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validate env limits in qfile-dom0-unpacker #209

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validate env limits in qfile-dom0-unpacker #209

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32 changes: 28 additions & 4 deletions dom0-updates/qfile-dom0-unpacker.c
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,32 @@
#define min(a,b) ((a) < (b) ? (a) : (b))
#define max(a,b) ((a) > (b) ? (a) : (b))

static long long parse_limit_env(const char *name, long long fallback)
{
const char *value = getenv(name);
if (!value)
return fallback;

if (*value < '0' || *value > '9') {
fprintf(stderr, "Invalid value for %s: %s\n", name, value);
exit(1);
}

errno = 0;
char *end = NULL;
long long limit = strtoll(value, &end, 10);
if (errno == ERANGE || *end != '\0' || limit < 0) {
fprintf(stderr, "Invalid value for %s: %s\n", name, value);
exit(1);
}
if (limit == 0 && strcmp(value, "0") != 0) {
fprintf(stderr, "Invalid value for %s: %s\n", name, value);
exit(1);
}

return limit;
}

int prepare_creds_return_uid(const char *username)
{
struct passwd *pwd;
Expand Down Expand Up @@ -88,10 +114,8 @@ int main(int argc, char ** argv)
perror("Failed to check free space");
}

if ((var=getenv("UPDATES_MAX_BYTES")))
bytes_limit = atoll(var);
if ((var=getenv("UPDATES_MAX_FILES")))
files_limit = atoll(var);
bytes_limit = parse_limit_env("UPDATES_MAX_BYTES", bytes_limit);
files_limit = parse_limit_env("UPDATES_MAX_FILES", files_limit);

set_size_limit(bytes_limit, files_limit);

Expand Down