This patch passes the full response so that the audit function can use all
of it. The audit function was updated to log the additional information in
the AUDIT_FANOTIFY record.

Currently the only type of fanotify info that is defined is an audit
rule number, but convert it to hex encoding to future-proof the field.
Hex encoding suggested by Paul Moore <paul@paul-moore.com>.

Sample records:
  type=FANOTIFY msg=audit(1600385147.372:590): resp=2 fan_type=1 fan_info=3137 subj_trust=3 obj_trust=5
  type=FANOTIFY msg=audit(1659730979.839:284): resp=1 fan_type=0 fan_info=3F subj_trust=2 obj_trust=2

Suggested-by: Steve Grubb <sgrubb@redhat.com>
Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
---
 fs/notify/fanotify/fanotify.c |  3 ++-
 include/linux/audit.h         |  9 +++++----
 kernel/auditsc.c              | 25 ++++++++++++++++++++++---
 3 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 24ec1d66d5a8..29bdd99b29fa 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -273,7 +273,8 @@ static int fanotify_get_response(struct fsnotify_group *group,
 
 	/* Check if the response should be audited */
 	if (event->response & FAN_AUDIT)
-		audit_fanotify(event->response & ~FAN_AUDIT);
+		audit_fanotify(event->response & ~FAN_AUDIT,
+			       &event->audit_rule);
 
 	pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
 		 group, event, ret);
diff --git a/include/linux/audit.h b/include/linux/audit.h
index d6b7d0c7ce43..31086a72e32a 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -14,6 +14,7 @@
 #include <linux/audit_arch.h>
 #include <uapi/linux/audit.h>
 #include <uapi/linux/netfilter/nf_tables.h>
+#include <uapi/linux/fanotify.h>
 
 #define AUDIT_INO_UNSET ((unsigned long)-1)
 #define AUDIT_DEV_UNSET ((dev_t)-1)
@@ -416,7 +417,7 @@ 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_openat2_how(struct open_how *how);
 extern void __audit_log_kern_module(char *name);
-extern void __audit_fanotify(u32 response);
+extern void __audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar);
 extern void __audit_tk_injoffset(struct timespec64 offset);
 extern void __audit_ntp_log(const struct audit_ntp_data *ad);
 extern void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries,
@@ -523,10 +524,10 @@ static inline void audit_log_kern_module(char *name)
 		__audit_log_kern_module(name);
 }
 
-static inline void audit_fanotify(u32 response)
+static inline void audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar)
 {
 	if (!audit_dummy_context())
-		__audit_fanotify(response);
+		__audit_fanotify(response, friar);
 }
 
 static inline void audit_tk_injoffset(struct timespec64 offset)
@@ -679,7 +680,7 @@ static inline void audit_log_kern_module(char *name)
 {
 }
 
-static inline void audit_fanotify(u32 response)
+static inline void audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar)
 { }
 
 static inline void audit_tk_injoffset(struct timespec64 offset)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index d1fb821de104..8d523066d81f 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -64,6 +64,7 @@
 #include <uapi/linux/limits.h>
 #include <uapi/linux/netfilter/nf_tables.h>
 #include <uapi/linux/openat2.h> // struct open_how
+#include <uapi/linux/fanotify.h>
 
 #include "audit.h"
 
@@ -2877,10 +2878,28 @@ void __audit_log_kern_module(char *name)
 	context->type = AUDIT_KERN_MODULE;
 }
 
-void __audit_fanotify(u32 response)
+void __audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar)
 {
-	audit_log(audit_context(), GFP_KERNEL,
-		AUDIT_FANOTIFY,	"resp=%u", response);
+	struct audit_context *ctx = audit_context();
+	struct audit_buffer *ab;
+	char numbuf[12];
+
+	if (friar->hdr.type == FAN_RESPONSE_INFO_NONE) {
+		audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
+			  "resp=%u fan_type=%u fan_info=3F subj_trust=2 obj_trust=2",
+			  response, FAN_RESPONSE_INFO_NONE);
+		return;
+	}
+	ab = audit_log_start(ctx, GFP_KERNEL, AUDIT_FANOTIFY);
+	if (ab) {
+		audit_log_format(ab, "resp=%u fan_type=%u fan_info=",
+				 response, friar->hdr.type);
+		snprintf(numbuf, sizeof(numbuf), "%u", friar->rule_number);
+		audit_log_n_hex(ab, numbuf, sizeof(numbuf));
+		audit_log_format(ab, " subj_trust=%u obj_trust=%u",
+				 friar->subj_trust, friar->obj_trust);
+		audit_log_end(ab);
+	}
 }
 
 void __audit_tk_injoffset(struct timespec64 offset)
-- 
2.27.0

Hello,

Sorry to take so long. Holidays and kernel build problems. However, I have 
built a kernel with these patches. I only have 2 comments. When I use an 
application that expected the old API, meaning it simply does:

        response.fd = metadata->fd;
        response.response = reply;
        close(metadata->fd);
        write(fd, &response, sizeof(struct fanotify_response));

I get access denials. Every time. If the program is using the new API and 
sets FAN_INFO, then it works as expected. I'll do some more testing but I 
think there is something wrong in the compatibility path.

On Monday, December 12, 2022 9:06:11 AM EST Richard Guy Briggs wrote:
> This patch passes the full response so that the audit function can use all
> of it. The audit function was updated to log the additional information in
> the AUDIT_FANOTIFY record.

What I'm seeing is:

type=FANOTIFY msg=audit(01/09/2023 18:43:16.306:366) : resp=deny fan_type=1 
fan_info=313300000000000000000000 subj_trust=0 obj_trust=0

Where fan_info was supposed to be 13 decimal. More below...

> Currently the only type of fanotify info that is defined is an audit
> rule number, but convert it to hex encoding to future-proof the field.
> Hex encoding suggested by Paul Moore <paul@paul-moore.com>.
> 
> Sample records:
>   type=FANOTIFY msg=audit(1600385147.372:590): resp=2 fan_type=1
> fan_info=3137 subj_trust=3 obj_trust=5 type=FANOTIFY
> msg=audit(1659730979.839:284): resp=1 fan_type=0 fan_info=3F subj_trust=2
> obj_trust=2
> 
> Suggested-by: Steve Grubb <sgrubb@redhat.com>
> Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
> Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> ---
>  fs/notify/fanotify/fanotify.c |  3 ++-
>  include/linux/audit.h         |  9 +++++----
>  kernel/auditsc.c              | 25 ++++++++++++++++++++++---
>  3 files changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 24ec1d66d5a8..29bdd99b29fa 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -273,7 +273,8 @@ static int fanotify_get_response(struct fsnotify_group
> *group,
> 
>  	/* Check if the response should be audited */
>  	if (event->response & FAN_AUDIT)
> -		audit_fanotify(event->response & ~FAN_AUDIT);
> +		audit_fanotify(event->response & ~FAN_AUDIT,
> +			       &event->audit_rule);
> 
>  	pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
>  		 group, event, ret);
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index d6b7d0c7ce43..31086a72e32a 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -14,6 +14,7 @@
>  #include <linux/audit_arch.h>
>  #include <uapi/linux/audit.h>
>  #include <uapi/linux/netfilter/nf_tables.h>
> +#include <uapi/linux/fanotify.h>
> 
>  #define AUDIT_INO_UNSET ((unsigned long)-1)
>  #define AUDIT_DEV_UNSET ((dev_t)-1)
> @@ -416,7 +417,7 @@ 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_openat2_how(struct open_how *how);
>  extern void __audit_log_kern_module(char *name);
> -extern void __audit_fanotify(u32 response);
> +extern void __audit_fanotify(u32 response, struct
> fanotify_response_info_audit_rule *friar); extern void
> __audit_tk_injoffset(struct timespec64 offset);
>  extern void __audit_ntp_log(const struct audit_ntp_data *ad);
>  extern void __audit_log_nfcfg(const char *name, u8 af, unsigned int
> nentries, @@ -523,10 +524,10 @@ static inline void
> audit_log_kern_module(char *name) __audit_log_kern_module(name);
>  }
> 
> -static inline void audit_fanotify(u32 response)
> +static inline void audit_fanotify(u32 response, struct
> fanotify_response_info_audit_rule *friar) {
>  	if (!audit_dummy_context())
> -		__audit_fanotify(response);
> +		__audit_fanotify(response, friar);
>  }
> 
>  static inline void audit_tk_injoffset(struct timespec64 offset)
> @@ -679,7 +680,7 @@ static inline void audit_log_kern_module(char *name)
>  {
>  }
> 
> -static inline void audit_fanotify(u32 response)
> +static inline void audit_fanotify(u32 response, struct
> fanotify_response_info_audit_rule *friar) { }
> 
>  static inline void audit_tk_injoffset(struct timespec64 offset)
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index d1fb821de104..8d523066d81f 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -64,6 +64,7 @@
>  #include <uapi/linux/limits.h>
>  #include <uapi/linux/netfilter/nf_tables.h>
>  #include <uapi/linux/openat2.h> // struct open_how
> +#include <uapi/linux/fanotify.h>
> 
>  #include "audit.h"
> 
> @@ -2877,10 +2878,28 @@ void __audit_log_kern_module(char *name)
>  	context->type = AUDIT_KERN_MODULE;
>  }
> 
> -void __audit_fanotify(u32 response)
> +void __audit_fanotify(u32 response, struct
> fanotify_response_info_audit_rule *friar) {
> -	audit_log(audit_context(), GFP_KERNEL,
> -		AUDIT_FANOTIFY,	"resp=%u", response);
> +	struct audit_context *ctx = audit_context();
> +	struct audit_buffer *ab;
> +	char numbuf[12];
> +
> +	if (friar->hdr.type == FAN_RESPONSE_INFO_NONE) {
> +		audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
> +			  "resp=%u fan_type=%u fan_info=3F subj_trust=2 
obj_trust=2",
> +			  response, FAN_RESPONSE_INFO_NONE);
> +		return;
> +	}
> +	ab = audit_log_start(ctx, GFP_KERNEL, AUDIT_FANOTIFY);
> +	if (ab) {
> +		audit_log_format(ab, "resp=%u fan_type=%u fan_info=",
> +				 response, friar->hdr.type);
> +		snprintf(numbuf, sizeof(numbuf), "%u", friar->rule_number);
> +		audit_log_n_hex(ab, numbuf, sizeof(numbuf));

I don't think it needs to be converted to ascii and then hexencoded. As Paul 
said, probably %X is all we need here.

-Steve


> +		audit_log_format(ab, " subj_trust=%u obj_trust=%u",
> +				 friar->subj_trust, friar->obj_trust);
> +		audit_log_end(ab);
> +	}
>  }
> 
>  void __audit_tk_injoffset(struct timespec64 offset)

On 2023-01-09 19:06, Steve Grubb wrote:
> Hello,
> 
> Sorry to take so long. Holidays and kernel build problems. However, I have 
> built a kernel with these patches. I only have 2 comments. When I use an 
> application that expected the old API, meaning it simply does:
> 
>         response.fd = metadata->fd;
>         response.response = reply;
>         close(metadata->fd);
>         write(fd, &response, sizeof(struct fanotify_response));
> 
> I get access denials. Every time. If the program is using the new API and 
> sets FAN_INFO, then it works as expected. I'll do some more testing but I 
> think there is something wrong in the compatibility path.

I'll have a closer look, because this wasn't the intended behaviour.

> On Monday, December 12, 2022 9:06:11 AM EST Richard Guy Briggs wrote:
> > This patch passes the full response so that the audit function can use all
> > of it. The audit function was updated to log the additional information in
> > the AUDIT_FANOTIFY record.
> 
> What I'm seeing is:
> 
> type=FANOTIFY msg=audit(01/09/2023 18:43:16.306:366) : resp=deny fan_type=1 
> fan_info=313300000000000000000000 subj_trust=0 obj_trust=0
> 
> Where fan_info was supposed to be 13 decimal. More below...

Well, it *is* 13 decimal, expressed as a hex-encoded string as was
requested for future-proofing, albeit longer than necessary...

> > Currently the only type of fanotify info that is defined is an audit
> > rule number, but convert it to hex encoding to future-proof the field.
> > Hex encoding suggested by Paul Moore <paul@paul-moore.com>.
> > 
> > Sample records:
> >   type=FANOTIFY msg=audit(1600385147.372:590): resp=2 fan_type=1
> > fan_info=3137 subj_trust=3 obj_trust=5 type=FANOTIFY
> > msg=audit(1659730979.839:284): resp=1 fan_type=0 fan_info=3F subj_trust=2
> > obj_trust=2
> > 
> > Suggested-by: Steve Grubb <sgrubb@redhat.com>
> > Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
> > Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> > ---
> >  fs/notify/fanotify/fanotify.c |  3 ++-
> >  include/linux/audit.h         |  9 +++++----
> >  kernel/auditsc.c              | 25 ++++++++++++++++++++++---
> >  3 files changed, 29 insertions(+), 8 deletions(-)
> > 
> > diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> > index 24ec1d66d5a8..29bdd99b29fa 100644
> > --- a/fs/notify/fanotify/fanotify.c
> > +++ b/fs/notify/fanotify/fanotify.c
> > @@ -273,7 +273,8 @@ static int fanotify_get_response(struct fsnotify_group
> > *group,
> > 
> >  	/* Check if the response should be audited */
> >  	if (event->response & FAN_AUDIT)
> > -		audit_fanotify(event->response & ~FAN_AUDIT);
> > +		audit_fanotify(event->response & ~FAN_AUDIT,
> > +			       &event->audit_rule);
> > 
> >  	pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
> >  		 group, event, ret);
> > diff --git a/include/linux/audit.h b/include/linux/audit.h
> > index d6b7d0c7ce43..31086a72e32a 100644
> > --- a/include/linux/audit.h
> > +++ b/include/linux/audit.h
> > @@ -14,6 +14,7 @@
> >  #include <linux/audit_arch.h>
> >  #include <uapi/linux/audit.h>
> >  #include <uapi/linux/netfilter/nf_tables.h>
> > +#include <uapi/linux/fanotify.h>
> > 
> >  #define AUDIT_INO_UNSET ((unsigned long)-1)
> >  #define AUDIT_DEV_UNSET ((dev_t)-1)
> > @@ -416,7 +417,7 @@ 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_openat2_how(struct open_how *how);
> >  extern void __audit_log_kern_module(char *name);
> > -extern void __audit_fanotify(u32 response);
> > +extern void __audit_fanotify(u32 response, struct
> > fanotify_response_info_audit_rule *friar); extern void
> > __audit_tk_injoffset(struct timespec64 offset);
> >  extern void __audit_ntp_log(const struct audit_ntp_data *ad);
> >  extern void __audit_log_nfcfg(const char *name, u8 af, unsigned int
> > nentries, @@ -523,10 +524,10 @@ static inline void
> > audit_log_kern_module(char *name) __audit_log_kern_module(name);
> >  }
> > 
> > -static inline void audit_fanotify(u32 response)
> > +static inline void audit_fanotify(u32 response, struct
> > fanotify_response_info_audit_rule *friar) {
> >  	if (!audit_dummy_context())
> > -		__audit_fanotify(response);
> > +		__audit_fanotify(response, friar);
> >  }
> > 
> >  static inline void audit_tk_injoffset(struct timespec64 offset)
> > @@ -679,7 +680,7 @@ static inline void audit_log_kern_module(char *name)
> >  {
> >  }
> > 
> > -static inline void audit_fanotify(u32 response)
> > +static inline void audit_fanotify(u32 response, struct
> > fanotify_response_info_audit_rule *friar) { }
> > 
> >  static inline void audit_tk_injoffset(struct timespec64 offset)
> > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > index d1fb821de104..8d523066d81f 100644
> > --- a/kernel/auditsc.c
> > +++ b/kernel/auditsc.c
> > @@ -64,6 +64,7 @@
> >  #include <uapi/linux/limits.h>
> >  #include <uapi/linux/netfilter/nf_tables.h>
> >  #include <uapi/linux/openat2.h> // struct open_how
> > +#include <uapi/linux/fanotify.h>
> > 
> >  #include "audit.h"
> > 
> > @@ -2877,10 +2878,28 @@ void __audit_log_kern_module(char *name)
> >  	context->type = AUDIT_KERN_MODULE;
> >  }
> > 
> > -void __audit_fanotify(u32 response)
> > +void __audit_fanotify(u32 response, struct
> > fanotify_response_info_audit_rule *friar) {
> > -	audit_log(audit_context(), GFP_KERNEL,
> > -		AUDIT_FANOTIFY,	"resp=%u", response);
> > +	struct audit_context *ctx = audit_context();
> > +	struct audit_buffer *ab;
> > +	char numbuf[12];
> > +
> > +	if (friar->hdr.type == FAN_RESPONSE_INFO_NONE) {
> > +		audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
> > +			  "resp=%u fan_type=%u fan_info=3F subj_trust=2 
> obj_trust=2",
> > +			  response, FAN_RESPONSE_INFO_NONE);
> > +		return;
> > +	}
> > +	ab = audit_log_start(ctx, GFP_KERNEL, AUDIT_FANOTIFY);
> > +	if (ab) {
> > +		audit_log_format(ab, "resp=%u fan_type=%u fan_info=",
> > +				 response, friar->hdr.type);
> > +		snprintf(numbuf, sizeof(numbuf), "%u", friar->rule_number);
> > +		audit_log_n_hex(ab, numbuf, sizeof(numbuf));
> 
> I don't think it needs to be converted to ascii and then hexencoded. As Paul 
> said, probably %X is all we need here.
> 
> -Steve
> 
> 
> > +		audit_log_format(ab, " subj_trust=%u obj_trust=%u",
> > +				 friar->subj_trust, friar->obj_trust);
> > +		audit_log_end(ab);
> > +	}
> >  }
> > 
> >  void __audit_tk_injoffset(struct timespec64 offset)
> 
> 
> 
> 

- RGB

--
Richard Guy Briggs <rgb@redhat.com>
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

Hello Richard,

On Monday, January 9, 2023 10:08:04 PM EST Richard Guy Briggs wrote:
> When I use an application that expected the old API, meaning it simply
> does:
> > 
> > response.fd = metadata->fd;
> > response.response = reply;
> > close(metadata->fd);
> > write(fd, &response, sizeof(struct fanotify_response));
> > 
> > I get access denials. Every time. If the program is using the new API and
> > sets FAN_INFO, then it works as expected. I'll do some more testing but I
> > think there is something wrong in the compatibility path.
> 
> I'll have a closer look, because this wasn't the intended behaviour.

I have done more testing. I think what I saw might have been caused by a 
stale selinux label (label exists, policy is deleted). With selinux in 
permissive mode it's all working as expected - both old and new API.

-Steve

On 2023-01-10 10:26, Steve Grubb wrote:
> Hello Richard,
> 
> On Monday, January 9, 2023 10:08:04 PM EST Richard Guy Briggs wrote:
> > When I use an application that expected the old API, meaning it simply
> > does:
> > > 
> > > response.fd = metadata->fd;
> > > response.response = reply;
> > > close(metadata->fd);
> > > write(fd, &response, sizeof(struct fanotify_response));
> > > 
> > > I get access denials. Every time. If the program is using the new API and
> > > sets FAN_INFO, then it works as expected. I'll do some more testing but I
> > > think there is something wrong in the compatibility path.
> > 
> > I'll have a closer look, because this wasn't the intended behaviour.
> 
> I have done more testing. I think what I saw might have been caused by a 
> stale selinux label (label exists, policy is deleted). With selinux in 
> permissive mode it's all working as expected - both old and new API.

Ah good, thank you.

> -Steve

- RGB

--
Richard Guy Briggs <rgb@redhat.com>
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

On Mon, Dec 12, 2022 at 9:06 AM Richard Guy Briggs <rgb@redhat.com> wrote:
>
> This patch passes the full response so that the audit function can use all
> of it. The audit function was updated to log the additional information in
> the AUDIT_FANOTIFY record.
>
> Currently the only type of fanotify info that is defined is an audit
> rule number, but convert it to hex encoding to future-proof the field.
> Hex encoding suggested by Paul Moore <paul@paul-moore.com>.
>
> Sample records:
>   type=FANOTIFY msg=audit(1600385147.372:590): resp=2 fan_type=1 fan_info=3137 subj_trust=3 obj_trust=5
>   type=FANOTIFY msg=audit(1659730979.839:284): resp=1 fan_type=0 fan_info=3F subj_trust=2 obj_trust=2
>
> Suggested-by: Steve Grubb <sgrubb@redhat.com>
> Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
> Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> ---
>  fs/notify/fanotify/fanotify.c |  3 ++-
>  include/linux/audit.h         |  9 +++++----
>  kernel/auditsc.c              | 25 ++++++++++++++++++++++---
>  3 files changed, 29 insertions(+), 8 deletions(-)

...

> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index d1fb821de104..8d523066d81f 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -64,6 +64,7 @@
>  #include <uapi/linux/limits.h>
>  #include <uapi/linux/netfilter/nf_tables.h>
>  #include <uapi/linux/openat2.h> // struct open_how
> +#include <uapi/linux/fanotify.h>
>
>  #include "audit.h"
>
> @@ -2877,10 +2878,28 @@ void __audit_log_kern_module(char *name)
>         context->type = AUDIT_KERN_MODULE;
>  }
>
> -void __audit_fanotify(u32 response)
> +void __audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar)
>  {
> -       audit_log(audit_context(), GFP_KERNEL,
> -               AUDIT_FANOTIFY, "resp=%u", response);
> +       struct audit_context *ctx = audit_context();
> +       struct audit_buffer *ab;
> +       char numbuf[12];
> +
> +       if (friar->hdr.type == FAN_RESPONSE_INFO_NONE) {
> +               audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
> +                         "resp=%u fan_type=%u fan_info=3F subj_trust=2 obj_trust=2",
> +                         response, FAN_RESPONSE_INFO_NONE);

The fan_info, subj_trust, and obj_trust constant values used here are
awfully magic-numbery and not the usual sentinel values one might
expect for a "none" operation, e.g. zeros/INT_MAX/etc. I believe a
comment here explaining the values would be a good idea.

> +               return;
> +       }
> +       ab = audit_log_start(ctx, GFP_KERNEL, AUDIT_FANOTIFY);
> +       if (ab) {
> +               audit_log_format(ab, "resp=%u fan_type=%u fan_info=",
> +                                response, friar->hdr.type);
> +               snprintf(numbuf, sizeof(numbuf), "%u", friar->rule_number);
> +               audit_log_n_hex(ab, numbuf, sizeof(numbuf));

It looks like the kernel's printf format string parsing supports %X so
why not just use that for now, we can always complicate it later if
needed.  It would probably also remove the need for the @ab, @numbuf,
and @ctx variables.  For example:

audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
  "resp=%u fan_type=%u fan_info=%X subj_trust=%u obj_trust=%u",
  response, friar->hdr.type, friar->rule_number,
  friar->subj_trust, friar->obj_trust);

Am I missing something?

> +               audit_log_format(ab, " subj_trust=%u obj_trust=%u",
> +                                friar->subj_trust, friar->obj_trust);
> +               audit_log_end(ab);
> +       }
>  }
>
>  void __audit_tk_injoffset(struct timespec64 offset)
> --
> 2.27.0

-- 
paul-moore.com

On 2022-12-20 18:31, Paul Moore wrote:
> On Mon, Dec 12, 2022 at 9:06 AM Richard Guy Briggs <rgb@redhat.com> wrote:
> >
> > This patch passes the full response so that the audit function can use all
> > of it. The audit function was updated to log the additional information in
> > the AUDIT_FANOTIFY record.
> >
> > Currently the only type of fanotify info that is defined is an audit
> > rule number, but convert it to hex encoding to future-proof the field.
> > Hex encoding suggested by Paul Moore <paul@paul-moore.com>.
> >
> > Sample records:
> >   type=FANOTIFY msg=audit(1600385147.372:590): resp=2 fan_type=1 fan_info=3137 subj_trust=3 obj_trust=5
> >   type=FANOTIFY msg=audit(1659730979.839:284): resp=1 fan_type=0 fan_info=3F subj_trust=2 obj_trust=2
> >
> > Suggested-by: Steve Grubb <sgrubb@redhat.com>
> > Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
> > Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> > ---
> >  fs/notify/fanotify/fanotify.c |  3 ++-
> >  include/linux/audit.h         |  9 +++++----
> >  kernel/auditsc.c              | 25 ++++++++++++++++++++++---
> >  3 files changed, 29 insertions(+), 8 deletions(-)
> 
> ...
> 
> > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > index d1fb821de104..8d523066d81f 100644
> > --- a/kernel/auditsc.c
> > +++ b/kernel/auditsc.c
> > @@ -64,6 +64,7 @@
> >  #include <uapi/linux/limits.h>
> >  #include <uapi/linux/netfilter/nf_tables.h>
> >  #include <uapi/linux/openat2.h> // struct open_how
> > +#include <uapi/linux/fanotify.h>
> >
> >  #include "audit.h"
> >
> > @@ -2877,10 +2878,28 @@ void __audit_log_kern_module(char *name)
> >         context->type = AUDIT_KERN_MODULE;
> >  }
> >
> > -void __audit_fanotify(u32 response)
> > +void __audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar)
> >  {
> > -       audit_log(audit_context(), GFP_KERNEL,
> > -               AUDIT_FANOTIFY, "resp=%u", response);
> > +       struct audit_context *ctx = audit_context();
> > +       struct audit_buffer *ab;
> > +       char numbuf[12];
> > +
> > +       if (friar->hdr.type == FAN_RESPONSE_INFO_NONE) {
> > +               audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
> > +                         "resp=%u fan_type=%u fan_info=3F subj_trust=2 obj_trust=2",
> > +                         response, FAN_RESPONSE_INFO_NONE);
> 
> The fan_info, subj_trust, and obj_trust constant values used here are
> awfully magic-numbery and not the usual sentinel values one might
> expect for a "none" operation, e.g. zeros/INT_MAX/etc. I believe a
> comment here explaining the values would be a good idea.

Ack.  I'll add a comment.  I would have preferred zero for default of
unset, but Steve requested 0/1/2 no/yes/unknown.

> > +               return;
> > +       }
> > +       ab = audit_log_start(ctx, GFP_KERNEL, AUDIT_FANOTIFY);
> > +       if (ab) {
> > +               audit_log_format(ab, "resp=%u fan_type=%u fan_info=",
> > +                                response, friar->hdr.type);
> > +               snprintf(numbuf, sizeof(numbuf), "%u", friar->rule_number);
> > +               audit_log_n_hex(ab, numbuf, sizeof(numbuf));
> 
> It looks like the kernel's printf format string parsing supports %X so
> why not just use that for now, we can always complicate it later if
> needed.  It would probably also remove the need for the @ab, @numbuf,
> and @ctx variables.  For example:
> 
> audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
>   "resp=%u fan_type=%u fan_info=%X subj_trust=%u obj_trust=%u",
>   response, friar->hdr.type, friar->rule_number,
>   friar->subj_trust, friar->obj_trust);
> 
> Am I missing something?

No, I am.  Thank you, that's much cleaner.

> > +               audit_log_format(ab, " subj_trust=%u obj_trust=%u",
> > +                                friar->subj_trust, friar->obj_trust);
> > +               audit_log_end(ab);
> > +       }
> >  }
> >
> >  void __audit_tk_injoffset(struct timespec64 offset)
> > --
> > 2.27.0
> 
> -- 
> paul-moore.com
> 
> --
> Linux-audit mailing list
> Linux-audit@redhat.com
> https://listman.redhat.com/mailman/listinfo/linux-audit
> 

- RGB

--
Richard Guy Briggs <rgb@redhat.com>
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

On Thu, Dec 22, 2022 at 3:42 PM Richard Guy Briggs <rgb@redhat.com> wrote:
> On 2022-12-20 18:31, Paul Moore wrote:
> > On Mon, Dec 12, 2022 at 9:06 AM Richard Guy Briggs <rgb@redhat.com> wrote:
> > >
> > > This patch passes the full response so that the audit function can use all
> > > of it. The audit function was updated to log the additional information in
> > > the AUDIT_FANOTIFY record.
> > >
> > > Currently the only type of fanotify info that is defined is an audit
> > > rule number, but convert it to hex encoding to future-proof the field.
> > > Hex encoding suggested by Paul Moore <paul@paul-moore.com>.
> > >
> > > Sample records:
> > >   type=FANOTIFY msg=audit(1600385147.372:590): resp=2 fan_type=1 fan_info=3137 subj_trust=3 obj_trust=5
> > >   type=FANOTIFY msg=audit(1659730979.839:284): resp=1 fan_type=0 fan_info=3F subj_trust=2 obj_trust=2
> > >
> > > Suggested-by: Steve Grubb <sgrubb@redhat.com>
> > > Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
> > > Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> > > ---
> > >  fs/notify/fanotify/fanotify.c |  3 ++-
> > >  include/linux/audit.h         |  9 +++++----
> > >  kernel/auditsc.c              | 25 ++++++++++++++++++++++---
> > >  3 files changed, 29 insertions(+), 8 deletions(-)
> >
> > ...
> >
> > > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > > index d1fb821de104..8d523066d81f 100644
> > > --- a/kernel/auditsc.c
> > > +++ b/kernel/auditsc.c
> > > @@ -64,6 +64,7 @@
> > >  #include <uapi/linux/limits.h>
> > >  #include <uapi/linux/netfilter/nf_tables.h>
> > >  #include <uapi/linux/openat2.h> // struct open_how
> > > +#include <uapi/linux/fanotify.h>
> > >
> > >  #include "audit.h"
> > >
> > > @@ -2877,10 +2878,28 @@ void __audit_log_kern_module(char *name)
> > >         context->type = AUDIT_KERN_MODULE;
> > >  }
> > >
> > > -void __audit_fanotify(u32 response)
> > > +void __audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar)
> > >  {
> > > -       audit_log(audit_context(), GFP_KERNEL,
> > > -               AUDIT_FANOTIFY, "resp=%u", response);
> > > +       struct audit_context *ctx = audit_context();
> > > +       struct audit_buffer *ab;
> > > +       char numbuf[12];
> > > +
> > > +       if (friar->hdr.type == FAN_RESPONSE_INFO_NONE) {
> > > +               audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
> > > +                         "resp=%u fan_type=%u fan_info=3F subj_trust=2 obj_trust=2",
> > > +                         response, FAN_RESPONSE_INFO_NONE);
> >
> > The fan_info, subj_trust, and obj_trust constant values used here are
> > awfully magic-numbery and not the usual sentinel values one might
> > expect for a "none" operation, e.g. zeros/INT_MAX/etc. I believe a
> > comment here explaining the values would be a good idea.
>
> Ack.  I'll add a comment.  I would have preferred zero for default of
> unset, but Steve requested 0/1/2 no/yes/unknown.

Yeah, if they were zeros I don't think we would need to comment on
them as zeros for unset/unknown/invalid is rather common, 2 ... not so
much.

-- 
paul-moore.com