diff options
| author | Amir Goldstein <amir73il@gmail.com> | 2019-11-15 13:33:03 +0200 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2019-12-10 16:00:55 +0100 |
| commit | cbe7fba8edfc8cb8e621599e376f8ac5c224fa72 (patch) | |
| tree | 59d6d9ebeb101e85f23544f25103fa9690898aad /fs/overlayfs/copy_up.c | |
| parent | 7e63c87fc2dcf3be9d3aab82d4a0ea085880bdca (diff) | |
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/copy_up.c')
| -rw-r--r-- | fs/overlayfs/copy_up.c | 30 |
1 files changed, 16 insertions, 14 deletions
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index b801c6353100..7f744a9541e5 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -251,18 +251,20 @@ struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper) WARN_ON(fh_type == FILEID_INVALID)) goto out; - BUILD_BUG_ON(MAX_HANDLE_SZ + offsetof(struct ovl_fh, fid) > 255); - fh_len = offsetof(struct ovl_fh, fid) + buflen; - fh = kmalloc(fh_len, GFP_KERNEL); + /* Make sure the real fid stays 32bit aligned */ + BUILD_BUG_ON(OVL_FH_FID_OFFSET % 4); + BUILD_BUG_ON(MAX_HANDLE_SZ + OVL_FH_FID_OFFSET > 255); + fh_len = OVL_FH_FID_OFFSET + buflen; + fh = kzalloc(fh_len, GFP_KERNEL); if (!fh) { fh = ERR_PTR(-ENOMEM); goto out; } - fh->version = OVL_FH_VERSION; - fh->magic = OVL_FH_MAGIC; - fh->type = fh_type; - fh->flags = OVL_FH_FLAG_CPU_ENDIAN; + fh->fb.version = OVL_FH_VERSION; + fh->fb.magic = OVL_FH_MAGIC; + fh->fb.type = fh_type; + fh->fb.flags = OVL_FH_FLAG_CPU_ENDIAN; /* * When we will want to decode an overlay dentry from this handle * and all layers are on the same fs, if we get a disconncted real @@ -270,10 +272,10 @@ struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper) * it to upperdentry or to lowerstack is by checking this flag. */ if (is_upper) - fh->flags |= OVL_FH_FLAG_PATH_UPPER; - fh->len = fh_len; - fh->uuid = *uuid; - memcpy(fh->fid, buf, buflen); + fh->fb.flags |= OVL_FH_FLAG_PATH_UPPER; + fh->fb.len = fh_len - OVL_FH_WIRE_OFFSET; + fh->fb.uuid = *uuid; + memcpy(fh->fb.fid, buf, buflen); out: kfree(buf); @@ -300,8 +302,8 @@ int ovl_set_origin(struct dentry *dentry, struct dentry *lower, /* * Do not fail when upper doesn't support xattrs. */ - err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh, - fh ? fh->len : 0, 0); + err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh->buf, + fh ? fh->fb.len : 0, 0); kfree(fh); return err; @@ -317,7 +319,7 @@ static int ovl_set_upper_fh(struct dentry *upper, struct dentry *index) if (IS_ERR(fh)) return PTR_ERR(fh); - err = ovl_do_setxattr(index, OVL_XATTR_UPPER, fh, fh->len, 0); + err = ovl_do_setxattr(index, OVL_XATTR_UPPER, fh->buf, fh->fb.len, 0); kfree(fh); return err; |