sdcard : inode numbers must be fully representable as uint32_t.
This works around a bug on on 64 bit kernels + sdcard daemons
where we were using memory addresses as inode numbers.
bug: 19012244
(cherry picked from commit faa0935ffb772759f795d6b29c6db6f83e8531c4)
Change-Id: Idbf9e285e507e702e04e7461a10153df68ef2322
diff --git a/sdcard/sdcard.c b/sdcard/sdcard.c
index a48906a..4d50bf0 100644
--- a/sdcard/sdcard.c
+++ b/sdcard/sdcard.c
@@ -169,6 +169,11 @@
__u32 refcount;
__u64 nid;
__u64 gen;
+ /*
+ * The inode number for this FUSE node. Note that this isn't stable across
+ * multiple invocations of the FUSE daemon.
+ */
+ __u32 ino;
/* State derived based on current position in hierarchy. */
perm_t perm;
@@ -225,6 +230,25 @@
struct node root;
char obbpath[PATH_MAX];
+ /* Used to allocate unique inode numbers for fuse nodes. We use
+ * a simple counter based scheme where inode numbers from deleted
+ * nodes aren't reused. Note that inode allocations are not stable
+ * across multiple invocation of the sdcard daemon, but that shouldn't
+ * be a huge problem in practice.
+ *
+ * Note that we restrict inodes to 32 bit unsigned integers to prevent
+ * truncation on 32 bit processes when unsigned long long stat.st_ino is
+ * assigned to an unsigned long ino_t type in an LP32 process.
+ *
+ * Also note that fuse_attr and fuse_dirent inode values are 64 bits wide
+ * on both LP32 and LP64, but the fuse kernel code doesn't squash 64 bit
+ * inode numbers into 32 bit values on 64 bit kernels (see fuse_squash_ino
+ * in fs/fuse/inode.c).
+ *
+ * Accesses must be guarded by |lock|.
+ */
+ __u32 inode_ctr;
+
Hashmap* package_to_appid;
Hashmap* appid_with_rw;
};
@@ -388,7 +412,7 @@
static void attr_from_stat(struct fuse_attr *attr, const struct stat *s, const struct node* node)
{
- attr->ino = node->nid;
+ attr->ino = node->ino;
attr->size = s->st_size;
attr->blocks = s->st_blocks;
attr->atime = s->st_atim.tv_sec;
@@ -576,6 +600,13 @@
struct node *node;
size_t namelen = strlen(name);
+ // Detect overflows in the inode counter. "4 billion nodes should be enough
+ // for everybody".
+ if (fuse->inode_ctr == 0) {
+ ERROR("No more inode numbers available");
+ return NULL;
+ }
+
node = calloc(1, sizeof(struct node));
if (!node) {
return NULL;
@@ -597,6 +628,7 @@
}
node->namelen = namelen;
node->nid = ptr_to_id(node);
+ node->ino = fuse->inode_ctr++;
node->gen = fuse->next_generation++;
derive_permissions_locked(fuse, parent, node);
@@ -701,6 +733,7 @@
fuse->derive = derive;
fuse->split_perms = split_perms;
fuse->write_gid = write_gid;
+ fuse->inode_ctr = 1;
memset(&fuse->root, 0, sizeof(fuse->root));
fuse->root.nid = FUSE_ROOT_ID; /* 1 */