From 2e1a532883cf77f01031bef4b83d864a46c1bed0 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Tue, 24 Oct 2017 15:12:15 +0300 Subject: ovl: factor out ovl_check_origin_fh() Re-factor ovl_check_origin() and ovl_get_origin(), so origin fh xattr is read from upper inode only once during lookup with multiple lower layers and only once when verifying index entry origin. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi --- fs/overlayfs/namei.c | 142 +++++++++++++++++++++++++++++++++------------------ 1 file changed, 92 insertions(+), 50 deletions(-) (limited to 'fs/overlayfs') diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index a38db76cbccd..a6b9bd2afca1 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -87,9 +87,36 @@ static int ovl_acceptable(void *ctx, struct dentry *dentry) return 1; } +/* + * Check validity of an overlay file handle buffer. + * + * Return 0 for a valid file handle. + * Return -ENODATA for "origin unknown". + * Return <0 for an invalid file handle. + */ +static int ovl_check_fh_len(struct ovl_fh *fh, int fh_len) +{ + if (fh_len < sizeof(struct ovl_fh) || fh_len < fh->len) + return -EINVAL; + + if (fh->magic != OVL_FH_MAGIC) + return -EINVAL; + + /* Treat larger version and unknown flags as "origin unknown" */ + if (fh->version > OVL_FH_VERSION || fh->flags & ~OVL_FH_FLAG_ALL) + return -ENODATA; + + /* Treat endianness mismatch as "origin unknown" */ + if (!(fh->flags & OVL_FH_FLAG_ANY_ENDIAN) && + (fh->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN) + return -ENODATA; + + return 0; +} + static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry) { - int res; + int res, err; struct ovl_fh *fh = NULL; res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0); @@ -102,7 +129,7 @@ static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry) if (res == 0) return NULL; - fh = kzalloc(res, GFP_KERNEL); + fh = kzalloc(res, GFP_KERNEL); if (!fh) return ERR_PTR(-ENOMEM); @@ -110,20 +137,12 @@ static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry) if (res < 0) goto fail; - if (res < sizeof(struct ovl_fh) || res < fh->len) - goto invalid; - - if (fh->magic != OVL_FH_MAGIC) + err = ovl_check_fh_len(fh, res); + if (err < 0) { + if (err == -ENODATA) + goto out; goto invalid; - - /* Treat larger version and unknown flags as "origin unknown" */ - if (fh->version > OVL_FH_VERSION || fh->flags & ~OVL_FH_FLAG_ALL) - goto out; - - /* Treat endianness mismatch as "origin unknown" */ - if (!(fh->flags & OVL_FH_FLAG_ANY_ENDIAN) && - (fh->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN) - goto out; + } return fh; @@ -139,22 +158,17 @@ invalid: goto out; } -static struct dentry *ovl_get_origin(struct dentry *dentry, - struct vfsmount *mnt) +static struct dentry *ovl_decode_fh(struct ovl_fh *fh, struct vfsmount *mnt) { - struct dentry *origin = NULL; - struct ovl_fh *fh = ovl_get_origin_fh(dentry); + struct dentry *origin; int bytes; - if (IS_ERR_OR_NULL(fh)) - return (struct dentry *)fh; - /* * Make sure that the stored uuid matches the uuid of the lower * layer where file handle will be decoded. */ if (!uuid_equal(&fh->uuid, &mnt->mnt_sb->s_uuid)) - goto out; + return NULL; bytes = (fh->len - offsetof(struct ovl_fh, fid)); origin = exportfs_decode_fh(mnt, (struct fid *)fh->fid, @@ -164,22 +178,15 @@ static struct dentry *ovl_get_origin(struct dentry *dentry, /* Treat stale file handle as "origin unknown" */ if (origin == ERR_PTR(-ESTALE)) origin = NULL; - goto out; + return origin; } - if (ovl_dentry_weird(origin) || - ((d_inode(origin)->i_mode ^ d_inode(dentry)->i_mode) & S_IFMT)) - goto invalid; + if (ovl_dentry_weird(origin)) { + dput(origin); + return NULL; + } -out: - kfree(fh); return origin; - -invalid: - pr_warn_ratelimited("overlayfs: invalid origin (%pd2)\n", origin); - dput(origin); - origin = NULL; - goto out; } static bool ovl_is_opaquedir(struct dentry *dentry) @@ -284,9 +291,9 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, } -static int ovl_check_origin(struct dentry *upperdentry, - struct ovl_path *lower, unsigned int numlower, - struct ovl_path **stackp, unsigned int *ctrp) +static int ovl_check_origin_fh(struct ovl_fh *fh, struct dentry *upperdentry, + struct ovl_path *lower, unsigned int numlower, + struct ovl_path **stackp) { struct vfsmount *mnt; struct dentry *origin = NULL; @@ -294,18 +301,20 @@ static int ovl_check_origin(struct dentry *upperdentry, for (i = 0; i < numlower; i++) { mnt = lower[i].layer->mnt; - origin = ovl_get_origin(upperdentry, mnt); - if (IS_ERR(origin)) - return PTR_ERR(origin); - + origin = ovl_decode_fh(fh, mnt); if (origin) break; } if (!origin) - return 0; + return -ESTALE; + else if (IS_ERR(origin)) + return PTR_ERR(origin); + + if (!ovl_is_whiteout(upperdentry) && + ((d_inode(origin)->i_mode ^ d_inode(upperdentry)->i_mode) & S_IFMT)) + goto invalid; - BUG_ON(*ctrp); if (!*stackp) *stackp = kmalloc(sizeof(struct ovl_path), GFP_KERNEL); if (!*stackp) { @@ -313,9 +322,41 @@ static int ovl_check_origin(struct dentry *upperdentry, return -ENOMEM; } **stackp = (struct ovl_path){.dentry = origin, .layer = lower[i].layer}; - *ctrp = 1; return 0; + +invalid: + pr_warn_ratelimited("overlayfs: invalid origin (%pd2, ftype=%x, origin ftype=%x).\n", + upperdentry, d_inode(upperdentry)->i_mode & S_IFMT, + d_inode(origin)->i_mode & S_IFMT); + dput(origin); + return -EIO; +} + +static int ovl_check_origin(struct dentry *upperdentry, + struct ovl_path *lower, unsigned int numlower, + struct ovl_path **stackp, unsigned int *ctrp) +{ + struct ovl_fh *fh = ovl_get_origin_fh(upperdentry); + int err; + + if (IS_ERR_OR_NULL(fh)) + return PTR_ERR(fh); + + err = ovl_check_origin_fh(fh, upperdentry, lower, numlower, stackp); + kfree(fh); + + if (err) { + if (err == -ESTALE) + return 0; + return err; + } + + if (WARN_ON(*ctrp)) + return -EIO; + + *ctrp = 1; + return 0; } /* @@ -389,7 +430,6 @@ int ovl_verify_index(struct dentry *index, struct ovl_path *lower, size_t len; struct ovl_path origin = { }; struct ovl_path *stack = &origin; - unsigned int ctr = 0; int err; if (!d_inode(index)) @@ -420,16 +460,18 @@ int ovl_verify_index(struct dentry *index, struct ovl_path *lower, goto fail; err = -EINVAL; - if (hex2bin((u8 *)fh, index->d_name.name, len) || len != fh->len) + if (hex2bin((u8 *)fh, index->d_name.name, len)) + goto fail; + + err = ovl_check_fh_len(fh, len); + if (err) goto fail; err = ovl_verify_origin_fh(index, fh); if (err) goto fail; - err = ovl_check_origin(index, lower, numlower, &stack, &ctr); - if (!err && !ctr) - err = -ESTALE; + err = ovl_check_origin_fh(fh, index, lower, numlower, &stack); if (err) goto fail; -- cgit v1.2.3-55-g7522