[352] | 1 | #include <unistd.h>
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| 2 | #include <fcntl.h>
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| 3 | #include <errno.h>
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| 4 | #include <sys/wait.h>
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| 5 | #include "syscall.h"
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| 6 | #include "pthread_impl.h"
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| 7 |
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| 8 | struct ctx {
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| 9 | int fd;
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| 10 | const char *filename;
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| 11 | int amode;
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| 12 | };
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| 13 |
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| 14 | static const int errors[] = {
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| 15 | 0, -EACCES, -ELOOP, -ENAMETOOLONG, -ENOENT, -ENOTDIR,
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| 16 | -EROFS, -EBADF, -EINVAL, -ETXTBSY,
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| 17 | -EFAULT, -EIO, -ENOMEM,
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| 18 | -EBUSY
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| 19 | };
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| 20 |
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| 21 | static int checker(void *p)
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| 22 | {
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| 23 | struct ctx *c = p;
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| 24 | int ret;
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| 25 | int i;
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| 26 | if (__syscall(SYS_setregid, __syscall(SYS_getegid), -1)
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| 27 | || __syscall(SYS_setreuid, __syscall(SYS_geteuid), -1))
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| 28 | __syscall(SYS_exit, 1);
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| 29 | ret = __syscall(SYS_faccessat, c->fd, c->filename, c->amode, 0);
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| 30 | for (i=0; i < sizeof errors/sizeof *errors - 1 && ret!=errors[i]; i++);
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| 31 | return i;
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| 32 | }
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| 33 |
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| 34 | int faccessat(int fd, const char *filename, int amode, int flag)
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| 35 | {
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| 36 | if (!flag || (flag==AT_EACCESS && getuid()==geteuid() && getgid()==getegid()))
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| 37 | return syscall(SYS_faccessat, fd, filename, amode, flag);
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| 38 |
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| 39 | if (flag != AT_EACCESS)
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| 40 | return __syscall_ret(-EINVAL);
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| 41 |
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| 42 | char stack[1024];
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| 43 | sigset_t set;
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| 44 | pid_t pid;
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| 45 | int ret = -EBUSY;
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| 46 | struct ctx c = { .fd = fd, .filename = filename, .amode = amode };
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| 47 |
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| 48 | __block_all_sigs(&set);
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| 49 |
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| 50 | pid = __clone(checker, stack+sizeof stack, 0, &c);
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| 51 | if (pid > 0) {
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| 52 | int status;
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| 53 | do {
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| 54 | __syscall(SYS_wait4, pid, &status, __WCLONE, 0);
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| 55 | } while (!WIFEXITED(status) && !WIFSIGNALED(status));
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| 56 | if (WIFEXITED(status))
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| 57 | ret = errors[WEXITSTATUS(status)];
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| 58 | }
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| 59 |
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| 60 | __restore_sigs(&set);
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| 61 |
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| 62 | return __syscall_ret(ret);
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| 63 | }
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