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Merge pull request #364 from 9elements/feature/pcr0tool_pcr_read
feat(pcr0tool): Add verb `pcrread`
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,79 @@ | ||
package pcrread | ||
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import ( | ||
"context" | ||
"flag" | ||
"fmt" | ||
"log" | ||
"os" | ||
"strconv" | ||
"strings" | ||
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"github.com/google/go-tpm/tpm2" | ||
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"github.com/9elements/converged-security-suite/v2/pkg/bootflow/subsystems/trustchains/tpm/pcr" | ||
"github.com/9elements/converged-security-suite/v2/pkg/tpm" | ||
) | ||
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func assertNoError(err error) { | ||
if err != nil { | ||
log.Fatal(err) | ||
} | ||
} | ||
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func usageAndExit() { | ||
flag.Usage() | ||
os.Exit(2) | ||
} | ||
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// Command is the implementation of `commands.Command`. | ||
type Command struct { | ||
hashAlgo *string | ||
} | ||
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// Usage prints the syntax of arguments for this command | ||
func (cmd Command) Usage() string { | ||
return "<PCR index>" | ||
} | ||
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// Description explains what this verb commands to do | ||
func (cmd Command) Description() string { | ||
return "read the PCR value" | ||
} | ||
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// SetupFlagSet is called to allow the command implementation | ||
// to setup which option flags it has. | ||
func (cmd *Command) SetupFlagSet(flag *flag.FlagSet) { | ||
cmd.hashAlgo = flag.String("hash-algo", tpm2.AlgSHA1.String(), "") | ||
} | ||
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// Execute is the main function here. It is responsible to | ||
// start the execution of the command. | ||
// | ||
// `args` are the arguments left unused by verb itself and options. | ||
func (cmd Command) Execute(ctx context.Context, args []string) { | ||
if len(args) < 1 { | ||
_, _ = fmt.Fprintf(flag.CommandLine.Output(), "error: no PCR index is specified\n") | ||
usageAndExit() | ||
} | ||
if len(args) > 1 { | ||
_, _ = fmt.Fprintf(flag.CommandLine.Output(), "error: too many parameters\n") | ||
usageAndExit() | ||
} | ||
pcrIndexString := args[0] | ||
pcrIndex, err := strconv.ParseUint(pcrIndexString, 10, 64) | ||
assertNoError(err) | ||
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hashAlgo := tpm2.AlgUnknown | ||
for _, alg := range []tpm2.Algorithm{tpm2.AlgSHA1, tpm2.AlgSHA256} { | ||
if strings.EqualFold(*cmd.hashAlgo, alg.String()) { | ||
hashAlgo = alg | ||
} | ||
} | ||
if hashAlgo == tpm2.AlgUnknown { | ||
log.Fatalf("algo '%s' is unknown", *cmd.hashAlgo) | ||
} | ||
pcr, err := tpm.ReadPCRFromTPM(pcr.ID(pcrIndex), hashAlgo) | ||
assertNoError(err) | ||
fmt.Printf("%X\n", pcr) | ||
} |
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