Commit 8b88a2e6 authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi

ovl: verify upper root dir matches lower root dir

When inodes index feature is enabled, verify that the file handle stored
in upper root dir matches the lower root dir or fail to mount.

If upper root dir has no stored file handle, encode and store the lower
root dir file handle in overlay.origin xattr.
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 02bcd157
...@@ -233,7 +233,7 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat) ...@@ -233,7 +233,7 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
return err; return err;
} }
static struct ovl_fh *ovl_encode_fh(struct dentry *lower) struct ovl_fh *ovl_encode_fh(struct dentry *lower)
{ {
struct ovl_fh *fh; struct ovl_fh *fh;
int fh_type, fh_len, dwords; int fh_type, fh_len, dwords;
......
...@@ -88,13 +88,10 @@ static int ovl_acceptable(void *ctx, struct dentry *dentry) ...@@ -88,13 +88,10 @@ static int ovl_acceptable(void *ctx, struct dentry *dentry)
return 1; return 1;
} }
static struct dentry *ovl_get_origin(struct dentry *dentry, static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry)
struct vfsmount *mnt)
{ {
int res; int res;
struct ovl_fh *fh = NULL; struct ovl_fh *fh = NULL;
struct dentry *origin = NULL;
int bytes;
res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0); res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
if (res < 0) { if (res < 0) {
...@@ -106,7 +103,7 @@ static struct dentry *ovl_get_origin(struct dentry *dentry, ...@@ -106,7 +103,7 @@ static struct dentry *ovl_get_origin(struct dentry *dentry,
if (res == 0) if (res == 0)
return NULL; return NULL;
fh = kzalloc(res, GFP_TEMPORARY); fh = kzalloc(res, GFP_TEMPORARY);
if (!fh) if (!fh)
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
...@@ -129,7 +126,29 @@ static struct dentry *ovl_get_origin(struct dentry *dentry, ...@@ -129,7 +126,29 @@ static struct dentry *ovl_get_origin(struct dentry *dentry,
(fh->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN) (fh->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN)
goto out; goto out;
bytes = (fh->len - offsetof(struct ovl_fh, fid)); return fh;
out:
kfree(fh);
return NULL;
fail:
pr_warn_ratelimited("overlayfs: failed to get origin (%i)\n", res);
goto out;
invalid:
pr_warn_ratelimited("overlayfs: invalid origin (%*phN)\n", res, fh);
goto out;
}
static struct dentry *ovl_get_origin(struct dentry *dentry,
struct vfsmount *mnt)
{
struct dentry *origin = NULL;
struct ovl_fh *fh = ovl_get_origin_fh(dentry);
int bytes;
if (IS_ERR_OR_NULL(fh))
return (struct dentry *)fh;
/* /*
* Make sure that the stored uuid matches the uuid of the lower * Make sure that the stored uuid matches the uuid of the lower
...@@ -138,6 +157,7 @@ static struct dentry *ovl_get_origin(struct dentry *dentry, ...@@ -138,6 +157,7 @@ static struct dentry *ovl_get_origin(struct dentry *dentry,
if (!uuid_equal(&fh->uuid, &mnt->mnt_sb->s_uuid)) if (!uuid_equal(&fh->uuid, &mnt->mnt_sb->s_uuid))
goto out; goto out;
bytes = (fh->len - offsetof(struct ovl_fh, fid));
origin = exportfs_decode_fh(mnt, (struct fid *)fh->fid, origin = exportfs_decode_fh(mnt, (struct fid *)fh->fid,
bytes >> 2, (int)fh->type, bytes >> 2, (int)fh->type,
ovl_acceptable, NULL); ovl_acceptable, NULL);
...@@ -149,21 +169,17 @@ static struct dentry *ovl_get_origin(struct dentry *dentry, ...@@ -149,21 +169,17 @@ static struct dentry *ovl_get_origin(struct dentry *dentry,
} }
if (ovl_dentry_weird(origin) || if (ovl_dentry_weird(origin) ||
((d_inode(origin)->i_mode ^ d_inode(dentry)->i_mode) & S_IFMT)) { ((d_inode(origin)->i_mode ^ d_inode(dentry)->i_mode) & S_IFMT))
dput(origin);
origin = NULL;
goto invalid; goto invalid;
}
out: out:
kfree(fh); kfree(fh);
return origin; return origin;
fail:
pr_warn_ratelimited("overlayfs: failed to get origin (%i)\n", res);
goto out;
invalid: invalid:
pr_warn_ratelimited("overlayfs: invalid origin (%*phN)\n", res, fh); pr_warn_ratelimited("overlayfs: invalid origin (%pd2)\n", origin);
dput(origin);
origin = NULL;
goto out; goto out;
} }
...@@ -303,6 +319,65 @@ static int ovl_check_origin(struct dentry *dentry, struct dentry *upperdentry, ...@@ -303,6 +319,65 @@ static int ovl_check_origin(struct dentry *dentry, struct dentry *upperdentry,
return 0; return 0;
} }
/*
* Verify that @fh matches the origin file handle stored in OVL_XATTR_ORIGIN.
* Return 0 on match, -ESTALE on mismatch, < 0 on error.
*/
static int ovl_verify_origin_fh(struct dentry *dentry, const struct ovl_fh *fh)
{
struct ovl_fh *ofh = ovl_get_origin_fh(dentry);
int err = 0;
if (!ofh)
return -ENODATA;
if (IS_ERR(ofh))
return PTR_ERR(ofh);
if (fh->len != ofh->len || memcmp(fh, ofh, fh->len))
err = -ESTALE;
kfree(ofh);
return err;
}
/*
* Verify that an inode matches the origin file handle stored in upper inode.
*
* If @set is true and there is no stored file handle, encode and store origin
* file handle in OVL_XATTR_ORIGIN.
*
* Return 0 on match, -ESTALE on mismatch, < 0 on error.
*/
int ovl_verify_origin(struct dentry *dentry, struct vfsmount *mnt,
struct dentry *origin, bool set)
{
struct inode *inode;
struct ovl_fh *fh;
int err;
fh = ovl_encode_fh(origin);
err = PTR_ERR(fh);
if (IS_ERR(fh))
goto fail;
err = ovl_verify_origin_fh(dentry, fh);
if (set && err == -ENODATA)
err = ovl_do_setxattr(dentry, OVL_XATTR_ORIGIN, fh, fh->len, 0);
if (err)
goto fail;
out:
kfree(fh);
return err;
fail:
inode = d_inode(origin);
pr_warn_ratelimited("overlayfs: failed to verify origin (%pd2, ino=%lu, err=%i)\n",
origin, inode ? inode->i_ino : 0, err);
goto out;
}
/* /*
* Returns next layer in stack starting from top. * Returns next layer in stack starting from top.
* Returns -1 if this is the last layer. * Returns -1 if this is the last layer.
......
...@@ -232,6 +232,8 @@ static inline bool ovl_is_impuredir(struct dentry *dentry) ...@@ -232,6 +232,8 @@ static inline bool ovl_is_impuredir(struct dentry *dentry)
/* namei.c */ /* namei.c */
int ovl_verify_origin(struct dentry *dentry, struct vfsmount *mnt,
struct dentry *origin, bool set);
int ovl_path_next(int idx, struct dentry *dentry, struct path *path); int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags); struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags);
bool ovl_lower_positive(struct dentry *dentry); bool ovl_lower_positive(struct dentry *dentry);
...@@ -290,3 +292,4 @@ int ovl_copy_up(struct dentry *dentry); ...@@ -290,3 +292,4 @@ int ovl_copy_up(struct dentry *dentry);
int ovl_copy_up_flags(struct dentry *dentry, int flags); int ovl_copy_up_flags(struct dentry *dentry, int flags);
int ovl_copy_xattr(struct dentry *old, struct dentry *new); int ovl_copy_xattr(struct dentry *old, struct dentry *new);
int ovl_set_attr(struct dentry *upper, struct kstat *stat); int ovl_set_attr(struct dentry *upper, struct kstat *stat);
struct ovl_fh *ovl_encode_fh(struct dentry *lower);
...@@ -1048,6 +1048,14 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) ...@@ -1048,6 +1048,14 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
ufs->same_sb = NULL; ufs->same_sb = NULL;
if (!(ovl_force_readonly(ufs)) && ufs->config.index) { if (!(ovl_force_readonly(ufs)) && ufs->config.index) {
/* Verify lower root is upper root origin */
err = ovl_verify_origin(upperpath.dentry, ufs->lower_mnt[0],
stack[0].dentry, true);
if (err) {
pr_err("overlayfs: failed to verify upper root origin\n");
goto out_put_lower_mnt;
}
ufs->indexdir = ovl_workdir_create(sb, ufs, workpath.dentry, ufs->indexdir = ovl_workdir_create(sb, ufs, workpath.dentry,
OVL_INDEXDIR_NAME, true); OVL_INDEXDIR_NAME, true);
err = PTR_ERR(ufs->indexdir); err = PTR_ERR(ufs->indexdir);
......
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