During regular metacopy, if lowerdata file has fs-verity enabled, and
the verity option is enabled, we add the digest to the metacopy xattr.
If verity is required, and lowerdata does not have fs-verity enabled,
fall back to full copy-up (or the generated metacopy would not
validate).
Signed-off-by: Alexander Larsson <alexl@xxxxxxxxxx>
---
fs/overlayfs/copy_up.c | 45 ++++++++++++++++++++++++++++++++++++++--
fs/overlayfs/overlayfs.h | 3 +++
fs/overlayfs/util.c | 33 ++++++++++++++++++++++++++++-
3 files changed, 78 insertions(+), 3 deletions(-)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 68f01fd7f211..fce7d048673c 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -544,6 +544,7 @@ struct ovl_copy_up_ctx {
bool origin;
bool indexed;
bool metacopy;
+ bool metacopy_digest;
};
static int ovl_link_up(struct ovl_copy_up_ctx *c)
@@ -641,8 +642,21 @@ static int ovl_copy_up_metadata(struct ovl_copy_up_ctx *c, struct dentry *temp)
}
if (c->metacopy) {
- err = ovl_check_setxattr(ofs, temp, OVL_XATTR_METACOPY,
- NULL, 0, -EOPNOTSUPP);
+ struct path lowerdatapath;
+ struct ovl_metacopy metacopy_data = OVL_METACOPY_INIT;
+
+ ovl_path_lowerdata(c->dentry, &lowerdatapath);
+ if (WARN_ON_ONCE(lowerdatapath.dentry == NULL))
+ err = -EIO;
+ else
+ err = ovl_set_verity_xattr_from(ofs, &lowerdatapath, &metacopy_data);
+
+ if (metacopy_data.digest_algo)
+ c->metacopy_digest = true;
+
+ if (!err)
+ err = ovl_set_metacopy_xattr(ofs, temp, &metacopy_data);
+
if (err)
return err;
}
@@ -751,6 +765,12 @@ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
if (err)
goto cleanup;
+ if (c->metacopy_digest)
+ ovl_set_flag(OVL_HAS_DIGEST, d_inode(c->dentry));
+ else
+ ovl_clear_flag(OVL_HAS_DIGEST, d_inode(c->dentry));
+ ovl_clear_flag(OVL_VERIFIED_DIGEST, d_inode(c->dentry));
+
if (!c->metacopy)
ovl_set_upperdata(d_inode(c->dentry));
inode = d_inode(c->dentry);
@@ -813,6 +833,12 @@ static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
if (err)
goto out_fput;
+ if (c->metacopy_digest)
+ ovl_set_flag(OVL_HAS_DIGEST, d_inode(c->dentry));
+ else
+ ovl_clear_flag(OVL_HAS_DIGEST, d_inode(c->dentry));
+ ovl_clear_flag(OVL_VERIFIED_DIGEST, d_inode(c->dentry));
+
if (!c->metacopy)
ovl_set_upperdata(d_inode(c->dentry));
ovl_inode_update(d_inode(c->dentry), dget(temp));
@@ -918,6 +944,19 @@ static bool ovl_need_meta_copy_up(struct dentry *dentry, umode_t mode,
if (flags && ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC)))
return false;
+ /* Fall back to full copy if no fsverity on source data and we require verity */
+ if (ofs->config.verity_mode == OVL_VERITY_REQUIRE) {
+ struct path lowerdata;
+
+ ovl_path_lowerdata(dentry, &lowerdata);
+
+ if (WARN_ON_ONCE(lowerdata.dentry == NULL) ||
+ ovl_ensure_verity_loaded(&lowerdata) ||
+ !fsverity_get_info(d_inode(lowerdata.dentry))) {
+ return false;
+ }
+ }
+
return true;
}
@@ -984,6 +1023,8 @@ static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c)
if (err)
goto out_free;
+ ovl_clear_flag(OVL_HAS_DIGEST, d_inode(c->dentry));
+ ovl_clear_flag(OVL_VERIFIED_DIGEST, d_inode(c->dentry));
ovl_set_upperdata(d_inode(c->dentry));
out_free:
kfree(capability);
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 9fbbc077643b..e728360c66ff 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -519,11 +519,14 @@ int ovl_set_metacopy_xattr(struct ovl_fs *ofs, struct dentry *d,
struct ovl_metacopy *metacopy);
bool ovl_is_metacopy_dentry(struct dentry *dentry);
char *ovl_get_redirect_xattr(struct ovl_fs *ofs, const struct path *path, int padding);
+int ovl_ensure_verity_loaded(struct path *path);
int ovl_get_verity_xattr(struct ovl_fs *ofs, const struct path *path,
u8 *digest_buf, int *buf_length);
int ovl_validate_verity(struct ovl_fs *ofs,
struct path *metapath,
struct path *datapath);
+int ovl_set_verity_xattr_from(struct ovl_fs *ofs, struct path *src,
+ struct ovl_metacopy *metacopy);
int ovl_sync_status(struct ovl_fs *ofs);
static inline void ovl_set_flag(unsigned long flag, struct inode *inode)
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 927a1133859d..439e23496713 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -1188,7 +1188,7 @@ char *ovl_get_redirect_xattr(struct ovl_fs *ofs, const struct path *path, int pa
}
/* Call with mounter creds as it may open the file */
-static int ovl_ensure_verity_loaded(struct path *datapath)
+int ovl_ensure_verity_loaded(struct path *datapath)
{
struct inode *inode = d_inode(datapath->dentry);
const struct fsverity_info *vi;
@@ -1264,6 +1264,37 @@ int ovl_validate_verity(struct ovl_fs *ofs,
return 0;
}
+int ovl_set_verity_xattr_from(struct ovl_fs *ofs, struct path *src,
+ struct ovl_metacopy *metacopy)
+{
+ int err, digest_size;
+
+ if (!ofs->config.verity_mode || !S_ISREG(d_inode(src->dentry)->i_mode))
+ return 0;
+
+ err = ovl_ensure_verity_loaded(src);
+ if (err < 0) {
+ pr_warn_ratelimited("lower file '%pd' failed to load fs-verity info\n",
+ src->dentry);
+ return -EIO;
+ }
+
+ digest_size = fsverity_get_digest(d_inode(src->dentry),
+ metacopy->digest, &metacopy->digest_algo, NULL);
+ if (digest_size == 0 ||
+ WARN_ON_ONCE(digest_size > FS_VERITY_MAX_DIGEST_SIZE)) {
+ if (ofs->config.verity_mode == OVL_VERITY_REQUIRE) {
+ pr_warn_ratelimited("lower file '%pd' has no fs-verity digest\n",
+ src->dentry);
+ return -EIO;
+ }
+ return 0;
+ }
+
+ metacopy->len += digest_size;
+ return 0;
+}
+
/*
* ovl_sync_status() - Check fs sync status for volatile mounts
*
--
2.40.1
