* [PATCH] sandbox/seunshare: switch seunshare_mount_file() to use open()
@ 2026-05-12 19:26 Stephen Smalley
2026-05-14 12:44 ` Petr Lautrbach
0 siblings, 1 reply; 4+ messages in thread
From: Stephen Smalley @ 2026-05-12 19:26 UTC (permalink / raw)
To: selinux; +Cc: jwcart2, plautrba, omosnace, paul, perfinion, Stephen Smalley
seunshare_mount_file() currently uses fopen() to create the dst
if it doesn't already exist. Switch to using open() with
explicitly specified flags including O_NOFOLLOW and an explicitly
specified mode for the new file.
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
---
sandbox/seunshare.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/sandbox/seunshare.c b/sandbox/seunshare.c
index a1900eaa..17a727e7 100644
--- a/sandbox/seunshare.c
+++ b/sandbox/seunshare.c
@@ -304,18 +304,20 @@ static int seunshare_mount(const char *src, const char *dst, struct stat *src_st
*/
static int seunshare_mount_file(const char *src, const char *dst)
{
- int flags = 0;
-
if (verbose)
printf(_("Mounting %s on %s\n"), src, dst);
if (access(dst, F_OK) == -1) {
- FILE *fptr;
- fptr = fopen(dst, "w");
- fclose(fptr);
+ int fd = open(dst, O_WRONLY | O_CREAT | O_NOFOLLOW | O_CLOEXEC, 0600);
+ if (fd < 0) {
+ fprintf(stderr, _("Failed to create mount point %s: %m\n"), dst);
+ return -1;
+ }
+ close(fd);
}
+
/* mount file */
- if (mount(src, dst, NULL, MS_BIND | flags, NULL) < 0) {
+ if (mount(src, dst, NULL, MS_BIND, NULL) < 0) {
fprintf(stderr, _("Failed to mount %s on %s: %s\n"), src, dst, strerror(errno));
return -1;
}
--
2.54.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] sandbox/seunshare: switch seunshare_mount_file() to use open()
2026-05-12 19:26 [PATCH] sandbox/seunshare: switch seunshare_mount_file() to use open() Stephen Smalley
@ 2026-05-14 12:44 ` Petr Lautrbach
2026-05-14 15:16 ` Stephen Smalley
2026-05-15 14:08 ` Petr Lautrbach
0 siblings, 2 replies; 4+ messages in thread
From: Petr Lautrbach @ 2026-05-14 12:44 UTC (permalink / raw)
To: Stephen Smalley, selinux
Cc: jwcart2, omosnace, paul, perfinion, Stephen Smalley
Stephen Smalley <stephen.smalley.work@gmail.com> writes:
> seunshare_mount_file() currently uses fopen() to create the dst
> if it doesn't already exist. Switch to using open() with
> explicitly specified flags including O_NOFOLLOW and an explicitly
> specified mode for the new file.
>
> Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Acked-by: Petr Lautrbach <lautrbach@redhat.com>
> ---
> sandbox/seunshare.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/sandbox/seunshare.c b/sandbox/seunshare.c
> index a1900eaa..17a727e7 100644
> --- a/sandbox/seunshare.c
> +++ b/sandbox/seunshare.c
> @@ -304,18 +304,20 @@ static int seunshare_mount(const char *src, const char *dst, struct stat *src_st
> */
> static int seunshare_mount_file(const char *src, const char *dst)
> {
> - int flags = 0;
> -
> if (verbose)
> printf(_("Mounting %s on %s\n"), src, dst);
>
> if (access(dst, F_OK) == -1) {
> - FILE *fptr;
> - fptr = fopen(dst, "w");
> - fclose(fptr);
> + int fd = open(dst, O_WRONLY | O_CREAT | O_NOFOLLOW | O_CLOEXEC, 0600);
> + if (fd < 0) {
> + fprintf(stderr, _("Failed to create mount point %s: %m\n"), dst);
> + return -1;
> + }
> + close(fd);
> }
> +
> /* mount file */
> - if (mount(src, dst, NULL, MS_BIND | flags, NULL) < 0) {
> + if (mount(src, dst, NULL, MS_BIND, NULL) < 0) {
> fprintf(stderr, _("Failed to mount %s on %s: %s\n"), src, dst, strerror(errno));
> return -1;
> }
> --
> 2.54.0
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] sandbox/seunshare: switch seunshare_mount_file() to use open()
2026-05-14 12:44 ` Petr Lautrbach
@ 2026-05-14 15:16 ` Stephen Smalley
2026-05-15 14:08 ` Petr Lautrbach
1 sibling, 0 replies; 4+ messages in thread
From: Stephen Smalley @ 2026-05-14 15:16 UTC (permalink / raw)
To: Petr Lautrbach; +Cc: selinux, jwcart2, omosnace, paul, perfinion
On Thu, May 14, 2026 at 8:44 AM Petr Lautrbach <plautrba@redhat.com> wrote:
>
> Stephen Smalley <stephen.smalley.work@gmail.com> writes:
>
> > seunshare_mount_file() currently uses fopen() to create the dst
> > if it doesn't already exist. Switch to using open() with
> > explicitly specified flags including O_NOFOLLOW and an explicitly
> > specified mode for the new file.
> >
> > Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
>
> Acked-by: Petr Lautrbach <lautrbach@redhat.com>
Thanks for the Acks; let me know if you plan to merge or if I should.
Also, I was wondering what if any validation we want to do for
seunshare_mount_file src/dst files before calling mount() on them;
there aren't currently verify_directory/check_owner_uid() calls for
them unlike for the directories passed to seunshare_mount().
>
> > ---
> > sandbox/seunshare.c | 14 ++++++++------
> > 1 file changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/sandbox/seunshare.c b/sandbox/seunshare.c
> > index a1900eaa..17a727e7 100644
> > --- a/sandbox/seunshare.c
> > +++ b/sandbox/seunshare.c
> > @@ -304,18 +304,20 @@ static int seunshare_mount(const char *src, const char *dst, struct stat *src_st
> > */
> > static int seunshare_mount_file(const char *src, const char *dst)
> > {
> > - int flags = 0;
> > -
> > if (verbose)
> > printf(_("Mounting %s on %s\n"), src, dst);
> >
> > if (access(dst, F_OK) == -1) {
> > - FILE *fptr;
> > - fptr = fopen(dst, "w");
> > - fclose(fptr);
> > + int fd = open(dst, O_WRONLY | O_CREAT | O_NOFOLLOW | O_CLOEXEC, 0600);
> > + if (fd < 0) {
> > + fprintf(stderr, _("Failed to create mount point %s: %m\n"), dst);
> > + return -1;
> > + }
> > + close(fd);
> > }
> > +
> > /* mount file */
> > - if (mount(src, dst, NULL, MS_BIND | flags, NULL) < 0) {
> > + if (mount(src, dst, NULL, MS_BIND, NULL) < 0) {
> > fprintf(stderr, _("Failed to mount %s on %s: %s\n"), src, dst, strerror(errno));
> > return -1;
> > }
> > --
> > 2.54.0
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] sandbox/seunshare: switch seunshare_mount_file() to use open()
2026-05-14 12:44 ` Petr Lautrbach
2026-05-14 15:16 ` Stephen Smalley
@ 2026-05-15 14:08 ` Petr Lautrbach
1 sibling, 0 replies; 4+ messages in thread
From: Petr Lautrbach @ 2026-05-15 14:08 UTC (permalink / raw)
To: Stephen Smalley, selinux
Cc: jwcart2, omosnace, paul, perfinion, Stephen Smalley
Petr Lautrbach <plautrba@redhat.com> writes:
> Stephen Smalley <stephen.smalley.work@gmail.com> writes:
>
>> seunshare_mount_file() currently uses fopen() to create the dst
>> if it doesn't already exist. Switch to using open() with
>> explicitly specified flags including O_NOFOLLOW and an explicitly
>> specified mode for the new file.
>>
>> Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
>
> Acked-by: Petr Lautrbach <lautrbach@redhat.com>
Merged, thanks!
>> ---
>> sandbox/seunshare.c | 14 ++++++++------
>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/sandbox/seunshare.c b/sandbox/seunshare.c
>> index a1900eaa..17a727e7 100644
>> --- a/sandbox/seunshare.c
>> +++ b/sandbox/seunshare.c
>> @@ -304,18 +304,20 @@ static int seunshare_mount(const char *src, const char *dst, struct stat *src_st
>> */
>> static int seunshare_mount_file(const char *src, const char *dst)
>> {
>> - int flags = 0;
>> -
>> if (verbose)
>> printf(_("Mounting %s on %s\n"), src, dst);
>>
>> if (access(dst, F_OK) == -1) {
>> - FILE *fptr;
>> - fptr = fopen(dst, "w");
>> - fclose(fptr);
>> + int fd = open(dst, O_WRONLY | O_CREAT | O_NOFOLLOW | O_CLOEXEC, 0600);
>> + if (fd < 0) {
>> + fprintf(stderr, _("Failed to create mount point %s: %m\n"), dst);
>> + return -1;
>> + }
>> + close(fd);
>> }
>> +
>> /* mount file */
>> - if (mount(src, dst, NULL, MS_BIND | flags, NULL) < 0) {
>> + if (mount(src, dst, NULL, MS_BIND, NULL) < 0) {
>> fprintf(stderr, _("Failed to mount %s on %s: %s\n"), src, dst, strerror(errno));
>> return -1;
>> }
>> --
>> 2.54.0
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-05-15 14:08 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2026-05-12 19:26 [PATCH] sandbox/seunshare: switch seunshare_mount_file() to use open() Stephen Smalley
2026-05-14 12:44 ` Petr Lautrbach
2026-05-14 15:16 ` Stephen Smalley
2026-05-15 14:08 ` Petr Lautrbach
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