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main/alsa-lib: avoid using wordexp

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wordexp implementation will execute /bin/sh (as suggested in posix).
This breaks firefox sandbox. We also need to expand ~/ so that alsa uses
~/.asoundrc so we cannot just trick the configurescript to think that we
dont have wordexp since the fallback code would not expand anything at
all.

ref #7454
This commit is contained in:
Natanael Copa 2017-07-11 19:08:15 +02:00
parent d992104977
commit 9e0f3ef79e
2 changed files with 133 additions and 6 deletions
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129
main/alsa-lib/0001-snd_user_file-avoid-use-wordexp.patch Normal file
View File

@ -0,0 +1,129 @@
From 1f9113336e8eb4bd89ca040e90c5fdc79b0c567f Mon Sep 17 00:00:00 2001
From: Natanael Copa <ncopa@alpinelinux.org>
Date: Tue, 11 Jul 2017 18:25:13 +0200
Subject: [PATCH] snd_user_file: avoid use wordexp
As suggested in POSIX[1], wordexp might execute the shell. If the libc
implementation does so, it will break the firefox sandbox which does
not allow exec. This happened on Alpine Linux with musl libc[2].
Since we cannot guarantee that the system wordexp implementation does
not execute shell, we cannot really use it, and need to implement the
~/ expansion ourselves.
[1]: http://pubs.opengroup.org/onlinepubs/9699919799/functions/wordexp.html#tag_16_684_08
[2]: http://bugs.alpinelinux.org/issues/7454#note-2
Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
---
src/userfile.c | 77 +++++++++++++++++++++++++++++++++++-----------------------
1 file changed, 47 insertions(+), 30 deletions(-)
diff --git a/src/userfile.c b/src/userfile.c
index 72779da4..0e3f5fae 100644
--- a/src/userfile.c
+++ b/src/userfile.c
@@ -21,6 +21,11 @@
#include <config.h>
#include <string.h>
#include <errno.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
/**
* \brief Get the full file name
@@ -28,46 +33,58 @@
* \param result The pointer to store the resultant file name
* \return 0 if successful, or a negative error code
*
- * Parses the given file name with POSIX-Shell-like expansion and
- * stores the first matchine one. The returned string is strdup'ed.
+ * Parses the given file name with POSIX-Shell-like expansion for ~/.
+ * The returned string is strdup'ed.
*/
-#ifdef HAVE_WORDEXP_H
-#include <wordexp.h>
#include <assert.h>
int snd_user_file(const char *file, char **result)
{
- wordexp_t we;
int err;
-
+ size_t len;
+ char *buf = NULL;
+
assert(file && result);
- err = wordexp(file, &we, WRDE_NOCMD);
- switch (err) {
- case WRDE_NOSPACE:
- wordfree(&we);
- return -ENOMEM;
- case 0:
- if (we.we_wordc == 1)
- break;
- wordfree(&we);
- /* fall thru */
- default:
- return -EINVAL;
+ *result = NULL;
+
+ /* expand ~/ if needed */
+ if (file[0] == '~' && file[1] == '/') {
+ const char *home = getenv("HOME");
+ if (home == NULL) {
+ struct passwd pwent, *p = NULL;
+ uid_t id = getuid();
+ size_t bufsize = 1024;
+
+ buf = malloc(bufsize);
+ if (buf == NULL)
+ goto out;
+
+ while ((err = getpwuid_r(id, &pwent, buf, bufsize, &p)) == ERANGE) {
+ char *newbuf;
+ bufsize += 1024;
+ if (bufsize < 1024)
+ break;
+ newbuf = realloc(buf, bufsize);
+ if (newbuf == NULL)
+ goto out;
+ buf = newbuf;
+ }
+ home = err ? "" : pwent.pw_dir;
+ }
+ len = strlen(home) + strlen(&file[2]) + 2;
+ *result = malloc(len);
+ if (*result)
+ snprintf(*result, len, "%s/%s", home, &file[2]);
+ } else {
+ *result = strdup(file);
}
- *result = strdup(we.we_wordv[0]);
- wordfree(&we);
+
+out:
+ if (buf)
+ free(buf);
+
if (*result == NULL)
return -ENOMEM;
return 0;
}
-#else /* !HAVE_WORDEXP_H */
-/* just copy the string - would be nicer to expand by ourselves, though... */
-int snd_user_file(const char *file, char **result)
-{
- *result = strdup(file);
- if (! *result)
- return -ENOMEM;
- return 0;
-}
-#endif /* HAVE_WORDEXP_H */
--
2.13.2

10
main/alsa-lib/APKBUILD
View File

@ -1,7 +1,7 @@
# Maintainer: Natanael Copa <ncopa@alpinelinux.org>
pkgname=alsa-lib
pkgver=1.1.4.1
pkgrel=1
pkgrel=2
pkgdesc="An alternative implementation of Linux sound support"
url="http://www.alsa-project.org"
arch="all"
@ -12,6 +12,7 @@ source="ftp://ftp.alsa-project.org/pub/lib/$pkgname-$pkgver.tar.bz2
alsa-lib-poll.patch
alsa-lib-stdint.patch
ucm_add_limits_h.patch
0001-snd_user_file-avoid-use-wordexp.patch
"
builddir="$srcdir/$pkgname-$pkgver"
@ -24,10 +25,6 @@ prepare() {
build() {
cd "$builddir"
# musl does support wordexp but we don't want alsa to use it since it will
# execute /bin/sh and break things like firefox sandbox
# https://bugs.alpinelinux.org/issues/7454
ac_cv_header_wordexp_h=no \
./configure \
--build=$CBUILD \
--host=$CHOST \
@ -51,4 +48,5 @@ package() {
sha512sums="7b548c4ee29c4a1230a0edcd5d19219831290f96a214180a6530628acc05278d1348376195287d188f4f44d6be1914391c63994f1b50985c3eee74352da26b0b alsa-lib-1.1.4.1.tar.bz2
bdf86a1b76b2e6e9b43af33989fe51e4900fa0c6f317d8d746f30c540df647dbe0f6d41ec35b36b1cf7e46cc5e910e0a62bc39c765f849356ecd6e98d1de5885 alsa-lib-poll.patch
2351262dade9a3c1a3de1b7d1a3a53a634a438b9b8aae7cc69e2b981500051f039e6381359b81392114ec6236e3d513b577bd4bf12c3d2ce1f871cd7651b2cab alsa-lib-stdint.patch
3b37652d50809443b5f8e80f8d447108195b0cd66fd917805bb393fc091584b6f3dad4414f568742b61745617e7a695862058a0a0f93dcc31e4c97177a520352 ucm_add_limits_h.patch"
3b37652d50809443b5f8e80f8d447108195b0cd66fd917805bb393fc091584b6f3dad4414f568742b61745617e7a695862058a0a0f93dcc31e4c97177a520352 ucm_add_limits_h.patch
e6baeee549533ea4b113bacfa772c183456ce51e6c84b378b82a6735159e43a11ff30c0a4a15207110c42dbd7be5e67bc5e2f593cdc99bd8b079204df7498ceb 0001-snd_user_file-avoid-use-wordexp.patch"