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Install scriptlets source root users .bashrc when pacman is run through sudo
by brainpower 14 Nov '21

14 Nov '21

Hi, recently I had very weird behavior when running pacman from an unprivileged user account using sudo compared to running `sudo -i` and then running pacman from the root user on one of my Arch Linux systems. In the first case, post_upgrade, post_install or similar where NOT run, in the second case they ran fine. I was very confused by that, spent quite some time staring at pacman.conf, /etc/sudoers and /etc/sudo.conf comparing those to machines where this weird behavior did not happen and not spotting any differences... I then had the idea to `strace -f` both cases, and found the following: When running `sudo pacman ...` the bash process spawned by pacman to execute the install script reads and executes "/root/.bashrc" and I had some old leftover code in there which basicly did `exit 0` (my default shell is zsh, so that went unnoticed) thus exiting bash before it could execute the packages install script. When executing pacman from a root shell (even when gained by `sudo -i` for example) the spawned bash does not source "/root/.bashrc". (Which is the behavior I'd expect, since it should be a non-interactive bash process, right?) I've added a simple testcase below that shows both behaviors. So, I guess in the first case bash considers itself to be interactive somehow even if it should not? I've got no idea how it could come to that conclusion... IIRC, one usually checks if stdin is a tty, pty or something like that and bash does indeed something like that if I read this correctly: https://git.savannah.gnu.org/cgit/bash.git/tree/shell.c#n523 Though having '-c' should even short-cuircuit that "if" to not even try to check for ttys. But maybe it does something weird later... Also in _alpm_run_chroot() I see that stdin, stdout and stderr get closed and then connected to pipes, before execv() so they couldn't even be a tty or pty... or can they? But then they would have to be even when pacman is not run through sudo... I'd guess. So I'm kind of stuck at figuring out why that happens. Anyone of you seeing something I'm missing here? I did of course remove that old code from that .bashrc which caused the initial problem, so package install scripts run fine now. But pacman should maybe try to disable/remove such side effects if it can? root@pc # cat /root/.bashrc echo "This is /root/.bashrc !" user@pc % sudo pacman -U installtest-1-1-x86_64.pkg.tar.zst loading packages... warning: installtest-1-1 is up to date -- reinstalling resolving dependencies... looking for conflicting packages... Package (1) Old Version New Version Net Change installtest 1-1 1-1 0.00 MiB :: Proceed with installation? [Y/n] (1/1) checking keys in keyring [######################] 100% (1/1) checking package integrity [######################] 100% (1/1) loading package files [######################] 100% (1/1) checking for file conflicts [######################] 100% (1/1) checking available disk space [######################] 100% :: Processing package changes... (1/1) reinstalling installtest [######################] 100% This is /root/.bashrc ! post_upgrade 1-1 1-1 :: Running post-transaction hooks... (1/1) Update pacman-ps data user@pc % sudo -i root@pc # pacman -U installtest-1-1-x86_64.pkg.tar.zst loading packages... warning: installtest-1-1 is up to date -- reinstalling resolving dependencies... looking for conflicting packages... Package (1) Old Version New Version Net Change installtest 1-1 1-1 0.00 MiB :: Proceed with installation? [Y/n] (1/1) checking keys in keyring [######################] 100% (1/1) checking package integrity [######################] 100% (1/1) loading package files [######################] 100% (1/1) checking for file conflicts [######################] 100% (1/1) checking available disk space [######################] 100% :: Processing package changes... (1/1) reinstalling installtest [######################] 100% post_upgrade 1-1 1-1 :: Running post-transaction hooks... (1/1) Update pacman-ps data user@pc % cat PKGBUILD pkgname=installtest pkgver=1 pkgrel=1 arch=(x86_64) install=installtest.install package() { true } user@pc % cat installtest.install post_upgrade() { echo "post_upgrade" "$@" } post_install() { echo "post_install" "$@" } post_remove() { echo "post_remove" "$@" } -- regards, brainpower

2 5

[PATCH] remove YouCompleteMe config
by Andrew Gregory 14 Nov '21

14 Nov '21

Added, seemingly by accident, with meson in 51db84750ece4de58923d4ce43cb0638ef150f5f Signed-off-by: Andrew Gregory <andrew.gregory.8(a)gmail.com> --- .ycm_extra_conf.py | 250 --------------------------------------------- 1 file changed, 250 deletions(-) delete mode 100644 .ycm_extra_conf.py diff --git a/.ycm_extra_conf.py b/.ycm_extra_conf.py deleted file mode 100644 index f297deef..00000000 --- a/.ycm_extra_conf.py +++ /dev/null @@ -1,250 +0,0 @@ -#!/usr/bin/env python - -# SPDX-License-Identifier: Unlicense -# -# Based on the template file provided by the 'YCM-Generator' project authored by -# Reuben D'Netto. -# Jiahui Xie has re-reformatted and expanded the original script in accordance -# to the requirements of the PEP 8 style guide and 'systemd' project, -# respectively. -# -# The original license is preserved as it is. -# -# -# This is free and unencumbered software released into the public domain. -# -# Anyone is free to copy, modify, publish, use, compile, sell, or -# distribute this software, either in source code form or as a compiled -# binary, for any purpose, commercial or non-commercial, and by any -# means. -# -# In jurisdictions that recognize copyright laws, the author or authors -# of this software dedicate any and all copyright interest in the -# software to the public domain. We make this dedication for the benefit -# of the public at large and to the detriment of our heirs and -# successors. We intend this dedication to be an overt act of -# relinquishment in perpetuity of all present and future rights to this -# software under copyright law. -# -# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, -# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF -# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. -# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR -# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, -# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR -# OTHER DEALINGS IN THE SOFTWARE. -# -# For more information, please refer to <http://unlicense.org/> - -""" -YouCompleteMe configuration file tailored to support the 'meson' build system -used by the 'systemd' project. -""" - -import glob -import os -import ycm_core - - -SOURCE_EXTENSIONS = (".C", ".cpp", ".cxx", ".cc", ".c", ".m", ".mm") -HEADER_EXTENSIONS = (".H", ".h", ".hxx", ".hpp", ".hh") - - -def DirectoryOfThisScript(): - """ - Return the absolute path of the parent directory containing this - script. - """ - return os.path.dirname(os.path.abspath(__file__)) - - -def GuessBuildDirectory(): - """ - Guess the build directory using the following heuristics: - - 1. Returns the current directory of this script plus 'build' - subdirectory in absolute path if this subdirectory exists. - - 2. Otherwise, probes whether there exists any directory - containing '.ninja_log' file two levels above the current directory; - returns this single directory only if there is one candidate. - """ - result = os.path.join(DirectoryOfThisScript(), "build") - - if os.path.exists(result): - return result - - result = glob.glob(os.path.join(DirectoryOfThisScript(), - "..", "..", "*", ".ninja_log")) - - if not result: - return "" - - if 1 != len(result): - return "" - - return os.path.split(result[0])[0] - - -def TraverseByDepth(root, include_extensions): - """ - Return a set of child directories of the 'root' containing file - extensions specified in 'include_extensions'. - - NOTE: - 1. The 'root' directory itself is excluded from the result set. - 2. No subdirectories would be excluded if 'include_extensions' is left - to 'None'. - 3. Each entry in 'include_extensions' must begin with string '.'. - """ - is_root = True - result = set() - # Perform a depth first top down traverse of the given directory tree. - for root_dir, subdirs, file_list in os.walk(root): - if not is_root: - # print("Relative Root: ", root_dir) - # print(subdirs) - if include_extensions: - get_ext = os.path.splitext - subdir_extensions = { - get_ext(f)[-1] for f in file_list if get_ext(f)[-1] - } - if subdir_extensions & include_extensions: - result.add(root_dir) - else: - result.add(root_dir) - else: - is_root = False - - return result - - -_project_src_dir = os.path.join(DirectoryOfThisScript(), "src") -_include_dirs_set = TraverseByDepth(_project_src_dir, frozenset({".h"})) -flags = [ - "-x", - "c" - # The following flags are partially redundant due to the existence of - # 'compile_commands.json'. - # '-Wall', - # '-Wextra', - # '-Wfloat-equal', - # '-Wpointer-arith', - # '-Wshadow', - # '-std=gnu99', -] - -for include_dir in _include_dirs_set: - flags.append("-I" + include_dir) - -# Set this to the absolute path to the folder (NOT the file!) containing the -# compile_commands.json file to use that instead of 'flags'. See here for -# more details: http://clang.llvm.org/docs/JSONCompilationDatabase.html -# -# You can get CMake to generate this file for you by adding: -# set( CMAKE_EXPORT_COMPILE_COMMANDS 1 ) -# to your CMakeLists.txt file. -# -# Most projects will NOT need to set this to anything; you can just change the -# 'flags' list of compilation flags. Notice that YCM itself uses that approach. -compilation_database_folder = GuessBuildDirectory() - -if os.path.exists(compilation_database_folder): - database = ycm_core.CompilationDatabase(compilation_database_folder) -else: - database = None - - -def MakeRelativePathsInFlagsAbsolute(flags, working_directory): - """ - Iterate through 'flags' and replace the relative paths prefixed by - '-isystem', '-I', '-iquote', '--sysroot=' with absolute paths - start with 'working_directory'. - """ - if not working_directory: - return list(flags) - new_flags = [] - make_next_absolute = False - path_flags = ["-isystem", "-I", "-iquote", "--sysroot="] - for flag in flags: - new_flag = flag - - if make_next_absolute: - make_next_absolute = False - if not flag.startswith("/"): - new_flag = os.path.join(working_directory, flag) - - for path_flag in path_flags: - if flag == path_flag: - make_next_absolute = True - break - - if flag.startswith(path_flag): - path = flag[len(path_flag):] - new_flag = path_flag + os.path.join(working_directory, path) - break - - if new_flag: - new_flags.append(new_flag) - return new_flags - - -def IsHeaderFile(filename): - """ - Check whether 'filename' is considered as a header file. - """ - extension = os.path.splitext(filename)[1] - return extension in HEADER_EXTENSIONS - - -def GetCompilationInfoForFile(filename): - """ - Helper function to look up compilation info of 'filename' in the 'database'. - """ - # The compilation_commands.json file generated by CMake does not have - # entries for header files. So we do our best by asking the db for flags for - # a corresponding source file, if any. If one exists, the flags for that - # file should be good enough. - if not database: - return None - - if IsHeaderFile(filename): - basename = os.path.splitext(filename)[0] - for extension in SOURCE_EXTENSIONS: - replacement_file = basename + extension - if os.path.exists(replacement_file): - compilation_info = \ - database.GetCompilationInfoForFile(replacement_file) - if compilation_info.compiler_flags_: - return compilation_info - return None - return database.GetCompilationInfoForFile(filename) - - -def FlagsForFile(filename, **kwargs): - """ - Callback function to be invoked by YouCompleteMe in order to get the - information necessary to compile 'filename'. - - It returns a dictionary with a single element 'flags'. This element is a - list of compiler flags to pass to libclang for the file 'filename'. - """ - if database: - # Bear in mind that compilation_info.compiler_flags_ does NOT return a - # python list, but a "list-like" StringVec object - compilation_info = GetCompilationInfoForFile(filename) - if not compilation_info: - return None - - final_flags = MakeRelativePathsInFlagsAbsolute( - compilation_info.compiler_flags_, - compilation_info.compiler_working_dir_) - - else: - relative_to = DirectoryOfThisScript() - final_flags = MakeRelativePathsInFlagsAbsolute(flags, relative_to) - - return { - "flags": final_flags, - "do_cache": True - } -- 2.33.1

1 0

Setting ld option in meson so that "--no-undefined" option can be toggled
by Budi 10 Nov '21

10 Nov '21

How are ww setting ld option in meson so that "--no-undefined" option can be omitted or toggled off and it'll link without this command option

2 1

Seting ld option in meson so that "--no-undefined" option can be off
by Budi 06 Nov '21

06 Nov '21

How do we set ld option in meson so that "--no-undefined" option can be toggled which in this case it is to omitted (toggled off)

2 1

Please help explain #include <> non system file
by Budi 06 Nov '21

06 Nov '21

Please help explain on pacman source code ready on home repo In pacman directory it has some #include <> non system file e.g. #include <alpm.h> Why should it be that path why not it refes to this local pacman code project e.g. #include <../lib/libalpm/> Is it different or is actually function the same ? it's so confusing, please help out!

2 1

[PATCH] Prevent translation of curl
by Allan McRae 06 Nov '21

06 Nov '21

Signed-off-by: Allan McRae <allan(a)archlinux.org> --- lib/libalpm/dload.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/libalpm/dload.c b/lib/libalpm/dload.c index 4322318b..1f75f5f0 100644 --- a/lib/libalpm/dload.c +++ b/lib/libalpm/dload.c @@ -490,8 +490,8 @@ static int curl_check_finished_download(CURLM *curlm, CURLMsg *msg, curl_gethost(payload->fileurl, hostname, sizeof(hostname)); curlerr = msg->data.result; - _alpm_log(handle, ALPM_LOG_DEBUG, "%s: curl returned result %d from transfer\n", - payload->remote_name, curlerr); + _alpm_log(handle, ALPM_LOG_DEBUG, "%s: %s returned result %d from transfer\n", + payload->remote_name, "curl", curlerr); /* was it a success? */ switch(curlerr) { -- 2.33.1

1 0

PKGBUILD-vcs.proto - prepare before pkgver?
by Darren Ng 12 Oct '21

12 Oct '21

Hi. prepare()[1] runs before pkgver()[2]. In PKGBUILD-vcs.proto[3], why put prepare() after pkgver()? Got nothing from my poor google-fu[4]. --- [1] https://gitlab.archlinux.org/pacman/pacman/-/blob/a33cdac10bf1a68279ea1b9ba… [2] https://gitlab.archlinux.org/pacman/pacman/-/blob/a33cdac10bf1a68279ea1b9ba… [3] https://gitlab.archlinux.org/pacman/pacman/-/blob/edce7555a6b7410d1a4da6d27… [4] https://www.google.com/search?q=site:lists.archlinux.org+pkgver+before+prep… https://www.google.com/search?q=site:lists.archlinux.org+prepare+before+pkg…

1 0

[pacman-dev] [PATCH] Add optional sandboxing when downloading files
by Remi Gacogne 10 Oct '21

10 Oct '21

[re-sending because my initial e-mail was rejected by spam filters, sorry!] Hi all, I would like to get some feedback on a optional sandboxing feature I would like to implement in pacman. The gist of it is to use a separate process for some sensitive operations, like downloading files, and to restrict the privileges of that process to reduce the risk of an exploitable bug turning into a code execution with full root privileges. I'm not too worried about the pacman code itself, but downloading files over the internet involves parsing HTTP payloads, as well as parsing X.509 certificates and doing cryptographic operations when HTTPS is used, which is more error-prone. For what it's worth, Debian's APT has similar options hidden behind the APT::Sandbox::Seccomp and APT::Sandbox::User parameters. The attached patch is clearly not in a finished state, but provides more details about the kind of changes needed to support this new feature. In a nutshell, what it currently does is that if the UseSandbox option is not set nothing changes. Otherwise internal and external downloads trigger the spawning of a new process, via fork(), whose result is communicated to the main process via a pipe, as is already done today for external downloads. Then: - If available, PR_SET_NO_NEW_PRIVS is called to ensure that the downloader will not be able to gain new privileges in the future, for example by executing a set-uid program. - If pacman has been built with libseccomp support and the kernel supports it, a list of system calls that are clearly of no use to a regular process downloading files is denied via a seccomp filter. That list is currently hard-coded but it would make more sense to make it configurable. - If the SandboxUser option is set to a valid user, the downloader process switches to that user via setgid, setgroups and setuid, dropping root privileges. This part requires making the download folder owned by that user. - If pacman has been built with libcap support and the downloader process still has privileged capabilities at this point, these are dropped. - If pacman has been built with landlock support (requires an updated linux-api-headers, >= 5.13) and the kernel supports it, the whole filesystem is set read-only with the exception of /tmp and DBPath. The list of writable paths is currently hard-coded but it would make sense to make it configurable as well. Any feedback will be welcome. Please be aware that I tried to keep the new code in line with the coding style and contributing guidelines but I'm not familiar with pacman's source code so I'm sure I did not do everything the right way, and that this code can be improved. What I would like to know first is whether there is any interest in that feature, then to get feedback about the "big picture" part of the design. If there is indeed interest and my approach is somewhat sane, then I can work on making the code less ugly, write the much needed documentation for the new feature and related options, and improve the logging of errors. Thanks! Remi Signed-off-by: Remi Gacogne <rgacogne(a)archlinux.org> --- lib/libalpm/alpm.h | 10 ++ lib/libalpm/alpm_sandbox.c | 341 +++++++++++++++++++++++++++++++++++++ lib/libalpm/alpm_sandbox.h | 31 ++++ lib/libalpm/dload.c | 83 ++++++++- lib/libalpm/handle.c | 20 +++ lib/libalpm/handle.h | 2 + lib/libalpm/meson.build | 1 + meson.build | 11 +- src/pacman/conf.c | 23 ++- src/pacman/conf.h | 2 + src/pacman/pacman-conf.c | 6 + 11 files changed, 526 insertions(+), 4 deletions(-) create mode 100644 lib/libalpm/alpm_sandbox.c create mode 100644 lib/libalpm/alpm_sandbox.h diff --git lib/libalpm/alpm.h lib/libalpm/alpm.h index a5f4a6ae..f414d811 100644 --- lib/libalpm/alpm.h +++ lib/libalpm/alpm.h @@ -1837,6 +1837,11 @@ int alpm_option_set_gpgdir(alpm_handle_t *handle, const char *gpgdir); /* End of gpdir accessors */ /** @} */ +/** Sets the user to switch to for sensitive operations like downloading a file. + * @param handle the context handle + * @param sandboxuser the user to set + */ +int alpm_option_set_sandboxuser(alpm_handle_t *handle, const char *sandboxuser); /** @name Accessors for use syslog * @@ -1859,6 +1864,11 @@ int alpm_option_set_usesyslog(alpm_handle_t *handle, int usesyslog); /* End of usesyslog accessors */ /** @} */ +/** Sets whether to use sandboxing for sensitive operations like downloading a file (0 is FALSE, TRUE otherwise). + * @param handle the context handle + * @param usesandbox whether to use the sandboxing (0 is FALSE, TRUE otherwise) + */ +int alpm_option_set_usesandbox(alpm_handle_t *handle, int usesandbox); /** @name Accessors to the list of no-upgrade files. * These functions modify the list of files which should diff --git lib/libalpm/alpm_sandbox.c lib/libalpm/alpm_sandbox.c new file mode 100644 index 00000000..29f46d58 --- /dev/null +++ lib/libalpm/alpm_sandbox.c @@ -0,0 +1,341 @@ +/* + * sandbox.c + * + * Copyright (c) 2021 Pacman Development Team <pacman-dev(a)archlinux.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <errno.h> +#include <fcntl.h> +#include <grp.h> +#include <pwd.h> +#include <sys/capability.h> +#include <sys/syscall.h> +#include <sys/types.h> +#include <unistd.h> + +#ifdef HAVE_LINUX_LANDLOCK_H +# include <linux/landlock.h> +# include <sys/prctl.h> +# include <sys/syscall.h> +#endif /* HAVE_LINUX_LANDLOCK_H */ + +#ifdef HAVE_LIBSECCOMP +# include <seccomp.h> +#endif /* HAVE_LIBSECCOMP */ + +#include "alpm_sandbox.h" + +#ifdef HAVE_LINUX_LANDLOCK_H +#ifndef landlock_create_ruleset +static inline int landlock_create_ruleset(const struct landlock_ruleset_attr *const attr, + const size_t size, const __u32 flags) +{ + return syscall(__NR_landlock_create_ruleset, attr, size, flags); +} +#endif /* landlock_create_ruleset */ + +#ifndef landlock_add_rule +static inline int landlock_add_rule(const int ruleset_fd, + const enum landlock_rule_type rule_type, + const void *const rule_attr, const __u32 flags) +{ + return syscall(__NR_landlock_add_rule, ruleset_fd, rule_type, rule_attr, flags); +} +#endif /* landlock_add_rule */ + +#ifndef landlock_restrict_self +static inline int landlock_restrict_self(const int ruleset_fd, const __u32 flags) +{ + return syscall(__NR_landlock_restrict_self, ruleset_fd, flags); +} +#endif /* landlock_restrict_self */ + +#define _LANDLOCK_ACCESS_FS_WRITE ( \ + LANDLOCK_ACCESS_FS_WRITE_FILE | \ + LANDLOCK_ACCESS_FS_REMOVE_DIR | \ + LANDLOCK_ACCESS_FS_REMOVE_FILE | \ + LANDLOCK_ACCESS_FS_MAKE_CHAR | \ + LANDLOCK_ACCESS_FS_MAKE_DIR | \ + LANDLOCK_ACCESS_FS_MAKE_REG | \ + LANDLOCK_ACCESS_FS_MAKE_SOCK | \ + LANDLOCK_ACCESS_FS_MAKE_FIFO | \ + LANDLOCK_ACCESS_FS_MAKE_BLOCK | \ + LANDLOCK_ACCESS_FS_MAKE_SYM) + +#define _LANDLOCK_ACCESS_FS_READ ( \ + LANDLOCK_ACCESS_FS_READ_FILE | \ + LANDLOCK_ACCESS_FS_READ_DIR) + +static int sandbox_write_only_beneath_cwd(void) +{ + const struct landlock_ruleset_attr ruleset_attr = { + .handled_access_fs = \ + _LANDLOCK_ACCESS_FS_READ | \ + _LANDLOCK_ACCESS_FS_WRITE | \ + LANDLOCK_ACCESS_FS_EXECUTE, + }; + struct landlock_path_beneath_attr path_beneath = { + .allowed_access = _LANDLOCK_ACCESS_FS_WRITE, + }; + int result = 0; + int ruleset_fd; + + ruleset_fd = landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0); + if(ruleset_fd < 0) { + return ruleset_fd; + } + + /* allow / as read-only */ + path_beneath.parent_fd = open("/", O_PATH | O_CLOEXEC | O_DIRECTORY); + path_beneath.allowed_access = _LANDLOCK_ACCESS_FS_READ | LANDLOCK_ACCESS_FS_EXECUTE; + + if(landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH, &path_beneath, 0)) { + result = errno; + } + + close(path_beneath.parent_fd); + + if(result == 0) { + /* allow the current working directory as read-write */ + path_beneath.parent_fd = open(".", O_PATH | O_CLOEXEC | O_DIRECTORY); + path_beneath.allowed_access = _LANDLOCK_ACCESS_FS_READ | _LANDLOCK_ACCESS_FS_WRITE | LANDLOCK_ACCESS_FS_EXECUTE; + + if(!landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH, &path_beneath, 0)) { + if(landlock_restrict_self(ruleset_fd, 0)) { + result = errno; + } + } else { + result = errno; + } + + close(path_beneath.parent_fd); + + if(result == 0) { + /* allow /tmp as well */ + path_beneath.parent_fd = open("/tmp", O_PATH | O_CLOEXEC | O_DIRECTORY); + path_beneath.allowed_access = _LANDLOCK_ACCESS_FS_READ | _LANDLOCK_ACCESS_FS_WRITE | LANDLOCK_ACCESS_FS_EXECUTE; + + if(!landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH, &path_beneath, 0)) { + if(landlock_restrict_self(ruleset_fd, 0)) { + result = errno; + } + } else { + result = errno; + } + + close(path_beneath.parent_fd); + } + } + + close(ruleset_fd); + return result; +} +#endif /* HAVE_LINUX_LANDLOCK_H */ + +#ifdef HAVE_LIBSECCOMP + +static int sandbox_filter_syscalls(void) +{ + int ret = 0; + /* see https://docs.docker.com/engine/security/seccomp/ for inspiration, + as well as systemd's src/shared/seccomp-util.c */ + const char* denied_syscalls[] = { + /* kernel modules */ + "delete_module", + "finit_module", + "init_module", + /* mount */ + "chroot", + "fsconfig", + "fsmount", + "fsopen", + "fspick", + "mount", + "move_mount", + "open_tree", + "pivot_root", + "umount", + "umount2", + /* keyring */ + "add_key", + "keyctl", + "request_key", + /* CPU emulation */ + "modify_ldt", + "subpage_prot", + "switch_endian", + "vm86", + "vm86old", + /* debug */ + "kcmp", + "lookup_dcookie", + "perf_event_open", + "ptrace", + "rtas", + "sys_debug_setcontext", + /* set clock */ + "adjtimex", + "clock_adjtime", + "clock_adjtime64", + "clock_settime", + "clock_settime64", + "settimeofday", + /* raw IO */ + "ioperm", + "iopl", + "pciconfig_iobase", + "pciconfig_read", + "pciconfig_write", + /* kexec */ + "kexec_file_load", + "kexec_load", + /* reboot */ + "reboot", + /* privileged */ + "acct", + "bpf", + "personality", + /* obsolete */ + "_sysctl", + "afs_syscall", + "bdflush", + "break", + "create_module", + "ftime", + "get_kernel_syms", + "getpmsg", + "gtty", + "idle", + "lock", + "mpx", + "prof", + "profil", + "putpmsg", + "query_module", + "security", + "sgetmask", + "ssetmask", + "stime", + "stty", + "sysfs", + "tuxcall", + "ulimit", + "uselib", + "ustat", + "vserver", + /* swap */ + "swapon", + "swapoff", + }; + /* allow all syscalls that are not listed */ + size_t idx; + scmp_filter_ctx ctx = seccomp_init(SCMP_ACT_ALLOW); + if(ctx == NULL) { + return errno; + } + + for(idx = 0; idx < sizeof(denied_syscalls) / sizeof(*denied_syscalls); idx++) { + int syscall = seccomp_syscall_resolve_name(denied_syscalls[idx]); + if(syscall != __NR_SCMP_ERROR) { + if(seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EPERM), syscall, 0) != 0) { + /* Do not fail but log something like: _("Error blocking syscall %s\n"), denied_syscalls[idx]); */ + } + } + } + + if(seccomp_load(ctx) != 0) { + ret = errno; + } + + seccomp_release(ctx); + return ret; +} +#endif /* HAVE_LIBSECCOMP */ + +static int switch_to_user(const char *user) +{ + struct passwd const *pw = NULL; + if(getuid() != 0) { + return 1; + } + pw = getpwnam(user); + if(pw == NULL) { + return errno; + } + if(setgid(pw->pw_gid) != 0) { + return errno; + } + if(setgroups(0, NULL)) { + return errno; + } + if(setuid(pw->pw_uid) != 0) { + return errno; + } + return 0; +} + +/* check exported library symbols with: nm -C -D <lib> */ +#define SYMEXPORT __attribute__((visibility("default"))) + +int SYMEXPORT alpm_sandbox_child(const char* sandboxuser) +{ + int result = 0; +#ifdef HAVE_LINUX_LANDLOCK_H + int ret = 0; +#endif/* HAVE_LINUX_LANDLOCK_H */ + + /* make sure that we cannot gain more privileges later */ + if(prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) != 0) { + result = errno; + } + +#ifdef HAVE_LIBSECCOMP + result = sandbox_filter_syscalls(); +#endif /* HAVE_LIBSECCOMP */ + + if(sandboxuser != NULL) { + result = switch_to_user(sandboxuser); + } + +#ifdef HAVE_LIBCAP + /* we might have some capabilities remaining, + * especially if sandboxuser is not set */ + cap_t caps = cap_get_proc(); + cap_clear(caps); + if(cap_set_mode(CAP_MODE_NOPRIV) != 0) { + cap_free(caps); + if(result == 0) { + result = errno; + } + } + if(cap_set_proc(caps) != 0) { + cap_free(caps); + if(result == 0) { + result = errno; + } + } + cap_free(caps); +#endif /* HAVE_LIBCAP */ + +#ifdef HAVE_LINUX_LANDLOCK_H + ret = sandbox_write_only_beneath_cwd(); + if(result == 0) { + result = ret; + } +#endif /* HAVE_LINUX_LANDLOCK_H */ + + return result; +} diff --git lib/libalpm/alpm_sandbox.h lib/libalpm/alpm_sandbox.h new file mode 100644 index 00000000..47611575 --- /dev/null +++ lib/libalpm/alpm_sandbox.h @@ -0,0 +1,31 @@ +/* + * sandbox.h + * + * Copyright (c) 2021 Pacman Development Team <pacman-dev(a)archlinux.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#ifndef ALPM_SANDBOX_H +#define ALPM_SANDBOX_H + +#ifdef __cplusplus +extern "C" { +#endif + +int alpm_sandbox_child(const char *sandboxuser); + +#ifdef __cplusplus +} +#endif +#endif /* ALPM_SANDBOX_H */ diff --git lib/libalpm/dload.c lib/libalpm/dload.c index ca6be7b6..6bb06b4c 100644 --- lib/libalpm/dload.c +++ lib/libalpm/dload.c @@ -28,6 +28,7 @@ #include <sys/time.h> #include <sys/types.h> #include <sys/stat.h> +#include <sys/wait.h> #include <signal.h> #ifdef HAVE_NETINET_IN_H @@ -44,6 +45,7 @@ /* libalpm */ #include "dload.h" #include "alpm_list.h" +#include "alpm_sandbox.h" #include "alpm.h" #include "log.h" #include "util.h" @@ -898,6 +900,81 @@ static int curl_download_internal(alpm_handle_t *handle, #endif +static int curl_download_internal_sandboxed(alpm_handle_t *handle, + alpm_list_t *payloads /* struct dload_payload */, + const char *localpath) +{ + int pid, err = 0, ret = -1, err_fd[2]; + sigset_t oldblock; + struct sigaction sa_ign = { .sa_handler = SIG_IGN }, oldint, oldquit; + + if(pipe(err_fd) != 0) { + return -1; + } + + sigaction(SIGINT, &sa_ign, &oldint); + sigaction(SIGQUIT, &sa_ign, &oldquit); + sigaddset(&sa_ign.sa_mask, SIGCHLD); + sigprocmask(SIG_BLOCK, &sa_ign.sa_mask, &oldblock); + + pid = fork(); + + /* child */ + if(pid == 0) { + close(err_fd[0]); + fcntl(err_fd[1], F_SETFD, FD_CLOEXEC); + + /* restore signal handling for the child to inherit */ + sigaction(SIGINT, &oldint, NULL); + sigaction(SIGQUIT, &oldquit, NULL); + sigprocmask(SIG_SETMASK, &oldblock, NULL); + + /* cwd to the download directory */ + ret = chdir(localpath); + if(ret != 0) { + _alpm_log(handle, ALPM_LOG_WARNING, _("could not chdir to download directory %s\n"), localpath); + ret = -1; + } else { + ret = alpm_sandbox_child(handle->sandboxuser); + if (ret != 0) { + _alpm_log(handle, ALPM_LOG_WARNING, _("sandboxing failed!\n")); + } + + ret = curl_download_internal(handle, payloads, localpath); + } + + /* pass the result back to the parent */ + while(write(err_fd[1], &ret, sizeof(ret)) == -1 && errno == EINTR); + _Exit(ret < 0 ? 1 : 0); + } + + /* parent */ + close(err_fd[1]); + + if(pid != -1) { + int wret; + while((wret = waitpid(pid, &ret, 0)) == -1 && errno == EINTR); + if(wret > 0) { + while(read(err_fd[0], &ret, sizeof(ret)) == -1 && errno == EINTR); + } + } else { + /* fork failed, make sure errno is preserved after cleanup */ + err = errno; + } + + close(err_fd[0]); + + sigaction(SIGINT, &oldint, NULL); + sigaction(SIGQUIT, &oldquit, NULL); + sigprocmask(SIG_SETMASK, &oldblock, NULL); + + if(err) { + errno = err; + ret = -1; + } + return ret; +} + /* Returns -1 if an error happened for a required file * Returns 0 if a payload was actually downloaded * Returns 1 if no files were downloaded and all errors were non-fatal @@ -908,7 +985,11 @@ int _alpm_download(alpm_handle_t *handle, { if(handle->fetchcb == NULL) { #ifdef HAVE_LIBCURL - return curl_download_internal(handle, payloads, localpath); + if(handle->usesandbox) { + return curl_download_internal_sandboxed(handle, payloads, localpath); + } else { + return curl_download_internal(handle, payloads, localpath); + } #else RET_ERR(handle, ALPM_ERR_EXTERNAL_DOWNLOAD, -1); #endif diff --git lib/libalpm/handle.c lib/libalpm/handle.c index e6b683cb..10ae44b2 100644 --- lib/libalpm/handle.c +++ lib/libalpm/handle.c @@ -573,6 +573,19 @@ int SYMEXPORT alpm_option_set_gpgdir(alpm_handle_t *handle, const char *gpgdir) return 0; } +int SYMEXPORT alpm_option_set_sandboxuser(alpm_handle_t *handle, const char *sandboxuser) +{ + CHECK_HANDLE(handle, return -1); + if(handle->sandboxuser) { + FREE(handle->sandboxuser); + } + + STRDUP(handle->sandboxuser, sandboxuser, RET_ERR(handle, ALPM_ERR_MEMORY, -1)); + + _alpm_log(handle, ALPM_LOG_DEBUG, "option 'sandboxuser' = %s\n", handle->sandboxuser); + return 0; +} + int SYMEXPORT alpm_option_set_usesyslog(alpm_handle_t *handle, int usesyslog) { CHECK_HANDLE(handle, return -1); @@ -580,6 +593,13 @@ int SYMEXPORT alpm_option_set_usesyslog(alpm_handle_t *handle, int usesyslog) return 0; } +int SYMEXPORT alpm_option_set_usesandbox(alpm_handle_t *handle, int usesandbox) +{ + CHECK_HANDLE(handle, return -1); + handle->usesandbox = usesandbox; + return 0; +} + static int _alpm_option_strlist_add(alpm_handle_t *handle, alpm_list_t **list, const char *str) { char *dup; diff --git lib/libalpm/handle.h lib/libalpm/handle.h index b1526c67..43550833 100644 --- lib/libalpm/handle.h +++ lib/libalpm/handle.h @@ -90,6 +90,7 @@ struct __alpm_handle_t { char *logfile; /* Name of the log file */ char *lockfile; /* Name of the lock file */ char *gpgdir; /* Directory where GnuPG files are stored */ + char *sandboxuser; /* User to switch to for sensitive operations like downloading files */ alpm_list_t *cachedirs; /* Paths to pacman cache directories */ alpm_list_t *hookdirs; /* Paths to hook directories */ alpm_list_t *overwrite_files; /* Paths that may be overwritten */ @@ -104,6 +105,7 @@ struct __alpm_handle_t { /* options */ alpm_list_t *architectures; /* Architectures of packages we should allow */ int usesyslog; /* Use syslog instead of logfile? */ /* TODO move to frontend */ + int usesandbox; /* Whether to enable sandboxing for sensitive operations like downloading files */ int checkspace; /* Check disk space before installing */ char *dbext; /* Sync DB extension */ int siglevel; /* Default signature verification level */ diff --git lib/libalpm/meson.build lib/libalpm/meson.build index 607e91a3..c36ae516 100644 --- lib/libalpm/meson.build +++ lib/libalpm/meson.build @@ -2,6 +2,7 @@ libalpm_sources = files(''' add.h add.c alpm.h alpm.c alpm_list.h alpm_list.c + alpm_sandbox.h alpm_sandbox.c backup.h backup.c base64.h base64.c be_local.c diff --git meson.build meson.build index 26c92b8e..88f0e3a1 100644 --- meson.build +++ meson.build @@ -91,6 +91,10 @@ libarchive = dependency('libarchive', version : '>=3.0.0', static : get_option('buildstatic')) +libcap = dependency('libcap', + static : get_option('buildstatic')) +conf.set('HAVE_LIBCAP', libcap.found()) + libcurl = dependency('libcurl', version : '>=7.55.0', required : get_option('curl'), @@ -120,7 +124,12 @@ else error('unhandled crypto value @0@'.format(want_crypto)) endif +libseccomp = dependency('libseccomp', + static : get_option('buildstatic')) +conf.set('HAVE_LIBSECCOMP', libseccomp.found()) + foreach header : [ + 'linux/landlock.h', 'mntent.h', 'sys/mnttab.h', 'sys/mount.h', @@ -305,7 +314,7 @@ libcommon = static_library( gnu_symbol_visibility : 'hidden', install : false) -alpm_deps = [crypto_provider, libarchive, libcurl, libintl, gpgme] +alpm_deps = [crypto_provider, libarchive, libcap, libcurl, libintl, libseccomp, gpgme] libalpm_a = static_library( 'alpm_objlib', diff --git src/pacman/conf.c src/pacman/conf.c index 12fee64c..9480a492 100644 --- src/pacman/conf.c +++ src/pacman/conf.c @@ -33,6 +33,8 @@ #include <unistd.h> #include <signal.h> +#include <alpm_sandbox.h> + /* pacman */ #include "conf.h" #include "ini.h" @@ -215,7 +217,7 @@ static char *get_tempfile(const char *path, const char *filename) * - not thread-safe * - errno may be set by fork(), pipe(), or execvp() */ -static int systemvp(const char *file, char *const argv[]) +static int systemvp(const char *file, char *const argv[], bool sandbox, const char *sandboxuser) { int pid, err = 0, ret = -1, err_fd[2]; sigset_t oldblock; @@ -242,6 +244,13 @@ static int systemvp(const char *file, char *const argv[]) sigaction(SIGQUIT, &oldquit, NULL); sigprocmask(SIG_SETMASK, &oldblock, NULL); + if (sandbox) { + ret = alpm_sandbox_child(sandboxuser); + if (ret != 0) { + pm_printf(ALPM_LOG_WARNING, _("sandboxing failed!\n")); + } + } + execvp(file, argv); /* execvp failed, pass the error back to the parent */ @@ -352,7 +361,7 @@ static int download_with_xfercommand(void *ctx, const char *url, free(cmd); } } - retval = systemvp(argv[0], (char**)argv); + retval = systemvp(argv[0], (char**)argv, config->usesandbox, config->sandboxuser); if(retval == -1) { pm_printf(ALPM_LOG_WARNING, _("running XferCommand: fork failed!\n")); @@ -601,6 +610,9 @@ static int _parse_options(const char *key, char *value, if(strcmp(key, "UseSyslog") == 0) { config->usesyslog = 1; pm_printf(ALPM_LOG_DEBUG, "config: usesyslog\n"); + } else if(strcmp(key, "UseSandbox") == 0) { + config->usesandbox = 1; + pm_printf(ALPM_LOG_DEBUG, "config: usesandbox\n"); } else if(strcmp(key, "ILoveCandy") == 0) { config->chomp = 1; pm_printf(ALPM_LOG_DEBUG, "config: chomp\n"); @@ -668,6 +680,11 @@ static int _parse_options(const char *key, char *value, config->logfile = strdup(value); pm_printf(ALPM_LOG_DEBUG, "config: logfile: %s\n", value); } + } else if(strcmp(key, "SandboxUser") == 0) { + if(!config->sandboxuser) { + config->sandboxuser = strdup(value); + pm_printf(ALPM_LOG_DEBUG, "config: sandboxuser: %s\n", value); + } } else if(strcmp(key, "XferCommand") == 0) { char **c; if((config->xfercommand_argv = wordsplit(value)) == NULL) { @@ -904,6 +921,8 @@ static int setup_libalpm(void) alpm_option_set_architectures(handle, config->architectures); alpm_option_set_checkspace(handle, config->checkspace); alpm_option_set_usesyslog(handle, config->usesyslog); + alpm_option_set_usesandbox(handle, config->usesandbox); + alpm_option_set_sandboxuser(handle, config->sandboxuser); alpm_option_set_ignorepkgs(handle, config->ignorepkg); alpm_option_set_ignoregroups(handle, config->ignoregrp); diff --git src/pacman/conf.h src/pacman/conf.h index 04350d39..8fced284 100644 --- src/pacman/conf.h +++ src/pacman/conf.h @@ -55,6 +55,7 @@ typedef struct __config_t { unsigned short print; unsigned short checkspace; unsigned short usesyslog; + unsigned short usesandbox; unsigned short color; unsigned short disable_dl_timeout; char *print_format; @@ -67,6 +68,7 @@ typedef struct __config_t { char *logfile; char *gpgdir; char *sysroot; + char *sandboxuser; alpm_list_t *hookdirs; alpm_list_t *cachedirs; alpm_list_t *architectures; diff --git src/pacman/pacman-conf.c src/pacman/pacman-conf.c index 600f1622..6da27937 100644 --- src/pacman/pacman-conf.c +++ src/pacman/pacman-conf.c @@ -251,6 +251,7 @@ static void dump_config(void) show_list_str("HookDir", config->hookdirs); show_str("GPGDir", config->gpgdir); show_str("LogFile", config->logfile); + show_str("SandboxUser", config->sandboxuser); show_list_str("HoldPkg", config->holdpkg); show_list_str("IgnorePkg", config->ignorepkg); @@ -268,6 +269,7 @@ static void dump_config(void) show_bool("DisableDownloadTimeout", config->disable_dl_timeout); show_bool("ILoveCandy", config->chomp); show_bool("NoProgressBar", config->noprogressbar); + show_bool("UseSandbox", config->usesandbox); show_int("ParallelDownloads", config->parallel_downloads); @@ -349,6 +351,8 @@ static int list_directives(void) show_str("GPGDir", config->gpgdir); } else if(strcasecmp(i->data, "LogFile") == 0) { show_str("LogFile", config->logfile); + } else if(strcasecmp(i->data, "SandboxUser") == 0) { + show_str("SandboxUser", config->sandboxuser); } else if(strcasecmp(i->data, "HoldPkg") == 0) { show_list_str("HoldPkg", config->holdpkg); @@ -369,6 +373,8 @@ static int list_directives(void) } else if(strcasecmp(i->data, "UseSyslog") == 0) { show_bool("UseSyslog", config->usesyslog); + } else if(strcasecmp(i->data, "UseSandbox") == 0) { + show_bool("UseSandbox", config->usesandbox); } else if(strcasecmp(i->data, "Color") == 0) { show_bool("Color", config->color); } else if(strcasecmp(i->data, "CheckSpace") == 0) { -- 2.33.0

3 8

[PATCH] makepkg: lint empty arrays
by morganamilo 07 Oct '21

07 Oct '21

While depend arrays are already linted, many array kinds are still not. An empty string is never a valid array value so check all arrays for it. --- .../libmakepkg/lint_pkgbuild/variable.sh.in | 20 ++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/scripts/libmakepkg/lint_pkgbuild/variable.sh.in b/scripts/libmakepkg/lint_pkgbuild/variable.sh.in index b4428344..d0951258 100644 --- a/scripts/libmakepkg/lint_pkgbuild/variable.sh.in +++ b/scripts/libmakepkg/lint_pkgbuild/variable.sh.in @@ -28,7 +28,7 @@ source "$LIBRARY/util/pkgbuild.sh" source "$LIBRARY/util/schema.sh" lint_pkgbuild_functions+=('lint_variable') - +lint_pkgbuild_functions+=('lint_array') lint_variable() { local i a pkg out bad ret=0 @@ -95,3 +95,21 @@ lint_variable() { return $ret } + +lint_array() { + local i var ret=0 + + for i in ${pkgbuild_schema_arrays[@]}; do + local l=() + get_pkgbuild_all_split_attributes $i l + + for var in "${l[@]}"; do + if [[ -z $var ]]; then + error "$(gettext "%s does not allow empty values.")" "$i" + ret=1 + fi + done + done + + return $ret +} -- 2.33.0

1 0

Re: [PATCH] alpm: return -1 for error in find_dl_candidates
by Andrew Gregory 07 Oct '21

07 Oct '21

On 10/05/21 at 12:53pm, Morgan Adamiec wrote: > On 4 Oct 2021 8:28 pm, Andrew Gregory <andrew.gregory.8(a)gmail.com> wrote: > > On 10/04/21 at 08:09pm, morganamilo wrote: > > This is the error value generally used and the calling function > > explicitly checks for -1, later causing the error to be missed > > and the transaction to continue. > > This result is not compared to -1, the result of download_files is. If > we want > to guarantee that download_files will return -1 on error, that's where > the > return should be normalized, not in find_dl_candidates. Tying the API > of one > function to another like this is just going to cause confusion and > breakage > when somebody forgets in the future. Really, the caller of > download_files > should just check for a successful return; we return 1 as an error from > lots of > functions. > > I'll change that too. This should still be accepted though. Why? If your reasoning is just that -1 is a better error value, we use 1 in lots of other places like I said and I don't want to change that one at a time. $ grep 'return 1;' lib/libalpm/*.c src/*/*.c | wc -l [0][1016] 132

2 4