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gh-94518: [_posixsubprocess] Replace variable validity flags with reserved values #94687

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Merged
merged 14 commits into from
Jan 14, 2023
Merged

gh-94518: [_posixsubprocess] Replace variable validity flags with reserved values #94687

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1b3250e
Replace call_setgid/call_setuid in _posixsubprocess with gid/uid==-1
arhadthedev Jul 8, 2022
c292331
Merge branch 'main' into posixsubprocess-no-callsetxid
arhadthedev Jul 22, 2022
7d431a3
Add a NEWS entry
arhadthedev Jul 22, 2022
06f2a01
Address Gregory's review in gh-94519
arhadthedev Jul 26, 2022
aaec16e
Use negative groups_size for "don't call setgroups"
arhadthedev Jul 27, 2022
c9bf4f6
Check num_groups for emptiness, not groups_list
arhadthedev Jul 27, 2022
069d769
Restore assertions in do_fork_exec()
arhadthedev Jul 27, 2022
6a236e5
Tighten scope of relevant short lived variables
arhadthedev Jul 27, 2022
8c06be1
Fix `PermissionError: [Errno 1] Operation not permitted` exception
arhadthedev Jul 27, 2022
3ccdb78
Merge branch 'main' into posixsubprocess-no-callsetxid
arhadthedev Oct 6, 2022
d3c0e6c
Merge branch 'main' into posixsubprocess-no-callsetxid
arhadthedev Oct 29, 2022
cfdf639
Merge branch 'main' into posixsubprocess-no-callsetxid
arhadthedev Nov 14, 2022
0e997c0
Merge branch 'main' into posixsubprocess-no-callsetxid
arhadthedev Nov 29, 2022
66c836b
Merge branch 'main' into posixsubprocess-no-callsetxid
arhadthedev Jan 14, 2023
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Use negative groups_size for "don't call setgroups" 
When we query `groups_list` size using `PySequence_Size()`, we get -1
for non-lists. It returns an ability to pass an empty list to
`setgroups()` that is valid but treated as a no-op:

> If `size` is zero, `list` is not modified, but the total number of
> supplementary group IDs for the process is returned. This allows the
> caller to determine the size of a dynamically allocated list to be
> used in a further call to getgroups().
>
> - <https://linux.die.net/man/2/setgroups>
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@arhadthedev
arhadthedev committed Jul 27, 2022
commit aaec16efae3da5bf3d3e78eb7355d34f39e86fb8
18 changes: 11 additions & 7 deletions Modules/_posixsubprocess.c
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Original file line number Diff line number Diff line change
Expand Up @@ -519,7 +519,7 @@ child_exec(char *const exec_array[],
int close_fds, int restore_signals,
int call_setsid, pid_t pgid_to_set,
gid_t gid,
size_t groups_size, const gid_t *groups,
Py_ssize_t groups_size, const gid_t *groups,
uid_t uid, int child_umask,
const void *child_sigmask,
PyObject *py_fds_to_keep,
Expand Down Expand Up @@ -619,7 +619,7 @@ child_exec(char *const exec_array[],
#endif

#ifdef HAVE_SETGROUPS
if (groups)
if (groups_size >= 0)
POSIX_CALL(setgroups(groups_size, groups));
#endif /* HAVE_SETGROUPS */

Expand Down Expand Up @@ -725,7 +725,7 @@ do_fork_exec(char *const exec_array[],
int close_fds, int restore_signals,
int call_setsid, pid_t pgid_to_set,
gid_t gid,
size_t groups_size, const gid_t *groups,
Py_ssize_t groups_size, const gid_t *groups,
uid_t uid, int child_umask,
const void *child_sigmask,
PyObject *py_fds_to_keep,
Expand Down Expand Up @@ -920,10 +920,14 @@ subprocess_fork_exec(PyObject *module, PyObject *args)
goto cleanup;
}

if ((groups = PyMem_RawMalloc(num_groups * sizeof(gid_t))) == NULL) {
PyErr_SetString(PyExc_MemoryError,
"failed to allocate memory for group list");
goto cleanup;
/* Deliberately keep groups == NULL for num_groups == 0 */
if (num_groups > 0) {
groups = PyMem_RawMalloc(num_groups * sizeof(gid_t));
if (groups == NULL) {
PyErr_SetString(PyExc_MemoryError,
"failed to allocate memory for group list");
goto cleanup;
}
}

for (i = 0; i < num_groups; i++) {
Expand Down