Merge tag 'debian/1.8.5p2-1' into squeeze

[debian/sudo] / src / exec_common.c

diff --git a/src/exec_common.c b/src/exec_common.c
new file mode 100644 (file)
index 0000000..a4cd540
--- /dev/null
+++ b/src/exec_common.c
@@ -0,0 +1,158 @@
+/*
+ * Copyright (c) 2009-2012 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <sys/param.h>
+#include <stdio.h>
+#ifdef STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# ifdef HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif /* STDC_HEADERS */
+#ifdef HAVE_STRING_H
+# include <string.h>
+#endif /* HAVE_STRING_H */
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif /* HAVE_STRINGS_H */
+#ifdef HAVE_UNISTD_H
+# include <unistd.h>
+#endif /* HAVE_UNISTD_H */
+#ifdef HAVE_PRIV_SET
+# include <priv.h>
+#endif
+#include <errno.h>
+
+#include "sudo.h"
+#include "sudo_exec.h"
+
+/*
+ * Disable execution of child processes in the command we are about
+ * to run.  On systems with privilege sets, we can remove the exec
+ * privilege.  On other systems we use LD_PRELOAD and the like.
+ */
+static char * const *
+disable_execute(char *const envp[])
+{
+#ifdef _PATH_SUDO_NOEXEC
+    char *preload, **nenvp = NULL;
+    int env_len, env_size;
+    int preload_idx = -1;
+# ifdef RTLD_PRELOAD_ENABLE_VAR
+    bool enabled = false;
+# endif
+#endif /* _PATH_SUDO_NOEXEC */
+    debug_decl(disable_execute, SUDO_DEBUG_UTIL)
+
+#ifdef HAVE_PRIV_SET
+    /* Solaris privileges, remove PRIV_PROC_EXEC post-execve. */
+    if (priv_set(PRIV_OFF, PRIV_LIMIT, "PRIV_PROC_EXEC", NULL) == 0)
+       debug_return_ptr(envp);
+    warning(_("unable to remove PRIV_PROC_EXEC from PRIV_LIMIT"));
+#endif /* HAVE_PRIV_SET */
+
+#ifdef _PATH_SUDO_NOEXEC
+    /*
+     * Preload a noexec file.  For a list of LD_PRELOAD-alikes, see
+     * http://www.fortran-2000.com/ArnaudRecipes/sharedlib.html
+     * XXX - need to support 32-bit and 64-bit variants
+     */
+
+    /* Count entries in envp, looking for LD_PRELOAD as we go. */
+    for (env_len = 0; envp[env_len] != NULL; env_len++) {
+       if (strncmp(envp[env_len], RTLD_PRELOAD_VAR "=", sizeof(RTLD_PRELOAD_VAR)) == 0) {
+           preload_idx = env_len;
+           continue;
+       }
+#ifdef RTLD_PRELOAD_ENABLE_VAR
+       if (strncmp(envp[env_len], RTLD_PRELOAD_ENABLE_VAR "=", sizeof(RTLD_PRELOAD_ENABLE_VAR)) == 0) {
+           enabled = true;
+           continue;
+       }
+#endif
+    }
+
+    /* Make a new copy of envp as needed. */
+    env_size = env_len + 1 + (preload_idx == -1);
+#ifdef RTLD_PRELOAD_ENABLE_VAR
+    if (!enabled)
+       env_size++;
+#endif
+    nenvp = emalloc2(env_size, sizeof(*envp));
+    memcpy(nenvp, envp, env_len * sizeof(*envp));
+    nenvp[env_len] = NULL;
+
+    /* Prepend our LD_PRELOAD to existing value or add new entry at the end. */
+    if (preload_idx == -1) {
+# ifdef RTLD_PRELOAD_DEFAULT
+       easprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR, sudo_conf_noexec_path(), RTLD_PRELOAD_DELIM, RTLD_PRELOAD_DEFAULT);
+# else
+       preload = fmt_string(RTLD_PRELOAD_VAR, sudo_conf_noexec_path());
+# endif
+       if (preload == NULL)
+           errorx(1, _("unable to allocate memory"));
+       nenvp[env_len++] = preload;
+       nenvp[env_len] = NULL;
+    } else {
+       easprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR, sudo_conf_noexec_path(), RTLD_PRELOAD_DELIM, nenvp[preload_idx]);
+       nenvp[preload_idx] = preload;
+    }
+# ifdef RTLD_PRELOAD_ENABLE_VAR
+    if (!enabled) {
+       nenvp[env_len++] = RTLD_PRELOAD_ENABLE_VAR "=";
+       nenvp[env_len] = NULL;
+    }
+# endif
+
+    /* Install new env pointer. */
+    envp = nenvp;
+#endif /* _PATH_SUDO_NOEXEC */
+
+    debug_return_ptr(envp);
+}
+
+/*
+ * Like execve(2) but falls back to running through /bin/sh
+ * ala execvp(3) if we get ENOEXEC.
+ */
+int
+sudo_execve(const char *path, char *const argv[], char *const envp[], int noexec)
+{
+    /* Modify the environment as needed to disable further execve(). */
+    if (noexec)
+       envp = disable_execute(envp);
+
+    execve(path, argv, envp);
+    if (errno == ENOEXEC) {
+       int argc;
+       char **nargv;
+
+       for (argc = 0; argv[argc] != NULL; argc++)
+           continue;
+       nargv = emalloc2(argc + 2, sizeof(char *));
+       nargv[0] = "sh";
+       nargv[1] = (char *)path;
+       memcpy(nargv + 2, argv + 1, argc * sizeof(char *));
+       execve(_PATH_BSHELL, nargv, envp);
+       efree(nargv);
+    }
+    return -1;
+}