On Fri, Nov 29, 2019 at 12:16:32PM +0100, Paolo Bonzini wrote: > 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> > --- > configure | 18 +------ > fsdev/virtfs-proxy-helper.c | 100 ++++++++++++++++-------------------- > 2 files changed, 46 insertions(+), 72 deletions(-)
The dockerfiles can also be updated to remove libcap-dev/devel > > diff --git a/configure b/configure > index afe9393f04..2216662bf6 100755 > --- a/configure > +++ b/configure > @@ -3863,22 +3863,6 @@ else > mpathpersist=no > fi > > -########################################## > -# libcap probe > - > -if test "$cap" != "no" ; then > - cat > $TMPC <<EOF > -#include <stdio.h> > -#include <sys/capability.h> > -int main(void) { cap_t caps; caps = cap_init(); return caps != NULL; } > -EOF > - if compile_prog "" "-lcap" ; then > - cap=yes > - else > - cap=no > - fi > -fi > - > ########################################## > # pthread probe > PTHREADLIBS_LIST="-pthread -lpthread -lpthreadGC2" > @@ -6204,7 +6188,7 @@ if test "$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 > diff --git a/fsdev/virtfs-proxy-helper.c b/fsdev/virtfs-proxy-helper.c > index 6f132c5ff1..0d4de49dcf 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 > Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|