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Always write "diskseq" entry
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Even if the kernel will ignore it, it is better to write the entry
anyway, and to leave the format of "physical-device" unchanged.  This
makes the code much simpler, as far less depends on old vs new kernel
behavior.
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@DemiMarie
DemiMarie committed Mar 11, 2023
1 parent c25e4ed commit 94066d9
Showing 1 changed file with 52 additions and 43 deletions.
95 changes: 52 additions & 43 deletions not-script/not-script.c
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Original file line number Diff line number Diff line change
Expand Up @@ -271,10 +271,9 @@ static bool get_opened(struct xs_handle *const h,
}

static void remove_device(struct xs_handle *const h, char *xenstore_path_buffer,
char *extra_path, bool autoclear)
char *extra_path)
{
char *physdev, *end_path, *diskseq_str;
unsigned int path_len, diskseq_len;
char *end_path;
int loop_control_fd, loop_fd;
uint64_t actual_diskseq, expected_diskseq;
uint64_t _major, _minor;
Expand All @@ -283,43 +282,49 @@ static void remove_device(struct xs_handle *const h, char *xenstore_path_buffer,
* Order matters here: the kernel only cares about "physical-device" for
* now, so ensure that it gets removed first.
*/
APPEND_TO_XENSTORE_PATH(extra_path, "physical-device");
physdev = xs_read(h, 0, xenstore_path_buffer, &path_len);
if (physdev == NULL) {
err(1, "Cannot obtain physical device from XenStore path %s", xenstore_path_buffer);
}
{
APPEND_TO_XENSTORE_PATH(extra_path, "physical-device");
unsigned int path_len;
char *physdev = xs_read(h, 0, xenstore_path_buffer, &path_len);
if (physdev == NULL) {
err(1, "Cannot obtain physical device from XenStore path %s", xenstore_path_buffer);
}

if (!xs_rm(h, 0, xenstore_path_buffer)) {
err(1, "xs_rm(\"%s\")", xenstore_path_buffer);
}

if (!xs_rm(h, 0, xenstore_path_buffer))
err(1, "xs_rm(\"%s\")", xenstore_path_buffer);
if ((!strict_strtoul_hex(end_path, &end_path, ':', &_major, UINT32_MAX)) ||
(!strict_strtoul_hex(end_path + 1, &end_path, '\0', &_minor, UINT32_MAX)) ||
(end_path != physdev + path_len))
{
errx(1, "Bad physical device value %s", physdev);
}
free(physdev);
}

if (autoclear) {
if (!strict_strtoul_hex(physdev, &end_path, '@', &expected_diskseq, UINT64_MAX))
goto bad_physdev;
end_path++;
} else {
{
APPEND_TO_XENSTORE_PATH(extra_path, "diskseq");
diskseq_str = xs_read(h, 0, xenstore_path_buffer, &diskseq_len);
unsigned int diskseq_len;
char *diskseq_str = xs_read(h, 0, xenstore_path_buffer, &diskseq_len);
if (diskseq_str == NULL) {
err(1, "Cannot obtain diskseq from XenStore path %s", xenstore_path_buffer);
}

if (!xs_rm(h, 0, xenstore_path_buffer))
if (!xs_rm(h, 0, xenstore_path_buffer)) {
err(1, "xs_rm(\"%s\")", xenstore_path_buffer);
}

if (!strict_strtoul_hex(diskseq_str, &end_path, '\0', &expected_diskseq, UINT64_MAX))
if ((!strict_strtoul_hex(diskseq_str, &end_path, '\0', &expected_diskseq, UINT64_MAX)) ||
(end_path != diskseq_str + diskseq_len))
{
errx(1, "Bad diskseq %s", diskseq_str);
end_path = physdev;
}
free(diskseq_str);
}

errno = 0;

if ((!strict_strtoul_hex(end_path, &end_path, ':', &_major, UINT32_MAX)) ||
(!strict_strtoul_hex(end_path + 1, &end_path, '\0', &_minor, UINT32_MAX)) ||
(end_path != physdev + path_len)) {
goto bad_physdev;
}

if (_major != LOOP_MAJOR)
return; /* Not a loop device */

Expand Down Expand Up @@ -362,8 +367,6 @@ static void remove_device(struct xs_handle *const h, char *xenstore_path_buffer,
err(1, "close(\"/dev/loop-control\")");

return;
bad_physdev:
errx(1, "Bad physical device value %s", physdev);
}


Expand Down Expand Up @@ -437,16 +440,17 @@ int main(int argc, char **argv)
xenstore_path_buffer[xs_path_len] = '/';
/* Buffer to copy extra data into */
char *const extra_path = xenstore_path_buffer + xs_path_len + 1;
unsigned int len, path_len;
APPEND_TO_XENSTORE_PATH(extra_path, OPENED_KEY);
bool const autoclear = get_opened(h, xenstore_path_buffer,
action == REMOVE ? '1' : '0');

if (action == REMOVE) {
remove_device(h, xenstore_path_buffer, extra_path, autoclear);
remove_device(h, xenstore_path_buffer, extra_path);
return 0;
}

unsigned int path_len;
APPEND_TO_XENSTORE_PATH(extra_path, OPENED_KEY);
bool const autoclear = getenv("QUBES_EXPERIMENTAL_XENSTORE_UAPI") ?
get_opened(h, xenstore_path_buffer, action == REMOVE ? '1' : '0') : false;

APPEND_TO_XENSTORE_PATH(extra_path, "params");
char *data = xs_read(h, 0, xenstore_path_buffer, &path_len);
if (data == NULL)
Expand All @@ -462,6 +466,7 @@ int main(int argc, char **argv)

{
APPEND_TO_XENSTORE_PATH(extra_path, "mode");
unsigned int len;
char *rw = xs_read(h, 0, xenstore_path_buffer, &len);
if (rw == NULL) {
if (errno != ENOENT)
Expand Down Expand Up @@ -491,18 +496,22 @@ int main(int argc, char **argv)

if ((fd = open(data, (writable ? O_RDWR : O_RDONLY) | O_NOCTTY | O_CLOEXEC | O_NONBLOCK)) < 0)
err(1, "open(%s)", data);
char phys_dev[16 + 8 + 8 + 2 + 1];
// Both major and minor are 8 hex digits, while colon and NUL
// terminator are one byte each.
char phys_dev[18];
char hex_diskseq[17];

process_blk_dev(fd, data, writable, &dev, &diskseq, autoclear);
unsigned const int l =
(unsigned)(autoclear ?
snprintf(phys_dev, sizeof phys_dev, "%" PRIx64 "@%lx:%lx",
diskseq, (unsigned long)major(dev), (unsigned long)minor(dev)) :
snprintf(phys_dev, sizeof phys_dev, "%lx:%lx",
(unsigned long)major(dev), (unsigned long)minor(dev)));

int const physdev_len =
snprintf(phys_dev, sizeof phys_dev, "%lx:%lx",
(unsigned long)major(dev), (unsigned long)minor(dev));
if (physdev_len < 3 || physdev_len >= (int)sizeof(phys_dev))
err(1, "snprintf");

if (l >= sizeof(phys_dev))
int const diskseq_len =
snprintf(hex_diskseq, sizeof(hex_diskseq), "%llx",
(unsigned long long)diskseq);
if (diskseq_len < 1 || diskseq_len >= (int)sizeof(hex_diskseq))
err(1, "snprintf");

if (autoclear) {
Expand All @@ -517,14 +526,14 @@ int main(int argc, char **argv)
err(1, "Cannot start XenStore transaction");

APPEND_TO_XENSTORE_PATH(extra_path, "physical-device");
if (!xs_write(h, t, xenstore_path_buffer, phys_dev, l))
if (!xs_write(h, t, xenstore_path_buffer, phys_dev, physdev_len))
err(1, "xs_write(\"%s\", \"%s\")", xenstore_path_buffer, phys_dev);

APPEND_TO_XENSTORE_PATH(extra_path, "physical-device-path");
if (!xs_write(h, t, xenstore_path_buffer, data, path_len))
err(1, "xs_write(\"%s\", \"%s\")", xenstore_path_buffer, data);

if (!autoclear) {
{
char hex_diskseq[17];
int diskseq_len =
snprintf(hex_diskseq, sizeof(hex_diskseq), "%llx",
Expand Down

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