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authorMisono Tomohiro <misono.tomohiro@jp.fujitsu.com>2020-02-27 14:59:27 +0900
committerDr. David Alan Gilbert <dgilbert@redhat.com>2020-03-03 15:13:24 +0000
commitbdfd66788349acc43cd3f1298718ad491663cfcc (patch)
treeb434c62919409565efd51d4840291abed6150857 /tools/virtiofsd/passthrough_ll.c
parent16e15a73089102c3d8846792d514e769300fcc3c (diff)
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virtiofsd: Fix xattr operations
Current virtiofsd has problems about xattr operations and they does not work properly for directory/symlink/special file. The fundamental cause is that virtiofsd uses openat() + f...xattr() systemcalls for xattr operation but we should not open symlink/special file in the daemon. Therefore the function is restricted. Fix this problem by: 1. during setup of each thread, call unshare(CLONE_FS) 2. in xattr operations (i.e. lo_getxattr), if inode is not a regular file or directory, use fchdir(proc_loot_fd) + ...xattr() + fchdir(root.fd) instead of openat() + f...xattr() (Note: for a regular file/directory openat() + f...xattr() is still used for performance reason) With this patch, xfstests generic/062 passes on virtiofs. This fix is suggested by Miklos Szeredi and Stefan Hajnoczi. The original discussion can be found here: https://www.redhat.com/archives/virtio-fs/2019-October/msg00046.html Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com> Message-Id: <20200227055927.24566-3-misono.tomohiro@jp.fujitsu.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Diffstat (limited to 'tools/virtiofsd/passthrough_ll.c')
-rw-r--r--tools/virtiofsd/passthrough_ll.c105
1 files changed, 58 insertions, 47 deletions
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 4690a97..4f259aa 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -123,7 +123,7 @@ struct lo_inode {
pthread_mutex_t plock_mutex;
GHashTable *posix_locks; /* protected by lo_inode->plock_mutex */
- bool is_symlink;
+ mode_t filetype;
};
struct lo_cred {
@@ -695,7 +695,7 @@ static int utimensat_empty(struct lo_data *lo, struct lo_inode *inode,
struct lo_inode *parent;
char path[PATH_MAX];
- if (inode->is_symlink) {
+ if (S_ISLNK(inode->filetype)) {
res = utimensat(inode->fd, "", tv, AT_EMPTY_PATH);
if (res == -1 && errno == EINVAL) {
/* Sorry, no race free way to set times on symlink. */
@@ -928,7 +928,8 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
goto out_err;
}
- inode->is_symlink = S_ISLNK(e->attr.st_mode);
+ /* cache only filetype */
+ inode->filetype = (e->attr.st_mode & S_IFMT);
/*
* One for the caller and one for nlookup (released in
@@ -1135,7 +1136,7 @@ static int linkat_empty_nofollow(struct lo_data *lo, struct lo_inode *inode,
struct lo_inode *parent;
char path[PATH_MAX];
- if (inode->is_symlink) {
+ if (S_ISLNK(inode->filetype)) {
res = linkat(inode->fd, "", dfd, name, AT_EMPTY_PATH);
if (res == -1 && (errno == ENOENT || errno == EINVAL)) {
/* Sorry, no race free way to hard-link a symlink. */
@@ -2189,12 +2190,6 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
fuse_log(FUSE_LOG_DEBUG, "lo_getxattr(ino=%" PRIu64 ", name=%s size=%zd)\n",
ino, name, size);
- if (inode->is_symlink) {
- /* Sorry, no race free way to getxattr on symlink. */
- saverr = EPERM;
- goto out;
- }
-
if (size) {
value = malloc(size);
if (!value) {
@@ -2203,12 +2198,25 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
}
sprintf(procname, "%i", inode->fd);
- fd = openat(lo->proc_self_fd, procname, O_RDONLY);
- if (fd < 0) {
- goto out_err;
+ /*
+ * It is not safe to open() non-regular/non-dir files in file server
+ * unless O_PATH is used, so use that method for regular files/dir
+ * only (as it seems giving less performance overhead).
+ * Otherwise, call fchdir() to avoid open().
+ */
+ if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) {
+ fd = openat(lo->proc_self_fd, procname, O_RDONLY);
+ if (fd < 0) {
+ goto out_err;
+ }
+ ret = fgetxattr(fd, name, value, size);
+ } else {
+ /* fchdir should not fail here */
+ assert(fchdir(lo->proc_self_fd) == 0);
+ ret = getxattr(procname, name, value, size);
+ assert(fchdir(lo->root.fd) == 0);
}
- ret = fgetxattr(fd, name, value, size);
if (ret == -1) {
goto out_err;
}
@@ -2262,12 +2270,6 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
fuse_log(FUSE_LOG_DEBUG, "lo_listxattr(ino=%" PRIu64 ", size=%zd)\n", ino,
size);
- if (inode->is_symlink) {
- /* Sorry, no race free way to listxattr on symlink. */
- saverr = EPERM;
- goto out;
- }
-
if (size) {
value = malloc(size);
if (!value) {
@@ -2276,12 +2278,19 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
}
sprintf(procname, "%i", inode->fd);
- fd = openat(lo->proc_self_fd, procname, O_RDONLY);
- if (fd < 0) {
- goto out_err;
+ if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) {
+ fd = openat(lo->proc_self_fd, procname, O_RDONLY);
+ if (fd < 0) {
+ goto out_err;
+ }
+ ret = flistxattr(fd, value, size);
+ } else {
+ /* fchdir should not fail here */
+ assert(fchdir(lo->proc_self_fd) == 0);
+ ret = listxattr(procname, value, size);
+ assert(fchdir(lo->root.fd) == 0);
}
- ret = flistxattr(fd, value, size);
if (ret == -1) {
goto out_err;
}
@@ -2335,20 +2344,21 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
fuse_log(FUSE_LOG_DEBUG, "lo_setxattr(ino=%" PRIu64
", name=%s value=%s size=%zd)\n", ino, name, value, size);
- if (inode->is_symlink) {
- /* Sorry, no race free way to setxattr on symlink. */
- saverr = EPERM;
- goto out;
- }
-
sprintf(procname, "%i", inode->fd);
- fd = openat(lo->proc_self_fd, procname, O_RDWR);
- if (fd < 0) {
- saverr = errno;
- goto out;
+ if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) {
+ fd = openat(lo->proc_self_fd, procname, O_RDONLY);
+ if (fd < 0) {
+ saverr = errno;
+ goto out;
+ }
+ ret = fsetxattr(fd, name, value, size, flags);
+ } else {
+ /* fchdir should not fail here */
+ assert(fchdir(lo->proc_self_fd) == 0);
+ ret = setxattr(procname, name, value, size, flags);
+ assert(fchdir(lo->root.fd) == 0);
}
- ret = fsetxattr(fd, name, value, size, flags);
saverr = ret == -1 ? errno : 0;
out:
@@ -2383,20 +2393,21 @@ static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name)
fuse_log(FUSE_LOG_DEBUG, "lo_removexattr(ino=%" PRIu64 ", name=%s)\n", ino,
name);
- if (inode->is_symlink) {
- /* Sorry, no race free way to setxattr on symlink. */
- saverr = EPERM;
- goto out;
- }
-
sprintf(procname, "%i", inode->fd);
- fd = openat(lo->proc_self_fd, procname, O_RDWR);
- if (fd < 0) {
- saverr = errno;
- goto out;
+ if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) {
+ fd = openat(lo->proc_self_fd, procname, O_RDONLY);
+ if (fd < 0) {
+ saverr = errno;
+ goto out;
+ }
+ ret = fremovexattr(fd, name);
+ } else {
+ /* fchdir should not fail here */
+ assert(fchdir(lo->proc_self_fd) == 0);
+ ret = removexattr(procname, name);
+ assert(fchdir(lo->root.fd) == 0);
}
- ret = fremovexattr(fd, name);
saverr = ret == -1 ? errno : 0;
out:
@@ -2796,7 +2807,7 @@ static void setup_root(struct lo_data *lo, struct lo_inode *root)
exit(1);
}
- root->is_symlink = false;
+ root->filetype = S_IFDIR;
root->fd = fd;
root->key.ino = stat.st_ino;
root->key.dev = stat.st_dev;