Change the cap_rights_t type from uint64_t to a structure that we can extend

in the future in a backward compatible (API and ABI) way.

The cap_rights_t represents capability rights. We used to use one bit to
represent one right, but we are running out of spare bits. Currently the new
structure provides place for 114 rights (so 50 more than the previous
cap_rights_t), but it is possible to grow the structure to hold at least 285
rights, although we can make it even larger if 285 rights won't be enough.

The structure definition looks like this:

	struct cap_rights {
		uint64_t	cr_rights[CAP_RIGHTS_VERSION + 2];
	};

The initial CAP_RIGHTS_VERSION is 0.

The top two bits in the first element of the cr_rights[] array contain total
number of elements in the array - 2. This means if those two bits are equal to
0, we have 2 array elements.

The top two bits in all remaining array elements should be 0.
The next five bits in all array elements contain array index. Only one bit is
used and bit position in this five-bits range defines array index. This means
there can be at most five array elements in the future.

To define new right the CAPRIGHT() macro must be used. The macro takes two
arguments - an array index and a bit to set, eg.

	#define	CAP_PDKILL	CAPRIGHT(1, 0x0000000000000800ULL)

We still support aliases that combine few rights, but the rights have to belong
to the same array element, eg:

	#define	CAP_LOOKUP	CAPRIGHT(0, 0x0000000000000400ULL)
	#define	CAP_FCHMOD	CAPRIGHT(0, 0x0000000000002000ULL)

	#define	CAP_FCHMODAT	(CAP_FCHMOD | CAP_LOOKUP)

There is new API to manage the new cap_rights_t structure:

	cap_rights_t *cap_rights_init(cap_rights_t *rights, ...);
	void cap_rights_set(cap_rights_t *rights, ...);
	void cap_rights_clear(cap_rights_t *rights, ...);
	bool cap_rights_is_set(const cap_rights_t *rights, ...);

	bool cap_rights_is_valid(const cap_rights_t *rights);
	void cap_rights_merge(cap_rights_t *dst, const cap_rights_t *src);
	void cap_rights_remove(cap_rights_t *dst, const cap_rights_t *src);
	bool cap_rights_contains(const cap_rights_t *big, const cap_rights_t *little);

Capability rights to the cap_rights_init(), cap_rights_set(),
cap_rights_clear() and cap_rights_is_set() functions are provided by
separating them with commas, eg:

	cap_rights_t rights;

	cap_rights_init(&rights, CAP_READ, CAP_WRITE, CAP_FSTAT);

There is no need to terminate the list of rights, as those functions are
actually macros that take care of the termination, eg:

	#define	cap_rights_set(rights, ...)				\
		__cap_rights_set((rights), __VA_ARGS__, 0ULL)
	void __cap_rights_set(cap_rights_t *rights, ...);

Thanks to using one bit as an array index we can assert in those functions that
there are no two rights belonging to different array elements provided
together. For example this is illegal and will be detected, because CAP_LOOKUP
belongs to element 0 and CAP_PDKILL to element 1:

	cap_rights_init(&rights, CAP_LOOKUP | CAP_PDKILL);

Providing several rights that belongs to the same array's element this way is
correct, but is not advised. It should only be used for aliases definition.

This commit also breaks compatibility with some existing Capsicum system calls,
but I see no other way to do that. This should be fine as Capsicum is still
experimental and this change is not going to 9.x.

Sponsored by:	The FreeBSD Foundation

1 files changed, 62 insertions, 20 deletions

diff --git a/sys/compat/linux/linux_ioctl.c b/sys/compat/linux/linux_ioctl.c
index 4df28aa..2a4016a 100644
--- a/sys/compat/linux/linux_ioctl.c
+++ b/sys/compat/linux/linux_ioctl.c
@@ -189,12 +189,14 @@ struct linux_hd_big_geometry {
 static int
 linux_ioctl_hdio(struct thread *td, struct linux_ioctl_args *args)
 {
+	cap_rights_t rights;
 	struct file *fp;
 	int error;
 	u_int sectorsize, fwcylinders, fwheads, fwsectors;
 	off_t mediasize, bytespercyl;
 
-	if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+	error = fget(td, args->fd, cap_rights_init(&rights, CAP_IOCTL), &fp);
+	if (error != 0)
 		return (error);
 	switch (args->cmd & 0xffff) {
 	case LINUX_HDIO_GET_GEO:
@@ -270,12 +272,14 @@ linux_ioctl_hdio(struct thread *td, struct linux_ioctl_args *args)
 static int
 linux_ioctl_disk(struct thread *td, struct linux_ioctl_args *args)
 {
+	cap_rights_t rights;
 	struct file *fp;
 	int error;
 	u_int sectorsize;
 	off_t mediasize;
 
-	if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+	error = fget(td, args->fd, cap_rights_init(&rights, CAP_IOCTL), &fp);
+	if (error != 0)
 		return (error);
 	switch (args->cmd & 0xffff) {
 	case LINUX_BLKGETSIZE:
@@ -698,10 +702,12 @@ linux_ioctl_termio(struct thread *td, struct linux_ioctl_args *args)
 	struct termios bios;
 	struct linux_termios lios;
 	struct linux_termio lio;
+	cap_rights_t rights;
 	struct file *fp;
 	int error;
 
-	if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+	error = fget(td, args->fd, cap_rights_init(&rights, CAP_IOCTL), &fp);
+	if (error != 0)
 		return (error);
 
 	switch (args->cmd & 0xffff) {
@@ -1438,10 +1444,12 @@ bsd_to_linux_dvd_authinfo(struct dvd_authinfo *bp, l_dvd_authinfo *lp)
 static int
 linux_ioctl_cdrom(struct thread *td, struct linux_ioctl_args *args)
 {
+	cap_rights_t rights;
 	struct file *fp;
 	int error;
 
-	if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+	error = fget(td, args->fd, cap_rights_init(&rights, CAP_IOCTL), &fp);
+	if (error != 0)
 		return (error);
 	switch (args->cmd & 0xffff) {
 
@@ -1963,10 +1971,12 @@ linux_ioctl_sound(struct thread *td, struct linux_ioctl_args *args)
 static int
 linux_ioctl_console(struct thread *td, struct linux_ioctl_args *args)
 {
+	cap_rights_t rights;
 	struct file *fp;
 	int error;
 
-	if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+	error = fget(td, args->fd, cap_rights_init(&rights, CAP_IOCTL), &fp);
+	if (error != 0)
 		return (error);
 	switch (args->cmd & 0xffff) {
 
@@ -2351,6 +2361,7 @@ static int
 linux_ioctl_socket(struct thread *td, struct linux_ioctl_args *args)
 {
 	char lifname[LINUX_IFNAMSIZ], ifname[IFNAMSIZ];
+	cap_rights_t rights;
 	struct ifnet *ifp;
 	struct file *fp;
 	int error, type;
@@ -2358,7 +2369,8 @@ linux_ioctl_socket(struct thread *td, struct linux_ioctl_args *args)
 	ifp = NULL;
 	error = 0;
 
-	if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+	error = fget(td, args->fd, cap_rights_init(&rights, CAP_IOCTL), &fp);
+	if (error != 0)
 		return (error);
 	type = fp->f_type;
 	fdrop(fp, td);
@@ -2581,10 +2593,12 @@ linux_ioctl_socket(struct thread *td, struct linux_ioctl_args *args)
 static int
 linux_ioctl_private(struct thread *td, struct linux_ioctl_args *args)
 {
+	cap_rights_t rights;
 	struct file *fp;
 	int error, type;
 
-	if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+	error = fget(td, args->fd, cap_rights_init(&rights, CAP_IOCTL), &fp);
+	if (error != 0)
 		return (error);
 	type = fp->f_type;
 	fdrop(fp, td);
@@ -2606,11 +2620,13 @@ linux_ioctl_drm(struct thread *td, struct linux_ioctl_args *args)
 static int
 linux_ioctl_sg(struct thread *td, struct linux_ioctl_args *args)
 {
+	cap_rights_t rights;
 	struct file *fp;
 	u_long cmd;
 	int error;
 
-	if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0) {
+	error = fget(td, args->fd, cap_rights_init(&rights, CAP_IOCTL), &fp);
+	if (error != 0) {
 		printf("sg_linux_ioctl: fget returned %d\n", error);
 		return (error);
 	}
@@ -2828,6 +2844,7 @@ linux_v4l_cliplist_copy(struct l_video_window *lvw, struct video_window *vw)
 static int
 linux_ioctl_v4l(struct thread *td, struct linux_ioctl_args *args)
 {
+	cap_rights_t rights;
 	struct file *fp;
 	int error;
 	struct video_tuner vtun;
@@ -2845,7 +2862,9 @@ linux_ioctl_v4l(struct thread *td, struct linux_ioctl_args *args)
 	case LINUX_VIDIOCSCHAN:		args->cmd = VIDIOCSCHAN; break;
 
 	case LINUX_VIDIOCGTUNER:
-		if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+		error = fget(td, args->fd,
+		    cap_rights_init(&rights, CAP_IOCTL), &fp);
+		if (error != 0)
 			return (error);
 		error = copyin((void *) args->arg, &l_vtun, sizeof(l_vtun));
 		if (error) {
@@ -2863,7 +2882,9 @@ linux_ioctl_v4l(struct thread *td, struct linux_ioctl_args *args)
 		return (error);
 
 	case LINUX_VIDIOCSTUNER:
-		if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+		error = fget(td, args->fd,
+		    cap_rights_init(&rights, CAP_IOCTL), &fp);
+		if (error != 0)
 			return (error);
 		error = copyin((void *) args->arg, &l_vtun, sizeof(l_vtun));
 		if (error) {
@@ -2880,7 +2901,9 @@ linux_ioctl_v4l(struct thread *td, struct linux_ioctl_args *args)
 	case LINUX_VIDIOCCAPTURE:	args->cmd = VIDIOCCAPTURE; break;
 
 	case LINUX_VIDIOCGWIN:
-		if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+		error = fget(td, args->fd,
+		    cap_rights_init(&rights, CAP_IOCTL), &fp);
+		if (error != 0)
 			return (error);
 		error = fo_ioctl(fp, VIDIOCGWIN, &vwin, td->td_ucred, td);
 		if (!error) {
@@ -2892,7 +2915,9 @@ linux_ioctl_v4l(struct thread *td, struct linux_ioctl_args *args)
 		return (error);
 
 	case LINUX_VIDIOCSWIN:
-		if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+		error = fget(td, args->fd,
+		    cap_rights_init(&rights, CAP_IOCTL), &fp);
+		if (error != 0)
 			return (error);
 		error = copyin((void *) args->arg, &l_vwin, sizeof(l_vwin));
 		if (error) {
@@ -2915,7 +2940,9 @@ linux_ioctl_v4l(struct thread *td, struct linux_ioctl_args *args)
 		return (error);
 
 	case LINUX_VIDIOCGFBUF:
-		if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+		error = fget(td, args->fd,
+		    cap_rights_init(&rights, CAP_IOCTL), &fp);
+		if (error != 0)
 			return (error);
 		error = fo_ioctl(fp, VIDIOCGFBUF, &vbuf, td->td_ucred, td);
 		if (!error) {
@@ -2927,7 +2954,9 @@ linux_ioctl_v4l(struct thread *td, struct linux_ioctl_args *args)
 		return (error);
 
 	case LINUX_VIDIOCSFBUF:
-		if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+		error = fget(td, args->fd,
+		    cap_rights_init(&rights, CAP_IOCTL), &fp);
+		if (error != 0)
 			return (error);
 		error = copyin((void *) args->arg, &l_vbuf, sizeof(l_vbuf));
 		if (error) {
@@ -2955,7 +2984,9 @@ linux_ioctl_v4l(struct thread *td, struct linux_ioctl_args *args)
 	case LINUX_VIDIOCGPLAYINFO:	args->cmd = VIDIOCGPLAYINFO; break;
 
 	case LINUX_VIDIOCSMICROCODE:
-		if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+		error = fget(td, args->fd,
+		    cap_rights_init(&rights, CAP_IOCTL), &fp);
+		if (error != 0)
 			return (error);
 		error = copyin((void *) args->arg, &l_vcode, sizeof(l_vcode));
 		if (error) {
@@ -3108,6 +3139,7 @@ bsd_to_linux_v4l2_format(struct v4l2_format *vf, struct l_v4l2_format *lvf)
 static int
 linux_ioctl_v4l2(struct thread *td, struct linux_ioctl_args *args)
 {
+	cap_rights_t rights;
 	struct file *fp;
 	int error;
 	struct v4l2_format vformat;
@@ -3199,7 +3231,9 @@ linux_ioctl_v4l2(struct thread *td, struct linux_ioctl_args *args)
 		error = copyin((void *)args->arg, &l_vformat, sizeof(l_vformat));
 		if (error)
 			return (error);
-		if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+		error = fget(td, args->fd,
+		    cap_rights_init(&rights, CAP_IOCTL), &fp);
+		if (error)
 			return (error);
 		if (linux_to_bsd_v4l2_format(&l_vformat, &vformat) != 0)
 			error = EINVAL;
@@ -3222,7 +3256,9 @@ linux_ioctl_v4l2(struct thread *td, struct linux_ioctl_args *args)
 		if (error)
 			return (error);
 		linux_to_bsd_v4l2_standard(&l_vstd, &vstd);
-		if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+		error = fget(td, args->fd,
+		    cap_rights_init(&rights, CAP_IOCTL), &fp);
+		if (error)
 			return (error);
 		error = fo_ioctl(fp, VIDIOC_ENUMSTD, (caddr_t)&vstd,
 		    td->td_ucred, td);
@@ -3244,7 +3280,9 @@ linux_ioctl_v4l2(struct thread *td, struct linux_ioctl_args *args)
 				sizeof(struct l_v4l2_input));
 		if (error != 0)
 			return (error);
-		if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+		error = fget(td, args->fd,
+		    cap_rights_init(&rights, CAP_IOCTL), &fp);
+		if (error != 0)
 			return (error);
 		error = fo_ioctl(fp, VIDIOC_ENUMINPUT, (caddr_t)&vinp,
 		    td->td_ucred, td);
@@ -3263,7 +3301,9 @@ linux_ioctl_v4l2(struct thread *td, struct linux_ioctl_args *args)
 		error = copyin((void *)args->arg, &l_vbuf, sizeof(l_vbuf));
 		if (error)
 			return (error);
-		if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+		error = fget(td, args->fd,
+		    cap_rights_init(&rights, CAP_IOCTL), &fp);
+		if (error)
 			return (error);
 		linux_to_bsd_v4l2_buffer(&l_vbuf, &vbuf);
 		if ((args->cmd & 0xffff) == LINUX_VIDIOC_QUERYBUF)
@@ -3432,6 +3472,7 @@ linux_ioctl_fbsd_usb(struct thread *td, struct linux_ioctl_args *args)
 int
 linux_ioctl(struct thread *td, struct linux_ioctl_args *args)
 {
+	cap_rights_t rights;
 	struct file *fp;
 	struct handler_element *he;
 	int error, cmd;
@@ -3442,7 +3483,8 @@ linux_ioctl(struct thread *td, struct linux_ioctl_args *args)
 		    (unsigned long)args->cmd);
 #endif
 
-	if ((error = fget(td, args->fd, CAP_IOCTL, &fp)) != 0)
+	error = fget(td, args->fd, cap_rights_init(&rights, CAP_IOCTL), &fp);
+	if (error != 0)
 		return (error);
 	if ((fp->f_flag & (FREAD|FWRITE)) == 0) {
 		fdrop(fp, td);