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ovl: Handle verity during copy-up

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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@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
This commit is contained in:
Alexander Larsson 2023-04-19 13:58:45 +02:00 committed by Amir Goldstein
parent 184996e92e
commit 0c71faf5a6
3 changed files with 79 additions and 5 deletions
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48
fs/overlayfs/copy_up.c
View file

@ -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 +642,20 @@ 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))
return -EIO;
err = ovl_get_verity_digest(ofs, &lowerdatapath, &metacopy_data);
if (err)
return err;
if (metacopy_data.digest_algo)
c->metacopy_digest = true;
err = ovl_set_metacopy_xattr(ofs, temp, &metacopy_data);
if (err)
return err;
}
@ -751,9 +764,15 @@ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
if (err)
goto cleanup;
if (!c->metacopy)
ovl_set_upperdata(d_inode(c->dentry));
inode = d_inode(c->dentry);
if (c->metacopy_digest)
ovl_set_flag(OVL_HAS_DIGEST, inode);
else
ovl_clear_flag(OVL_HAS_DIGEST, inode);
ovl_clear_flag(OVL_VERIFIED_DIGEST, inode);
if (!c->metacopy)
ovl_set_upperdata(inode);
ovl_inode_update(inode, temp);
if (S_ISDIR(inode->i_mode))
ovl_set_flag(OVL_WHITEOUTS, inode);
@ -813,6 +832,12 @@ 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 +943,19 @@ 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_active(d_inode(lowerdata.dentry))) {
return false;
}
}
return true;
}
@ -984,6 +1022,8 @@ 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);

3
fs/overlayfs/overlayfs.h
View file

@ -487,11 +487,14 @@ 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_get_verity_digest(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)

33
fs/overlayfs/util.c
View file

@ -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);
struct file *filp;
@ -1262,6 +1262,37 @@ int ovl_validate_verity(struct ovl_fs *ofs,
return 0;
}
int ovl_get_verity_digest(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
*