virfile: Introduce virFileUnlink

In an NFS root-squashed environment the 'vol-delete' command will fail to
'unlink' the target volume since it was created under a different uid:gid.

This code continues the concepts introduced in virFileOpenForked and
virDirCreate[NoFork] with respect to running the unlink command under
the uid/gid of the child. Unlike the other two, don't retry on EACCES
(that's why we're here doing this now).
This commit is contained in:
John Ferlan 2015-08-24 17:00:02 -04:00
parent 1fafc1bc1c
commit 35847860f6
4 changed files with 110 additions and 1 deletions

View File

@ -1462,6 +1462,7 @@ virFileSanitizePath;
virFileSkipRoot; virFileSkipRoot;
virFileStripSuffix; virFileStripSuffix;
virFileTouch; virFileTouch;
virFileUnlink;
virFileUnlock; virFileUnlock;
virFileUpdatePerm; virFileUpdatePerm;
virFileWaitForDevices; virFileWaitForDevices;

View File

@ -1203,7 +1203,8 @@ virStorageBackendFileSystemVolDelete(virConnectPtr conn ATTRIBUTE_UNUSED,
switch ((virStorageVolType) vol->type) { switch ((virStorageVolType) vol->type) {
case VIR_STORAGE_VOL_FILE: case VIR_STORAGE_VOL_FILE:
if (unlink(vol->target.path) < 0) { if (virFileUnlink(vol->target.path, vol->target.perms->uid,
vol->target.perms->gid) < 0) {
/* Silently ignore failures where the vol has already gone away */ /* Silently ignore failures where the vol has already gone away */
if (errno != ENOENT) { if (errno != ENOENT) {
virReportSystemError(errno, virReportSystemError(errno,

View File

@ -2311,6 +2311,112 @@ virFileOpenAs(const char *path, int openflags, mode_t mode,
return ret; return ret;
} }
/* virFileUnlink:
* @path: file to unlink
* @uid: uid that was used to create the file (not required)
* @gid: gid that was used to create the file (not required)
*
* If a file/volume was created in an NFS root-squash environment,
* then we must 'unlink' the file in the same environment. Unlike
* the virFileOpenAs[Forked] and virDirCreate[NoFork], this code
* takes no extra flags and does not bother with EACCES failures
* from the child.
*/
int
virFileUnlink(const char *path,
uid_t uid,
gid_t gid)
{
pid_t pid;
int waitret;
int status, ret = 0;
gid_t *groups;
int ngroups;
/* If not running as root or if a non explicit uid/gid was being used for
* the file/volume, then use unlink directly
*/
if ((geteuid() != 0) ||
((uid == (uid_t) -1) && (gid == (gid_t) -1)))
return unlink(path);
/* Otherwise, we have to deal with the NFS root-squash craziness
* to run under the uid/gid that created the volume in order to
* perform the unlink of the volume.
*/
if (uid == (uid_t) -1)
uid = geteuid();
if (gid == (gid_t) -1)
gid = getegid();
ngroups = virGetGroupList(uid, gid, &groups);
if (ngroups < 0)
return -errno;
pid = virFork();
if (pid < 0) {
ret = -errno;
VIR_FREE(groups);
return ret;
}
if (pid) { /* parent */
/* wait for child to complete, and retrieve its exit code */
VIR_FREE(groups);
while ((waitret = waitpid(pid, &status, 0)) == -1 && errno == EINTR);
if (waitret == -1) {
ret = -errno;
virReportSystemError(errno,
_("failed to wait for child unlinking '%s'"),
path);
goto parenterror;
}
/*
* If waitpid succeeded, but if the child exited abnormally or
* reported non-zero status, report failure
*/
if (!WIFEXITED(status) || (WEXITSTATUS(status)) != 0) {
char *msg = virProcessTranslateStatus(status);
virReportError(VIR_ERR_INTERNAL_ERROR,
_("child failed to unlink '%s': %s"),
path, msg);
VIR_FREE(msg);
if (WIFEXITED(status))
ret = -WEXITSTATUS(status);
else
ret = -EACCES;
}
parenterror:
return ret;
}
/* child */
/* set desired uid/gid, then attempt to unlink the file */
if (virSetUIDGID(uid, gid, groups, ngroups) < 0) {
ret = errno;
goto childerror;
}
if (unlink(path) < 0) {
ret = errno;
goto childerror;
}
childerror:
if ((ret & 0xff) != ret) {
VIR_WARN("unable to pass desired return value %d", ret);
ret = 0xff;
}
_exit(ret);
}
/* return -errno on failure, or 0 on success */ /* return -errno on failure, or 0 on success */
static int static int
virDirCreateNoFork(const char *path, virDirCreateNoFork(const char *path,

View File

@ -219,6 +219,7 @@ int virFileOpenAs(const char *path, int openflags, mode_t mode,
uid_t uid, gid_t gid, uid_t uid, gid_t gid,
unsigned int flags) unsigned int flags)
ATTRIBUTE_NONNULL(1) ATTRIBUTE_RETURN_CHECK; ATTRIBUTE_NONNULL(1) ATTRIBUTE_RETURN_CHECK;
int virFileUnlink(const char *path, uid_t uid, gid_t gid);
enum { enum {
VIR_DIR_CREATE_NONE = 0, VIR_DIR_CREATE_NONE = 0,