From: Paolo Bonzini <pbonz...@redhat.com>
virtfs-proxy-helper is the only user of libcap; everyone else is using
the simpler libcap-ng API. Switch and remove the configure code to
detect libcap.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
Reviewed-by: Daniel P. Berrangé <berra...@redhat.com>
Reviewed-by: Greg Kurz <gr...@kaod.org>
[groug: - drop remaining -lcap from Makefile
- fix error message in configure]
Signed-off-by: Greg Kurz <gr...@kaod.org>
---
Makefile | 1 -
configure | 20 +-------
fsdev/virtfs-proxy-helper.c | 100 ++++++++++++++++--------------------
3 files changed, 47 insertions(+), 74 deletions(-)
diff --git a/Makefile b/Makefile
index b437a346d71a..1361def1441c 100644
--- a/Makefile
+++ b/Makefile
@@ -575,7 +575,6 @@ qemu-keymap$(EXESUF): qemu-keymap.o ui/input-keymap.o
$(COMMON_LDADDS)
qemu-edid$(EXESUF): qemu-edid.o hw/display/edid-generate.o $(COMMON_LDADDS)
fsdev/virtfs-proxy-helper$(EXESUF): fsdev/virtfs-proxy-helper.o
fsdev/9p-marshal.o fsdev/9p-iov-marshal.o $(COMMON_LDADDS)
-fsdev/virtfs-proxy-helper$(EXESUF): LIBS += -lcap
scsi/qemu-pr-helper$(EXESUF): scsi/qemu-pr-helper.o scsi/utils.o
$(authz-obj-y) $(crypto-obj-y) $(io-obj-y) $(qom-obj-y) $(COMMON_LDADDS)
ifdef CONFIG_MPATH
diff --git a/configure b/configure
index 6099be1d848c..2c72e04d23f3 100755
--- a/configure
+++ b/configure
@@ -3863,22 +3863,6 @@ else
mpathpersist=no
fi
-##########################################
-# libcap probe
-
-if test "$cap" != "no" ; then
- cat > $TMPC <<EOF
-#include <stdio.h>
-#include <sys/capability.h>
-int main(void) { cap_t caps; caps = cap_init(); return caps != NULL; }
-EOF
- if compile_prog "" "-lcap" ; then
- cap=yes
- else
- cap=no
- fi
-fi
-
##########################################
# pthread probe
PTHREADLIBS_LIST="-pthread -lpthread -lpthreadGC2"
@@ -6204,12 +6188,12 @@ if test "$want_tools" = "yes" ; then
fi
if test "$softmmu" = yes ; then
if test "$linux" = yes; then
- if test "$virtfs" != no && test "$cap" = yes && test "$attr" = yes ; then
+ if test "$virtfs" != no && test "$cap_ng" = yes && test "$attr" = yes ;
then
virtfs=yes
tools="$tools fsdev/virtfs-proxy-helper\$(EXESUF)"
else
if test "$virtfs" = yes; then
- error_exit "VirtFS requires libcap devel and libattr devel"
+ error_exit "VirtFS requires libcap-ng devel and libattr devel"
fi
virtfs=no
fi
diff --git a/fsdev/virtfs-proxy-helper.c b/fsdev/virtfs-proxy-helper.c
index 6f132c5ff15a..0d4de49dcf75 100644
--- a/fsdev/virtfs-proxy-helper.c
+++ b/fsdev/virtfs-proxy-helper.c
@@ -13,7 +13,6 @@
#include <sys/resource.h>
#include <getopt.h>
#include <syslog.h>
-#include <sys/capability.h>
#include <sys/fsuid.h>
#include <sys/vfs.h>
#include <sys/ioctl.h>
@@ -21,6 +20,7 @@
#ifdef CONFIG_LINUX_MAGIC_H
#include <linux/magic.h>
#endif
+#include <cap-ng.h>
#include "qemu-common.h"
#include "qemu/sockets.h"
#include "qemu/xattr.h"
@@ -79,49 +79,10 @@ static void do_perror(const char *string)
}
}
-static int do_cap_set(cap_value_t *cap_value, int size, int reset)
-{
- cap_t caps;
- if (reset) {
- /*
- * Start with an empty set and set permitted and effective
- */
- caps = cap_init();
- if (caps == NULL) {
- do_perror("cap_init");
- return -1;
- }
- if (cap_set_flag(caps, CAP_PERMITTED, size, cap_value, CAP_SET) < 0) {
- do_perror("cap_set_flag");
- goto error;
- }
- } else {
- caps = cap_get_proc();
- if (!caps) {
- do_perror("cap_get_proc");
- return -1;
- }
- }
- if (cap_set_flag(caps, CAP_EFFECTIVE, size, cap_value, CAP_SET) < 0) {
- do_perror("cap_set_flag");
- goto error;
- }
- if (cap_set_proc(caps) < 0) {
- do_perror("cap_set_proc");
- goto error;
- }
- cap_free(caps);
- return 0;
-
-error:
- cap_free(caps);
- return -1;
-}
-
static int init_capabilities(void)
{
/* helper needs following capabilities only */
- cap_value_t cap_list[] = {
+ int cap_list[] = {
CAP_CHOWN,
CAP_DAC_OVERRIDE,
CAP_FOWNER,
@@ -130,7 +91,34 @@ static int init_capabilities(void)
CAP_MKNOD,
CAP_SETUID,
};
- return do_cap_set(cap_list, ARRAY_SIZE(cap_list), 1);
+ int i;
+
+ capng_clear(CAPNG_SELECT_BOTH);
+ for (i = 0; i < ARRAY_SIZE(cap_list); i++) {
+ if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED,
+ cap_list[i]) < 0) {
+ do_perror("capng_update");
+ return -1;
+ }
+ }
+ if (capng_apply(CAPNG_SELECT_BOTH) < 0) {
+ do_perror("capng_apply");
+ return -1;
+ }
+
+ /* Prepare effective set for setugid. */
+ for (i = 0; i < ARRAY_SIZE(cap_list); i++) {
+ if (cap_list[i] == CAP_DAC_OVERRIDE) {
+ continue;
+ }
+
+ if (capng_update(CAPNG_DROP, CAPNG_EFFECTIVE,
+ cap_list[i]) < 0) {
+ do_perror("capng_update");
+ return -1;
+ }
+ }
+ return 0;
}
static int socket_read(int sockfd, void *buff, ssize_t size)
@@ -295,14 +283,6 @@ static int setugid(int uid, int gid, int *suid, int *sgid)
{
int retval;
- /*
- * We still need DAC_OVERRIDE because we don't change
- * supplementary group ids, and hence may be subjected DAC rules
- */
- cap_value_t cap_list[] = {
- CAP_DAC_OVERRIDE,
- };
-
*suid = geteuid();
*sgid = getegid();
@@ -316,11 +296,21 @@ static int setugid(int uid, int gid, int *suid, int *sgid)
goto err_sgid;
}
- if (uid != 0 || gid != 0) {
- if (do_cap_set(cap_list, ARRAY_SIZE(cap_list), 0) < 0) {
- retval = -errno;
- goto err_suid;
- }
+ if (uid == 0 && gid == 0) {
+ /* Linux has already copied the permitted set to the effective set. */
+ return 0;
+ }
+
+ /*
+ * All capabilities have been cleared from the effective set. However
+ * we still need DAC_OVERRIDE because we don't change supplementary
+ * group ids, and hence may be subject to DAC rules. init_capabilities
+ * left the set of capabilities that we want in libcap-ng's state.
+ */
+ if (capng_apply(CAPNG_SELECT_CAPS) < 0) {
+ retval = -errno;
+ do_perror("capng_apply");
+ goto err_suid;
}
return 0;
--
2.21.0
