[libvirt] [PATCH 1/1] lxc: use our own hand-rolled code in place of unlockpt and grantpt

[Eli Qiao]

hi Serge :


     I checked the code ,  only in lxc_controller.c call virFileOpenTtyAt().
     I didn't test the path, but my suggestion is that modify the 
utility function in /src/util/util.c instead of adding a new function.

> The glibc ones cannot handle ptys opened in a devpts not mounted at
> /dev/pts.
>
> Signed-off-by: Serge Hallyn<serge.hallyn at canonical.com>
> ---
>   src/lxc/lxc_controller.c |   82 +++++++++++++++++++++++++++++++++++++++++++--
>   1 files changed, 78 insertions(+), 4 deletions(-)
>
> diff --git a/src/lxc/lxc_controller.c b/src/lxc/lxc_controller.c
> index 89ce7f5..d79f5ba 100644
> --- a/src/lxc/lxc_controller.c
> +++ b/src/lxc/lxc_controller.c
> @@ -41,6 +41,8 @@
>   #include<locale.h>
>   #include<linux/loop.h>
>   #include<dirent.h>
> +#include<grp.h>
> +#include<sys/stat.h>
>
>   #if HAVE_CAPNG
>   # include<cap-ng.h>
> @@ -781,6 +783,81 @@ static int lxcSetPersonality(virDomainDefPtr def)
>   #endif
>
>   static int
> +lxcGetTtyGid(void) {
> +    char *grtmpbuf;
> +    struct group grbuf;
> +    size_t grbuflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> +    struct group *p;
> +    int ret;
> +    gid_t tty_gid = -1;
> +
> +    /* Get the group ID of the special `tty' group.  */
> +    if (grbuflen == (size_t) -1L)
> +        /* `sysconf' does not support _SC_GETGR_R_SIZE_MAX.
> +           Try a moderate value.  */
> +        grbuflen = 1024;
> +
> +    grtmpbuf = (char *) alloca (grbuflen);
use this macro VIR_ALLOC_N(ptr, count) to allocate memory and you should 
also check if it is valid.
> +    ret = getgrnam_r("tty",&grbuf, grtmpbuf, grbuflen,&p);
> +    if (ret || p != NULL)
> +        tty_gid = p->gr_gid;
> +
> +    return tty_gid == -1 ? getgid() : tty_gid;
> +}
> +
> +#define ACCESSPERMS (S_IRWXU|S_IRWXG|S_IRWXO) /* 0777 */
> +
> +/* heavily borrowed from glibc, but don't assume devpts == "/dev/pts" */
> +static int
> +lxcCreateTty(char *ptmx, int *ttymaster, char **ttyName)
> +{
> +    int rc = -1;
> +    int ret;
> +    int ptyno;
> +    uid_t uid;
> +    gid_t gid;
> +    struct stat st;
> +    int unlock = 0;
> +
> +    if ((*ttymaster = open(ptmx, O_RDWR|O_NOCTTY|O_NONBLOCK))<  0)
> +        goto cleanup;
> +
> +    if (ioctl(*ttymaster, TIOCSPTLCK,&unlock)<  0)
> +        goto cleanup;
> +
> +    ret = ioctl(*ttymaster, TIOCGPTN,&ptyno);
> +    if (ret<  0)
> +        goto cleanup;
      if (ioctl(*ttymaster, TIOCGPTN, &ptyno) < 0)
          goto clearup;
> +
> +    ret = fstat(*ttymaster,&st);
> +
> +    uid = getuid();
> +    gid = lxcGetTtyGid();
> +    if (st.st_uid != uid || st.st_gid != gid)
> +        if (fchown(*ttymaster, uid, gid)<  0)
> +            goto cleanup;
> +
> +    if ((st.st_mode&  ACCESSPERMS) != (S_IRUSR|S_IWUSR|S_IWGRP))
> +        if (fchmod(*ttymaster, S_IRUSR|S_IWUSR|S_IWGRP)<  0)
> +            goto cleanup;
> +
> +    if (VIR_ALLOC_N(*ttyName, PATH_MAX)<  0) {
> +        errno = ENOMEM;
> +        goto cleanup;
> +    }
> +
> +    snprintf(*ttyName, PATH_MAX, "/dev/pts/%d", ptyno);
> +
> +    rc = 0;
> +
> +cleanup:
> +    if (rc != 0)
> +        VIR_FORCE_CLOSE(*ttymaster);
> +
> +    return rc;
> +}
> +
> +static int
>   lxcControllerRun(virDomainDefPtr def,
>                    unsigned int nveths,
>                    char **veths,
> @@ -894,10 +971,7 @@ lxcControllerRun(virDomainDefPtr def,
>
>       if (devptmx) {
>           VIR_DEBUG("Opening tty on private %s", devptmx);
> -        if (virFileOpenTtyAt(devptmx,
> -&containerPty,
> -&containerPtyPath,
> -                             0)<  0) {
> +        if (lxcCreateTty(devptmx,&containerPty,&containerPtyPath)<  0) {
>               virReportSystemError(errno, "%s",
>                                    _("Failed to allocate tty"));
>               goto cleanup;
> -- 1.7.5.4 -- libvir-list mailing list libvir-list at redhat.com 
> https://www.redhat.com/mailman/listinfo/libvir-list


-- 
best regards
eli

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