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https://github.com/morgan9e/systemd
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c1631ee124
This moves the code for setting chattr file attributes appropriate for "secrets" files from journalctl into generic chattr-util.c code so that we can use it elsewhere. Also, let's reuse the "bitwise" logic already implemented in the chattr code, instead of doing it again.
142 lines
4.5 KiB
C
142 lines
4.5 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <sys/stat.h>
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#include <linux/fs.h>
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#include "chattr-util.h"
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#include "errno-util.h"
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#include "fd-util.h"
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#include "macro.h"
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#include "string-util.h"
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int chattr_full(const char *path,
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int fd,
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unsigned value,
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unsigned mask,
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unsigned *ret_previous,
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unsigned *ret_final,
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ChattrApplyFlags flags) {
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_cleanup_close_ int fd_will_close = -1;
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unsigned old_attr, new_attr;
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struct stat st;
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assert(path || fd >= 0);
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if (fd < 0) {
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fd = fd_will_close = open(path, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
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if (fd < 0)
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return -errno;
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}
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if (fstat(fd, &st) < 0)
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return -errno;
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/* Explicitly check whether this is a regular file or directory. If it is anything else (such
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* as a device node or fifo), then the ioctl will not hit the file systems but possibly
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* drivers, where the ioctl might have different effects. Notably, DRM is using the same
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* ioctl() number. */
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if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode))
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return -ENOTTY;
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if (mask == 0 && !ret_previous && !ret_final)
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return 0;
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if (ioctl(fd, FS_IOC_GETFLAGS, &old_attr) < 0)
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return -errno;
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new_attr = (old_attr & ~mask) | (value & mask);
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if (new_attr == old_attr) {
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if (ret_previous)
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*ret_previous = old_attr;
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if (ret_final)
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*ret_final = old_attr;
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return 0;
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}
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if (ioctl(fd, FS_IOC_SETFLAGS, &new_attr) >= 0) {
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if (ret_previous)
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*ret_previous = old_attr;
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if (ret_final)
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*ret_final = new_attr;
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return 1;
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}
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if ((errno != EINVAL && !ERRNO_IS_NOT_SUPPORTED(errno)) ||
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!FLAGS_SET(flags, CHATTR_FALLBACK_BITWISE))
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return -errno;
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/* When -EINVAL is returned, we assume that incompatible attributes are simultaneously
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* specified. E.g., compress(c) and nocow(C) attributes cannot be set to files on btrfs.
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* As a fallback, let's try to set attributes one by one.
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*
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* Also, when we get EOPNOTSUPP (or a similar error code) we assume a flag might just not be
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* supported, and we can ignore it too */
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unsigned current_attr = old_attr;
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for (unsigned i = 0; i < sizeof(unsigned) * 8; i++) {
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unsigned new_one, mask_one = 1u << i;
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if (!FLAGS_SET(mask, mask_one))
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continue;
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new_one = UPDATE_FLAG(current_attr, mask_one, FLAGS_SET(value, mask_one));
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if (new_one == current_attr)
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continue;
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if (ioctl(fd, FS_IOC_SETFLAGS, &new_one) < 0) {
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if (errno != EINVAL && !ERRNO_IS_NOT_SUPPORTED(errno))
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return -errno;
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log_full_errno(FLAGS_SET(flags, CHATTR_WARN_UNSUPPORTED_FLAGS) ? LOG_WARNING : LOG_DEBUG,
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errno,
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"Unable to set file attribute 0x%x on %s, ignoring: %m", mask_one, strna(path));
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continue;
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}
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if (ioctl(fd, FS_IOC_GETFLAGS, ¤t_attr) < 0)
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return -errno;
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}
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if (ret_previous)
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*ret_previous = old_attr;
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if (ret_final)
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*ret_final = current_attr;
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return current_attr == new_attr ? 1 : -ENOANO; /* -ENOANO indicates that some attributes cannot be set. */
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}
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int read_attr_fd(int fd, unsigned *ret) {
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struct stat st;
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assert(fd >= 0);
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if (fstat(fd, &st) < 0)
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return -errno;
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if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode))
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return -ENOTTY;
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if (ioctl(fd, FS_IOC_GETFLAGS, ret) < 0)
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return -errno;
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return 0;
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}
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int read_attr_path(const char *p, unsigned *ret) {
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_cleanup_close_ int fd = -1;
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assert(p);
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assert(ret);
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fd = open(p, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
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if (fd < 0)
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return -errno;
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return read_attr_fd(fd, ret);
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}
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