103 lines
3.4 KiB
Diff
103 lines
3.4 KiB
Diff
From 5e7a3c2e7e118c7f12d5dfda9f9140f638976aa2 Mon Sep 17 00:00:00 2001
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From: Benno Schulenberg <bensberg@telfort.nl>
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Date: Sun, 28 Apr 2024 10:51:52 +0200
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Subject: files: run `chmod` and `chown` on the descriptor, not on the filename
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This closes a window of opportunity where the emergency file could be
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replaced by a malicious symlink.
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The issue was reported by `MartinJM` and `InvisibleMeerkat`.
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Problem existed since version 2.2.0, commit 123110c5, when chmodding
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and chowning of the emergency .save file was added.
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Cherry-picked-by: Lukáš Zaoral <lzaoral@redhat.com>
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Upstream-commit: 5e7a3c2e7e118c7f12d5dfda9f9140f638976aa2
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diff --git a/src/definitions.h b/src/definitions.h
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index af3a793..55d8235 100644
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--- a/src/definitions.h
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+++ b/src/definitions.h
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@@ -254,7 +254,7 @@ typedef enum {
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} message_type;
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typedef enum {
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- OVERWRITE, APPEND, PREPEND
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+ OVERWRITE, APPEND, PREPEND, EMERGENCY
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} kind_of_writing_type;
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typedef enum {
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diff --git a/src/files.c b/src/files.c
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index 57c2001..584b579 100644
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--- a/src/files.c
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+++ b/src/files.c
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@@ -1751,6 +1751,8 @@ bool write_file(const char *name, FILE *thefile, bool normal,
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#endif
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char *realname = real_dir_from_tilde(name);
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/* The filename after tilde expansion. */
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+ int fd = 0;
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+ /* The descriptor that is assigned when opening the file. */
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char *tempname = NULL;
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/* The name of the temporary file we use when prepending. */
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linestruct *line = openfile->filetop;
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@@ -1830,7 +1830,6 @@ bool write_file(const char *name, FILE *thefile, bool normal,
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* For an emergency file, access is restricted to just the owner. */
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if (thefile == NULL) {
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mode_t permissions = (tmp ? S_IRUSR|S_IWUSR : RW_FOR_ALL);
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- int fd;
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#ifndef NANO_TINY
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block_sigwinch(TRUE);
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@@ -1953,6 +1953,16 @@ bool write_file(const char *name, FILE *thefile, bool normal,
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goto cleanup_and_exit;
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}
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+#ifndef NANO_TINY
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+ /* Change permissions and owner of an emergency save file to the values
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+ * of the original file, but ignore any failure as we are in a hurry. */
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+ if (method == EMERGENCY && fd && openfile->statinfo) {
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+ IGNORE_CALL_RESULT(fchmod(fd, openfile->statinfo->st_mode));
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+ IGNORE_CALL_RESULT(fchown(fd, openfile->statinfo->st_uid,
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+ openfile->statinfo->st_gid));
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+ }
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+#endif
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+
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if (fclose(thefile) != 0) {
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statusline(ALERT, _("Error writing %s: %s"), realname, strerror(errno));
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goto cleanup_and_exit;
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diff --git a/src/nano.c b/src/nano.c
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index 90b4a0b..973054f 100644
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--- a/src/nano.c
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+++ b/src/nano.c
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@@ -321,25 +321,15 @@ void emergency_save(const char *filename)
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targetname = get_next_filename(plainname, ".save");
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if (*targetname != '\0')
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- failed = !write_file(targetname, NULL, TRUE, OVERWRITE, FALSE);
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+ failed = !write_file(targetname, NULL, TRUE, EMERGENCY, FALSE);
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if (!failed)
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fprintf(stderr, _("\nBuffer written to %s\n"), targetname);
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else if (*targetname != '\0')
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fprintf(stderr, _("\nBuffer not written to %s: %s\n"),
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targetname, strerror(errno));
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else
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fprintf(stderr, _("\nToo many .save files"));
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-
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-#ifndef NANO_TINY
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- /* Try to chmod/chown the saved file to the values of the original file,
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- * but ignore any failure as we are in a hurry to get out. */
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- if (openfile->statinfo) {
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- IGNORE_CALL_RESULT(chmod(targetname, openfile->statinfo->st_mode));
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- IGNORE_CALL_RESULT(chown(targetname, openfile->statinfo->st_uid,
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- openfile->statinfo->st_gid));
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- }
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-#endif
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free(targetname);
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}
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--
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cgit v1.1
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