Commit 571e5c0e authored by Richard Guy Briggs's avatar Richard Guy Briggs Committed by Paul Moore
Browse files

audit: add OPENAT2 record to list "how" info 

Since the openat2(2) syscall uses a struct open_how pointer to communicate
its parameters they are not usefully recorded by the audit SYSCALL record's
four existing arguments.

Add a new audit record type OPENAT2 that reports the parameters in its
third argument, struct open_how with fields oflag, mode and resolve.

The new record in the context of an event would look like:
time->Wed Mar 17 16:28:53 2021
type=PROCTITLE msg=audit(1616012933.531:184): proctitle=
  73797363616C6C735F66696C652F6F70656E617432002F746D702F61756469742D
  7465737473756974652D737641440066696C652D6F70656E617432
type=PATH msg=audit(1616012933.531:184): item=1 name="file-openat2"
  inode=29 dev=00:1f mode=0100600 ouid=0 ogid=0 rdev=00:00
  obj=unconfined_u:object_r:user_tmp_t:s0 nametype=CREATE
  cap_fp=0 cap_fi=0 cap_fe=0 cap_fver=0 cap_frootid=0
type=PATH msg=audit(1616012933.531:184):
  item=0 name="/root/rgb/git/audit-testsuite/tests"
  inode=25 dev=00:1f mode=040700 ouid=0 ogid=0 rdev=00:00
  obj=unconfined_u:object_r:user_tmp_t:s0 nametype=PARENT
  cap_fp=0 cap_fi=0 cap_fe=0 cap_fver=0 cap_frootid=0
type=CWD msg=audit(1616012933.531:184):
  cwd="/root/rgb/git/audit-testsuite/tests"
type=OPENAT2 msg=audit(1616012933.531:184):
  oflag=0100302 mode=0600 resolve=0xa
type=SYSCALL msg=audit(1616012933.531:184): arch=c000003e syscall=437
  success=yes exit=4 a0=3 a1=7ffe315f1c53 a2=7ffe315f1550 a3=18
  items=2 ppid=528 pid=540 auid=0 uid=0 gid=0 euid=0 suid=0
  fsuid=0 egid=0 sgid=0 fsgid=0 tty=ttyS0 ses=1 comm="openat2"
  exe="/root/rgb/git/audit-testsuite/tests/syscalls_file/openat2"
  subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
  key="testsuite-1616012933-bjAUcEPO"

Link: https://lore.kernel.org/r/d23fbb89186754487850367224b060e26f9b7181.1621363275.git.rgb@redhat.com


Signed-off-by: default avatarRichard Guy Briggs <rgb@redhat.com>
Acked-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
[PM: tweak subject, wrap example, move AUDIT_OPENAT2 to 1337]
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
parent 1c30e3af

fs/open.c

+2 −0
Original line number Diff line number Diff line
@@ -1248,6 +1248,8 @@ SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename, 
	if (err)

		return err;



	audit_openat2_how(&tmp);



	/* O_LARGEFILE is only allowed for non-O_PATH. */

	if (!(tmp.flags & O_PATH) && force_o_largefile())

		tmp.flags |= O_LARGEFILE;

include/linux/audit.h

+10 −0
Original line number Diff line number Diff line
@@ -399,6 +399,7 @@ 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_openat2_how(struct open_how *how);

extern void __audit_log_kern_module(char *name);

extern void __audit_fanotify(unsigned int response);

extern void __audit_tk_injoffset(struct timespec64 offset);
@@ -495,6 +496,12 @@ static inline void audit_mmap_fd(int fd, int flags) 
		__audit_mmap_fd(fd, flags);

}



static inline void audit_openat2_how(struct open_how *how)

{

	if (unlikely(!audit_dummy_context()))

		__audit_openat2_how(how);

}



static inline void audit_log_kern_module(char *name)

{

	if (!audit_dummy_context())
@@ -646,6 +653,9 @@ static inline void audit_log_capset(const struct cred *new, 
static inline void audit_mmap_fd(int fd, int flags)

{ }



static inline void audit_openat2_how(struct open_how *how)

{ }



static inline void audit_log_kern_module(char *name)

{

}

include/uapi/linux/audit.h

+1 −0
Original line number Diff line number Diff line
@@ -118,6 +118,7 @@ 
#define AUDIT_TIME_ADJNTPVAL	1333	/* NTP value adjustment */

#define AUDIT_BPF		1334	/* BPF subsystem */

#define AUDIT_EVENT_LISTENER	1335	/* Task joined multicast read socket */

#define AUDIT_OPENAT2		1337	/* Record showing openat2 how args */



#define AUDIT_AVC		1400	/* SE Linux avc denial or grant */

#define AUDIT_SELINUX_ERR	1401	/* Internal SE Linux Errors */

kernel/audit.h

+2 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/skbuff.h>

#include <uapi/linux/mqueue.h>

#include <linux/tty.h>

#include <uapi/linux/openat2.h> // struct open_how



/* AUDIT_NAMES is the number of slots we reserve in the audit_context

 * for saving names from getname().  If we get more names we will allocate
@@ -188,6 +189,7 @@ struct audit_context { 
			int			fd;

			int			flags;

		} mmap;

		struct open_how openat2;

		struct {

			int			argc;

		} execve;

kernel/auditsc.c

+17 −1
Original line number Diff line number Diff line
@@ -63,7 +63,7 @@ 
#include <linux/fsnotify_backend.h>

#include <uapi/linux/limits.h>

#include <uapi/linux/netfilter/nf_tables.h>

#include <uapi/linux/openat2.h>

#include <uapi/linux/openat2.h> // struct open_how



#include "audit.h"
@@ -1306,6 +1306,12 @@ static void show_special(struct audit_context *context, int *call_panic) 
		audit_log_format(ab, "fd=%d flags=0x%x", context->mmap.fd,

				 context->mmap.flags);

		break;

	case AUDIT_OPENAT2:

		audit_log_format(ab, "oflag=0%llo mode=0%llo resolve=0x%llx",

				 context->openat2.flags,

				 context->openat2.mode,

				 context->openat2.resolve);

		break;

	case AUDIT_EXECVE:

		audit_log_execve_info(context, &ab);

		break;
@@ -2536,6 +2542,16 @@ void __audit_mmap_fd(int fd, int flags) 
	context->type = AUDIT_MMAP;

}



void __audit_openat2_how(struct open_how *how)

{

	struct audit_context *context = audit_context();



	context->openat2.flags = how->flags;

	context->openat2.mode = how->mode;

	context->openat2.resolve = how->resolve;

	context->type = AUDIT_OPENAT2;

}



void __audit_log_kern_module(char *name)

{

	struct audit_context *context = audit_context();