Opt out link scripts execution

docs/source/advanced_usage/detailed_operations.rst

@@ -66,3 +66,11 @@ When installing a ``noarch: python`` package, the installation process will comp
 All installed files are later referenced in the ``$TARGET_PREFIX/conda-meta/mypkg-version-build.json`` file, to facilitate the removal (e.g. when upgrading or removing a package).
 
 If the package contains a ``menu/*.json`` entry that follows the spec introduced by ``menuinst``, a start-menu entry is created on Windows. This is currently not implemented on Linux or macOS but that might change in the future.
+
+Package link scripts
+--------------------
+
+Some packages also include ``pre-link``, ``post-link``, ``pre-unlink``,
+or ``post-unlink`` scripts that are executed during the linking step.
+Because these scripts can contain arbitrary code, they have security
+implications. See :ref:`security` for more details.

docs/source/advanced_usage/security.rst

@@ -0,0 +1,54 @@
+.. _security:
+
+Security
+========
+
+Package link scripts
+--------------------
+
+Some packages include ``pre-link``, ``post-link``, ``pre-unlink``, or
+``post-unlink`` scripts that execute during package installation, update
+or removal.
+
+Note that ``post-unlink`` scripts are **deprecated** and therefore
+not executed.
+
+These scripts run in a shell subprocess and can perform arbitrary
+operations on the system.
+
+``pre-link`` scripts are particularly high-risk: they run from the
+package cache and can modify the package itself, affecting all
+environments that use that cached package.
+
+By default, Mamba shows a security warning in case a transaction
+involves packages with scripts and prompts for confirmation.
+
+Disabling link scripts
+^^^^^^^^^^^^^^^^^^^^^^
+
+You can disable execution of all link scripts using the
+``--skip-run-link-scripts`` flag:
+
+.. code-block:: bash
+
+   mamba install somepackage --skip-run-link-scripts
+   mamba remove somepackage --skip-run-link-scripts
+
+Or via configuration:
+
+.. code-block:: yaml
+
+   # ~/.mambarc
+   skip_run_link_scripts: true
+
+.. code-block:: bash
+
+   export MAMBA_SKIP_RUN_LINK_SCRIPTS=true
+
+When disabled, scripts are silently skipped and the security warning
+is suppressed.
+
+.. note::
+   Some packages rely on link scripts for correct setup.
+   Disable only when you understand the trade-offs, such as when
+   installing from untrusted sources.

docs/source/index.rst

@@ -48,8 +48,9 @@ You can try Mamba now by visiting the installation for
 
    advanced_usage/more_concepts
    advanced_usage/detailed_operations
-   advanced_usage/artifacts_verification
    advanced_usage/package_resolution
+   advanced_usage/artifacts_verification
+   advanced_usage/security
 
 .. toctree::
    :caption: LIBMAMBA USAGE

docs/source/installation/mamba-installation.rst

@@ -65,7 +65,7 @@ uninstalling ``mamba`` involves removing the entire Miniforge installation.
    Use these paths to adapt the commands below to your specific installation.
 
 1. Remove shell initialization
-   ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
    If you initialized your shell with ``mamba shell init``, you need to remove the initialization code from your shell configuration files.
    Run the following command for each shell you initialized:
@@ -88,7 +88,7 @@ uninstalling ``mamba`` involves removing the entire Miniforge installation.
    This will remove the mamba initialization block from your shell configuration files (``.bashrc``, ``.zshrc``, ``config.fish``, etc.).
 
 2. Remove the Miniforge installation directory and package cache
-   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
    The Miniforge installation directory contains ``mamba``, ``conda``, and all installed packages and environments.
    Check ``mamba info`` to find the exact location:
@@ -129,7 +129,7 @@ uninstalling ``mamba`` involves removing the entire Miniforge installation.
       Make sure you have backed up any important environments or data before removing this directory.
 
 3. Remove configuration files (optional)
-   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
    Check ``mamba info`` for the exact paths to your configuration files:
 
@@ -157,7 +157,7 @@ uninstalling ``mamba`` involves removing the entire Miniforge installation.
       If you also use ``conda`` from another distribution (like Anaconda), be careful not to delete shared configuration files that are still needed.
 
 4. Remove from PATH (if manually added)
-   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
    If you manually added Miniforge to your PATH, remove those entries from your shell configuration files (``.bashrc``, ``.zshrc``, ``.profile``, etc.).
 

docs/source/installation/micromamba-installation.rst

@@ -272,7 +272,7 @@ To completely remove ``micromamba`` from your system, follow these steps:
    Use these paths to adapt the commands below to your specific installation.
 
 1. Remove shell initialization
-   ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
    If you initialized your shell with ``micromamba shell init``, you need to remove the initialization code from your shell configuration files.
    Run the following command for each shell you initialized:
@@ -295,7 +295,7 @@ To completely remove ``micromamba`` from your system, follow these steps:
    This will remove the mamba initialization block from your shell configuration files (``.bashrc``, ``.zshrc``, ``config.fish``, etc.).
 
 2. Remove the micromamba executable
-   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
    The location of the ``micromamba`` executable depends on your installation method:
 
@@ -311,7 +311,7 @@ To completely remove ``micromamba`` from your system, follow these steps:
    Remove the directory where you extracted or installed the ``micromamba`` executable.
 
 3. Remove the root prefix directory and package cache
-   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
    ``micromamba`` stores all environments, packages, and cache in specific directories.
    Check ``micromamba info`` to find the exact locations for your installation:
@@ -346,7 +346,7 @@ To completely remove ``micromamba`` from your system, follow these steps:
       This will delete all environments, installed packages, and cached data. Make sure you have backed up any important environments or data before removing this directory.
 
 4. Remove configuration files (optional)
-   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
    Check ``micromamba info`` for the exact paths to your configuration files:
 

libmamba/include/mamba/core/context_params.hpp

@@ -38,6 +38,7 @@ namespace mamba
         bool always_copy = false;
         bool always_softlink = false;
         bool compile_pyc = true;
+        bool skip_run_link_scripts = false;
     };
 
     struct ThreadsParams

libmamba/src/api/configuration.cpp

@@ -1893,6 +1893,14 @@ namespace mamba
                    .set_env_var_names()
                    .description("Defines if PYC files will be compiled or not"));
 
+        insert(
+            Configurable("skip_run_link_scripts", &m_context.link_params.skip_run_link_scripts)
+                .group("Extract, Link & Install")
+                .set_rc_configurable()
+                .set_env_var_names()
+                .description("Whether pre/post-un/link scripts will be skipped. Defaults to false.")
+        );
+
         insert(
             Configurable("use_uv", &m_context.use_uv)
                 .group("Extract, Link & Install")

libmamba/src/core/link.cpp

@@ -13,6 +13,7 @@
 #include <string>
 #include <string_view>
 #include <tuple>
+#include <unordered_map>
 #include <vector>
 
 #include <fmt/format.h>
@@ -567,7 +568,14 @@ namespace mamba
             return true;
         }
 
-        std::map<std::string, std::string> envmap;
+        if (transaction_params.link_params.skip_run_link_scripts)
+        {
+            LOG_DEBUG << "Skipping " << action << " script for '" << pkg_info.name
+                      << "' (disabled via config)";
+            return true;
+        }
+
+        std::unordered_map<std::string, std::string> envmap;
         if (action == "pre-link")
         {
             LOG_WARNING

libmamba/src/core/transaction.cpp

@@ -1172,9 +1172,12 @@ namespace mamba
             return true;
         }
 
-        LOG_WARNING
-            << "Security Warning: This transaction includes executing package scripts (pre/post-link/unlink) if present. "
-            << "These scripts can contain arbitrary code. Please ensure you trust the package sources.";
+        if (!ctx.link_params.skip_run_link_scripts)
+        {
+            LOG_WARNING
+                << "Security Warning: This transaction includes executing package scripts (pre/post-link/unlink) if present. "
+                << "These scripts can contain arbitrary code. Please ensure you trust the package sources.";
+        }
 
         return Console::prompt("Confirm changes", 'y');
     }

libmamba/tests/src/core/test_configuration.cpp

@@ -1127,6 +1127,10 @@ namespace mamba
 
             TEST_BOOL_CONFIGURABLE(always_copy, ctx.link_params.always_copy);
 
+            TEST_BOOL_CONFIGURABLE(compile_pyc, ctx.link_params.compile_pyc);
+
+            TEST_BOOL_CONFIGURABLE(skip_run_link_scripts, ctx.link_params.skip_run_link_scripts);
+
             TEST_CASE_METHOD(Configuration, "always_softlink_and_copy")
             {
                 util::set_env("MAMBA_ALWAYS_COPY", "true");

libmamba/tests/src/core/test_link_scripts.cpp

@@ -57,14 +57,16 @@ namespace mamba
                 fs::create_directories(prefix / "bin");
                 auto conda_path = prefix / "bin" / "conda";
                 auto out = open_ofstream(conda_path);
-                out << "#!/bin/sh\n";
-                out << "if [ \"$1\" = \"shell.posix\" ] && [ \"$2\" = \"hook\" ]; then\n";
-                out << "  echo 'conda() { :; }'\n";  // Define conda as a no-op function
-                out << "fi\n";
+                out << R"(#!/bin/sh
+                    if [ "$1" = "shell.posix" ] && [ "$2" = "hook" ]; then
+                      # Define conda as a no-op function
+                      echo 'conda() { :; }'
+                    fi
+                    )";
                 make_executable(conda_path);
             }
 
-            const auto make_tx_context = [&]
+            const auto make_tx_context = [&](const LinkParams& link_params = {})
             {
                 TransactionParams tx_params{
                     .is_mamba_exe = false,
@@ -80,7 +82,7 @@ namespace mamba
                             .conda_prefix = prefix,
                             .relocate_prefix = prefix,
                         },
-                    .link_params = {},
+                    .link_params = link_params,
                     .threads_params = {},
                 };
 
@@ -92,11 +94,11 @@ namespace mamba
                 );
             };
 
-            std::string script_ext = util::on_win ? ".bat" : ".sh";
-            std::string pre_link_name = ".test_pkg-pre-link" + script_ext;
-            std::string post_link_name = ".test_pkg-post-link" + script_ext;
-            std::string pre_unlink_name = ".test_pkg-pre-unlink" + script_ext;
-            std::string post_unlink_name = ".test_pkg-post-unlink" + script_ext;
+            const std::string script_ext = util::on_win ? ".bat" : ".sh";
+            const std::string pre_link_name = ".test_pkg-pre-link" + script_ext;
+            const std::string post_link_name = ".test_pkg-post-link" + script_ext;
+            const std::string pre_unlink_name = ".test_pkg-pre-unlink" + script_ext;
+            const std::string post_unlink_name = ".test_pkg-post-unlink" + script_ext;
 
             auto create_script = [](const fs::u8path& p, const fs::u8path& marker_path)
             {
@@ -165,7 +167,22 @@ namespace mamba
 
                 REQUIRE(fs::exists(pre_unlink_marker));
                 // post-unlink script should not be executed as deprecated
-                REQUIRE(!fs::exists(post_unlink_marker));
+                REQUIRE_FALSE(fs::exists(post_unlink_marker));
+            }
+
+            SECTION("link scripts disabled")
+            {
+                auto tx_context = make_tx_context({ .skip_run_link_scripts = true });
+                LinkPackage link_pkg(pkg, cache_dir, &tx_context);
+                UnlinkPackage unlink_pkg(pkg, cache_dir, &tx_context);
+
+                REQUIRE(link_pkg.execute());
+                REQUIRE(unlink_pkg.execute());
+
+                REQUIRE_FALSE(fs::exists(pre_link_marker));
+                REQUIRE_FALSE(fs::exists(post_link_marker));
+                REQUIRE_FALSE(fs::exists(pre_unlink_marker));
+                REQUIRE_FALSE(fs::exists(post_unlink_marker));
             }
         }
     }

libmambapy/bindings/legacy.cpp

@@ -1137,25 +1137,32 @@ bind_submodule_impl(pybind11::module_ m)
     pyLinkParams
         .def(
             py::init(
-                [](bool allow_softlinks, bool always_copy, bool always_softlink, bool compile_pyc) -> LinkParams
+                [](bool allow_softlinks,
+                   bool always_copy,
+                   bool always_softlink,
+                   bool compile_pyc,
+                   bool skip_run_link_scripts) -> LinkParams
                 {
                     return {
                         .allow_softlinks = allow_softlinks,
                         .always_copy = always_copy,
                         .always_softlink = always_softlink,
                         .compile_pyc = compile_pyc,
+                        .skip_run_link_scripts = skip_run_link_scripts,
                     };
                 }
             ),
             py::arg("allow_softlinks") = default_link_params.allow_softlinks,
             py::arg("always_copy") = default_link_params.always_copy,
             py::arg("always_softlink") = default_link_params.always_softlink,
-            py::arg("compile_pyc") = default_link_params.compile_pyc
+            py::arg("compile_pyc") = default_link_params.compile_pyc,
+            py::arg("skip_run_link_scripts") = default_link_params.skip_run_link_scripts
         )
         .def_readwrite("allow_softlinks", &LinkParams::allow_softlinks)
         .def_readwrite("always_copy", &LinkParams::always_copy)
         .def_readwrite("always_softlink", &LinkParams::always_softlink)
-        .def_readwrite("compile_pyc", &LinkParams::compile_pyc);
+        .def_readwrite("compile_pyc", &LinkParams::compile_pyc)
+        .def_readwrite("skip_run_link_scripts", &LinkParams::skip_run_link_scripts);
 
     static const auto default_validation_params = ValidationParams{};
     pyValidationParams

micromamba/src/common_options.cpp

@@ -346,6 +346,17 @@ no_channel_priority_hook(Configuration& config, bool&)
     }
 }
 
+void
+init_link_options(CLI::App* subcom, Configuration& config)
+{
+    auto& skip_run_link_scripts = config.at("skip_run_link_scripts");
+    subcom->add_flag(
+        "--skip-run-link-scripts,!--run-link-scripts",
+        skip_run_link_scripts.get_cli_config<bool>(),
+        skip_run_link_scripts.description()
+    );
+}
+
 void
 init_install_options(CLI::App* subcom, Configuration& config)
 {
@@ -354,6 +365,7 @@ init_install_options(CLI::App* subcom, Configuration& config)
     init_prefix_options(subcom, config);
     init_network_options(subcom, config);
     init_channel_parser(subcom, config);
+    init_link_options(subcom, config);
 
     auto& specs = config.at("specs");
     subcom

micromamba/src/common_options.hpp

@@ -22,6 +22,9 @@ init_general_options(CLI::App* subcom, mamba::Configuration& config);
 void
 init_prefix_options(CLI::App* subcom, mamba::Configuration& config);
 
+void
+init_link_options(CLI::App* subcom, mamba::Configuration& config);
+
 void
 init_install_options(CLI::App* subcom, mamba::Configuration& config);
 

micromamba/src/env.cpp

@@ -295,6 +295,7 @@ set_env_command(CLI::App* com, mamba::Configuration& config)
     auto* remove_subcom = com->add_subcommand("remove", "Remove an environment");
     init_general_options(remove_subcom, config);
     init_prefix_options(remove_subcom, config);
+    init_link_options(remove_subcom, config);
 
     remove_subcom->callback(
         [&config]
@@ -351,6 +352,7 @@ set_env_command(CLI::App* com, mamba::Configuration& config)
 
     init_general_options(update_subcom, config);
     init_prefix_options(update_subcom, config);
+    init_link_options(update_subcom, config);
 
     auto& file_specs = config.at("file_specs");
     update_subcom

micromamba/src/remove.cpp

@@ -18,6 +18,7 @@ set_remove_command(CLI::App* subcom, Configuration& config)
     using string_list = std::vector<std::string>;
     init_general_options(subcom, config);
     init_prefix_options(subcom, config);
+    init_link_options(subcom, config);
 
     auto& specs = config.at("specs");
     subcom