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containerfs: support uids/gids shift
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Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
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@giuseppe
giuseppe committed Jun 28, 2018
1 parent 09771b9 commit 3378869
Showing 1 changed file with 119 additions and 33 deletions.
152 changes: 119 additions & 33 deletions main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -87,6 +87,14 @@ str_compare (const void *n1, const void *n2)
return strcmp (s1, s2) == 0 ? true : false;
}

struct lo_mapping
{
struct lo_mapping *next;
unsigned int host;
unsigned int to;
unsigned int len;
};

struct lo_node
{
struct lo_node *parent;
Expand All @@ -107,8 +115,10 @@ struct lo_data
{
struct fuse_session *se;
int debug;
int uid;
int gid;
char *uid_str;
char *gid_str;
struct lo_mapping *uid_mappings;
struct lo_mapping *gid_mappings;
char *lowerdir;
char *context;
char *upperdir;
Expand All @@ -126,10 +136,10 @@ static const struct fuse_opt lo_opts[] = {
offsetof (struct lo_data, upperdir), 0},
{"workdir=%s",
offsetof (struct lo_data, workdir), 0},
{"uid=%i",
offsetof (struct lo_data, uid), -1},
{"gid=%i",
offsetof (struct lo_data, gid), -1},
{"uid=%s",
offsetof (struct lo_data, uid_str), 0},
{"gid=%s",
offsetof (struct lo_data, gid_str), 0},
FUSE_OPT_END
};

Expand All @@ -139,6 +149,61 @@ lo_data (fuse_req_t req)
return (struct lo_data *) fuse_req_userdata (req);
}

static struct lo_mapping *
read_mappings (const char *str)
{
char *buf = NULL, *saveptr = NULL, *it;
struct lo_mapping *tmp, *ret = NULL;
unsigned int a, b, c;
int state = 0;

buf = alloca (strlen (str) + 1);
strcpy (buf, str);

for (it = strtok_r (buf, ":", &saveptr); it; it = strtok_r (NULL, ":", &saveptr))
{
switch (state)
{
case 0:
a = strtol (it, NULL, 10);
state++;
break;

case 1:
b = strtol (it, NULL, 10);
state++;
break;

case 2:
c = strtol (it, NULL, 10);
state = 0;

tmp = malloc (sizeof (*tmp));
if (tmp == NULL)
return NULL;
tmp->next = ret;
tmp->host = a;
tmp->to = b;
tmp->len = c;
ret = tmp;
break;
}
}

return ret;
}

static void
free_mapping (struct lo_mapping *it)
{
struct lo_mapping *next = NULL;
for (; it; it = next)
{
next = it->next;
free (it);
}
}

/* Useful in a gdb session. */
void
dump_directory (struct lo_node *node)
Expand All @@ -165,23 +230,6 @@ lo_init (void *userdata, struct fuse_conn_info *conn)
conn->want &= ~FUSE_CAP_PARALLEL_DIROPS;
}

/* FIXME: support proper ID ranges. */
static uid_t
get_uid (struct lo_data *lo, uid_t id)
{
if (lo->uid == id)
return geteuid ();
return id;
}

static uid_t
get_gid (struct lo_data *lo, gid_t id)
{
if (lo->gid == id)
return getegid ();
return id;
}

static inline bool
node_dirp (struct lo_node *n)
{
Expand Down Expand Up @@ -232,6 +280,39 @@ hide_node (struct lo_data *lo, struct lo_node *node)
return 0;
}

static unsigned int
find_mapping (unsigned int id, struct lo_mapping *mapping, bool direct)
{
if (mapping == NULL)
return id;
for (; mapping; mapping = mapping->next)
{
if (direct)
{
if (id >= mapping->host && id < mapping->host + mapping->len)
return mapping->to + (id - mapping->host);
}
else
{
if (id >= mapping->to && id < mapping->to + mapping->len)
return mapping->host + (id - mapping->to);
}
}
return 65534;
}

static uid_t
get_uid (struct lo_data *data, uid_t id)
{
return find_mapping (id, data->uid_mappings, false);
}

static uid_t
get_gid (struct lo_data *data, gid_t id)
{
return find_mapping (id, data->gid_mappings, false);
}

static int
rpl_stat (fuse_req_t req, struct lo_node *node, struct stat *st)
{
Expand All @@ -246,11 +327,8 @@ rpl_stat (fuse_req_t req, struct lo_node *node, struct stat *st)
if (ret < 0)
return ret;

if (data->uid >= 0)
st->st_uid = data->uid;
if (data->gid >= 0)
st->st_gid = data->gid;

st->st_uid = find_mapping (st->st_uid, data->uid_mappings, true);
st->st_gid = find_mapping (st->st_gid, data->gid_mappings, true);

st->st_ino = NODE_TO_INODE (node);

Expand Down Expand Up @@ -838,7 +916,7 @@ do_lookup_file (struct lo_data *lo, fuse_ino_t parent, const char *path)
if (*path == '\0')
return node;

b = alloca (strlen (path));
b = alloca (strlen (path) + 1);
strcpy (b, path);

for (it = strtok_r (b, "/", &saveptr); it; it = strtok_r (NULL, "/", &saveptr))
Expand Down Expand Up @@ -2745,8 +2823,10 @@ main (int argc, char *argv[])
struct fuse_session *se;
struct fuse_cmdline_opts opts;
struct lo_data lo = {.debug = 0,
.uid = -1,
.gid = -1,
.uid_mappings = NULL,
.gid_mappings = NULL,
.uid_str = NULL,
.gid_str = NULL,
.root_lower = NULL,
.root_upper = NULL,
.lowerdir = NULL,
Expand Down Expand Up @@ -2789,13 +2869,16 @@ main (int argc, char *argv[])
goto err_out1;
}

printf ("UID=%i\n", lo.uid);
printf ("GID=%i\n", lo.gid);
printf ("UID=%s\n", lo.uid_str ? : "unchanged");
printf ("GID=%s\n", lo.gid_str ? : "unchanged");
printf ("UPPERDIR=%s\n", lo.upperdir);
printf ("WORKDIR=%s\n", lo.workdir);
printf ("LOWERDIR=%s\n", lo.lowerdir);
printf ("MOUNTPOINT=%s\n", opts.mountpoint);

lo.uid_mappings = lo.uid_str ? read_mappings (lo.uid_str) : NULL;
lo.gid_mappings = lo.gid_str ? read_mappings (lo.gid_str) : NULL;

lo.root_lower = read_dirs (lo.lowerdir, NULL, true);
if (lo.root_lower == NULL)
error (EXIT_FAILURE, errno, "cannot read lower dirs");
Expand Down Expand Up @@ -2844,6 +2927,9 @@ main (int argc, char *argv[])
node_free (lo.root_lower);
node_free (lo.root_upper);

free_mapping (lo.uid_mappings);
free_mapping (lo.gid_mappings);

free (opts.mountpoint);
fuse_opt_free_args (&args);

Expand Down

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