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Merge "libcutils: Stop checking the uid of netlink messages"

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Treehugger Robot 2018-01-09 17:35:31 +00:00 • committed by Gerrit Code Review
commit f008571a4f
1 changed files with 0 additions and 53 deletions
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53
libcutils/uevent.cpp
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@ -27,54 +27,6 @@
#include <linux/netlink.h> #include <linux/netlink.h>
#include <fstream>
#include <private/android_filesystem_config.h>
namespace {
// Returns the uid of root in the current user namespace.
// Returns AID_OVERFLOWUID if the root user is not mapped in the current
// namespace.
// Returns 0 if the kernel is not user namespace-aware (for backwards
// compatibility) or if AID_OVERFLOWUID could not be validated to match what the
// kernel would return.
uid_t GetRootUid() {
constexpr uid_t kParentRootUid = 0;
std::ifstream uid_map_file("/proc/self/uid_map");
if (!uid_map_file) {
// The kernel does not support user namespaces.
return kParentRootUid;
}
uid_t current_namespace_uid, parent_namespace_uid;
uint32_t length;
while (uid_map_file >> current_namespace_uid >> parent_namespace_uid >> length) {
// Since kParentRootUid is 0, it should be the first entry in the mapped
// range.
if (parent_namespace_uid != kParentRootUid || length < 1) continue;
return current_namespace_uid;
}
// Sanity check: verify that the overflow UID is the one to be returned by
// the kernel.
std::ifstream overflowuid_file("/proc/sys/kernel/overflowuid");
if (!overflowuid_file) {
// It's better to return 0 in case we cannot make sure that the overflow
// UID matches.
return kParentRootUid;
}
uid_t kernel_overflow_uid;
if (!(overflowuid_file >> kernel_overflow_uid) || kernel_overflow_uid != AID_OVERFLOWUID)
return kParentRootUid;
// root is unmapped, use the kernel "overflow" uid.
return AID_OVERFLOWUID;
}
} // namespace
extern "C" { extern "C" {
/** /**
@ -99,7 +51,6 @@ ssize_t uevent_kernel_multicast_uid_recv(int socket, void* buffer, size_t length
} }
ssize_t uevent_kernel_recv(int socket, void* buffer, size_t length, bool require_group, uid_t* uid) { ssize_t uevent_kernel_recv(int socket, void* buffer, size_t length, bool require_group, uid_t* uid) {
static const uid_t root_uid = GetRootUid();
struct iovec iov = {buffer, length}; struct iovec iov = {buffer, length};
struct sockaddr_nl addr; struct sockaddr_nl addr;
char control[CMSG_SPACE(sizeof(struct ucred))]; char control[CMSG_SPACE(sizeof(struct ucred))];
@ -122,10 +73,6 @@ ssize_t uevent_kernel_recv(int socket, void* buffer, size_t length, bool require
cred = (struct ucred*)CMSG_DATA(cmsg); cred = (struct ucred*)CMSG_DATA(cmsg);
*uid = cred->uid; *uid = cred->uid;
if (cred->uid != root_uid) {
/* ignoring netlink message from non-root user */
goto out;
}
if (addr.nl_pid != 0) { if (addr.nl_pid != 0) {
/* ignore non-kernel */ /* ignore non-kernel */