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Diffstat (limited to 'src/unistd/setxid.c')
-rw-r--r--src/unistd/setxid.c49
1 files changed, 49 insertions, 0 deletions
diff --git a/src/unistd/setxid.c b/src/unistd/setxid.c
new file mode 100644
index 00000000..d3bfaf62
--- /dev/null
+++ b/src/unistd/setxid.c
@@ -0,0 +1,49 @@
+#include <unistd.h>
+#include <errno.h>
+#include <sys/resource.h>
+#include "syscall.h"
+#include "libc.h"
+
+struct ctx {
+ int id, eid, sid;
+ int nr, rlim, err;
+};
+
+/* We jump through hoops to eliminate the possibility of partial failures. */
+
+static void do_setxid(void *p)
+{
+ struct ctx *c = p;
+ if (c->err) return;
+ if (c->rlim && c->id >= 0 && c->id != getuid()) {
+ struct rlimit inf = { RLIM_INFINITY, RLIM_INFINITY }, old;
+ getrlimit(RLIMIT_NPROC, &old);
+ if (setrlimit(RLIMIT_NPROC, &inf) && libc.threads_minus_1) {
+ c->err = errno;
+ return;
+ }
+ if (__syscall(c->nr, c->id, c->eid, c->sid))
+ c->err = errno;
+ setrlimit(RLIMIT_NPROC, &old);
+ return;
+ }
+ if (__syscall(c->nr, c->id, c->eid, c->sid))
+ c->err = errno;
+}
+
+int __setxid(int nr, int id, int eid, int sid)
+{
+ struct ctx c = { .nr = nr, .id = id, .eid = eid, .sid = sid };
+ switch (nr) {
+ case SYS_setuid:
+ case SYS_setreuid:
+ case SYS_setresuid:
+ c.rlim = 1;
+ }
+ __synccall(do_setxid, &c);
+ if (c.err) {
+ errno = c.err;
+ return -1;
+ }
+ return 0;
+}