[CRIU] [PATCH 4/5] userns: parse /proc/PID/{u,g}id_map

[Pavel Emelyanov]

On 02/11/2014 12:58 AM, Andrey Vagin wrote:
> Signed-off-by: Andrey Vagin <avagin at openvz.org>
> ---
>  namespaces.c | 107 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 105 insertions(+), 2 deletions(-)
> 
> diff --git a/namespaces.c b/namespaces.c
> index 8119d99..524b47b 100644
> --- a/namespaces.c
> +++ b/namespaces.c
> @@ -15,6 +15,7 @@
>  
>  #include "protobuf.h"
>  #include "protobuf/ns.pb-c.h"
> +#include "protobuf/userns.pb-c.h"
>  
>  static struct ns_desc *ns_desc_array[] = {
>  	&net_ns_desc,
> @@ -388,12 +389,114 @@ int gen_predump_ns_mask(void)
>  	return 0;
>  }
>  
> -static int dump_user_ns(pid_t pid, int ns_id)
> +static int parse_id_map(pid_t pid, char *name, UidGidExtent ***pb_exts)
>  {
> -	pr_err("User namesapces are not supported yet\n");
> +	UidGidExtent *extents = NULL;
> +	int len = 0, size = 0, fd, ret, i;
> +	FILE *f;
> +
> +	fd = open_proc(pid, "%s", name);

fd is left opened.

> +	if (fd < 0) {
> +		pr_perror("Unable to open %s", name);
> +		return -1;

Will it always fail on Fedora with USER_NS turned off?

> +	}
> +
> +	f = fdopen(fd, "r");

Why not fopen_proc() instead?

> +	if (f == NULL) {
> +		close(fd);
> +		return -1;
> +	}
> +
> +	ret = -1;
> +	while (1) {
> +		UidGidExtent *ext;
> +
> +		if (len == size) {
> +			UidGidExtent *t;
> +
> +			size = size * 2 + 1;
> +			t = xrealloc(extents, size * sizeof(UidGidExtent));
> +			if (t == NULL)
> +				break;
> +			extents = t;
> +		}
> +
> +		ext = &extents[len];
> +
> +		uid_gid_extent__init(ext);
> +		ret = fscanf(f, "%d %d %d", &ext->first,
> +				&ext->lower_first, &ext->count);
> +		if (ret != 3) {
> +			if (errno != 0) {
> +				pr_perror("Unable to parse extents");
> +				ret = -1;
> +			} else
> +				ret = 0;
> +			break;
> +		}
> +		pr_err("%d %d %d\n", ext->first, ext->lower_first, ext->count);
> +		len++;
> +	}
> +
> +	fclose(f);
> +
> +	if (ret)
> +		goto err;
> +
> +	if (len) {
> +		*pb_exts = xmalloc(sizeof(UidGidExtent *) * len);
> +		if (*pb_exts == NULL)
> +			goto err;
> +
> +		for (i = 0; i < len; i++)
> +			*pb_exts[i] = &extents[i];
> +	} else {
> +		xfree(extents);
> +		*pb_exts = NULL;
> +	}
> +
> +	return len;
> +err:
> +	xfree(extents);
>  	return -1;
>  }
>  
> +static int dump_user_ns(pid_t pid, int ns_id)
> +{
> +	UsernsEntry e = USERNS_ENTRY__INIT;
> +	int fd, ret, exit_code = -1;
> +
> +	ret = parse_id_map(pid, "uid_map", &e.uid_map);
> +	if (ret < 0)
> +		goto err;
> +	e.n_uid_map = ret;
> +
> +	ret = parse_id_map(pid, "gid_map", &e.gid_map);
> +	if (ret < 0)
> +		goto err;
> +	e.n_gid_map = ret;
> +
> +	fd = open_image(CR_FD_USERNS, O_DUMP, ns_id);
> +	if (fd < 0)
> +		goto err;
> +	ret = pb_write_one(fd, &e, PB_USERNS);
> +	close(fd);
> +	if (ret < 0)
> +		goto err;
> +
> +	exit_code = 0;
> +err:
> +	if (e.uid_map) {
> +		xfree(e.uid_map[0]);
> +		xfree(e.uid_map);
> +	}
> +	if (e.gid_map) {
> +		xfree(e.gid_map[0]);
> +		xfree(e.gid_map);
> +	}
> +	return exit_code;
> +}
> +
>  static int do_dump_namespaces(struct ns_id *ns)
>  {
>  	int ret = -1;
>