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Merge branch 'maint-0.4.4'
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commit
2ee33765ae
6
changes/bug27315
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6
changes/bug27315
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@ -0,0 +1,6 @@
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o Minor bugfixes (linux seccomp2 sandbox):
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- Fix a regression on sandboxing rules for the openat() syscall.
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The fix for bug 25440 fixed the problem on systems with glibc >=
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2.27 but broke tor on previous versions of glibc. We now apply
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the correct seccomp rule according to the running glibc version.
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Patch from Daniel Pinto. Fixes bug 27315; bugfix on 0.3.5.11.
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@ -137,6 +137,10 @@ static sandbox_cfg_t *filter_dynamic = NULL;
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* the high bits of the value might get masked out improperly. */
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#define SCMP_CMP_MASKED(a,b,c) \
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SCMP_CMP4((a), SCMP_CMP_MASKED_EQ, ~(scmp_datum_t)(b), (c))
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/* For negative constants, the rule to add depends on the glibc version. */
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#define SCMP_CMP_NEG(a,op,b) (libc_negative_constant_needs_cast() ? \
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(SCMP_CMP((a), (op), (unsigned int)(b))) : \
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(SCMP_CMP_STR((a), (op), (b))))
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/** Variable used for storing all syscall numbers that will be allowed with the
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* stage 1 general Tor sandbox.
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@ -438,31 +442,49 @@ sb_mmap2(scmp_filter_ctx ctx, sandbox_cfg_t *filter)
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#endif
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#endif
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/* Return true if we think we're running with a libc that always uses
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* openat on linux. */
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/* Return true the libc version is greater or equal than
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* <b>major</b>.<b>minor</b>. Returns false otherwise. */
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static int
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libc_uses_openat_for_everything(void)
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is_libc_at_least(int major, int minor)
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{
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#ifdef CHECK_LIBC_VERSION
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const char *version = gnu_get_libc_version();
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if (version == NULL)
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return 0;
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int major = -1;
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int minor = -1;
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int libc_major = -1;
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int libc_minor = -1;
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tor_sscanf(version, "%d.%d", &major, &minor);
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if (major >= 3)
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tor_sscanf(version, "%d.%d", &libc_major, &libc_minor);
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if (libc_major > major)
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return 1;
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else if (major == 2 && minor >= 26)
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else if (libc_major == major && libc_minor >= minor)
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return 1;
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else
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return 0;
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#else /* !defined(CHECK_LIBC_VERSION) */
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(void)major;
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(void)minor;
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return 0;
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#endif /* defined(CHECK_LIBC_VERSION) */
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}
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/* Return true if we think we're running with a libc that always uses
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* openat on linux. */
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static int
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libc_uses_openat_for_everything(void)
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{
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return is_libc_at_least(2, 26);
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}
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/* Return true if we think we're running with a libc that needs to cast
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* negative arguments like AT_FDCWD for seccomp rules. */
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static int
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libc_negative_constant_needs_cast(void)
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{
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return is_libc_at_least(2, 27);
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}
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/** Allow a single file to be opened. If <b>use_openat</b> is true,
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* we're using a libc that remaps all the opens into openats. */
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static int
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@ -470,7 +492,7 @@ allow_file_open(scmp_filter_ctx ctx, int use_openat, const char *file)
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{
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if (use_openat) {
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return seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(openat),
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SCMP_CMP(0, SCMP_CMP_EQ, (unsigned int)AT_FDCWD),
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SCMP_CMP_NEG(0, SCMP_CMP_EQ, AT_FDCWD),
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SCMP_CMP_STR(1, SCMP_CMP_EQ, file));
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} else {
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return seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(open),
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@ -606,7 +628,7 @@ sb_openat(scmp_filter_ctx ctx, sandbox_cfg_t *filter)
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if (param != NULL && param->prot == 1 && param->syscall
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== SCMP_SYS(openat)) {
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rc = seccomp_rule_add_3(ctx, SCMP_ACT_ALLOW, SCMP_SYS(openat),
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SCMP_CMP(0, SCMP_CMP_EQ, AT_FDCWD),
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SCMP_CMP_NEG(0, SCMP_CMP_EQ, AT_FDCWD),
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SCMP_CMP_STR(1, SCMP_CMP_EQ, param->value),
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SCMP_CMP(2, SCMP_CMP_EQ, O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|
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O_CLOEXEC));
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