ncurses 6.4 - patch 20240414

[ncurses.git] / ncurses / tinfo / access.c

diff --git a/ncurses/tinfo/access.c b/ncurses/tinfo/access.c
index 6c4df591784a074575d71c1727edd5fde7cd0354..50a5769c3d6358fef4af8f67e9ee7cc8aeddc2b0 100644 (file)
--- a/ncurses/tinfo/access.c
+++ b/ncurses/tinfo/access.c
@@ -1,5 +1,6 @@
 /****************************************************************************
- * Copyright (c) 1998-2010,2011 Free Software Foundation, Inc.              *
+ * Copyright 2019-2021,2023 Thomas E. Dickey                                *
+ * Copyright 1998-2011,2012 Free Software Foundation, Inc.                  *
  *                                                                          *
  * Permission is hereby granted, free of charge, to any person obtaining a  *
  * copy of this software and associated documentation files (the            *
@@ -34,20 +35,33 @@
 
 #include <ctype.h>
 
-#include <tic.h>
-
-MODULE_ID("$Id: access.c,v 1.20 2011/06/05 00:48:00 tom Exp $")
-
-#ifdef __TANDEM
-#define ROOT_UID 65535
+#ifndef USE_ROOT_ACCESS
+#if HAVE_SETFSUID
+#include <sys/fsuid.h>
+#else
+#include <sys/stat.h>
+#endif
 #endif
 
-#ifndef ROOT_UID
-#define ROOT_UID 0
+#if HAVE_GETAUXVAL && HAVE_SYS_AUXV_H && defined(__GLIBC__) && (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 19)
+#include <sys/auxv.h>
+#define USE_GETAUXVAL 1
+#else
+#define USE_GETAUXVAL 0
 #endif
 
+#include <tic.h>
+
+MODULE_ID("$Id: access.c,v 1.37 2023/06/24 21:55:09 tom Exp $")
+
 #define LOWERCASE(c) ((isalpha(UChar(c)) && isupper(UChar(c))) ? tolower(UChar(c)) : (c))
 
+#ifdef _NC_MSC
+# define ACCESS(FN, MODE) access((FN), (MODE)&(R_OK|W_OK))
+#else
+# define ACCESS access
+#endif
+
 NCURSES_EXPORT(char *)
 _nc_rootname(char *path)
 {
@@ -56,11 +70,11 @@ _nc_rootname(char *path)
     static char *temp;
     char *s;
 
-    temp = strdup(result);
-    result = temp;
+    if ((temp = strdup(result)) != 0)
+       result = temp;
 #if !MIXEDCASE_FILENAMES
     for (s = result; *s != '\0'; ++s) {
-       *s = LOWERCASE(*s);
+       *s = (char) LOWERCASE(*s);
     }
 #endif
 #if defined(PROG_EXT)
@@ -119,20 +133,22 @@ _nc_access(const char *path, int mode)
 
     if (path == 0) {
        result = -1;
-    } else if (access(path, mode) < 0) {
+    } else if (ACCESS(path, mode) < 0) {
        if ((mode & W_OK) != 0
            && errno == ENOENT
            && strlen(path) < PATH_MAX) {
            char head[PATH_MAX];
-           char *leaf = _nc_basename(strcpy(head, path));
+           char *leaf;
 
+           _nc_STRCPY(head, path, sizeof(head));
+           leaf = _nc_basename(head);
            if (leaf == 0)
                leaf = head;
            *leaf = '\0';
            if (head == leaf)
-               (void) strcpy(head, ".");
+               _nc_STRCPY(head, ".", sizeof(head));
 
-           result = access(head, R_OK | W_OK | X_OK);
+           result = ACCESS(head, R_OK | W_OK | X_OK);
        } else {
            result = -1;
        }
@@ -168,23 +184,101 @@ _nc_is_file_path(const char *path)
     return result;
 }
 
-#ifndef USE_ROOT_ENVIRON
+#if HAVE_GETEUID && HAVE_GETEGID
+#define is_posix_elevated() \
+       (getuid() != geteuid() \
+        || getgid() != getegid())
+#else
+#define is_posix_elevated() FALSE
+#endif
+
+#if HAVE_ISSETUGID
+#define is_elevated() issetugid()
+#elif USE_GETAUXVAL && defined(AT_SECURE)
+#define is_elevated() \
+       (getauxval(AT_SECURE) \
+        ? TRUE \
+        : (errno != ENOENT \
+           ? FALSE \
+           : is_posix_elevated()))
+#else
+#define is_elevated() is_posix_elevated()
+#endif
+
+#if HAVE_SETFSUID
+#define lower_privileges() \
+           int save_err = errno; \
+           setfsuid(getuid()); \
+           setfsgid(getgid()); \
+           errno = save_err
+#define resume_elevation() \
+           save_err = errno; \
+           setfsuid(geteuid()); \
+           setfsgid(getegid()); \
+           errno = save_err
+#else
+#define lower_privileges()     /* nothing */
+#define resume_elevation()     /* nothing */
+#endif
+
 /*
- * Returns true if we allow application to use environment variables that are
- * used for searching lists of directories, etc.
+ * Returns true if not running as root or setuid.  We use this check to allow
+ * applications to use environment variables that are used for searching lists
+ * of directories, etc.
  */
 NCURSES_EXPORT(int)
 _nc_env_access(void)
 {
-#if HAVE_ISSETUGID
-    if (issetugid())
-       return FALSE;
-#elif HAVE_GETEUID && HAVE_GETEGID
-    if (getuid() != geteuid()
-       || getgid() != getegid())
-       return FALSE;
-#endif
-    /* ...finally, disallow root */
-    return (getuid() != ROOT_UID) && (geteuid() != ROOT_UID);
+    int result = TRUE;
+
+#if HAVE_GETUID && HAVE_GETEUID
+#if !defined(USE_SETUID_ENVIRON)
+    if (is_elevated()) {
+       result = FALSE;
+    }
+#endif
+#if !defined(USE_ROOT_ENVIRON)
+    if ((getuid() == ROOT_UID) || (geteuid() == ROOT_UID)) {
+       result = FALSE;
+    }
+#endif
+#endif /* HAVE_GETUID && HAVE_GETEUID */
+    return result;
+}
+
+#ifndef USE_ROOT_ACCESS
+/*
+ * Limit privileges if possible; otherwise disallow access for updating files.
+ */
+NCURSES_EXPORT(FILE *)
+_nc_safe_fopen(const char *path, const char *mode)
+{
+    FILE *result = NULL;
+#if HAVE_SETFSUID
+    lower_privileges();
+    result = fopen(path, mode);
+    resume_elevation();
+#else
+    if (!is_elevated() || *mode == 'r') {
+       result = fopen(path, mode);
+    }
+#endif
+    return result;
 }
+
+NCURSES_EXPORT(int)
+_nc_safe_open3(const char *path, int flags, mode_t mode)
+{
+    int result = -1;
+#if HAVE_SETFSUID
+    lower_privileges();
+    result = open(path, flags, mode);
+    resume_elevation();
+#else
+    if (!is_elevated() || (flags & O_RDONLY)) {
+       result = open(path, flags, mode);
+    }
 #endif
+    return result;
+}
+#endif /* USE_ROOT_ACCESS */