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user-util: add get{pw,gr}{uid,gid,name}_malloc() helpers

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These are wrappers around getpwuid_r() and friends, and will allocate the
right-sized buffer for this call.

We so far had multiple implementations of a buffer allocation loop
around getpwuid_r() and friends, and they all suck in some way. Let's
clean this up and add a common implementation, and use it everywhere.

Also, be more careful with error numbers, in particular systematically
turn ENOENT into ENOSRCH (the former is what is returned if /etc/passwd
is absent, which we want to consider identical to user not existing,
which is ENOSRCH). We so far did this at some invocations, but not all.

There are some invocations of getpwuid() left in the codebase. We really
should fix those too, and have a single unified implementation of the
logic, but those are not as trivial to convert, so left for another
time.
This commit is contained in:
Lennart Poettering
2024-01-22 17:55:07 +01:00
parent 829854afa5
commit 75673cd8ae
10 changed files with 311 additions and 255 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/core/dynamic-user.c
+12 -17
View File
@@ -293,8 +293,8 @@ static int pick_uid(char **suggested_paths, const char *name, uid_t *ret_uid) {
}
/* Some superficial check whether this UID/GID might already be taken by some static user */
if (getpwuid(candidate) ||
getgrgid((gid_t) candidate) ||
if (getpwuid_malloc(candidate, /* ret= */ NULL) >= 0 ||
getgrgid_malloc((gid_t) candidate, /* ret= */ NULL) >= 0 ||
search_ipc(candidate, (gid_t) candidate) != 0) {
(void) unlink(lock_path);
continue;
@@ -417,30 +417,26 @@ static int dynamic_user_realize(
/* First, let's parse this as numeric UID */
r = parse_uid(d->name, &num);
if (r < 0) {
struct passwd *p;
struct group *g;
_cleanup_free_ struct passwd *p = NULL;
_cleanup_free_ struct group *g = NULL;
if (is_user) {
/* OK, this is not a numeric UID. Let's see if there's a user by this name */
p = getpwnam(d->name);
if (p) {
if (getpwnam_malloc(d->name, &p) >= 0) {
num = p->pw_uid;
gid = p->pw_gid;
} else {
/* if the user does not exist but the group with the same name exists, refuse operation */
g = getgrnam(d->name);
if (g)
if (getgrnam_malloc(d->name, /* ret= */ NULL) >= 0)
return -EILSEQ;
}
} else {
/* Let's see if there's a group by this name */
g = getgrnam(d->name);
if (g)
if (getgrnam_malloc(d->name, &g) >= 0)
num = (uid_t) g->gr_gid;
else {
/* if the group does not exist but the user with the same name exists, refuse operation */
p = getpwnam(d->name);
if (p)
if (getpwnam_malloc(d->name, /* ret= */ NULL) >= 0)
return -EILSEQ;
}
}
@@ -482,13 +478,12 @@ static int dynamic_user_realize(
uid_lock_fd = new_uid_lock_fd;
}
} else if (is_user && !uid_is_dynamic(num)) {
struct passwd *p;
_cleanup_free_ struct passwd *p = NULL;
/* Statically allocated user may have different uid and gid. So, let's obtain the gid. */
errno = 0;
p = getpwuid(num);
if (!p)
return errno_or_else(ESRCH);
r = getpwuid_malloc(num, &p);
if (r < 0)
return r;
gid = p->pw_gid;
}