<p>laforge has uploaded this change for <strong>review</strong>.</p><p><a href="https://gerrit.osmocom.org/c/libosmocore/+/17852">View Change</a></p><pre style="font-family: monospace,monospace; white-space: pre-wrap;">exec: Introduce osmo_system_nowait2() to allow specify a user<br><br>For a process running as root, it may be desirable to drop privileges<br>down to a normal user  before executing an external command.  Let's<br>add a new API function for that.<br><br>Change-Id: If1431f930f72a8d6c1d102426874a11b7a2debd9<br>---<br>M include/osmocom/core/exec.h<br>M src/exec.c<br>2 files changed, 28 insertions(+), 1 deletion(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;">git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/52/17852/1</pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/include/osmocom/core/exec.h b/include/osmocom/core/exec.h</span><br><span>index 6bbd352..e63ec11 100644</span><br><span>--- a/include/osmocom/core/exec.h</span><br><span>+++ b/include/osmocom/core/exec.h</span><br><span>@@ -25,4 +25,5 @@</span><br><span> int osmo_environment_filter(char **out, size_t out_len, char **in, const char **whitelist);</span><br><span> int osmo_environment_append(char **out, size_t out_len, char **in);</span><br><span> int osmo_close_all_fds_above(int last_fd_to_keep);</span><br><span style="color: hsl(120, 100%, 40%);">+int osmo_system_nowait2(const char *command, const char **env_whitelist, char **addl_env, const char *user);</span><br><span> int osmo_system_nowait(const char *command, const char **env_whitelist, char **addl_env);</span><br><span>diff --git a/src/exec.c b/src/exec.c</span><br><span>index 62f5919..dfe019b 100644</span><br><span>--- a/src/exec.c</span><br><span>+++ b/src/exec.c</span><br><span>@@ -23,6 +23,7 @@</span><br><span> #include "config.h"</span><br><span> #ifndef EMBEDDED</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+#define _GNU_SOURCE</span><br><span> #include <unistd.h></span><br><span> </span><br><span> #include <errno.h></span><br><span>@@ -31,6 +32,7 @@</span><br><span> #include <stdio.h></span><br><span> #include <dirent.h></span><br><span> #include <sys/types.h></span><br><span style="color: hsl(120, 100%, 40%);">+#include <pwd.h></span><br><span> </span><br><span> #include <osmocom/core/logging.h></span><br><span> #include <osmocom/core/utils.h></span><br><span>@@ -203,12 +205,20 @@</span><br><span>  *  \param[in] command the shell command to be executed, see system(3)</span><br><span>  *  \param[in] env_whitelist A white-list of keys for environment variables</span><br><span>  *  \param[in] addl_env any additional environment variables to be appended</span><br><span style="color: hsl(120, 100%, 40%);">+ *  \param[in] user name of the user to which we should switch before executing the command</span><br><span>  *  \returns PID of generated child process; negative on error</span><br><span>  */</span><br><span style="color: hsl(0, 100%, 40%);">-int osmo_system_nowait(const char *command, const char **env_whitelist, char **addl_env)</span><br><span style="color: hsl(120, 100%, 40%);">+int osmo_system_nowait2(const char *command, const char **env_whitelist, char **addl_env, const char *user)</span><br><span> {</span><br><span style="color: hsl(120, 100%, 40%);">+   struct passwd *pw = NULL;</span><br><span>    int rc;</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+   if (user) {</span><br><span style="color: hsl(120, 100%, 40%);">+           pw = getpwnam(user);</span><br><span style="color: hsl(120, 100%, 40%);">+          if (!pw)</span><br><span style="color: hsl(120, 100%, 40%);">+                      return -EINVAL;</span><br><span style="color: hsl(120, 100%, 40%);">+       }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span>  rc = fork();</span><br><span>         if (rc == 0) {</span><br><span>               /* we are in the child */</span><br><span>@@ -232,6 +242,16 @@</span><br><span>                             return rc;</span><br><span>           }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+         /* drop privileges */</span><br><span style="color: hsl(120, 100%, 40%);">+         if (pw) {</span><br><span style="color: hsl(120, 100%, 40%);">+                     if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) < 0)</span><br><span style="color: hsl(120, 100%, 40%);">+                            exit(1);</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+                    if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) < 0)</span><br><span style="color: hsl(120, 100%, 40%);">+                            exit(1);</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+            }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span>          /* if we want to behave like system(3), we must go via the shell */</span><br><span>          execle("/bin/sh", "sh", "-c", command, (char *) NULL, new_env);</span><br><span>                /* only reached in case of error */</span><br><span>@@ -244,4 +264,10 @@</span><br><span>   }</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+int osmo_system_nowait(const char *command, const char **env_whitelist, char **addl_env)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+       return osmo_system_nowait2(command, env_whitelist, addl_env, NULL);</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> #endif /* EMBEDDED */</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/c/libosmocore/+/17852">change 17852</a>. To unsubscribe, or for help writing mail filters, visit <a href="https://gerrit.osmocom.org/settings">settings</a>.</p><div itemscope itemtype="http://schema.org/EmailMessage"><div itemscope itemprop="action" itemtype="http://schema.org/ViewAction"><link itemprop="url" href="https://gerrit.osmocom.org/c/libosmocore/+/17852"/><meta itemprop="name" content="View Change"/></div></div>

<div style="display:none"> Gerrit-Project: libosmocore </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-Change-Id: If1431f930f72a8d6c1d102426874a11b7a2debd9 </div>
<div style="display:none"> Gerrit-Change-Number: 17852 </div>
<div style="display:none"> Gerrit-PatchSet: 1 </div>
<div style="display:none"> Gerrit-Owner: laforge <laforge@osmocom.org> </div>
<div style="display:none"> Gerrit-MessageType: newchange </div>