49 lines
2.0 KiB
Diff
49 lines
2.0 KiB
Diff
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# HG changeset patch
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# User Jed Davis <jld@mozilla.com>
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# Date 1603832709 0
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# Node ID 13d5867b039948a79fa80fc2081a17b8089f1ed7
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# Parent 0322427df80a91fdeace25c1508105074dc8adad
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Bug 1673202 - Call fstat directly in Linux sandbox fstatat interception. r=gcp, a=RyanVM
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Sandbox policies handle the case of `fstatat(fd, "", AT_EMPTY_PATH|...)`
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by invoking the SIGSYS handler (because seccomp-bpf can't tell if the
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string will be empty when the syscall would use it), which makes the
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equivalent call to `fstat`.
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Unfortunately, recent development versions of glibc implement `fstat` by
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calling `fstatat`, which causes unbounded recursion and stack overflow.
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(This depends on the headers present at build time; see the bug for more
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details.) This patch switches it to use the `fstat` (or `fstat64` on
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32-bit) syscall directly.
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Differential Revision: https://phabricator.services.mozilla.com/D94798
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diff --git a/security/sandbox/linux/SandboxFilter.cpp b/security/sandbox/linux/SandboxFilter.cpp
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--- a/security/sandbox/linux/SandboxFilter.cpp
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+++ b/security/sandbox/linux/SandboxFilter.cpp
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@@ -241,17 +241,21 @@ class SandboxPolicyCommon : public Sandb
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auto broker = static_cast<SandboxBrokerClient*>(aux);
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auto fd = static_cast<int>(aArgs.args[0]);
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auto path = reinterpret_cast<const char*>(aArgs.args[1]);
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auto buf = reinterpret_cast<statstruct*>(aArgs.args[2]);
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auto flags = static_cast<int>(aArgs.args[3]);
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if (fd != AT_FDCWD && (flags & AT_EMPTY_PATH) != 0 &&
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strcmp(path, "") == 0) {
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- return ConvertError(fstatsyscall(fd, buf));
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+#ifdef __NR_fstat64
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+ return DoSyscall(__NR_fstat64, fd, buf);
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+#else
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+ return DoSyscall(__NR_fstat, fd, buf);
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+#endif
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}
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if (fd != AT_FDCWD && path[0] != '/') {
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SANDBOX_LOG_ERROR("unsupported fd-relative fstatat(%d, \"%s\", %p, %d)",
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fd, path, buf, flags);
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return BlockedSyscallTrap(aArgs, nullptr);
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}
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if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT)) != 0) {
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