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Cache vdso.so's __kernel_rt_sigreturn location. 

PiperOrigin-RevId: 394300607
This commit is contained in:
Jamie Liu 2021-09-01 13:21:40 -07:00 committed by gVisor bot
parent 5da4270a88
commit 702fe7d60d
2 changed files with 19 additions and 31 deletions
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10
pkg/sentry/loader/loader.go
View File

@ -295,15 +295,7 @@ func Load(ctx context.Context, args LoadArgs, extraAuxv []arch.AuxEntry, vdso *V
m.SetEnvvEnd(sl.EnvvEnd)
m.SetAuxv(auxv)
m.SetExecutable(ctx, file)
symbolValue, err := getSymbolValueFromVDSO("rt_sigreturn")
if err != nil {
return 0, nil, "", syserr.NewDynamic(fmt.Sprintf("Failed to find rt_sigreturn in vdso: %v", err), syserr.FromError(err).ToLinux())
}
// Found rt_sigretrun.
addr := uint64(vdsoAddr) + symbolValue - vdsoPrelink
m.SetVDSOSigReturn(addr)
m.SetVDSOSigReturn(uint64(vdsoAddr) + vdsoSigreturnOffset - vdsoPrelink)
ac.SetIP(uintptr(loaded.entry))
ac.SetStack(uintptr(stack.Bottom))

40
pkg/sentry/loader/vdso.go
View File

@ -19,7 +19,6 @@ import (
"debug/elf"
"fmt"
"io"
"strings"
"gvisor.dev/gvisor/pkg/abi"
"gvisor.dev/gvisor/pkg/context"
@ -177,27 +176,6 @@ type VDSO struct {
phdrs []elf.ProgHeader `state:".([]elfProgHeader)"`
}
// getSymbolValueFromVDSO returns the specific symbol value in vdso.so.
func getSymbolValueFromVDSO(symbol string) (uint64, error) {
f, err := elf.NewFile(bytes.NewReader(vdsodata.Binary))
if err != nil {
return 0, err
}
syms, err := f.Symbols()
if err != nil {
return 0, err
}
for _, sym := range syms {
if elf.ST_BIND(sym.Info) != elf.STB_LOCAL && sym.Section != elf.SHN_UNDEF {
if strings.Contains(sym.Name, symbol) {
return sym.Value, nil
}
}
}
return 0, fmt.Errorf("no %v in vdso.so", symbol)
}
// PrepareVDSO validates the system VDSO and returns a VDSO, containing the
// param page for updating by the kernel.
func PrepareVDSO(mfp pgalloc.MemoryFileProvider) (*VDSO, error) {
@ -388,3 +366,21 @@ func (v *VDSO) Release(ctx context.Context) {
v.ParamPage.DecRef(ctx)
v.vdso.DecRef(ctx)
}
var vdsoSigreturnOffset = func() uint64 {
f, err := elf.NewFile(bytes.NewReader(vdsodata.Binary))
if err != nil {
panic(fmt.Sprintf("failed to parse vdso.so as ELF file: %v", err))
}
syms, err := f.Symbols()
if err != nil {
panic(fmt.Sprintf("failed to read symbols from vdso.so: %v", err))
}
const sigreturnSymbol = "__kernel_rt_sigreturn"
for _, sym := range syms {
if elf.ST_BIND(sym.Info) != elf.STB_LOCAL && sym.Section != elf.SHN_UNDEF && sym.Name == sigreturnSymbol {
return sym.Value
}
}
panic(fmt.Sprintf("no symbol %q in vdso.so", sigreturnSymbol))
}()