ncurses 6.3

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

diff --git a/ncurses/tinfo/access.c b/ncurses/tinfo/access.c
index 6dd1d69befcf6e6624fc69f631ab7b3658b61a4e..a735db26eee600c5fb218c83224de4324aeb75bf 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 2019-2020,2021 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            *
@@ -33,22 +34,27 @@
 #include <curses.priv.h>
 
 #include <ctype.h>
+
+#ifndef USE_ROOT_ACCESS
+#if HAVE_SETFSUID
+#include <sys/fsuid.h>
+#else
 #include <sys/stat.h>
+#endif
+#endif
 
 #include <tic.h>
 
-MODULE_ID("$Id: access.c,v 1.17 2011/05/07 15:02:03 tom Exp $")
+MODULE_ID("$Id: access.c,v 1.31 2021/08/29 10:35:17 tom Exp $")
 
-#ifdef __TANDEM
-#define ROOT_UID 65535
-#endif
+#define LOWERCASE(c) ((isalpha(UChar(c)) && isupper(UChar(c))) ? tolower(UChar(c)) : (c))
 
-#ifndef ROOT_UID
-#define ROOT_UID 0
+#ifdef _NC_MSC
+# define ACCESS(FN, MODE) access((FN), (MODE)&(R_OK|W_OK))
+#else
+# define ACCESS access
 #endif
 
-#define LOWERCASE(c) ((isalpha(UChar(c)) && isupper(UChar(c))) ? tolower(UChar(c)) : (c))
-
 NCURSES_EXPORT(char *)
 _nc_rootname(char *path)
 {
@@ -61,7 +67,7 @@ _nc_rootname(char *path)
     result = temp;
 #if !MIXEDCASE_FILENAMES
     for (s = result; *s != '\0'; ++s) {
-       *s = LOWERCASE(*s);
+       *s = (char) LOWERCASE(*s);
     }
 #endif
 #if defined(PROG_EXT)
@@ -116,24 +122,33 @@ _nc_basename(char *path)
 NCURSES_EXPORT(int)
 _nc_access(const char *path, int mode)
 {
-    if (access(path, mode) < 0) {
+    int result;
+
+    if (path == 0) {
+       result = -1;
+    } 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));
 
-           return access(head, R_OK | W_OK | X_OK);
+           result = ACCESS(head, R_OK | W_OK | X_OK);
+       } else {
+           result = -1;
        }
-       return -1;
+    } else {
+       result = 0;
     }
-    return 0;
+    return result;
 }
 
 NCURSES_EXPORT(bool)
@@ -143,7 +158,7 @@ _nc_is_dir_path(const char *path)
     struct stat sb;
 
     if (stat(path, &sb) == 0
-       && (sb.st_mode & S_IFMT) == S_IFDIR) {
+       && S_ISDIR(sb.st_mode)) {
        result = TRUE;
     }
     return result;
@@ -156,12 +171,38 @@ _nc_is_file_path(const char *path)
     struct stat sb;
 
     if (stat(path, &sb) == 0
-       && (sb.st_mode & S_IFMT) == S_IFREG) {
+       && S_ISREG(sb.st_mode)) {
        result = TRUE;
     }
     return result;
 }
 
+#if HAVE_ISSETUGID
+#define is_elevated() issetugid()
+#elif HAVE_GETEUID && HAVE_GETEGID
+#define is_elevated() \
+       (getuid() != geteuid() \
+        || getgid() != getegid())
+#else
+#define is_elevated() FALSE
+#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
+
 #ifndef USE_ROOT_ENVIRON
 /*
  * Returns true if we allow application to use environment variables that are
@@ -170,15 +211,50 @@ _nc_is_file_path(const char *path)
 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;
+    int result = TRUE;
+
+    if (is_elevated()) {
+       result = FALSE;
+    } else if ((getuid() == ROOT_UID) || (geteuid() == ROOT_UID)) {
+       result = FALSE;
+    }
+    return result;
+}
+#endif /* USE_ROOT_ENVIRON */
+
+#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
-    /* ...finally, disallow root */
-    return (getuid() != ROOT_UID) && (geteuid() != ROOT_UID);
+    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_ENVIRON */