
>  	if (err < 0)
>  		goto bug_cleanup;