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ed8b0de5a3
"rm -rf" is bricking some peoples' laptops because of variables being used to store non-reinitializable firmware driver data that's required to POST the hardware. These are 100% bugs, and they need to be fixed, but in the mean time it shouldn't be easy to *accidentally* brick machines. We have to have delete working, and picking which variables do and don't work for deletion is quite intractable, so instead make everything immutable by default (except for a whitelist), and make tools that aren't quite so broad-spectrum unset the immutable flag. Signed-off-by: Peter Jones <pjones@redhat.com> Tested-by: Lee, Chun-Yi <jlee@suse.com> Acked-by: Matthew Garrett <mjg59@coreos.com> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
134 lines
2.2 KiB
C
134 lines
2.2 KiB
C
#include <errno.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/ioctl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <linux/fs.h>
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static int set_immutable(const char *path, int immutable)
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{
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unsigned int flags;
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int fd;
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int rc;
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int error;
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fd = open(path, O_RDONLY);
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if (fd < 0)
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return fd;
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rc = ioctl(fd, FS_IOC_GETFLAGS, &flags);
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if (rc < 0) {
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error = errno;
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close(fd);
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errno = error;
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return rc;
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}
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if (immutable)
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flags |= FS_IMMUTABLE_FL;
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else
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flags &= ~FS_IMMUTABLE_FL;
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rc = ioctl(fd, FS_IOC_SETFLAGS, &flags);
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error = errno;
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close(fd);
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errno = error;
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return rc;
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}
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static int get_immutable(const char *path)
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{
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unsigned int flags;
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int fd;
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int rc;
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int error;
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fd = open(path, O_RDONLY);
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if (fd < 0)
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return fd;
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rc = ioctl(fd, FS_IOC_GETFLAGS, &flags);
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if (rc < 0) {
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error = errno;
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close(fd);
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errno = error;
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return rc;
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}
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close(fd);
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if (flags & FS_IMMUTABLE_FL)
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return 1;
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return 0;
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}
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int main(int argc, char **argv)
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{
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const char *path;
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char buf[5];
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int fd, rc;
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if (argc < 2) {
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fprintf(stderr, "usage: %s <path>\n", argv[0]);
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return EXIT_FAILURE;
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}
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path = argv[1];
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/* attributes: EFI_VARIABLE_NON_VOLATILE |
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* EFI_VARIABLE_BOOTSERVICE_ACCESS |
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* EFI_VARIABLE_RUNTIME_ACCESS
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*/
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*(uint32_t *)buf = 0x7;
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buf[4] = 0;
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/* create a test variable */
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fd = open(path, O_WRONLY | O_CREAT, 0600);
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if (fd < 0) {
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perror("open(O_WRONLY)");
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return EXIT_FAILURE;
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}
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rc = write(fd, buf, sizeof(buf));
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if (rc != sizeof(buf)) {
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perror("write");
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return EXIT_FAILURE;
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}
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close(fd);
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rc = get_immutable(path);
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if (rc < 0) {
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perror("ioctl(FS_IOC_GETFLAGS)");
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return EXIT_FAILURE;
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} else if (rc) {
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rc = set_immutable(path, 0);
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if (rc < 0) {
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perror("ioctl(FS_IOC_SETFLAGS)");
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return EXIT_FAILURE;
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}
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}
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fd = open(path, O_RDONLY);
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if (fd < 0) {
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perror("open");
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return EXIT_FAILURE;
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}
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if (unlink(path) < 0) {
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perror("unlink");
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return EXIT_FAILURE;
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}
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rc = read(fd, buf, sizeof(buf));
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if (rc > 0) {
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fprintf(stderr, "reading from an unlinked variable "
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"shouldn't be possible\n");
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return EXIT_FAILURE;
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}
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return EXIT_SUCCESS;
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}
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