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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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e7749f1
validate env limits in qfile-dom0-unpacker
rishi-jat Apr 26, 2026
3cc072c
improve validation error messages
rishi-jat Jun 14, 2026
f553089
qfile-dom0-unpacker: use shared integer parsing helper
rishi-jat Jun 17, 2026
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2 changes: 1 addition & 1 deletion dom0-updates/Makefile
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
CC=gcc
CFLAGS=-g -I. -Wall -Wextra -Werror -fPIC -pie
qfile-dom0-unpacker: qfile-dom0-unpacker.o
$(CC) -pie -g -o $@ $^ -lqubes-rpc-filecopy
$(CC) -pie -g -o $@ $^ -lqubes-rpc-filecopy -lqubes-pure
27 changes: 23 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 @@ -12,13 +12,34 @@
#include <errno.h>
#include <limits.h>
#include <libqubes-rpc-filecopy.h>
#include <qubes/pure.h>

#define DEFAULT_MAX_UPDATES_BYTES (4LL<<30)
#define DEFAULT_MAX_UPDATES_FILES 4096

#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;

long long limit;
int rc = qubes_pure_parse_nonneg_ll(value, &limit);
if (rc == -ERANGE) {
fprintf(stderr, "Invalid value for %s: %s: out of range\n", name, value);
exit(1);
}
if (rc != 0) {
fprintf(stderr, "Invalid value for %s: %s: not a valid non-negative integer\n", name, value);
exit(1);
}

return limit;
}

int prepare_creds_return_uid(const char *username)
{
struct passwd *pwd;
Expand Down Expand Up @@ -88,10 +109,8 @@ 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