103 lines
2.6 KiB
C
103 lines
2.6 KiB
C
/*
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* Copyright (c) 2016 Red Hat, Inc.
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*
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* This program is free software: you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be
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* useful, but WITHOUT ANY WARRANTY; without even the implied
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* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see http://www.gnu.org/licenses/.
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*
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*/
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#include <linux/memfd.h>
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#include <linux/fcntl.h>
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#include <sys/syscall.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <stdio.h>
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#define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); \
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} while (0)
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int main(int argc, char *argv[])
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{
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int fd;
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unsigned int seals;
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char *addr;
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char *name, *seals_arg;
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ssize_t len;
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char* message = "this is a test message for memfd\n";
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if (argc < 3) {
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fprintf(stderr, "%s name size [seals]\n", argv[0]);
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fprintf(stderr, "\t'seals' can contain any of the "
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"following characters:\n");
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fprintf(stderr, "\t\tg - F_SEAL_GROW\n");
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fprintf(stderr, "\t\ts - F_SEAL_SHRINK\n");
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fprintf(stderr, "\t\tw - F_SEAL_WRITE\n");
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fprintf(stderr, "\t\tS - F_SEAL_SEAL\n");
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exit(EXIT_FAILURE);
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}
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name = argv[1];
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len = atoi(argv[2]);
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seals_arg = argv[3];
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/* Create an anonymous file in tmpfs; allow seals to be
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placed on the file */
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fd = syscall(SYS_memfd_create, name, MFD_ALLOW_SEALING);
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if (fd == -1)
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errExit("memfd_create");
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/* Size the file as specified on the command line */
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if (ftruncate(fd, len) == -1)
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errExit("truncate");
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if (write(fd, message, strlen(message)) <= 0)
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errExit("write");
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//printf("PID: %ld; fd: %d; /proc/%ld/fd/%d\n",
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// (long) getpid(), fd, (long) getpid(), fd);
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printf("/proc/%ld/fd/%d\n", (long) getpid(), fd);
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/* Code to map the file and populate the mapping with data
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omitted */
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/* If a 'seals' command-line argument was supplied, set some
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seals on the file */
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if (seals_arg != NULL) {
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seals = 0;
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if (strchr(seals_arg, 'g') != NULL)
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seals |= F_SEAL_GROW;
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if (strchr(seals_arg, 's') != NULL)
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seals |= F_SEAL_SHRINK;
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if (strchr(seals_arg, 'w') != NULL)
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seals |= F_SEAL_WRITE;
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if (strchr(seals_arg, 'S') != NULL)
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seals |= F_SEAL_SEAL;
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if (fcntl(fd, F_ADD_SEALS, seals) == -1)
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errExit("fcntl");
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}
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/* Keep running, so that the file created by memfd_create()
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continues to exist */
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pause();
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exit(EXIT_SUCCESS);
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}
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