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Platform BpfLoader: do not support mismatching bpf map/prog struct sizes

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This is not needed, as all platform bpf .o's are built at the same time
(and thus from the same bpf map/prog structure definitions) as
the loader itself.

This effectively undoes much of aosp/1754794
'bpf loader improvements for better long term compatibility with mainline'

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I8cd6865cfb49bb282b2dcff1957dd9826e501da1
This commit is contained in:
Maciej Żenczykowski 2024-03-10 14:37:24 -07:00
parent 97e633a6ea
commit c82f56679a
1 changed files with 14 additions and 64 deletions
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78
libbpf_android/Loader.cpp
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@ -371,33 +371,19 @@ static string getSectionName(enum bpf_prog_type type)
return "UNKNOWN SECTION NAME " + std::to_string(type);
}
static int readProgDefs(ifstream& elfFile, vector<struct bpf_prog_def>& pd,
size_t sizeOfBpfProgDef) {
static int readProgDefs(ifstream& elfFile, vector<struct bpf_prog_def>& pd) {
vector<char> pdData;
int ret = readSectionByName("progs", elfFile, pdData);
if (ret) return ret;
if (pdData.size() % sizeOfBpfProgDef) {
if (pdData.size() % sizeof(struct bpf_prog_def)) {
ALOGE("readProgDefs failed due to improper sized progs section, %zu %% %zu != 0",
pdData.size(), sizeOfBpfProgDef);
pdData.size(), sizeof(struct bpf_prog_def));
return -1;
};
int progCount = pdData.size() / sizeOfBpfProgDef;
pd.resize(progCount);
size_t trimmedSize = std::min(sizeOfBpfProgDef, sizeof(struct bpf_prog_def));
const char* dataPtr = pdData.data();
for (auto& p : pd) {
// First we zero initialize
memset(&p, 0, sizeof(p));
// Then we set non-zero defaults
p.bpfloader_max_ver = DEFAULT_BPFLOADER_MAX_VER; // v1.0
// Then we copy over the structure prefix from the ELF file.
memcpy(&p, dataPtr, trimmedSize);
// Move to next struct in the ELF file
dataPtr += sizeOfBpfProgDef;
}
pd.resize(pdData.size() / sizeof(struct bpf_prog_def));
memcpy(pd.data(), pdData.data(), pdData.size());
return 0;
}
@ -460,7 +446,7 @@ static bool IsAllowed(bpf_prog_type type, const bpf_prog_type* allowed, size_t n
}
/* Read a section by its index - for ex to get sec hdr strtab blob */
static int readCodeSections(ifstream& elfFile, vector<codeSection>& cs, size_t sizeOfBpfProgDef,
static int readCodeSections(ifstream& elfFile, vector<codeSection>& cs,
const bpf_prog_type* allowed, size_t numAllowed) {
vector<Elf64_Shdr> shTable;
int entries, ret = 0;
@ -470,7 +456,7 @@ static int readCodeSections(ifstream& elfFile, vector<codeSection>& cs, size_t s
entries = shTable.size();
vector<struct bpf_prog_def> pd;
ret = readProgDefs(elfFile, pd, sizeOfBpfProgDef);
ret = readProgDefs(elfFile, pd);
if (ret) return ret;
vector<string> progDefNames;
ret = getSectionSymNames(elfFile, "progs", progDefNames);
@ -599,8 +585,7 @@ static bool mapMatchesExpectations(const unique_fd& fd, const string& mapName,
}
static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>& mapFds,
const char* prefix, const unsigned long long allowedDomainBitmask,
const size_t sizeOfBpfMapDef) {
const char* prefix, const unsigned long long allowedDomainBitmask) {
int ret;
vector<char> mdData;
vector<struct bpf_map_def> md;
@ -611,28 +596,13 @@ static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>&
if (ret == -2) return 0; // no maps to read
if (ret) return ret;
if (mdData.size() % sizeOfBpfMapDef) {
if (mdData.size() % sizeof(struct bpf_map_def)) {
ALOGE("createMaps failed due to improper sized maps section, %zu %% %zu != 0",
mdData.size(), sizeOfBpfMapDef);
mdData.size(), sizeof(struct bpf_map_def));
return -1;
};
int mapCount = mdData.size() / sizeOfBpfMapDef;
md.resize(mapCount);
size_t trimmedSize = std::min(sizeOfBpfMapDef, sizeof(struct bpf_map_def));
const char* dataPtr = mdData.data();
for (auto& m : md) {
// First we zero initialize
memset(&m, 0, sizeof(m));
// Then we set non-zero defaults
m.bpfloader_max_ver = DEFAULT_BPFLOADER_MAX_VER; // v1.0
m.max_kver = 0xFFFFFFFFu; // matches KVER_INF from bpf_helpers.h
// Then we copy over the structure prefix from the ELF file.
memcpy(&m, dataPtr, trimmedSize);
// Move to next struct in the ELF file
dataPtr += sizeOfBpfMapDef;
}
md.resize(mdData.size() / sizeof(struct bpf_map_def));
memcpy(md.data(), mdData.data(), mdData.size());
ret = getSectionSymNames(elfFile, "maps", mapNames);
if (ret) return ret;
@ -1048,28 +1018,9 @@ int loadProg(const char* elfPath, bool* isCritical, const Location& location) {
elfPath, (char*)license.data());
}
// the following default values are for bpfloader V0.0 format which does not include them
size_t sizeOfBpfMapDef =
readSectionUint("size_of_bpf_map_def", elfFile, DEFAULT_SIZEOF_BPF_MAP_DEF);
size_t sizeOfBpfProgDef =
readSectionUint("size_of_bpf_prog_def", elfFile, DEFAULT_SIZEOF_BPF_PROG_DEF);
ALOGI("Platform BpfLoader processing ELF object %s", elfPath);
if (sizeOfBpfMapDef < DEFAULT_SIZEOF_BPF_MAP_DEF) {
ALOGE("sizeof(bpf_map_def) of %zu is too small (< %d)", sizeOfBpfMapDef,
DEFAULT_SIZEOF_BPF_MAP_DEF);
return -1;
}
if (sizeOfBpfProgDef < DEFAULT_SIZEOF_BPF_PROG_DEF) {
ALOGE("sizeof(bpf_prog_def) of %zu is too small (< %d)", sizeOfBpfProgDef,
DEFAULT_SIZEOF_BPF_PROG_DEF);
return -1;
}
ret = readCodeSections(elfFile, cs, sizeOfBpfProgDef, location.allowedProgTypes,
location.allowedProgTypesLength);
ret = readCodeSections(elfFile, cs, location.allowedProgTypes, location.allowedProgTypesLength);
if (ret) {
ALOGE("Couldn't read all code sections in %s", elfPath);
return ret;
@ -1078,8 +1029,7 @@ int loadProg(const char* elfPath, bool* isCritical, const Location& location) {
/* Just for future debugging */
if (0) dumpAllCs(cs);
ret = createMaps(elfPath, elfFile, mapFds, location.prefix, location.allowedDomainBitmask,
sizeOfBpfMapDef);
ret = createMaps(elfPath, elfFile, mapFds, location.prefix, location.allowedDomainBitmask);
if (ret) {
ALOGE("Failed to create maps: (ret=%d) in %s", ret, elfPath);
return ret;