Re: [PATCH 3/3] virtiofsd: Allow addition or removal of capabilities

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Thu, Jun 25, 2020 at 05:29:29PM +0100, Dr. David Alan Gilbert (git) wrote:
> +    /*
> +     * The modcaps option is a colon separated list of caps,
> +     * each preceded by either + or -.
> +     */
> +    while (lo->modcaps) {
> +        capng_act_t action;
> +        int cap;
> +
> +        char *next = strchr(lo->modcaps, ':');
> +        if (next) {
> +            *next = '\0';
> +            next++;
> +        }
> +
> +        switch (lo->modcaps[0]) {
> +        case '+':
> +            action = CAPNG_ADD;
> +            break;
> +
> +        case '-':
> +            action = CAPNG_DROP;
> +            break;
> +
> +        default:
> +            fuse_log(FUSE_LOG_ERR,
> +                     "%s: Expecting '+'/'-' in modcaps but found '%c'\n",
> +                     __func__, lo->modcaps[0]);
> +            exit(1);
> +        }
> +        cap = capng_name_to_capability(lo->modcaps + 1);
> +        if (cap < 0) {
> +            fuse_log(FUSE_LOG_ERR, "%s: Unknown capability '%s'\n", __func__,
> +                     lo->modcaps);
> +            exit(1);
> +        }
> +        if (capng_update(action, CAPNG_PERMITTED | CAPNG_EFFECTIVE, cap)) {
> +            fuse_log(FUSE_LOG_ERR, "%s: capng_update failed for '%s'\n",
> +                     __func__, lo->modcaps);
> +            exit(1);
> +        }
> +
> +        lo->modcaps = next;

How about passing char *modcaps into this function so that lo->modcaps
isn't modified by the parsing loop? That seems a bit cleaner and if we
ever decide to free lo->modcaps it will work as expected.

Stefan

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