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

5 files changed, 72 insertions, 61 deletions

diff --git a/usr.bin/kdump/kdump.c b/usr.bin/kdump/kdump.c
index 06be0c0..0de183c 100644
--- a/usr.bin/kdump/kdump.c
+++ b/usr.bin/kdump/kdump.c
@@ -103,6 +103,7 @@ void ktrcsw_old(struct ktr_csw_old *);
 void ktruser_malloc(unsigned char *);
 void ktruser_rtld(int, unsigned char *);
 void ktruser(int, unsigned char *);
+void ktrcaprights(cap_rights_t *);
 void ktrsockaddr(struct sockaddr *);
 void ktrstat(struct stat *);
 void ktrstruct(char *, size_t);
@@ -379,21 +380,21 @@ limitfd(int fd)
 	cap_rights_t rights;
 	unsigned long cmd;
 
-	rights = CAP_FSTAT;
+	cap_rights_init(&rights, CAP_FSTAT);
 	cmd = -1;
 
 	switch (fd) {
 	case STDIN_FILENO:
-		rights |= CAP_READ;
+		cap_rights_set(&rights, CAP_READ);
 		break;
 	case STDOUT_FILENO:
-		rights |= CAP_IOCTL | CAP_WRITE;
+		cap_rights_set(&rights, CAP_IOCTL, CAP_WRITE);
 		cmd = TIOCGETA;	/* required by isatty(3) in printf(3) */
 		break;
 	case STDERR_FILENO:
-		rights |= CAP_WRITE;
+		cap_rights_set(&rights, CAP_WRITE);
 		if (!suppressdata) {
-			rights |= CAP_IOCTL;
+			cap_rights_set(&rights, CAP_IOCTL);
 			cmd = TIOCGWINSZ;
 		}
 		break;
@@ -401,7 +402,7 @@ limitfd(int fd)
 		abort();
 	}
 
-	if (cap_rights_limit(fd, rights) < 0 && errno != ENOSYS)
+	if (cap_rights_limit(fd, &rights) < 0 && errno != ENOSYS)
 		err(1, "unable to limit rights for descriptor %d", fd);
 	if (cmd != -1 && cap_ioctls_limit(fd, &cmd, 1) < 0 && errno != ENOSYS)
 		err(1, "unable to limit ioctls for descriptor %d", fd);
@@ -1120,35 +1121,6 @@ ktrsyscall(struct ktr_syscall *ktr, u_int flags)
 				ip++;
 				narg--;
 				break;
-			case SYS_cap_new:
-			case SYS_cap_rights_limit:
-				print_number(ip, narg, c);
-				putchar(',');
-				arg = *ip;
-				ip++;
-				narg--;
-				/*
-				 * Hack: the second argument is a
-				 * cap_rights_t, which 64 bits wide, so on
-				 * 32-bit systems, it is split between two
-				 * registers.
-				 *
-				 * Since sizeof() is not evaluated by the
-				 * preprocessor, we can't use an #ifdef,
-				 * but the compiler will probably optimize
-				 * the code out anyway.
-				 */
-				if (sizeof(cap_rights_t) > sizeof(register_t)) {
-#if _BYTE_ORDER == _LITTLE_ENDIAN
-					arg = ((intmax_t)*ip << 32) + arg;
-#else
-					arg = (arg << 32) + *ip;
-#endif
-					ip++;
-					narg--;
-				}
-				capname(arg);
-				break;
 			case SYS_cap_fcntls_limit:
 				print_number(ip, narg, c);
 				putchar(',');
@@ -1536,6 +1508,15 @@ ktruser(int len, unsigned char *p)
 }
 
 void
+ktrcaprights(cap_rights_t *rightsp)
+{
+
+	printf("cap_rights_t ");
+	capname(rightsp);
+	printf("\n");
+}
+
+void
 ktrsockaddr(struct sockaddr *sa)
 {
 /*
@@ -1712,6 +1693,7 @@ ktrstruct(char *buf, size_t buflen)
 	char *name, *data;
 	size_t namelen, datalen;
 	int i;
+	cap_rights_t rights;
 	struct stat sb;
 	struct sockaddr_storage ss;
 
@@ -1731,7 +1713,12 @@ ktrstruct(char *buf, size_t buflen)
 	for (i = 0; i < (int)namelen; ++i)
 		if (!isalpha(name[i]))
 			goto invalid;
-	if (strcmp(name, "stat") == 0) {
+	if (strcmp(name, "caprights") == 0) {
+		if (datalen != sizeof(cap_rights_t))
+			goto invalid;
+		memcpy(&rights, data, datalen);
+		ktrcaprights(&rights);
+	} else if (strcmp(name, "stat") == 0) {
 		if (datalen != sizeof(struct stat))
 			goto invalid;
 		memcpy(&sb, data, datalen);
@@ -1758,16 +1745,16 @@ ktrcapfail(struct ktr_cap_fail *ktr)
 	case CAPFAIL_NOTCAPABLE:
 		/* operation on fd with insufficient capabilities */
 		printf("operation requires ");
-		capname((intmax_t)ktr->cap_needed);
+		capname(&ktr->cap_needed);
 		printf(", process holds ");
-		capname((intmax_t)ktr->cap_held);
+		capname(&ktr->cap_held);
 		break;
 	case CAPFAIL_INCREASE:
 		/* requested more capabilities than fd already has */
 		printf("attempt to increase capabilities from ");
-		capname((intmax_t)ktr->cap_held);
+		capname(&ktr->cap_held);
 		printf(" to ");
-		capname((intmax_t)ktr->cap_needed);
+		capname(&ktr->cap_needed);
 		break;
 	case CAPFAIL_SYSCALL:
 		/* called restricted syscall */
@@ -1779,9 +1766,9 @@ ktrcapfail(struct ktr_cap_fail *ktr)
 		break;
 	default:
 		printf("unknown capability failure: ");
-		capname((intmax_t)ktr->cap_needed);
+		capname(&ktr->cap_needed);
 		printf(" ");
-		capname((intmax_t)ktr->cap_held);
+		capname(&ktr->cap_held);
 		break;
 	}
 	printf("\n");
diff --git a/usr.bin/kdump/mksubr b/usr.bin/kdump/mksubr
index b10af94..676e9e2 100644
--- a/usr.bin/kdump/mksubr
+++ b/usr.bin/kdump/mksubr
@@ -385,7 +385,6 @@ _EOF_
 
 auto_or_type     "accessmodename"      "[A-Z]_OK[[:space:]]+0?x?[0-9A-Fa-f]+"         "sys/unistd.h"
 auto_switch_type "acltypename"         "ACL_TYPE_[A-Z4_]+[[:space:]]+0x[0-9]+"        "sys/acl.h"
-auto_or_type     "capname"             "CAP_[A-Z]+[[:space:]]+0x[01248]{16}ULL"       "sys/capability.h"
 auto_or_type     "capfcntlname"        "CAP_FCNTL_[A-Z]+[[:space:]]+\(1"              "sys/capability.h"
 auto_switch_type "extattrctlname"      "EXTATTR_NAMESPACE_[A-Z]+[[:space:]]+0x[0-9]+" "sys/extattr.h"
 auto_switch_type "fadvisebehavname"    "POSIX_FADV_[A-Z]+[[:space:]]+[0-9]+"          "sys/fcntl.h"
@@ -609,3 +608,26 @@ cat <<_EOF_
 		}
 	}
 }
+
+_EOF_
+egrep '#define[[:space:]]+CAP_[A-Z_]+[[:space:]]+CAPRIGHT\([0-9],[[:space:]]+0x[0-9]{16}ULL\)' \
+	$include_dir/sys/capability.h | \
+	sed -E 's/[	]+/ /g' | \
+	awk -F '[   \(,\)]' '
+	BEGIN {
+		printf "void\n"
+		printf "capname(const cap_rights_t *rightsp)\n"
+		printf "{\n"
+		printf "\tint comma = 0;\n\n"
+		printf "\tprintf(\"<\");\n"
+	}
+	{
+		printf "\tif ((rightsp->cr_rights[%s] & %s) == %s) {\n", $4, $2, $2
+		printf "\t\tif (comma) printf(\",\"); else comma = 1;\n"
+		printf "\t\tprintf(\"%s\");\n", $2
+		printf "\t}\n"
+	}
+	END {
+		printf "\tprintf(\">\");\n"
+		printf "}\n"
+	}'
diff --git a/usr.bin/procstat/procstat_files.c b/usr.bin/procstat/procstat_files.c
index 72600de..d65c1ae 100644
--- a/usr.bin/procstat/procstat_files.c
+++ b/usr.bin/procstat/procstat_files.c
@@ -133,7 +133,7 @@ print_address(struct sockaddr_storage *ss)
 }
 
 static struct cap_desc {
-	cap_rights_t	 cd_right;
+	uint64_t	 cd_right;
 	const char	*cd_desc;
 } cap_desc[] = {
 	/* General file I/O. */
@@ -244,14 +244,14 @@ static const u_int	cap_desc_count = sizeof(cap_desc) /
 			    sizeof(cap_desc[0]);
 
 static u_int
-width_capability(cap_rights_t rights)
+width_capability(cap_rights_t *rightsp)
 {
 	u_int count, i, width;
 
 	count = 0;
 	width = 0;
 	for (i = 0; i < cap_desc_count; i++) {
-		if ((cap_desc[i].cd_right & ~rights) == 0) {
+		if (cap_rights_is_set(rightsp, cap_desc[i].cd_right)) {
 			width += strlen(cap_desc[i].cd_desc);
 			if (count)
 				width++;
@@ -262,20 +262,20 @@ width_capability(cap_rights_t rights)
 }
 
 static void
-print_capability(cap_rights_t rights, u_int capwidth)
+print_capability(cap_rights_t *rightsp, u_int capwidth)
 {
 	u_int count, i, width;
 
 	count = 0;
 	width = 0;
-	for (i = width_capability(rights); i < capwidth; i++) {
-		if (rights || i != 0)
+	for (i = width_capability(rightsp); i < capwidth; i++) {
+		if (i != 0)
 			printf(" ");
 		else
 			printf("-");
 	}
 	for (i = 0; i < cap_desc_count; i++) {
-		if ((cap_desc[i].cd_right & ~rights) == 0) {
+		if (cap_rights_is_set(rightsp, cap_desc[i].cd_right)) {
 			printf("%s%s", count ? "," : "", cap_desc[i].cd_desc);
 			width += strlen(cap_desc[i].cd_desc);
 			if (count)
@@ -306,7 +306,7 @@ procstat_files(struct procstat *procstat, struct kinfo_proc *kipp)
 	head = procstat_getfiles(procstat, kipp, 0);
 	if (head != NULL && Cflag) {
 		STAILQ_FOREACH(fst, head, next) {
-			width = width_capability(fst->fs_cap_rights);
+			width = width_capability(&fst->fs_cap_rights);
 			if (width > capwidth)
 				capwidth = width;
 		}
@@ -460,7 +460,7 @@ procstat_files(struct procstat *procstat, struct kinfo_proc *kipp)
 				printf("%7c ", '-');
 		}
 		if (Cflag) {
-			print_capability(fst->fs_cap_rights, capwidth);
+			print_capability(&fst->fs_cap_rights, capwidth);
 			printf(" ");
 		}
 		switch (fst->fs_type) {
diff --git a/usr.bin/rwho/rwho.c b/usr.bin/rwho/rwho.c
index bcb5adb..8c985f0 100644
--- a/usr.bin/rwho/rwho.c
+++ b/usr.bin/rwho/rwho.c
@@ -93,6 +93,7 @@ main(int argc, char *argv[])
 	struct whod *w;
 	struct whoent *we;
 	struct myutmp *mp;
+	cap_rights_t rights;
 	int f, n, i;
 	int d_first;
 	int dfd;
@@ -124,7 +125,8 @@ main(int argc, char *argv[])
 		err(1, "opendir(%s)", _PATH_RWHODIR);
 	dfd = dirfd(dirp);
 	mp = myutmp;
-	if (cap_rights_limit(dfd, CAP_READ | CAP_LOOKUP) < 0 && errno != ENOSYS)
+	cap_rights_init(&rights, CAP_READ, CAP_LOOKUP);
+	if (cap_rights_limit(dfd, &rights) < 0 && errno != ENOSYS)
 		err(1, "cap_rights_limit failed: %s", _PATH_RWHODIR);
 	/*
 	 * Cache files required for time(3) and localtime(3) before entering
@@ -135,13 +137,14 @@ main(int argc, char *argv[])
 	if (cap_enter() < 0 && errno != ENOSYS)
 		err(1, "cap_enter");
 	(void) time(&now);
+	cap_rights_init(&rights, CAP_READ);
 	while ((dp = readdir(dirp)) != NULL) {
 		if (dp->d_ino == 0 || strncmp(dp->d_name, "whod.", 5) != 0)
 			continue;
 		f = openat(dfd, dp->d_name, O_RDONLY);
 		if (f < 0)
 			continue;
-		if (cap_rights_limit(f, CAP_READ) < 0 && errno != ENOSYS)
+		if (cap_rights_limit(f, &rights) < 0 && errno != ENOSYS)
 			err(1, "cap_rights_limit failed: %s", dp->d_name);
 		cc = read(f, (char *)&wd, sizeof(struct whod));
 		if (cc < WHDRSIZE) {
diff --git a/usr.bin/uniq/uniq.c b/usr.bin/uniq/uniq.c
index d34b0c0..8e7f40f 100644
--- a/usr.bin/uniq/uniq.c
+++ b/usr.bin/uniq/uniq.c
@@ -145,20 +145,19 @@ main (int argc, char *argv[])
 	ofp = stdout;
 	if (argc > 0 && strcmp(argv[0], "-") != 0)
 		ifp = file(ifn = argv[0], "r");
-	if (cap_rights_limit(fileno(ifp), CAP_FSTAT | CAP_READ) < 0 &&
-	    errno != ENOSYS) {
+	cap_rights_init(&rights, CAP_FSTAT, CAP_READ);
+	if (cap_rights_limit(fileno(ifp), &rights) < 0 && errno != ENOSYS)
 		err(1, "unable to limit rights for %s", ifn);
-	}
-	rights = CAP_FSTAT | CAP_WRITE;
+	cap_rights_init(&rights, CAP_FSTAT, CAP_WRITE);
 	if (argc > 1)
 		ofp = file(argv[1], "w");
 	else
-		rights |= CAP_IOCTL;
-	if (cap_rights_limit(fileno(ofp), rights) < 0 && errno != ENOSYS) {
+		cap_rights_set(&rights, CAP_IOCTL);
+	if (cap_rights_limit(fileno(ofp), &rights) < 0 && errno != ENOSYS) {
 		err(1, "unable to limit rights for %s",
 		    argc > 1 ? argv[1] : "stdout");
 	}
-	if ((rights & CAP_IOCTL) != 0) {
+	if (cap_rights_is_set(&rights, CAP_IOCTL)) {
 		unsigned long cmd;
 
 		cmd = TIOCGETA; /* required by isatty(3) in printf(3) */