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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include "alloc-util.h"
#include "errno-util.h"
#include "fd-util.h"
#include "format-util.h"
#include "macro.h"
#include "path-util.h"
#include "sort-util.h"
#include "stat-util.h"
#include "uid-range.h"
#include "user-util.h"
UidRange *uid_range_free(UidRange *range) {
if (!range)
return NULL;
free(range->entries);
return mfree(range);
}
static bool uid_range_entry_intersect(const UidRangeEntry *a, const UidRangeEntry *b) {
assert(a);
assert(b);
return a->start <= b->start + b->nr && a->start + a->nr >= b->start;
}
static int uid_range_entry_compare(const UidRangeEntry *a, const UidRangeEntry *b) {
int r;
assert(a);
assert(b);
r = CMP(a->start, b->start);
if (r != 0)
return r;
return CMP(a->nr, b->nr);
}
static void uid_range_coalesce(UidRange *range) {
assert(range);
if (range->n_entries <= 0)
return;
typesafe_qsort(range->entries, range->n_entries, uid_range_entry_compare);
for (size_t i = 0; i < range->n_entries; i++) {
UidRangeEntry *x = range->entries + i;
for (size_t j = i + 1; j < range->n_entries; j++) {
UidRangeEntry *y = range->entries + j;
uid_t begin, end;
if (!uid_range_entry_intersect(x, y))
break;
begin = MIN(x->start, y->start);
end = MAX(x->start + x->nr, y->start + y->nr);
x->start = begin;
x->nr = end - begin;
if (range->n_entries > j + 1)
memmove(y, y + 1, sizeof(UidRangeEntry) * (range->n_entries - j - 1));
range->n_entries--;
j--;
}
}
}
int uid_range_add_internal(UidRange **range, uid_t start, uid_t nr, bool coalesce) {
_cleanup_(uid_range_freep) UidRange *range_new = NULL;
UidRange *p;
assert(range);
if (nr <= 0)
return 0;
if (start > UINT32_MAX - nr) /* overflow check */
return -ERANGE;
if (*range)
p = *range;
else {
range_new = new0(UidRange, 1);
if (!range_new)
return -ENOMEM;
p = range_new;
}
if (!GREEDY_REALLOC(p->entries, p->n_entries + 1))
return -ENOMEM;
p->entries[p->n_entries++] = (UidRangeEntry) {
.start = start,
.nr = nr,
};
if (coalesce)
uid_range_coalesce(p);
TAKE_PTR(range_new);
*range = p;
return 0;
}
int uid_range_add_str(UidRange **range, const char *s) {
uid_t start, end;
int r;
assert(range);
assert(s);
r = parse_uid_range(s, &start, &end);
if (r < 0)
return r;
return uid_range_add_internal(range, start, end - start + 1, /* coalesce = */ true);
}
int uid_range_next_lower(const UidRange *range, uid_t *uid) {
uid_t closest = UID_INVALID, candidate;
assert(range);
assert(uid);
if (*uid == 0)
return -EBUSY;
candidate = *uid - 1;
for (size_t i = 0; i < range->n_entries; i++) {
uid_t begin, end;
begin = range->entries[i].start;
end = range->entries[i].start + range->entries[i].nr - 1;
if (candidate >= begin && candidate <= end) {
*uid = candidate;
return 1;
}
if (end < candidate)
closest = end;
}
if (closest == UID_INVALID)
return -EBUSY;
*uid = closest;
return 1;
}
bool uid_range_covers(const UidRange *range, uid_t start, uid_t nr) {
if (nr == 0) /* empty range? always covered... */
return true;
if (start > UINT32_MAX - nr) /* range overflows? definitely not covered... */
return false;
if (!range)
return false;
for (size_t i = 0; i < range->n_entries; i++)
if (start >= range->entries[i].start &&
start + nr <= range->entries[i].start + range->entries[i].nr)
return true;
return false;
}
int uid_range_load_userns(UidRange **ret, const char *path) {
_cleanup_(uid_range_freep) UidRange *range = NULL;
_cleanup_fclose_ FILE *f = NULL;
int r;
/* If 'path' is NULL loads the UID range of the userns namespace we run. Otherwise load the data from
* the specified file (which can be either uid_map or gid_map, in case caller needs to deal with GID
* maps).
*
* To simplify things this will modify the passed array in case of later failure. */
assert(ret);
if (!path)
path = "/proc/self/uid_map";
f = fopen(path, "re");
if (!f) {
r = -errno;
if (r == -ENOENT && path_startswith(path, "/proc/"))
return proc_mounted() > 0 ? -EOPNOTSUPP : -ENOSYS;
return r;
}
range = new0(UidRange, 1);
if (!range)
return -ENOMEM;
for (;;) {
uid_t uid_base, uid_shift, uid_range;
int k;
errno = 0;
k = fscanf(f, UID_FMT " " UID_FMT " " UID_FMT "\n", &uid_base, &uid_shift, &uid_range);
if (k == EOF) {
if (ferror(f))
return errno_or_else(EIO);
break;
}
if (k != 3)
return -EBADMSG;
r = uid_range_add_internal(&range, uid_base, uid_range, /* coalesce = */ false);
if (r < 0)
return r;
}
uid_range_coalesce(range);
*ret = TAKE_PTR(range);
return 0;
}
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