When merging layers from different filesystems with casefold enabled, all layers should use the same encoding version and have the same flags to avoid any kind of incompatibility issues. Also, set the encoding and the encoding flags for the ovl super block as the same as used by the first valid layer. Reviewed-by: Amir Goldstein Signed-off-by: André Almeida --- fs/overlayfs/super.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index df85a76597e910d00323018f1d2cd720c5db921d..b1dbd3c79961094d00c7f99cc622e515d544d22f 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -991,6 +991,18 @@ static int ovl_get_data_fsid(struct ovl_fs *ofs) return ofs->numfs; } +/* + * Set the ovl sb encoding as the same one used by the first layer + */ +static void ovl_set_encoding(struct super_block *sb, struct super_block *fs_sb) +{ +#if IS_ENABLED(CONFIG_UNICODE) + if (sb_has_encoding(fs_sb)) { + sb->s_encoding = fs_sb->s_encoding; + sb->s_encoding_flags = fs_sb->s_encoding_flags; + } +#endif +} static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, struct ovl_fs_context *ctx, struct ovl_layer *layers) @@ -1024,6 +1036,9 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, if (ovl_upper_mnt(ofs)) { ofs->fs[0].sb = ovl_upper_mnt(ofs)->mnt_sb; ofs->fs[0].is_lower = false; + + if (ofs->casefold) + ovl_set_encoding(sb, ofs->fs[0].sb); } nr_merged_lower = ctx->nr - ctx->nr_data; @@ -1083,6 +1098,16 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, l->name = NULL; ofs->numlayer++; ofs->fs[fsid].is_lower = true; + + if (ofs->casefold) { + if (!ovl_upper_mnt(ofs) && !sb_has_encoding(sb)) + ovl_set_encoding(sb, ofs->fs[fsid].sb); + + if (!sb_has_encoding(sb) || !sb_same_encoding(sb, mnt->mnt_sb)) { + pr_err("all layers must have the same encoding\n"); + return -EINVAL; + } + } } /* -- 2.50.1