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authorAmir Goldstein <amir73il@gmail.com>2019-11-15 14:33:03 +0300
committerMiklos Szeredi <mszeredi@redhat.com>2019-12-10 18:00:55 +0300
commitcbe7fba8edfc8cb8e621599e376f8ac5c224fa72 (patch)
tree59d6d9ebeb101e85f23544f25103fa9690898aad /fs/overlayfs/export.c
parent7e63c87fc2dcf3be9d3aab82d4a0ea085880bdca (diff)
downloadlinux-cbe7fba8edfc8cb8e621599e376f8ac5c224fa72.tar.xz
ovl: make sure that real fid is 32bit aligned in memory
Seprate on-disk encoding from in-memory and on-wire resresentation of overlay file handle. In-memory and on-wire we only ever pass around pointers to struct ovl_fh, which encapsulates at offset 3 the on-disk format struct ovl_fb. struct ovl_fb encapsulates at offset 21 the real file handle. That makes sure that the real file handle is always 32bit aligned in-memory when passed down to the underlying filesystem. On-disk format remains the same and store/load are done into correctly aligned buffer. New nfs exported file handles are exported with aligned real fid. Old nfs file handles are copied to an aligned buffer before being decoded. Reported-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs/export.c')
-rw-r--r--fs/overlayfs/export.c80
1 files changed, 49 insertions, 31 deletions
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index 73c9775215b3..70e55588aedc 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -211,10 +211,11 @@ static int ovl_check_encode_origin(struct dentry *dentry)
return 1;
}
-static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen)
+static int ovl_dentry_to_fid(struct dentry *dentry, u32 *fid, int buflen)
{
struct ovl_fh *fh = NULL;
int err, enc_lower;
+ int len;
/*
* Check if we should encode a lower or upper file handle and maybe
@@ -231,11 +232,12 @@ static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen)
return PTR_ERR(fh);
err = -EOVERFLOW;
- if (fh->len > buflen)
+ len = OVL_FH_LEN(fh);
+ if (len > buflen)
goto fail;
- memcpy(buf, (char *)fh, fh->len);
- err = fh->len;
+ memcpy(fid, fh, len);
+ err = len;
out:
kfree(fh);
@@ -243,31 +245,16 @@ out:
fail:
pr_warn_ratelimited("overlayfs: failed to encode file handle (%pd2, err=%i, buflen=%d, len=%d, type=%d)\n",
- dentry, err, buflen, fh ? (int)fh->len : 0,
- fh ? fh->type : 0);
+ dentry, err, buflen, fh ? (int)fh->fb.len : 0,
+ fh ? fh->fb.type : 0);
goto out;
}
-static int ovl_dentry_to_fh(struct dentry *dentry, u32 *fid, int *max_len)
-{
- int res, len = *max_len << 2;
-
- res = ovl_d_to_fh(dentry, (char *)fid, len);
- if (res <= 0)
- return FILEID_INVALID;
-
- len = res;
-
- /* Round up to dwords */
- *max_len = (len + 3) >> 2;
- return OVL_FILEID;
-}
-
static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len,
struct inode *parent)
{
struct dentry *dentry;
- int type;
+ int bytes = *max_len << 2;
/* TODO: encode connectable file handles */
if (parent)
@@ -277,10 +264,14 @@ static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len,
if (WARN_ON(!dentry))
return FILEID_INVALID;
- type = ovl_dentry_to_fh(dentry, fid, max_len);
-
+ bytes = ovl_dentry_to_fid(dentry, fid, bytes);
dput(dentry);
- return type;
+ if (bytes <= 0)
+ return FILEID_INVALID;
+
+ *max_len = bytes >> 2;
+
+ return OVL_FILEID_V1;
}
/*
@@ -777,24 +768,45 @@ out_err:
goto out;
}
+static struct ovl_fh *ovl_fid_to_fh(struct fid *fid, int buflen, int fh_type)
+{
+ struct ovl_fh *fh;
+
+ /* If on-wire inner fid is aligned - nothing to do */
+ if (fh_type == OVL_FILEID_V1)
+ return (struct ovl_fh *)fid;
+
+ if (fh_type != OVL_FILEID_V0)
+ return ERR_PTR(-EINVAL);
+
+ fh = kzalloc(buflen, GFP_KERNEL);
+ if (!fh)
+ return ERR_PTR(-ENOMEM);
+
+ /* Copy unaligned inner fh into aligned buffer */
+ memcpy(&fh->fb, fid, buflen - OVL_FH_WIRE_OFFSET);
+ return fh;
+}
+
static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type)
{
struct dentry *dentry = NULL;
- struct ovl_fh *fh = (struct ovl_fh *) fid;
+ struct ovl_fh *fh = NULL;
int len = fh_len << 2;
unsigned int flags = 0;
int err;
- err = -EINVAL;
- if (fh_type != OVL_FILEID)
+ fh = ovl_fid_to_fh(fid, len, fh_type);
+ err = PTR_ERR(fh);
+ if (IS_ERR(fh))
goto out_err;
err = ovl_check_fh_len(fh, len);
if (err)
goto out_err;
- flags = fh->flags;
+ flags = fh->fb.flags;
dentry = (flags & OVL_FH_FLAG_PATH_UPPER) ?
ovl_upper_fh_to_d(sb, fh) :
ovl_lower_fh_to_d(sb, fh);
@@ -802,12 +814,18 @@ static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid,
if (IS_ERR(dentry) && err != -ESTALE)
goto out_err;
+out:
+ /* We may have needed to re-align OVL_FILEID_V0 */
+ if (!IS_ERR_OR_NULL(fh) && fh != (void *)fid)
+ kfree(fh);
+
return dentry;
out_err:
pr_warn_ratelimited("overlayfs: failed to decode file handle (len=%d, type=%d, flags=%x, err=%i)\n",
- len, fh_type, flags, err);
- return ERR_PTR(err);
+ fh_len, fh_type, flags, err);
+ dentry = ERR_PTR(err);
+ goto out;
}
static struct dentry *ovl_fh_to_parent(struct super_block *sb, struct fid *fid,