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 <[email protected]>.
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 <[email protected]>
Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
Signed-off-by: Richard Guy Briggs <[email protected]>
---
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
On Mon, Dec 12, 2022 at 9:06 AM Richard Guy Briggs <[email protected]> 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 <[email protected]>.
>
> 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 <[email protected]>
> Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
> Signed-off-by: Richard Guy Briggs <[email protected]>
> ---
> 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 <[email protected]> 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 <[email protected]>.
> >
> > 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 <[email protected]>
> > Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
> > Signed-off-by: Richard Guy Briggs <[email protected]>
> > ---
> > 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
> [email protected]
> https://listman.redhat.com/mailman/listinfo/linux-audit
>
- RGB
--
Richard Guy Briggs <[email protected]>
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 <[email protected]> wrote:
> On 2022-12-20 18:31, Paul Moore wrote:
> > On Mon, Dec 12, 2022 at 9:06 AM Richard Guy Briggs <[email protected]> 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 <[email protected]>.
> > >
> > > 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 <[email protected]>
> > > Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
> > > Signed-off-by: Richard Guy Briggs <[email protected]>
> > > ---
> > > 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
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 <[email protected]>.
>
> 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 <[email protected]>
> Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
> Signed-off-by: Richard Guy Briggs <[email protected]>
> ---
> 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 <[email protected]>.
> >
> > 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 <[email protected]>
> > Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
> > Signed-off-by: Richard Guy Briggs <[email protected]>
> > ---
> > 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 <[email protected]>
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 <[email protected]>
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