[libvirt] [PATCH v2 3/4] virfile: Introduce internal API for managing ACL
Michal Privoznik
mprivozn at redhat.com
Wed Mar 6 14:05:55 UTC 2013
For now, only two APIs are implemented:
virFileSetACL for setting requested permissions for a specific user,
virFileRemoveACL to remove those permissions.
Both these traverse the whole path from root directory and set or
unset S_IXUSR flag on all directories met so user can really
access the file.
---
configure.ac | 1 +
libvirt.spec.in | 3 +
src/libvirt_private.syms | 2 +
src/util/virfile.c | 202 +++++++++++++++++++++++++++++++++++++++++++++++
src/util/virfile.h | 7 ++
5 files changed, 215 insertions(+)
diff --git a/configure.ac b/configure.ac
index cbb20c4..0df8a72 100644
--- a/configure.ac
+++ b/configure.ac
@@ -276,6 +276,7 @@ AM_CONDITIONAL([HAVE_LIBTASN1], [test "x$ac_cv_header_libtasn1_h" = "xyes"])
AC_CHECK_LIB([intl],[gettext],[])
AC_CHECK_LIB([attr],[getxattr])
+AC_CHECK_LIB([acl], [acl_init])
dnl Do we have rpcgen?
AC_PATH_PROG([RPCGEN], [rpcgen], [no])
diff --git a/libvirt.spec.in b/libvirt.spec.in
index 90629c8..67c5799 100644
--- a/libvirt.spec.in
+++ b/libvirt.spec.in
@@ -580,6 +580,9 @@ BuildRequires: scrub
# For xattr
BuildRequires: libattr-devel
+# For ACL
+BuildRequires: libacl-devel
+
%if %{with_numad}
BuildRequires: numad
%endif
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index fc7568e..980e3ea 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1275,8 +1275,10 @@ virFileFclose;
virFileFdopen;
virFileGetAttr;
virFileLoopDeviceAssociate;
+virFileRemoveACL;
virFileRemoveAttr;
virFileRewrite;
+virFileSetACL;
virFileSetAttr;
virFileTouch;
virFileUpdatePerm;
diff --git a/src/util/virfile.c b/src/util/virfile.c
index aa4579e..5d4254d 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -42,6 +42,11 @@
# include <sys/types.h>
#endif
+#ifdef HAVE_LIBACL
+# include <sys/acl.h>
+# include <sys/types.h>
+#endif
+
#include "vircommand.h"
#include "configmake.h"
#include "viralloc.h"
@@ -750,3 +755,200 @@ virFileRemoveAttr(const char *file ATTRIBUTE_UNUSED,
return -1;
}
#endif /* HAVE_LIBATTR */
+
+#ifdef HAVE_LIBACL /* HAVE_LIBACL */
+static acl_entry_t
+findACLEntry(acl_t acl, acl_tag_t type, id_t id)
+{
+ acl_entry_t ent;
+ acl_tag_t e_type;
+ id_t *e_id_p;
+
+ /* acl_get_entry returns 1 if there's an entry in @acl */
+ if (acl_get_entry(acl, ACL_FIRST_ENTRY, &ent) != 1)
+ return NULL;
+
+ while (true) {
+ acl_get_tag_type(ent, &e_type);
+ if (e_type == type) {
+ if (id == ACL_UNDEFINED_ID)
+ return ent;
+
+ if (!(e_id_p = acl_get_qualifier(ent)))
+ return NULL;
+ if (*e_id_p == id) {
+ acl_free(e_id_p);
+ return ent;
+ }
+ acl_free(e_id_p);
+ }
+ if (acl_get_entry(acl, ACL_NEXT_ENTRY, &ent) != 1)
+ return NULL;
+ }
+}
+
+static void
+setACLPerms(acl_entry_t ent, mode_t perms)
+{
+ acl_permset_t set;
+
+ acl_get_permset(ent, &set);
+ if (perms & S_IRUSR)
+ acl_add_perm(set, ACL_READ);
+ else
+ acl_delete_perm(set, ACL_READ);
+ if (perms & S_IWUSR)
+ acl_add_perm(set, ACL_WRITE);
+ else
+ acl_delete_perm(set, ACL_WRITE);
+ if (perms & S_IXUSR)
+ acl_add_perm(set, ACL_EXECUTE);
+ else
+ acl_delete_perm(set, ACL_EXECUTE);
+}
+
+static int
+cloneACLEntry(acl_t fromAcl, acl_tag_t fromType, id_t user,
+ acl_t *toAcl, acl_tag_t toType)
+{
+ acl_entry_t fromEntry, toEntry;
+ if (!(fromEntry = findACLEntry(fromAcl, fromType, user)))
+ return 1;
+
+ if (acl_create_entry(toAcl, &toEntry) != 0) {
+ virReportSystemError(errno, "%s", _("Unable to clone ACL entry"));
+ return -1;
+ }
+
+ acl_copy_entry(toEntry, fromEntry);
+ acl_set_tag_type(toEntry, toType);
+ return 0;
+}
+
+static int
+virFileSetOrRemoveACLHelper(const char *path,
+ uid_t user,
+ mode_t perms,
+ bool set)
+{
+ int ret = -1;
+ acl_t acl;
+ acl_entry_t ent;
+
+ if (!(acl = acl_get_file(path, ACL_TYPE_ACCESS))) {
+ virReportSystemError(errno, _("Unable to get ACL on %s"), path);
+ return ret;
+ }
+
+ ent = findACLEntry(acl, ACL_USER, user);
+ if (!ent && set) {
+ if (acl_create_entry(&acl, &ent) < 0) {
+ virReportSystemError(errno, "%s", _("Unable to create ACL entity"));
+ goto cleanup;
+ }
+ acl_set_tag_type(ent, ACL_USER);
+ acl_set_qualifier(ent, &user);
+
+ setACLPerms(ent, perms);
+
+ /* Recompute mask */
+ if (!findACLEntry(acl, ACL_MASK, ACL_UNDEFINED_ID) &&
+ cloneACLEntry(acl, ACL_USER, user, &acl, ACL_MASK) < 0)
+ goto cleanup;
+ } else if (ent && !set) {
+ if (acl_delete_entry(acl, ent) < 0) {
+ virReportSystemError(errno, "%s", _("Unable to delete ACL entity"));
+ goto cleanup;
+ }
+
+ if ((ent = findACLEntry(acl, ACL_MASK, user)) &&
+ acl_delete_entry(acl, ent) < 0) {
+ virReportSystemError(errno, "%s", _("Unable to delete ACL entity"));
+ goto cleanup;
+ }
+ }
+
+ if (acl_set_file(path, ACL_TYPE_ACCESS, acl) < 0) {
+ virReportSystemError(errno, _("Unable to set ACL on %s"), path);
+ goto cleanup;
+ }
+
+ ret = 0;
+cleanup:
+ acl_free(acl);
+ return ret;
+}
+
+static int
+virFileSetOrRemoveACL(const char *file,
+ uid_t user,
+ mode_t perms,
+ bool set)
+{
+ int ret = -1;
+ char *fileDup = NULL;
+ char *p;
+
+ if (!(fileDup = strdup(file))) {
+ virReportOOMError();
+ return ret;
+ }
+
+ if (virFileSetOrRemoveACLHelper(file, user, perms, set) < 0)
+ goto cleanup;
+
+ /* For parent directories we want executable flag */
+ perms |= S_IXUSR;
+
+ while ((p = strrchr(fileDup, '/')) != fileDup) {
+ if (!p) {
+ virReportSystemError(EINVAL, _("Invalid relative path '%s'"), file);
+ goto cleanup;
+ }
+
+ *p = '\0';
+
+ if (virFileSetOrRemoveACLHelper(fileDup, user, perms, set) < 0)
+ goto cleanup;
+ }
+
+ ret = 0;
+
+cleanup:
+ VIR_FREE(fileDup);
+ return ret;
+}
+
+int
+virFileSetACL(const char *file,
+ uid_t user,
+ mode_t perms)
+{
+ return virFileSetOrRemoveACL(file, user, perms, true);
+}
+
+int
+virFileRemoveACL(const char *file,
+ uid_t user)
+{
+ return virFileSetOrRemoveACL(file, user, 0, false);
+}
+
+#else /* HAVE_LIBACL */
+int
+virFileSetACL(const char *file ATTRIBUTE_UNUSED,
+ uid_t user ATTRIBUTE_UNUSED,
+ mode_t perms ATTRIBUTE_UNUSED)
+{
+ virReportSystemError(ENOSYS, "%s", _("Unable to set ACL"));
+ return -1;
+}
+
+int
+virFileRemoveACL(const char *file ATTRIBUTE_UNUSED,
+ uid_t user ATTRIBUTE_UNUSED)
+{
+ virReportSystemError(ENOSYS, "%s", _("Unable to remove ACL"));
+ return -1;
+}
+#endif /* HAVE_LIBACL */
diff --git a/src/util/virfile.h b/src/util/virfile.h
index 3b4d672..b530aed 100644
--- a/src/util/virfile.h
+++ b/src/util/virfile.h
@@ -120,4 +120,11 @@ int virFileGetAttr(const char *file,
int virFileRemoveAttr(const char *file,
const char *name);
+int virFileSetACL(const char *file,
+ uid_t user,
+ mode_t perms);
+
+int virFileRemoveACL(const char *file,
+ uid_t user);
+
#endif /* __VIR_FILES_H */
--
1.8.1.5
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