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[PATCH v3 06/10] virtiofsd: Let lo_inode_open() return a TempFd
From: |
Max Reitz |
Subject: |
[PATCH v3 06/10] virtiofsd: Let lo_inode_open() return a TempFd |
Date: |
Fri, 30 Jul 2021 17:01:30 +0200 |
Strictly speaking, this is not necessary, because lo_inode_open() will
always return a new FD owned by the caller, so TempFd.owned will always
be true.
However, auto-cleanup is nice, and in some cases this plays nicely with
an lo_inode_fd() call in another conditional branch (see lo_setattr()).
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
tools/virtiofsd/passthrough_ll.c | 138 +++++++++++++------------------
1 file changed, 59 insertions(+), 79 deletions(-)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 9e1bc37af8..292b7f7e27 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -291,10 +291,8 @@ static void temp_fd_clear(TempFd *temp_fd)
/**
* Return an owned fd from *temp_fd that will not be closed when
* *temp_fd goes out of scope.
- *
- * (TODO: Remove __attribute__ once this is used.)
*/
-static __attribute__((unused)) int temp_fd_steal(TempFd *temp_fd)
+static int temp_fd_steal(TempFd *temp_fd)
{
if (temp_fd->owned) {
temp_fd->owned = false;
@@ -673,9 +671,12 @@ static int lo_fd(fuse_req_t req, fuse_ino_t ino, TempFd
*tfd)
* when a malicious client opens special files such as block device nodes.
* Symlink inodes are also rejected since symlinks must already have been
* traversed on the client side.
+ *
+ * The fd is returned in tfd->fd. The return value is 0 on success and -errno
+ * otherwise.
*/
-static int lo_inode_open(struct lo_data *lo, struct lo_inode *inode,
- int open_flags)
+static int lo_inode_open(const struct lo_data *lo, const struct lo_inode
*inode,
+ int open_flags, TempFd *tfd)
{
g_autofree char *fd_str = g_strdup_printf("%d", inode->fd);
int fd;
@@ -694,7 +695,13 @@ static int lo_inode_open(struct lo_data *lo, struct
lo_inode *inode,
if (fd < 0) {
return -errno;
}
- return fd;
+
+ *tfd = (TempFd) {
+ .fd = fd,
+ .owned = true,
+ };
+
+ return 0;
}
static void lo_init(void *userdata, struct fuse_conn_info *conn)
@@ -852,7 +859,12 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino,
struct stat *attr,
return;
}
- res = lo_inode_fd(inode, &inode_fd);
+ if (!fi && (valid & FUSE_SET_ATTR_SIZE)) {
+ /* We need an O_RDWR FD for ftruncate() */
+ res = lo_inode_open(lo, inode, O_RDWR, &inode_fd);
+ } else {
+ res = lo_inode_fd(inode, &inode_fd);
+ }
if (res < 0) {
saverr = -res;
goto out_err;
@@ -900,18 +912,11 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino,
struct stat *attr,
if (fi) {
truncfd = fd;
} else {
- truncfd = lo_inode_open(lo, inode, O_RDWR);
- if (truncfd < 0) {
- saverr = -truncfd;
- goto out_err;
- }
+ truncfd = inode_fd.fd;
}
saverr = drop_security_capability(lo, truncfd);
if (saverr) {
- if (!fi) {
- close(truncfd);
- }
goto out_err;
}
@@ -919,9 +924,6 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino,
struct stat *attr,
res = drop_effective_cap("FSETID", &cap_fsetid_dropped);
if (res != 0) {
saverr = res;
- if (!fi) {
- close(truncfd);
- }
goto out_err;
}
}
@@ -934,9 +936,6 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino,
struct stat *attr,
fuse_log(FUSE_LOG_ERR, "Failed to gain CAP_FSETID\n");
}
}
- if (!fi) {
- close(truncfd);
- }
if (res == -1) {
goto out_err;
}
@@ -1822,11 +1821,12 @@ static struct lo_dirp *lo_dirp(fuse_req_t req, struct
fuse_file_info *fi)
static void lo_opendir(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi)
{
+ g_auto(TempFd) inode_fd = TEMP_FD_INIT;
int error = ENOMEM;
struct lo_data *lo = lo_data(req);
struct lo_inode *inode;
struct lo_dirp *d = NULL;
- int fd;
+ int res;
ssize_t fh;
inode = lo_inode(req, ino);
@@ -1840,13 +1840,13 @@ static void lo_opendir(fuse_req_t req, fuse_ino_t ino,
goto out_err;
}
- fd = lo_inode_open(lo, inode, O_RDONLY);
- if (fd < 0) {
- error = -fd;
+ res = lo_inode_open(lo, inode, O_RDONLY, &inode_fd);
+ if (res < 0) {
+ error = -res;
goto out_err;
}
- d->dp = fdopendir(fd);
+ d->dp = fdopendir(temp_fd_steal(&inode_fd));
if (d->dp == NULL) {
goto out_errno;
}
@@ -1876,8 +1876,6 @@ out_err:
if (d) {
if (d->dp) {
closedir(d->dp);
- } else if (fd != -1) {
- close(fd);
}
free(d);
}
@@ -2077,6 +2075,7 @@ static void update_open_flags(int writeback, int
allow_direct_io,
static int lo_do_open(struct lo_data *lo, struct lo_inode *inode,
int existing_fd, struct fuse_file_info *fi)
{
+ g_auto(TempFd) inode_fd = TEMP_FD_INIT;
ssize_t fh;
int fd = existing_fd;
int err;
@@ -2093,16 +2092,18 @@ static int lo_do_open(struct lo_data *lo, struct
lo_inode *inode,
}
}
- fd = lo_inode_open(lo, inode, fi->flags);
+ err = lo_inode_open(lo, inode, fi->flags, &inode_fd);
if (cap_fsetid_dropped) {
if (gain_effective_cap("FSETID")) {
fuse_log(FUSE_LOG_ERR, "Failed to gain CAP_FSETID\n");
}
}
- if (fd < 0) {
- return -fd;
+ if (err < 0) {
+ return -err;
}
+ fd = temp_fd_steal(&inode_fd);
+
if (fi->flags & (O_TRUNC)) {
int err = drop_security_capability(lo, fd);
if (err) {
@@ -2212,8 +2213,9 @@ static struct lo_inode_plock
*lookup_create_plock_ctx(struct lo_data *lo,
uint64_t lock_owner,
pid_t pid, int *err)
{
+ g_auto(TempFd) inode_fd = TEMP_FD_INIT;
struct lo_inode_plock *plock;
- int fd;
+ int res;
plock =
g_hash_table_lookup(inode->posix_locks, GUINT_TO_POINTER(lock_owner));
@@ -2230,15 +2232,15 @@ static struct lo_inode_plock
*lookup_create_plock_ctx(struct lo_data *lo,
/* Open another instance of file which can be used for ofd locks. */
/* TODO: What if file is not writable? */
- fd = lo_inode_open(lo, inode, O_RDWR);
- if (fd < 0) {
- *err = -fd;
+ res = lo_inode_open(lo, inode, O_RDWR, &inode_fd);
+ if (res < 0) {
+ *err = -res;
free(plock);
return NULL;
}
plock->lock_owner = lock_owner;
- plock->fd = fd;
+ plock->fd = temp_fd_steal(&inode_fd);
g_hash_table_insert(inode->posix_locks,
GUINT_TO_POINTER(plock->lock_owner),
plock);
return plock;
@@ -2454,6 +2456,7 @@ static void lo_flush(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi)
static void lo_fsync(fuse_req_t req, fuse_ino_t ino, int datasync,
struct fuse_file_info *fi)
{
+ g_auto(TempFd) inode_fd = TEMP_FD_INIT;
struct lo_inode *inode = lo_inode(req, ino);
struct lo_data *lo = lo_data(req);
int res;
@@ -2468,11 +2471,12 @@ static void lo_fsync(fuse_req_t req, fuse_ino_t ino,
int datasync,
}
if (!fi) {
- fd = lo_inode_open(lo, inode, O_RDWR);
- if (fd < 0) {
- res = -fd;
+ res = lo_inode_open(lo, inode, O_RDWR, &inode_fd);
+ if (res < 0) {
+ res = -res;
goto out;
}
+ fd = inode_fd.fd;
} else {
fd = lo_fi_fd(req, fi);
}
@@ -2482,9 +2486,6 @@ static void lo_fsync(fuse_req_t req, fuse_ino_t ino, int
datasync,
} else {
res = fsync(fd) == -1 ? errno : 0;
}
- if (!fi) {
- close(fd);
- }
out:
lo_inode_put(lo, &inode);
fuse_reply_err(req, res);
@@ -3047,7 +3048,6 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino,
const char *in_name,
struct lo_inode *inode;
ssize_t ret;
int saverr;
- int fd = -1;
if (block_xattr(lo, in_name)) {
fuse_reply_err(req, EOPNOTSUPP);
@@ -3099,12 +3099,12 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino,
const char *in_name,
* Otherwise, call fchdir() to avoid open().
*/
if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) {
- fd = lo_inode_open(lo, inode, O_RDONLY);
- if (fd < 0) {
- saverr = -fd;
+ ret = lo_inode_open(lo, inode, O_RDONLY, &inode_fd);
+ if (ret < 0) {
+ saverr = -ret;
goto out;
}
- ret = fgetxattr(fd, name, value, size);
+ ret = fgetxattr(inode_fd.fd, name, value, size);
saverr = ret == -1 ? errno : 0;
} else {
ret = lo_inode_fd(inode, &inode_fd);
@@ -3133,10 +3133,6 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino,
const char *in_name,
fuse_reply_xattr(req, ret);
}
out_free:
- if (fd >= 0) {
- close(fd);
- }
-
lo_inode_put(lo, &inode);
return;
@@ -3157,7 +3153,6 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino,
size_t size)
struct lo_inode *inode;
ssize_t ret;
int saverr;
- int fd = -1;
inode = lo_inode(req, ino);
if (!inode) {
@@ -3181,12 +3176,12 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t
ino, size_t size)
}
if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) {
- fd = lo_inode_open(lo, inode, O_RDONLY);
- if (fd < 0) {
- saverr = -fd;
+ ret = lo_inode_open(lo, inode, O_RDONLY, &inode_fd);
+ if (ret < 0) {
+ saverr = -ret;
goto out;
}
- ret = flistxattr(fd, value, size);
+ ret = flistxattr(inode_fd.fd, value, size);
saverr = ret == -1 ? errno : 0;
} else {
ret = lo_inode_fd(inode, &inode_fd);
@@ -3273,10 +3268,6 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino,
size_t size)
fuse_reply_xattr(req, ret);
}
out_free:
- if (fd >= 0) {
- close(fd);
- }
-
lo_inode_put(lo, &inode);
return;
@@ -3299,7 +3290,6 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino,
const char *in_name,
struct lo_inode *inode;
ssize_t ret;
int saverr;
- int fd = -1;
bool switched_creds = false;
bool cap_fsetid_dropped = false;
struct lo_cred old = {};
@@ -3345,9 +3335,9 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino,
const char *in_name,
*/
open_inode = S_ISREG(inode->filetype) || S_ISDIR(inode->filetype);
if (open_inode) {
- fd = lo_inode_open(lo, inode, O_RDONLY);
- if (fd < 0) {
- saverr = -fd;
+ ret = lo_inode_open(lo, inode, O_RDONLY, &inode_fd);
+ if (ret < 0) {
+ saverr = -ret;
goto out;
}
} else {
@@ -3382,8 +3372,7 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino,
const char *in_name,
switched_creds = true;
}
if (open_inode) {
- assert(fd >= 0);
- ret = fsetxattr(fd, name, value, size, flags);
+ ret = fsetxattr(inode_fd.fd, name, value, size, flags);
saverr = ret == -1 ? errno : 0;
} else {
ret = setxattr(procname, name, value, size, flags);
@@ -3402,10 +3391,6 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino,
const char *in_name,
}
out:
- if (fd >= 0) {
- close(fd);
- }
-
lo_inode_put(lo, &inode);
g_free(mapped_name);
fuse_reply_err(req, saverr);
@@ -3421,7 +3406,6 @@ static void lo_removexattr(fuse_req_t req, fuse_ino_t
ino, const char *in_name)
struct lo_inode *inode;
ssize_t ret;
int saverr;
- int fd = -1;
if (block_xattr(lo, in_name)) {
fuse_reply_err(req, EOPNOTSUPP);
@@ -3457,12 +3441,12 @@ static void lo_removexattr(fuse_req_t req, fuse_ino_t
ino, const char *in_name)
name);
if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) {
- fd = lo_inode_open(lo, inode, O_RDONLY);
- if (fd < 0) {
- saverr = -fd;
+ ret = lo_inode_open(lo, inode, O_RDONLY, &inode_fd);
+ if (ret < 0) {
+ saverr = -ret;
goto out;
}
- ret = fremovexattr(fd, name);
+ ret = fremovexattr(inode_fd.fd, name);
saverr = ret == -1 ? errno : 0;
} else {
ret = lo_inode_fd(inode, &inode_fd);
@@ -3479,10 +3463,6 @@ static void lo_removexattr(fuse_req_t req, fuse_ino_t
ino, const char *in_name)
}
out:
- if (fd >= 0) {
- close(fd);
- }
-
lo_inode_put(lo, &inode);
g_free(mapped_name);
fuse_reply_err(req, saverr);
--
2.31.1
- [PATCH v3 00/10] virtiofsd: Allow using file handles instead of O_PATH FDs, Max Reitz, 2021/07/30
- [PATCH v3 04/10] virtiofsd: Add lo_inode_fd() helper, Max Reitz, 2021/07/30
- [PATCH v3 01/10] virtiofsd: Limit setxattr()'s creds-dropped region, Max Reitz, 2021/07/30
- [PATCH v3 05/10] virtiofsd: Let lo_fd() return a TempFd, Max Reitz, 2021/07/30
- [PATCH v3 02/10] virtiofsd: Add TempFd structure, Max Reitz, 2021/07/30
- [PATCH v3 07/10] virtiofsd: Add lo_inode.fhandle, Max Reitz, 2021/07/30
- [PATCH v3 08/10] virtiofsd: Add inodes_by_handle hash table, Max Reitz, 2021/07/30
- [PATCH v3 03/10] virtiofsd: Use lo_inode_open() instead of openat(), Max Reitz, 2021/07/30
- [PATCH v3 06/10] virtiofsd: Let lo_inode_open() return a TempFd,
Max Reitz <=
- [PATCH v3 09/10] virtiofsd: Optionally fill lo_inode.fhandle, Max Reitz, 2021/07/30
- [PATCH v3 10/10] virtiofsd: Add lazy lo_do_find(), Max Reitz, 2021/07/30