On 1/14/22 5:29 AM, Daniel Gerber wrote:
Hi,
Thanks for this feature. I've been trying it out... (This is with lib-musl-x86_64.)
Automatic mapping works:
$ unshare --map-users=auto cat /proc/self/uid_map
0 100000 65536
But parsing id ranges does not:
$ unshare --map-users=100000,0,65536 cat /proc/self/uid_map
unshare: could not parse ID: '100000,0,65536'
Fix:
---
diff --git a/sys-utils/unshare.c b/sys-utils/unshare.c
index 443358952..52bd9702a 100644
--- a/sys-utils/unshare.c
+++ b/sys-utils/unshare.c
@@ -388,7 +388,7 @@ static int uint_to_id(const char *name, size_t sz)
char buf[UID_BUFSIZ];
mem2strcpy(buf, name, sz, sizeof(buf));
- return strtoul_or_err(name, _("could not parse ID"));
+ return strtoul_or_err(buf, _("could not parse ID"));
}
/**
---
Then, the value passed to newuidmap is still incorrect:
$ unshare --map-users=100000,0,65536 cat /proc/self/uid_map
newuidmap: uid range [0-655360) -> [100000-755360) not allowed
$ unshare --map-users=100000,0,0065536 cat /proc/self/uid_map
0 100000 65536
The count value gets zero-padded to the right at some place I've not pinned down.
It's stack garbage. Try
diff --git i/sys-utils/unshare.c w/sys-utils/unshare.c
index 3cdd90329..5ac7af3de 100644
--- i/sys-utils/unshare.c
+++ w/sys-utils/unshare.c
@@ -385,10 +385,10 @@ struct map_range {
*/
static int uint_to_id(const char *name, size_t sz)
{
- char buf[UID_BUFSIZ];
+ char buf[UID_BUFSIZ] = {0};
- mem2strcpy(buf, name, sz, sizeof(buf));
- return strtoul_or_err(name, _("could not parse ID"));
+ memcpy(buf, name, min(sz, sizeof(buf) - 1));
+ return strtoul_or_err(buf, _("could not parse ID"));
}
/**
--
(actually, I have no idea what mem2strcpy is for if it doesn't put the nul-terminator at the end of sz)
Also, I would suggest adopting the same argument order as in /proc/<pid>/uid_map and newuidmap -- inner,outer,count.
I think this is a rather silly order. Since this is a mapping, the "natural" order is
outer -> inner
and only from the new namespace's PoV is it
inner -> outer
It certainly helped me remember things once I reversed the order...
This doc string has it reversed:
As noted above, this is intended.
---
/**
* struct map_range - A range of IDs to map
* @outer: First ID inside the namespace
* @inner: First ID outside the namespace
---
And this one has inconsistent terminology:
---
* get_map_range() - Parse a mapping range from a string
* @s: A string of the format upper,lower,count
*
* Parse a string of the form upper,lower,count into a new mapping range.
---
And here you can see that I've been reading too much of shadow's man pages :)
--Sean
