Re-factor ovl_check_origin() and ovl_get_origin(), so origin fh xattr is
read from upper inode only once during lookup with multiple lower layers
and only once when verifying index entry origin.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/namei.c | 142 +++++++++++++++++++++++++++++++++------------------
1 file changed, 92 insertions(+), 50 deletions(-)
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index a48ee02c4524..4cc8fb64c879 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -87,9 +87,36 @@ static int ovl_acceptable(void *ctx, struct dentry *dentry)
return 1;
}
+/*
+ * Check validity of an overlay file handle buffer.
+ *
+ * Return 0 for a valid file handle.
+ * Return -ENODATA for "origin unknown".
+ * Return <0 for an invalid file handle.
+ */
+static int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
+{
+ if (fh_len < sizeof(struct ovl_fh) || fh_len < fh->len)
+ return -EINVAL;
+
+ if (fh->magic != OVL_FH_MAGIC)
+ return -EINVAL;
+
+ /* Treat larger version and unknown flags as "origin unknown" */
+ if (fh->version > OVL_FH_VERSION || fh->flags & ~OVL_FH_FLAG_ALL)
+ return -ENODATA;
+
+ /* Treat endianness mismatch as "origin unknown" */
+ if (!(fh->flags & OVL_FH_FLAG_ANY_ENDIAN) &&
+ (fh->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN)
+ return -ENODATA;
+
+ return 0;
+}
+
static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry)
{
- int res;
+ int res, err;
struct ovl_fh *fh = NULL;
res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
@@ -102,7 +129,7 @@ static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry)
if (res == 0)
return NULL;
- fh = kzalloc(res, GFP_KERNEL);
+ fh = kzalloc(res, GFP_KERNEL);
if (!fh)
return ERR_PTR(-ENOMEM);
@@ -110,20 +137,12 @@ static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry)
if (res < 0)
goto fail;
- if (res < sizeof(struct ovl_fh) || res < fh->len)
- goto invalid;
-
- if (fh->magic != OVL_FH_MAGIC)
+ err = ovl_check_fh_len(fh, res);
+ if (err < 0) {
+ if (err == -ENODATA)
+ goto out;
goto invalid;
-
- /* Treat larger version and unknown flags as "origin unknown" */
- if (fh->version > OVL_FH_VERSION || fh->flags & ~OVL_FH_FLAG_ALL)
- goto out;
-
- /* Treat endianness mismatch as "origin unknown" */
- if (!(fh->flags & OVL_FH_FLAG_ANY_ENDIAN) &&
- (fh->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN)
- goto out;
+ }
return fh;
@@ -139,22 +158,17 @@ static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry)
goto out;
}
-static struct dentry *ovl_get_origin(struct dentry *dentry,
- struct vfsmount *mnt)
+static struct dentry *ovl_decode_fh(struct ovl_fh *fh, struct vfsmount *mnt)
{
- struct dentry *origin = NULL;
- struct ovl_fh *fh = ovl_get_origin_fh(dentry);
+ struct dentry *origin;
int bytes;
- if (IS_ERR_OR_NULL(fh))
- return (struct dentry *)fh;
-
/*
* Make sure that the stored uuid matches the uuid of the lower
* layer where file handle will be decoded.
*/
if (!uuid_equal(&fh->uuid, &mnt->mnt_sb->s_uuid))
- goto out;
+ return NULL;
bytes = (fh->len - offsetof(struct ovl_fh, fid));
origin = exportfs_decode_fh(mnt, (struct fid *)fh->fid,
@@ -164,22 +178,15 @@ static struct dentry *ovl_get_origin(struct dentry *dentry,
/* Treat stale file handle as "origin unknown" */
if (origin == ERR_PTR(-ESTALE))
origin = NULL;
- goto out;
+ return origin;
}
- if (ovl_dentry_weird(origin) ||
- ((d_inode(origin)->i_mode ^ d_inode(dentry)->i_mode) & S_IFMT))
- goto invalid;
+ if (ovl_dentry_weird(origin)) {
+ dput(origin);
+ return NULL;
+ }
-out:
- kfree(fh);
return origin;
-
-invalid:
- pr_warn_ratelimited("overlayfs: invalid origin (%pd2)\n", origin);
- dput(origin);
- origin = NULL;
- goto out;
}
static bool ovl_is_opaquedir(struct dentry *dentry)
@@ -284,9 +291,9 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,
}
-static int ovl_check_origin(struct dentry *upperdentry,
- struct ovl_path *lower, unsigned int numlower,
- struct ovl_path **stackp, unsigned int *ctrp)
+static int ovl_check_origin_fh(struct ovl_fh *fh, struct dentry *upperdentry,
+ struct ovl_path *lower, unsigned int numlower,
+ struct ovl_path **stackp)
{
struct vfsmount *mnt;
struct dentry *origin = NULL;
@@ -294,18 +301,20 @@ static int ovl_check_origin(struct dentry *upperdentry,
for (i = 0; i < numlower; i++) {
mnt = lower[i].layer->mnt;
- origin = ovl_get_origin(upperdentry, mnt);
- if (IS_ERR(origin))
- return PTR_ERR(origin);
-
+ origin = ovl_decode_fh(fh, mnt);
if (origin)
break;
}
if (!origin)
- return 0;
+ return -ESTALE;
+ else if (IS_ERR(origin))
+ return PTR_ERR(origin);
+
+ if (!ovl_is_whiteout(upperdentry) &&
+ ((d_inode(origin)->i_mode ^ d_inode(upperdentry)->i_mode) & S_IFMT))
+ goto invalid;
- BUG_ON(*ctrp);
if (!*stackp)
*stackp = kmalloc(sizeof(struct ovl_path), GFP_KERNEL);
if (!*stackp) {
@@ -313,9 +322,41 @@ static int ovl_check_origin(struct dentry *upperdentry,
return -ENOMEM;
}
**stackp = (struct ovl_path){.dentry = origin, .layer = lower[i].layer};
- *ctrp = 1;
return 0;
+
+invalid:
+ pr_warn_ratelimited("overlayfs: invalid origin (%pd2, ftype=%x, origin ftype=%x).\n",
+ upperdentry, d_inode(upperdentry)->i_mode & S_IFMT,
+ d_inode(origin)->i_mode & S_IFMT);
+ dput(origin);
+ return -EIO;
+}
+
+static int ovl_check_origin(struct dentry *upperdentry,
+ struct ovl_path *lower, unsigned int numlower,
+ struct ovl_path **stackp, unsigned int *ctrp)
+{
+ struct ovl_fh *fh = ovl_get_origin_fh(upperdentry);
+ int err;
+
+ if (IS_ERR_OR_NULL(fh))
+ return PTR_ERR(fh);
+
+ err = ovl_check_origin_fh(fh, upperdentry, lower, numlower, stackp);
+ kfree(fh);
+
+ if (err) {
+ if (err == -ESTALE)
+ return 0;
+ return err;
+ }
+
+ if (WARN_ON(*ctrp))
+ return -EIO;
+
+ *ctrp = 1;
+ return 0;
}
/*
@@ -389,7 +430,6 @@ int ovl_verify_index(struct dentry *index, struct ovl_path *lower,
size_t len;
struct ovl_path origin = { };
struct ovl_path *stack = &origin;
- unsigned int ctr = 0;
int err;
if (!d_inode(index))
@@ -420,16 +460,18 @@ int ovl_verify_index(struct dentry *index, struct ovl_path *lower,
goto fail;
err = -EINVAL;
- if (hex2bin((u8 *)fh, index->d_name.name, len) || len != fh->len)
+ if (hex2bin((u8 *)fh, index->d_name.name, len))
+ goto fail;
+
+ err = ovl_check_fh_len(fh, len);
+ if (err)
goto fail;
err = ovl_verify_origin_fh(index, fh);
if (err)
goto fail;
- err = ovl_check_origin(index, lower, numlower, &stack, &ctr);
- if (!err && !ctr)
- err = -ESTALE;
+ err = ovl_check_origin_fh(fh, index, lower, numlower, &stack);
if (err)
goto fail;
--
2.7.4
--
To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
