From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 732895BAD7 for ; Tue, 2 Apr 2024 21:40:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712094027; cv=none; b=QhQdTIDlj3C+9F73TJA1xmETyGOSeEhk7gsU9nNJ9Zg/DBXL9pzVxFXCKUhhPMoPvs4memctl5NcuLpnMAvm8bFYvYOTA37aV2ccvOCX5HzcvqkzN8pOhYLpR0pKAmqrYVAo5MKABghj2bJXsD1iTNMJVhm1uWmA64C71TKRQis= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712094027; c=relaxed/simple; bh=pEvvwp2uF+BoaAPGzbRrw8FkMpC0RI9U/huBZlSJSAQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=tJ6szpZfLGSIEJIaJsrcOGizRuqgLtnzhp9+/htRhm4OdQ7PKjSGpv7m0Y0IUTZs/k8KrUTQo9S+GYWKhMyocv83ANgZEy25HSkAH/7p4qpCEA1hgv4YGPBfELGadsesOL5I2vp50NyH5t4rDZi4F3vPNg6n/za+iBjvWQs8ge8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PfD7vPyM; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="PfD7vPyM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5C8DCC433F1; Tue, 2 Apr 2024 21:40:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1712094027; bh=pEvvwp2uF+BoaAPGzbRrw8FkMpC0RI9U/huBZlSJSAQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=PfD7vPyMi4ZRAYbY9DXWosj8AeoLyQil3iAEHYFuPulyF23CX70w2izAEmOBoTm5P Ztab41SdnUYCzFWXyVlRE1MSeeVw9t2am4Of4TukPmjXSZBT5oC1VLcfZTHtzoACo5 S1AxHsgc7UNtWJgG0EsoM3IqRcPn01lKrQOeQtRO+IAuwHsoTWxtePNqrAHJalNPwS 4jKHmlM8Wxf9WiNhmHrQ+V/V2rbWWjjaNw3JNKM+IAT8HZNJve0TC5iZCXZd3FWiIY ljs/A6XQE7dkIIBBPkChgC2ZiibMoXc9J+Yu6BO3GW+lqcEEKh7AjTjXuXwwYNxupV lg5sZd5mVjJxg== Message-ID: <45c72ae1-ab0d-439b-8237-80a38e15f571@kernel.org> Date: Tue, 2 Apr 2024 22:40:22 +0100 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH bpf-next v4] bpftool: Mount bpffs on provided dir instead of parent dir To: Sahil Siddiq , ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org Cc: martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, bpf@vger.kernel.org References: <20240401190407.20363-1-icegambit91@gmail.com> From: Quentin Monnet Content-Language: en-GB In-Reply-To: <20240401190407.20363-1-icegambit91@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 01/04/2024 20:04, Sahil Siddiq wrote: > When pinning programs/objects under PATH (eg: during "bpftool prog > loadall") the bpffs is mounted on the parent dir of PATH in the > following situations: > - the given dir exists but it is not bpffs. > - the given dir doesn't exist and the parent dir is not bpffs. > > Mounting on the parent dir can also have the unintentional side- > effect of hiding other files located under the parent dir. > > If the given dir exists but is not bpffs, then the bpffs should > be mounted on the given dir and not its parent dir. > > Similarly, if the given dir doesn't exist and its parent dir is not > bpffs, then the given dir should be created and the bpffs should be > mounted on this new dir. > > Link: https://lore.kernel.org/bpf/2da44d24-74ae-a564-1764-afccf395eeec@isovalent.com/T/#t > Closes: https://github.com/libbpf/bpftool/issues/100 > Fixes: 2a36c26fe3b8 ("bpftool: Support bpffs mountpoint as pin path for prog loadall") > > Changes since v1: > - Split "mount_bpffs_for_pin" into two functions. > This is done to improve maintainability and readability. > > Changes since v2: > - mount_bpffs_for_pin: rename to "create_and_mount_bpffs_dir". > - mount_bpffs_given_file: rename to "mount_bpffs_given_file". > - create_and_mount_bpffs_dir: > - introduce "dir_exists" boolean. > - remove new dir if "mnt_fs" fails. > - improve error handling and error messages. > > Changes since v3: > - Rectify function name. > - Improve error messages and formatting. > - mount_bpffs_for_file: > - Check if dir exists before block_mount check. > > Signed-off-by: Sahil Siddiq Tested-by: Quentin Monnet Reviewed-by: Quentin Monnet > --- > tools/bpf/bpftool/common.c | 98 +++++++++++++++++++++++++++++----- > tools/bpf/bpftool/iter.c | 2 +- > tools/bpf/bpftool/main.h | 3 +- > tools/bpf/bpftool/prog.c | 5 +- > tools/bpf/bpftool/struct_ops.c | 2 +- > 5 files changed, 94 insertions(+), 16 deletions(-) > > diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c > index cc6e6aae2447..56a5abbb1bf8 100644 > --- a/tools/bpf/bpftool/common.c > +++ b/tools/bpf/bpftool/common.c > @@ -244,29 +244,103 @@ int open_obj_pinned_any(const char *path, enum bpf_obj_type exp_type) > return fd; > } > > -int mount_bpffs_for_pin(const char *name, bool is_dir) > +int create_and_mount_bpffs_dir(const char *dir_name) > { > char err_str[ERR_MAX_LEN]; > - char *file; > - char *dir; > + bool dir_exists; > int err = 0; > > - if (is_dir && is_bpffs(name)) > + if (is_bpffs(dir_name)) > return err; > > - file = malloc(strlen(name) + 1); > - if (!file) { > + dir_exists = (access(dir_name, F_OK) == 0); > + > + if (!dir_exists) { > + char *temp_name; > + char *parent_name; > + > + temp_name = malloc(strlen(dir_name) + 1); > + if (!temp_name) { > + p_err("mem alloc failed"); > + return -1; > + } > + > + strcpy(temp_name, dir_name); > + parent_name = dirname(temp_name); > + > + if (is_bpffs(parent_name)) { > + /* nothing to do if already mounted */ > + free(temp_name); > + return err; > + } > + > + if (access(parent_name, F_OK) == -1) { > + p_err("can't create dir '%s' to pin BPF object: parent dir '%s' doesn't exist", > + dir_name, parent_name); > + free(temp_name); > + return -1; > + } > + > + free(temp_name); > + } > + > + if (block_mount) { > + p_err("no BPF file system found, not mounting it due to --nomount option"); > + return -1; > + } > + > + if (!dir_exists) { > + err = mkdir(dir_name, 0700); > + if (err) { > + p_err("failed to create dir '%s': %s", dir_name, strerror(errno)); > + return err; > + } > + } > + > + err = mnt_fs(dir_name, "bpf", err_str, ERR_MAX_LEN); > + if (err) { > + err_str[ERR_MAX_LEN - 1] = '\0'; > + p_err("can't mount BPF file system on given dir '%s': %s", > + dir_name, err_str); > + > + if (!dir_exists) > + rmdir(dir_name); > + } > + > + return err; > +} > + > +int mount_bpffs_for_file(const char *file_name) > +{ > + char err_str[ERR_MAX_LEN]; > + char *temp_name; > + char *dir; > + int err = 0; > + > + if (access(file_name, F_OK) != -1) { > + p_err("can't pin BPF object: path '%s' already exists", file_name); > + return -1; > + } > + > + temp_name = malloc(strlen(file_name) + 1); > + if (!temp_name) { > p_err("mem alloc failed"); > return -1; > } > > - strcpy(file, name); > - dir = dirname(file); > + strcpy(temp_name, file_name); > + dir = dirname(temp_name); > > if (is_bpffs(dir)) > /* nothing to do if already mounted */ > goto out_free; > > + if (access(dir, F_OK) == -1) { > + p_err("can't pin BPF object: dir '%s' doesn't exist", dir); > + free(temp_name); > + return -1; Or: p_err(...); err = -1; goto out_free; to be more consistent with the other error paths. But that's fine, no need to respin for that. Thanks a lot!