375 lines
11 KiB
Diff
375 lines
11 KiB
Diff
From: Stefan Hajnoczi <stefanha@redhat.com>
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Date: Mon, 27 Jan 2020 19:01:26 +0000
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Subject: [PATCH] virtiofsd: use /proc/self/fd/ O_PATH file descriptor
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Sandboxing will remove /proc from the mount namespace so we can no
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longer build string paths into "/proc/self/fd/...".
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Keep an O_PATH file descriptor so we can still re-open fds via
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/proc/self/fd.
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit 9f59d175e2ca96f0b87f534dba69ea547dd35945)
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---
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tools/virtiofsd/passthrough_ll.c | 130 ++++++++++++++++++++++++-------
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1 file changed, 103 insertions(+), 27 deletions(-)
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diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
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index e3d65c3676..e2e2211ea1 100644
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--- a/tools/virtiofsd/passthrough_ll.c
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+++ b/tools/virtiofsd/passthrough_ll.c
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@@ -110,6 +110,9 @@ struct lo_data {
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struct lo_map ino_map; /* protected by lo->mutex */
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struct lo_map dirp_map; /* protected by lo->mutex */
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struct lo_map fd_map; /* protected by lo->mutex */
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+
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+ /* An O_PATH file descriptor to /proc/self/fd/ */
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+ int proc_self_fd;
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};
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static const struct fuse_opt lo_opts[] = {
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@@ -379,9 +382,9 @@ static int lo_parent_and_name(struct lo_data *lo, struct lo_inode *inode,
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int res;
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retry:
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- sprintf(procname, "/proc/self/fd/%i", inode->fd);
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+ sprintf(procname, "%i", inode->fd);
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- res = readlink(procname, path, PATH_MAX);
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+ res = readlinkat(lo->proc_self_fd, procname, path, PATH_MAX);
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if (res < 0) {
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fuse_log(FUSE_LOG_WARNING, "%s: readlink failed: %m\n", __func__);
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goto fail_noretry;
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@@ -477,9 +480,9 @@ static int utimensat_empty(struct lo_data *lo, struct lo_inode *inode,
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}
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return res;
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}
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- sprintf(path, "/proc/self/fd/%i", inode->fd);
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+ sprintf(path, "%i", inode->fd);
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- return utimensat(AT_FDCWD, path, tv, 0);
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+ return utimensat(lo->proc_self_fd, path, tv, 0);
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fallback:
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res = lo_parent_and_name(lo, inode, path, &parent);
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@@ -535,8 +538,8 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
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if (fi) {
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res = fchmod(fd, attr->st_mode);
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} else {
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- sprintf(procname, "/proc/self/fd/%i", ifd);
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- res = chmod(procname, attr->st_mode);
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+ sprintf(procname, "%i", ifd);
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+ res = fchmodat(lo->proc_self_fd, procname, attr->st_mode, 0);
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}
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if (res == -1) {
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goto out_err;
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@@ -552,11 +555,23 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
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}
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}
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if (valid & FUSE_SET_ATTR_SIZE) {
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+ int truncfd;
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+
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if (fi) {
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- res = ftruncate(fd, attr->st_size);
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+ truncfd = fd;
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} else {
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- sprintf(procname, "/proc/self/fd/%i", ifd);
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- res = truncate(procname, attr->st_size);
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+ sprintf(procname, "%i", ifd);
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+ truncfd = openat(lo->proc_self_fd, procname, O_RDWR);
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+ if (truncfd < 0) {
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+ goto out_err;
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+ }
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+ }
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+
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+ res = ftruncate(truncfd, attr->st_size);
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+ if (!fi) {
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+ saverr = errno;
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+ close(truncfd);
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+ errno = saverr;
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}
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if (res == -1) {
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goto out_err;
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@@ -874,9 +889,9 @@ static int linkat_empty_nofollow(struct lo_data *lo, struct lo_inode *inode,
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return res;
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}
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- sprintf(path, "/proc/self/fd/%i", inode->fd);
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+ sprintf(path, "%i", inode->fd);
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- return linkat(AT_FDCWD, path, dfd, name, AT_SYMLINK_FOLLOW);
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+ return linkat(lo->proc_self_fd, path, dfd, name, AT_SYMLINK_FOLLOW);
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fallback:
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res = lo_parent_and_name(lo, inode, path, &parent);
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@@ -1404,8 +1419,8 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
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fi->flags &= ~O_APPEND;
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}
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- sprintf(buf, "/proc/self/fd/%i", lo_fd(req, ino));
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- fd = open(buf, fi->flags & ~O_NOFOLLOW);
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+ sprintf(buf, "%i", lo_fd(req, ino));
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+ fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
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if (fd == -1) {
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return (void)fuse_reply_err(req, errno);
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}
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@@ -1458,7 +1473,6 @@ static void lo_fsync(fuse_req_t req, fuse_ino_t ino, int datasync,
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struct fuse_file_info *fi)
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{
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int res;
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- (void)ino;
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int fd;
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char *buf;
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@@ -1466,12 +1480,14 @@ static void lo_fsync(fuse_req_t req, fuse_ino_t ino, int datasync,
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(void *)fi);
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if (!fi) {
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- res = asprintf(&buf, "/proc/self/fd/%i", lo_fd(req, ino));
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+ struct lo_data *lo = lo_data(req);
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+
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+ res = asprintf(&buf, "%i", lo_fd(req, ino));
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if (res == -1) {
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return (void)fuse_reply_err(req, errno);
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}
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- fd = open(buf, O_RDWR);
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+ fd = openat(lo->proc_self_fd, buf, O_RDWR);
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free(buf);
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if (fd == -1) {
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return (void)fuse_reply_err(req, errno);
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@@ -1587,11 +1603,13 @@ static void lo_flock(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi,
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static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
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size_t size)
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{
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+ struct lo_data *lo = lo_data(req);
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char *value = NULL;
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char procname[64];
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struct lo_inode *inode;
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ssize_t ret;
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int saverr;
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+ int fd = -1;
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inode = lo_inode(req, ino);
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if (!inode) {
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@@ -1616,7 +1634,11 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
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goto out;
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}
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- sprintf(procname, "/proc/self/fd/%i", inode->fd);
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+ sprintf(procname, "%i", inode->fd);
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+ fd = openat(lo->proc_self_fd, procname, O_RDONLY);
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+ if (fd < 0) {
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+ goto out_err;
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+ }
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if (size) {
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value = malloc(size);
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@@ -1624,7 +1646,7 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
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goto out_err;
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}
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- ret = getxattr(procname, name, value, size);
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+ ret = fgetxattr(fd, name, value, size);
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if (ret == -1) {
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goto out_err;
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}
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@@ -1635,7 +1657,7 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
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fuse_reply_buf(req, value, ret);
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} else {
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- ret = getxattr(procname, name, NULL, 0);
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+ ret = fgetxattr(fd, name, NULL, 0);
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if (ret == -1) {
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goto out_err;
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}
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@@ -1644,6 +1666,10 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
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}
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out_free:
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free(value);
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+
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+ if (fd >= 0) {
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+ close(fd);
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+ }
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return;
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out_err:
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@@ -1655,11 +1681,13 @@ out:
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static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
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{
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+ struct lo_data *lo = lo_data(req);
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char *value = NULL;
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char procname[64];
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struct lo_inode *inode;
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ssize_t ret;
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int saverr;
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+ int fd = -1;
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inode = lo_inode(req, ino);
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if (!inode) {
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@@ -1683,7 +1711,11 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
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goto out;
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}
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- sprintf(procname, "/proc/self/fd/%i", inode->fd);
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+ sprintf(procname, "%i", inode->fd);
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+ fd = openat(lo->proc_self_fd, procname, O_RDONLY);
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+ if (fd < 0) {
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+ goto out_err;
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+ }
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if (size) {
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value = malloc(size);
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@@ -1691,7 +1723,7 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
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goto out_err;
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}
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- ret = listxattr(procname, value, size);
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+ ret = flistxattr(fd, value, size);
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if (ret == -1) {
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goto out_err;
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}
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@@ -1702,7 +1734,7 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
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fuse_reply_buf(req, value, ret);
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} else {
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- ret = listxattr(procname, NULL, 0);
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+ ret = flistxattr(fd, NULL, 0);
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if (ret == -1) {
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goto out_err;
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}
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@@ -1711,6 +1743,10 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
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}
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out_free:
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free(value);
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+
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+ if (fd >= 0) {
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+ close(fd);
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+ }
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return;
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out_err:
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@@ -1724,9 +1760,11 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
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const char *value, size_t size, int flags)
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{
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char procname[64];
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+ struct lo_data *lo = lo_data(req);
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struct lo_inode *inode;
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ssize_t ret;
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int saverr;
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+ int fd = -1;
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inode = lo_inode(req, ino);
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if (!inode) {
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@@ -1751,21 +1789,31 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
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goto out;
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}
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- sprintf(procname, "/proc/self/fd/%i", inode->fd);
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+ sprintf(procname, "%i", inode->fd);
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+ fd = openat(lo->proc_self_fd, procname, O_RDWR);
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+ if (fd < 0) {
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+ saverr = errno;
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+ goto out;
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+ }
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- ret = setxattr(procname, name, value, size, flags);
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+ ret = fsetxattr(fd, name, value, size, flags);
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saverr = ret == -1 ? errno : 0;
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out:
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+ if (fd >= 0) {
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+ close(fd);
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+ }
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fuse_reply_err(req, saverr);
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}
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static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name)
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{
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char procname[64];
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+ struct lo_data *lo = lo_data(req);
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struct lo_inode *inode;
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ssize_t ret;
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int saverr;
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+ int fd = -1;
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inode = lo_inode(req, ino);
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if (!inode) {
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@@ -1789,12 +1837,20 @@ static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name)
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goto out;
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}
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- sprintf(procname, "/proc/self/fd/%i", inode->fd);
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+ sprintf(procname, "%i", inode->fd);
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+ fd = openat(lo->proc_self_fd, procname, O_RDWR);
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+ if (fd < 0) {
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+ saverr = errno;
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+ goto out;
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+ }
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- ret = removexattr(procname, name);
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+ ret = fremovexattr(fd, name);
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saverr = ret == -1 ? errno : 0;
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out:
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+ if (fd >= 0) {
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+ close(fd);
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+ }
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fuse_reply_err(req, saverr);
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}
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@@ -1887,12 +1943,25 @@ static void print_capabilities(void)
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printf("}\n");
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}
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+static void setup_proc_self_fd(struct lo_data *lo)
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+{
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+ lo->proc_self_fd = open("/proc/self/fd", O_PATH);
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+ if (lo->proc_self_fd == -1) {
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+ fuse_log(FUSE_LOG_ERR, "open(/proc/self/fd, O_PATH): %m\n");
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+ exit(1);
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+ }
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+}
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+
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int main(int argc, char *argv[])
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{
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struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
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struct fuse_session *se;
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struct fuse_cmdline_opts opts;
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- struct lo_data lo = { .debug = 0, .writeback = 0 };
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+ struct lo_data lo = {
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+ .debug = 0,
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+ .writeback = 0,
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+ .proc_self_fd = -1,
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+ };
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struct lo_map_elem *root_elem;
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int ret = -1;
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@@ -2003,6 +2072,9 @@ int main(int argc, char *argv[])
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fuse_daemonize(opts.foreground);
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+ /* Must be after daemonize to get the right /proc/self/fd */
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+ setup_proc_self_fd(&lo);
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+
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/* Block until ctrl+c or fusermount -u */
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ret = virtio_loop(se);
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@@ -2018,6 +2090,10 @@ err_out1:
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lo_map_destroy(&lo.dirp_map);
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lo_map_destroy(&lo.ino_map);
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+ if (lo.proc_self_fd >= 0) {
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+ close(lo.proc_self_fd);
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+ }
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+
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if (lo.root.fd >= 0) {
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close(lo.root.fd);
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}
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