[lxc-devel] [PATCH 2/1] proc update - don't assume we are pid 1

[Stéphane Graber]

On Sun, May 17, 2015 at 08:14:13PM +0000, Serge Hallyn wrote:
> (I erred in the first patch, causing every lxc-attach to unmount the
> container-'s /proc)
> 
> Since we now use mount_proc_if_needed() from attach, as opposed to only
> from start, we cannot assume we are pid 1.  So fix the check for whether
> to mount a new proc.
> 
> Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>

Acked-by: Stéphane Graber <stgraber at ubuntu.com>

> ---
>  src/lxc/utils.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/src/lxc/utils.c b/src/lxc/utils.c
> index 0588fdd..e56f4a3 100644
> --- a/src/lxc/utils.c
> +++ b/src/lxc/utils.c
> @@ -1679,6 +1679,7 @@ int mount_proc_if_needed(const char *rootfs)
>  	char path[MAXPATHLEN];
>  	char link[20];
>  	int linklen, ret;
> +	int mypid;
>  
>  	ret = snprintf(path, MAXPATHLEN, "%s/proc/self", rootfs);
>  	if (ret < 0 || ret >= MAXPATHLEN) {
> @@ -1687,12 +1688,12 @@ int mount_proc_if_needed(const char *rootfs)
>  	}
>  	memset(link, 0, 20);
>  	linklen = readlink(path, link, 20);
> -	INFO("I am %d, /proc/self points to '%s'", getpid(), link);
> +	mypid = (int)getpid();
> +	INFO("I am %d, /proc/self points to '%s'", mypid, link);
>  	ret = snprintf(path, MAXPATHLEN, "%s/proc", rootfs);
>  	if (linklen < 0) /* /proc not mounted */
>  		goto domount;
> -	/* can't be longer than rootfs/proc/1 */
> -	if (strncmp(link, "1", linklen) != 0) {
> +	if (atoi(link) != mypid) {
>  		/* wrong /procs mounted */
>  		umount2(path, MNT_DETACH); /* ignore failure */
>  		goto domount;
> -- 
> 2.1.4
> 
> _______________________________________________
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> lxc-devel at lists.linuxcontainers.org
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-- 
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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