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46 lines
1.6 KiB
46 lines
1.6 KiB
From 520f09be3c2d351722c33daf7389d6ac4716be98 Mon Sep 17 00:00:00 2001 |
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From: Jann Horn <jannh@google.com> |
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Date: Fri, 13 Jul 2018 15:15:36 -0700 |
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Subject: [PATCH] fusermount: don't feed "escaped commas" into mount options |
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The old code permits the following behavior: |
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$ _FUSE_COMMFD=10000 priv_strace -etrace=mount -s200 fusermount -o 'foobar=\,allow_other' mount |
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mount("/dev/fuse", ".", "fuse", MS_NOSUID|MS_NODEV, "foobar=\\,allow_other,fd=3,rootmode=40000,user_id=1000,group_id=1000") = -1 EINVAL (Invalid argument) |
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However, backslashes do not have any special meaning for the kernel here. |
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As it happens, you can't abuse this because there is no FUSE mount option |
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that takes a string value that can contain backslashes; but this is very |
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brittle. Don't interpret "escape characters" in places where they don't |
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work. |
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--- |
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util/fusermount.c | 5 ++++- |
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1 file changed, 4 insertions(+), 1 deletion(-) |
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diff --git a/util/fusermount.c b/util/fusermount.c |
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index 26a0b75bbecb..5175c0115a05 100644 |
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--- a/util/fusermount.c |
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+++ b/util/fusermount.c |
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@@ -29,6 +29,7 @@ |
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#include <sys/socket.h> |
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#include <sys/utsname.h> |
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#include <sched.h> |
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+#include <stdbool.h> |
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#define FUSE_COMMFD_ENV "_FUSE_COMMFD" |
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@@ -739,8 +740,10 @@ static int do_mount(const char *mnt, char **typep, mode_t rootmode, |
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unsigned len; |
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const char *fsname_str = "fsname="; |
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const char *subtype_str = "subtype="; |
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+ bool escape_ok = begins_with(s, fsname_str) || |
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+ begins_with(s, subtype_str); |
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for (len = 0; s[len]; len++) { |
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- if (s[len] == '\\' && s[len + 1]) |
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+ if (escape_ok && s[len] == '\\' && s[len + 1]) |
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len++; |
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else if (s[len] == ',') |
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break; |
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-- |
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2.14.3
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