mirror of
https://github.com/libfuse/libfuse.git
synced 2024-11-27 06:04:27 +08:00
passthrough_ll: remove symlink fallbacks (#514)
* passthrough_ll/hp: remove symlink fallbacks Path lookup in the kernel has special rules for looking up magic symlinks under /proc. If a filesystem operation is instructed to follow symlinks (e.g. via AT_SYMLINK_FOLLOW or lack of AT_SYMLINK_NOFOLLOW), and the final component is such a proc symlink, then the target of the magic symlink is used for the operation, even if the target itself is a symlink. I.e. path lookup is always terminated after following a final magic symlink. I was erronously assuming that in the above case the target symlink would also be followed, and so workarounds were added for a couple of operations to handle the symlink case. Since the symlink can be handled simply by following the proc symlink, these workardouds are not needed. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Co-authored-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi
GitHub
parent
fc25c5002c
commit
ded868455a
@ -121,7 +121,6 @@ typedef std::unordered_map<SrcId, Inode> InodeMap;
|
||||
|
||||
struct Inode {
|
||||
int fd {-1};
|
||||
bool is_symlink {false};
|
||||
dev_t src_dev {0};
|
||||
ino_t src_ino {0};
|
||||
uint64_t nlookup {0};
|
||||
@ -217,28 +216,6 @@ static void sfs_getattr(fuse_req_t req, fuse_ino_t ino, fuse_file_info *fi) {
|
||||
}
|
||||
|
||||
|
||||
#ifdef HAVE_UTIMENSAT
|
||||
static int utimensat_empty_nofollow(Inode& inode,
|
||||
const struct timespec *tv) {
|
||||
if (inode.is_symlink) {
|
||||
/* Does not work on current kernels, but may in the future:
|
||||
https://marc.info/?l=linux-kernel&m=154158217810354&w=2 */
|
||||
auto res = utimensat(inode.fd, "", tv, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW);
|
||||
if (res == -1 && errno == EINVAL) {
|
||||
/* Sorry, no race free way to set times on symlink. */
|
||||
errno = EPERM;
|
||||
}
|
||||
return res;
|
||||
}
|
||||
|
||||
char procname[64];
|
||||
sprintf(procname, "/proc/self/fd/%i", inode.fd);
|
||||
|
||||
return utimensat(AT_FDCWD, procname, tv, 0);
|
||||
}
|
||||
#endif
|
||||
|
||||
|
||||
static void do_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
|
||||
int valid, struct fuse_file_info* fi) {
|
||||
Inode& inode = get_inode(ino);
|
||||
@ -297,7 +274,9 @@ static void do_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
|
||||
res = futimens(fi->fh, tv);
|
||||
else {
|
||||
#ifdef HAVE_UTIMENSAT
|
||||
res = utimensat_empty_nofollow(inode, tv);
|
||||
char procname[64];
|
||||
sprintf(procname, "/proc/self/fd/%i", ifd);
|
||||
res = utimensat(AT_FDCWD, procname, tv, 0);
|
||||
#else
|
||||
res = -1;
|
||||
errno = EOPNOTSUPP;
|
||||
@ -378,7 +357,6 @@ static int do_lookup(fuse_ino_t parent, const char *name,
|
||||
lock_guard<mutex> g {inode.m};
|
||||
inode.src_ino = e->attr.st_ino;
|
||||
inode.src_dev = e->attr.st_dev;
|
||||
inode.is_symlink = S_ISLNK(e->attr.st_mode);
|
||||
inode.nlookup = 1;
|
||||
inode.fd = newfd;
|
||||
fs_lock.unlock();
|
||||
@ -460,22 +438,6 @@ static void sfs_symlink(fuse_req_t req, const char *link, fuse_ino_t parent,
|
||||
}
|
||||
|
||||
|
||||
static int linkat_empty_nofollow(Inode& inode, int dfd, const char *name) {
|
||||
if (inode.is_symlink) {
|
||||
auto 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. */
|
||||
errno = EOPNOTSUPP;
|
||||
}
|
||||
return res;
|
||||
}
|
||||
|
||||
char procname[64];
|
||||
sprintf(procname, "/proc/self/fd/%i", inode.fd);
|
||||
return linkat(AT_FDCWD, procname, dfd, name, AT_SYMLINK_FOLLOW);
|
||||
}
|
||||
|
||||
|
||||
static void sfs_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent,
|
||||
const char *name) {
|
||||
Inode& inode = get_inode(ino);
|
||||
@ -485,7 +447,9 @@ static void sfs_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent,
|
||||
e.attr_timeout = fs.timeout;
|
||||
e.entry_timeout = fs.timeout;
|
||||
|
||||
auto res = linkat_empty_nofollow(inode, inode_p.fd, name);
|
||||
char procname[64];
|
||||
sprintf(procname, "/proc/self/fd/%i", inode.fd);
|
||||
auto res = linkat(AT_FDCWD, procname, inode_p.fd, name, AT_SYMLINK_FOLLOW);
|
||||
if (res == -1) {
|
||||
fuse_reply_err(req, errno);
|
||||
return;
|
||||
@ -965,12 +929,6 @@ static void sfs_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
|
||||
ssize_t ret;
|
||||
int saverr;
|
||||
|
||||
if (inode.is_symlink) {
|
||||
/* Sorry, no race free way to getxattr on symlink. */
|
||||
saverr = ENOTSUP;
|
||||
goto out;
|
||||
}
|
||||
|
||||
char procname[64];
|
||||
sprintf(procname, "/proc/self/fd/%i", inode.fd);
|
||||
|
||||
@ -1014,12 +972,6 @@ static void sfs_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) {
|
||||
ssize_t ret;
|
||||
int saverr;
|
||||
|
||||
if (inode.is_symlink) {
|
||||
/* Sorry, no race free way to listxattr on symlink. */
|
||||
saverr = ENOTSUP;
|
||||
goto out;
|
||||
}
|
||||
|
||||
char procname[64];
|
||||
sprintf(procname, "/proc/self/fd/%i", inode.fd);
|
||||
|
||||
@ -1062,19 +1014,12 @@ static void sfs_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
|
||||
ssize_t ret;
|
||||
int saverr;
|
||||
|
||||
if (inode.is_symlink) {
|
||||
/* Sorry, no race free way to setxattr on symlink. */
|
||||
saverr = ENOTSUP;
|
||||
goto out;
|
||||
}
|
||||
|
||||
char procname[64];
|
||||
sprintf(procname, "/proc/self/fd/%i", inode.fd);
|
||||
|
||||
ret = setxattr(procname, name, value, size, flags);
|
||||
saverr = ret == -1 ? errno : 0;
|
||||
|
||||
out:
|
||||
fuse_reply_err(req, saverr);
|
||||
}
|
||||
|
||||
@ -1085,17 +1030,10 @@ static void sfs_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name) {
|
||||
ssize_t ret;
|
||||
int saverr;
|
||||
|
||||
if (inode.is_symlink) {
|
||||
/* Sorry, no race free way to setxattr on symlink. */
|
||||
saverr = ENOTSUP;
|
||||
goto out;
|
||||
}
|
||||
|
||||
sprintf(procname, "/proc/self/fd/%i", inode.fd);
|
||||
ret = removexattr(procname, name);
|
||||
saverr = ret == -1 ? errno : 0;
|
||||
|
||||
out:
|
||||
fuse_reply_err(req, saverr);
|
||||
}
|
||||
#endif
|
||||
@ -1221,7 +1159,6 @@ int main(int argc, char *argv[]) {
|
||||
// Initialize filesystem root
|
||||
fs.root.fd = -1;
|
||||
fs.root.nlookup = 9999;
|
||||
fs.root.is_symlink = false;
|
||||
fs.timeout = options.count("nocache") ? 0 : 86400.0;
|
||||
|
||||
struct stat stat;
|
||||
|
||||
@ -74,7 +74,6 @@ struct lo_inode {
|
||||
struct lo_inode *next; /* protected by lo->mutex */
|
||||
struct lo_inode *prev; /* protected by lo->mutex */
|
||||
int fd;
|
||||
bool is_symlink;
|
||||
ino_t ino;
|
||||
dev_t dev;
|
||||
uint64_t refcount; /* protected by lo->mutex */
|
||||
@ -188,26 +187,6 @@ static void lo_getattr(fuse_req_t req, fuse_ino_t ino,
|
||||
fuse_reply_attr(req, &buf, lo->timeout);
|
||||
}
|
||||
|
||||
static int utimensat_empty_nofollow(struct lo_inode *inode,
|
||||
const struct timespec *tv)
|
||||
{
|
||||
int res;
|
||||
char procname[64];
|
||||
|
||||
if (inode->is_symlink) {
|
||||
res = utimensat(inode->fd, "", tv,
|
||||
AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW);
|
||||
if (res == -1 && errno == EINVAL) {
|
||||
/* Sorry, no race free way to set times on symlink. */
|
||||
errno = EPERM;
|
||||
}
|
||||
return res;
|
||||
}
|
||||
sprintf(procname, "/proc/self/fd/%i", inode->fd);
|
||||
|
||||
return utimensat(AT_FDCWD, procname, tv, 0);
|
||||
}
|
||||
|
||||
static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
|
||||
int valid, struct fuse_file_info *fi)
|
||||
{
|
||||
@ -268,8 +247,10 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
|
||||
|
||||
if (fi)
|
||||
res = futimens(fi->fh, tv);
|
||||
else
|
||||
res = utimensat_empty_nofollow(inode, tv);
|
||||
else {
|
||||
sprintf(procname, "/proc/self/fd/%i", ifd);
|
||||
res = utimensat(AT_FDCWD, procname, tv, 0);
|
||||
}
|
||||
if (res == -1)
|
||||
goto out_err;
|
||||
}
|
||||
@ -332,7 +313,6 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
|
||||
if (!inode)
|
||||
goto out_err;
|
||||
|
||||
inode->is_symlink = S_ISLNK(e->attr.st_mode);
|
||||
inode->refcount = 1;
|
||||
inode->fd = newfd;
|
||||
inode->ino = e->attr.st_ino;
|
||||
@ -426,26 +406,6 @@ static void lo_symlink(fuse_req_t req, const char *link,
|
||||
lo_mknod_symlink(req, parent, name, S_IFLNK, 0, link);
|
||||
}
|
||||
|
||||
static int linkat_empty_nofollow(struct lo_inode *inode, int dfd,
|
||||
const char *name)
|
||||
{
|
||||
int res;
|
||||
char procname[64];
|
||||
|
||||
if (inode->is_symlink) {
|
||||
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. */
|
||||
errno = EPERM;
|
||||
}
|
||||
return res;
|
||||
}
|
||||
|
||||
sprintf(procname, "/proc/self/fd/%i", inode->fd);
|
||||
|
||||
return linkat(AT_FDCWD, procname, dfd, name, AT_SYMLINK_FOLLOW);
|
||||
}
|
||||
|
||||
static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent,
|
||||
const char *name)
|
||||
{
|
||||
@ -453,13 +413,16 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent,
|
||||
struct lo_data *lo = lo_data(req);
|
||||
struct lo_inode *inode = lo_inode(req, ino);
|
||||
struct fuse_entry_param e;
|
||||
char procname[64];
|
||||
int saverr;
|
||||
|
||||
memset(&e, 0, sizeof(struct fuse_entry_param));
|
||||
e.attr_timeout = lo->timeout;
|
||||
e.entry_timeout = lo->timeout;
|
||||
|
||||
res = linkat_empty_nofollow(inode, lo_fd(req, parent), name);
|
||||
sprintf(procname, "/proc/self/fd/%i", inode->fd);
|
||||
res = linkat(AT_FDCWD, procname, lo_fd(req, parent), name,
|
||||
AT_SYMLINK_FOLLOW);
|
||||
if (res == -1)
|
||||
goto out_err;
|
||||
|
||||
@ -976,12 +939,6 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
|
||||
ino, name, size);
|
||||
}
|
||||
|
||||
if (inode->is_symlink) {
|
||||
/* Sorry, no race free way to getxattr on symlink. */
|
||||
saverr = EPERM;
|
||||
goto out;
|
||||
}
|
||||
|
||||
sprintf(procname, "/proc/self/fd/%i", inode->fd);
|
||||
|
||||
if (size) {
|
||||
@ -1032,12 +989,6 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
|
||||
ino, size);
|
||||
}
|
||||
|
||||
if (inode->is_symlink) {
|
||||
/* Sorry, no race free way to listxattr on symlink. */
|
||||
saverr = EPERM;
|
||||
goto out;
|
||||
}
|
||||
|
||||
sprintf(procname, "/proc/self/fd/%i", inode->fd);
|
||||
|
||||
if (size) {
|
||||
@ -1088,12 +1039,6 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
|
||||
ino, name, value, size);
|
||||
}
|
||||
|
||||
if (inode->is_symlink) {
|
||||
/* Sorry, no race free way to setxattr on symlink. */
|
||||
saverr = EPERM;
|
||||
goto out;
|
||||
}
|
||||
|
||||
sprintf(procname, "/proc/self/fd/%i", inode->fd);
|
||||
|
||||
ret = setxattr(procname, name, value, size, flags);
|
||||
@ -1119,12 +1064,6 @@ static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name)
|
||||
ino, name);
|
||||
}
|
||||
|
||||
if (inode->is_symlink) {
|
||||
/* Sorry, no race free way to setxattr on symlink. */
|
||||
saverr = EPERM;
|
||||
goto out;
|
||||
}
|
||||
|
||||
sprintf(procname, "/proc/self/fd/%i", inode->fd);
|
||||
|
||||
ret = removexattr(procname, name);
|
||||
@ -1274,7 +1213,6 @@ int main(int argc, char *argv[])
|
||||
} else {
|
||||
lo.source = "/";
|
||||
}
|
||||
lo.root.is_symlink = false;
|
||||
if (!lo.timeout_set) {
|
||||
switch (lo.cache) {
|
||||
case CACHE_NEVER:
|
||||
|
||||
Loading…
Reference in New Issue
Block a user