35 lines
901 B
C
35 lines
901 B
C
#include <unistd.h>
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#include <signal.h>
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#include "syscall.h"
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#include "libc.h"
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struct ctx {
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int id, eid, sid;
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int nr, ret;
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};
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static void do_setxid(void *p)
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{
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struct ctx *c = p;
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if (c->ret<0) return;
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int ret = __syscall(c->nr, c->id, c->eid, c->sid);
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if (ret && !c->ret) {
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/* If one thread fails to set ids after another has already
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* succeeded, forcibly killing the process is the only safe
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* thing to do. State is inconsistent and dangerous. Use
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* SIGKILL because it is uncatchable. */
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__block_all_sigs(0);
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__syscall(SYS_kill, __syscall(SYS_getpid), SIGKILL);
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}
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c->ret = ret;
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}
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int __setxid(int nr, int id, int eid, int sid)
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{
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/* ret is initially nonzero so that failure of the first thread does not
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* trigger the safety kill above. */
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struct ctx c = { .nr = nr, .id = id, .eid = eid, .sid = sid, .ret = 1 };
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__synccall(do_setxid, &c);
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return __syscall_ret(c.ret);
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}
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