Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
fuse: don't require /dev/fuse fd to be kept open during mount
With the new mount API the sequence of syscalls would be:
fs_fd = fsopen("fuse", 0);
snprintf(opt, sizeof(opt), "%i", devfd);
fsconfig(fs_fd, FSCONFIG_SET_STRING, "fd", opt, 0);
/* ... */
fsconfig(fs_fd, FSCONFIG_CMD_CREATE, 0, 0, 0);
Current mount code just stores the value of devfd in the fs_context and
uses it in during FSCONFIG_CMD_CREATE, which is inelegant.
Instead grab a reference to the underlying fuse_dev, and use that during
the filesystem creation.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
+34
-27
+1
-3
fs/fuse/fuse_i.h
+1
-3
fs/fuse/fuse_i.h
···
606
606
}
607
607
608
608
struct fuse_fs_context {
609
-
int fd;
610
-
struct file *file;
609
+
struct fuse_dev *fud;
611
610
unsigned int rootmode;
612
611
kuid_t user_id;
613
612
kgid_t group_id;
614
613
bool is_bdev:1;
615
-
bool fd_present:1;
616
614
bool rootmode_present:1;
617
615
bool user_id_present:1;
618
616
bool group_id_present:1;
+33
-24
fs/fuse/inode.c
+33
-24
fs/fuse/inode.c
···
803
803
{}
804
804
};
805
805
806
+
static int fuse_opt_fd(struct fs_context *fsc, int fd)
807
+
{
808
+
struct fuse_fs_context *ctx = fsc->fs_private;
809
+
struct file *file __free(fput) = fget(fd);
810
+
811
+
if (!file)
812
+
return -EBADF;
813
+
814
+
if (file->f_op != &fuse_dev_operations)
815
+
return invalfc(fsc, "fd is not a fuse device");
816
+
/*
817
+
* Require mount to happen from the same user namespace which
818
+
* opened /dev/fuse to prevent potential attacks.
819
+
*/
820
+
if (file->f_cred->user_ns != fsc->user_ns)
821
+
return invalfc(fsc, "wrong user namespace for fuse device");
822
+
823
+
ctx->fud = file->private_data;
824
+
refcount_inc(&ctx->fud->ref);
825
+
826
+
return 0;
827
+
}
828
+
806
829
static int fuse_parse_param(struct fs_context *fsc, struct fs_parameter *param)
807
830
{
808
831
struct fs_parse_result result;
···
865
842
return 0;
866
843
867
844
case OPT_FD:
868
-
ctx->fd = result.uint_32;
869
-
ctx->fd_present = true;
870
-
break;
845
+
return fuse_opt_fd(fsc, result.uint_32);
871
846
872
847
case OPT_ROOTMODE:
873
848
if (!fuse_valid_type(result.uint_32))
···
928
907
struct fuse_fs_context *ctx = fsc->fs_private;
929
908
930
909
if (ctx) {
910
+
if (ctx->fud)
911
+
fuse_dev_put(ctx->fud);
931
912
kfree(ctx->subtype);
932
913
kfree(ctx);
933
914
}
···
1872
1849
1873
1850
int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
1874
1851
{
1875
-
struct fuse_dev *fud = ctx->file ? fuse_file_to_fud(ctx->file) : NULL;
1852
+
struct fuse_dev *fud = ctx->fud;
1876
1853
struct fuse_mount *fm = get_fuse_mount_super(sb);
1877
1854
struct fuse_conn *fc = fm->fc;
1878
1855
struct inode *root;
···
1973
1950
struct fuse_mount *fm;
1974
1951
int err;
1975
1952
1976
-
if (!ctx->file || !ctx->rootmode_present ||
1953
+
if (!ctx->fud || !ctx->rootmode_present ||
1977
1954
!ctx->user_id_present || !ctx->group_id_present)
1978
-
return -EINVAL;
1979
-
1980
-
/*
1981
-
* Require mount to happen from the same user namespace which
1982
-
* opened /dev/fuse to prevent potential attacks.
1983
-
*/
1984
-
if ((ctx->file->f_op != &fuse_dev_operations) ||
1985
-
(ctx->file->f_cred->user_ns != sb->s_user_ns))
1986
1955
return -EINVAL;
1987
1956
1988
1957
err = fuse_fill_super_common(sb, ctx);
···
1997
1982
1998
1983
static int fuse_test_super(struct super_block *sb, struct fs_context *fsc)
1999
1984
{
1985
+
struct fuse_dev *fud = fsc->sget_key;
2000
1986
2001
-
return fsc->sget_key == get_fuse_conn_super(sb);
1987
+
return fuse_dev_fc_get(fud) == get_fuse_conn_super(sb);
2002
1988
}
2003
1989
2004
1990
static int fuse_get_tree(struct fs_context *fsc)
2005
1991
{
2006
1992
struct fuse_fs_context *ctx = fsc->fs_private;
2007
-
struct fuse_dev *fud;
2008
1993
struct fuse_conn *fc;
2009
1994
struct fuse_mount *fm;
2010
1995
struct super_block *sb;
···
2025
2010
2026
2011
fsc->s_fs_info = fm;
2027
2012
2028
-
if (ctx->fd_present)
2029
-
ctx->file = fget(ctx->fd);
2030
-
2031
2013
if (IS_ENABLED(CONFIG_BLOCK) && ctx->is_bdev) {
2032
2014
err = get_tree_bdev(fsc, fuse_fill_super);
2033
2015
goto out;
···
2034
2022
* (found by device name), normal fuse mounts can't
2035
2023
*/
2036
2024
err = -EINVAL;
2037
-
if (!ctx->file)
2025
+
if (!ctx->fud)
2038
2026
goto out;
2039
2027
2040
2028
/*
2041
2029
* Allow creating a fuse mount with an already initialized fuse
2042
2030
* connection
2043
2031
*/
2044
-
fud = __fuse_get_dev(ctx->file);
2045
-
if (ctx->file->f_op == &fuse_dev_operations && fud) {
2046
-
fsc->sget_key = fud->fc;
2032
+
if (fuse_dev_fc_get(ctx->fud)) {
2033
+
fsc->sget_key = ctx->fud;
2047
2034
sb = sget_fc(fsc, fuse_test_super, fuse_set_no_super);
2048
2035
err = PTR_ERR_OR_ZERO(sb);
2049
2036
if (!IS_ERR(sb))
···
2053
2042
out:
2054
2043
if (fsc->s_fs_info)
2055
2044
fuse_mount_destroy(fm);
2056
-
if (ctx->file)
2057
-
fput(ctx->file);
2058
2045
return err;
2059
2046
}
2060
2047