* [PATCH 0/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC @ 2020-10-13 14:06 ` Giuseppe Scrivano 0 siblings, 0 replies; 22+ messages in thread From: Giuseppe Scrivano @ 2020-10-13 14:06 UTC (permalink / raw) To: linux-kernel; +Cc: linux-fsdevel, containers, viro When the new flag is used, close_range will set the close-on-exec bit for the file descriptors instead of close()-ing them. It is useful for e.g. container runtimes that want to minimize the number of syscalls used after a seccomp profile is installed but want to keep some fds open until the container process is executed. Giuseppe Scrivano (2): fs, close_range: add flag CLOSE_RANGE_CLOEXEC selftests: add tests for CLOSE_RANGE_CLOEXEC fs/file.c | 56 +++++++++++++------ include/uapi/linux/close_range.h | 3 + .../testing/selftests/core/close_range_test.c | 44 +++++++++++++++ 3 files changed, 86 insertions(+), 17 deletions(-) -- 2.26.2 _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/containers ^ permalink raw reply [flat|nested] 22+ messages in thread
* [PATCH 0/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC @ 2020-10-13 14:06 ` Giuseppe Scrivano 0 siblings, 0 replies; 22+ messages in thread From: Giuseppe Scrivano @ 2020-10-13 14:06 UTC (permalink / raw) To: linux-kernel; +Cc: viro, linux-fsdevel, christian.brauner, containers When the new flag is used, close_range will set the close-on-exec bit for the file descriptors instead of close()-ing them. It is useful for e.g. container runtimes that want to minimize the number of syscalls used after a seccomp profile is installed but want to keep some fds open until the container process is executed. Giuseppe Scrivano (2): fs, close_range: add flag CLOSE_RANGE_CLOEXEC selftests: add tests for CLOSE_RANGE_CLOEXEC fs/file.c | 56 +++++++++++++------ include/uapi/linux/close_range.h | 3 + .../testing/selftests/core/close_range_test.c | 44 +++++++++++++++ 3 files changed, 86 insertions(+), 17 deletions(-) -- 2.26.2 ^ permalink raw reply [flat|nested] 22+ messages in thread
* [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC 2020-10-13 14:06 ` Giuseppe Scrivano @ 2020-10-13 14:06 ` Giuseppe Scrivano -1 siblings, 0 replies; 22+ messages in thread From: Giuseppe Scrivano @ 2020-10-13 14:06 UTC (permalink / raw) To: linux-kernel; +Cc: linux-fsdevel, containers, viro When the flag CLOSE_RANGE_CLOEXEC is set, close_range doesn't immediately close the files but it sets the close-on-exec bit. Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com> --- fs/file.c | 56 ++++++++++++++++++++++---------- include/uapi/linux/close_range.h | 3 ++ 2 files changed, 42 insertions(+), 17 deletions(-) diff --git a/fs/file.c b/fs/file.c index 21c0893f2f1d..ad4ebee41e09 100644 --- a/fs/file.c +++ b/fs/file.c @@ -672,6 +672,17 @@ int __close_fd(struct files_struct *files, unsigned fd) } EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ +static unsigned int __get_max_fds(struct files_struct *cur_fds) +{ + unsigned int max_fds; + + rcu_read_lock(); + /* cap to last valid index into fdtable */ + max_fds = files_fdtable(cur_fds)->max_fds; + rcu_read_unlock(); + return max_fds; +} + /** * __close_range() - Close all file descriptors in a given range. * @@ -683,27 +694,23 @@ EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ */ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) { - unsigned int cur_max; + unsigned int cur_max = UINT_MAX; struct task_struct *me = current; struct files_struct *cur_fds = me->files, *fds = NULL; - if (flags & ~CLOSE_RANGE_UNSHARE) + if (flags & ~(CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC)) return -EINVAL; if (fd > max_fd) return -EINVAL; - rcu_read_lock(); - cur_max = files_fdtable(cur_fds)->max_fds; - rcu_read_unlock(); - - /* cap to last valid index into fdtable */ - cur_max--; - if (flags & CLOSE_RANGE_UNSHARE) { int ret; unsigned int max_unshare_fds = NR_OPEN_MAX; + /* cap to last valid index into fdtable */ + cur_max = __get_max_fds(cur_fds) - 1; + /* * If the requested range is greater than the current maximum, * we're closing everything so only copy all file descriptors @@ -724,16 +731,31 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) swap(cur_fds, fds); } - max_fd = min(max_fd, cur_max); - while (fd <= max_fd) { - struct file *file; + if (flags & CLOSE_RANGE_CLOEXEC) { + struct fdtable *fdt; - file = pick_file(cur_fds, fd++); - if (!file) - continue; + spin_lock(&cur_fds->file_lock); + fdt = files_fdtable(cur_fds); + cur_max = fdt->max_fds - 1; + max_fd = min(max_fd, cur_max); + while (fd <= max_fd) + __set_close_on_exec(fd++, fdt); + spin_unlock(&cur_fds->file_lock); + } else { + /* Initialize cur_max if needed. */ + if (cur_max == UINT_MAX) + cur_max = __get_max_fds(cur_fds) - 1; + max_fd = min(max_fd, cur_max); + while (fd <= max_fd) { + struct file *file; - filp_close(file, cur_fds); - cond_resched(); + file = pick_file(cur_fds, fd++); + if (!file) + continue; + + filp_close(file, cur_fds); + cond_resched(); + } } if (fds) { diff --git a/include/uapi/linux/close_range.h b/include/uapi/linux/close_range.h index 6928a9fdee3c..2d804281554c 100644 --- a/include/uapi/linux/close_range.h +++ b/include/uapi/linux/close_range.h @@ -5,5 +5,8 @@ /* Unshare the file descriptor table before closing file descriptors. */ #define CLOSE_RANGE_UNSHARE (1U << 1) +/* Set the FD_CLOEXEC bit instead of closing the file descriptor. */ +#define CLOSE_RANGE_CLOEXEC (1U << 2) + #endif /* _UAPI_LINUX_CLOSE_RANGE_H */ -- 2.26.2 _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/containers ^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC @ 2020-10-13 14:06 ` Giuseppe Scrivano 0 siblings, 0 replies; 22+ messages in thread From: Giuseppe Scrivano @ 2020-10-13 14:06 UTC (permalink / raw) To: linux-kernel; +Cc: viro, linux-fsdevel, christian.brauner, containers When the flag CLOSE_RANGE_CLOEXEC is set, close_range doesn't immediately close the files but it sets the close-on-exec bit. Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com> --- fs/file.c | 56 ++++++++++++++++++++++---------- include/uapi/linux/close_range.h | 3 ++ 2 files changed, 42 insertions(+), 17 deletions(-) diff --git a/fs/file.c b/fs/file.c index 21c0893f2f1d..ad4ebee41e09 100644 --- a/fs/file.c +++ b/fs/file.c @@ -672,6 +672,17 @@ int __close_fd(struct files_struct *files, unsigned fd) } EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ +static unsigned int __get_max_fds(struct files_struct *cur_fds) +{ + unsigned int max_fds; + + rcu_read_lock(); + /* cap to last valid index into fdtable */ + max_fds = files_fdtable(cur_fds)->max_fds; + rcu_read_unlock(); + return max_fds; +} + /** * __close_range() - Close all file descriptors in a given range. * @@ -683,27 +694,23 @@ EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ */ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) { - unsigned int cur_max; + unsigned int cur_max = UINT_MAX; struct task_struct *me = current; struct files_struct *cur_fds = me->files, *fds = NULL; - if (flags & ~CLOSE_RANGE_UNSHARE) + if (flags & ~(CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC)) return -EINVAL; if (fd > max_fd) return -EINVAL; - rcu_read_lock(); - cur_max = files_fdtable(cur_fds)->max_fds; - rcu_read_unlock(); - - /* cap to last valid index into fdtable */ - cur_max--; - if (flags & CLOSE_RANGE_UNSHARE) { int ret; unsigned int max_unshare_fds = NR_OPEN_MAX; + /* cap to last valid index into fdtable */ + cur_max = __get_max_fds(cur_fds) - 1; + /* * If the requested range is greater than the current maximum, * we're closing everything so only copy all file descriptors @@ -724,16 +731,31 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) swap(cur_fds, fds); } - max_fd = min(max_fd, cur_max); - while (fd <= max_fd) { - struct file *file; + if (flags & CLOSE_RANGE_CLOEXEC) { + struct fdtable *fdt; - file = pick_file(cur_fds, fd++); - if (!file) - continue; + spin_lock(&cur_fds->file_lock); + fdt = files_fdtable(cur_fds); + cur_max = fdt->max_fds - 1; + max_fd = min(max_fd, cur_max); + while (fd <= max_fd) + __set_close_on_exec(fd++, fdt); + spin_unlock(&cur_fds->file_lock); + } else { + /* Initialize cur_max if needed. */ + if (cur_max == UINT_MAX) + cur_max = __get_max_fds(cur_fds) - 1; + max_fd = min(max_fd, cur_max); + while (fd <= max_fd) { + struct file *file; - filp_close(file, cur_fds); - cond_resched(); + file = pick_file(cur_fds, fd++); + if (!file) + continue; + + filp_close(file, cur_fds); + cond_resched(); + } } if (fds) { diff --git a/include/uapi/linux/close_range.h b/include/uapi/linux/close_range.h index 6928a9fdee3c..2d804281554c 100644 --- a/include/uapi/linux/close_range.h +++ b/include/uapi/linux/close_range.h @@ -5,5 +5,8 @@ /* Unshare the file descriptor table before closing file descriptors. */ #define CLOSE_RANGE_UNSHARE (1U << 1) +/* Set the FD_CLOEXEC bit instead of closing the file descriptor. */ +#define CLOSE_RANGE_CLOEXEC (1U << 2) + #endif /* _UAPI_LINUX_CLOSE_RANGE_H */ -- 2.26.2 ^ permalink raw reply related [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC 2020-10-13 14:06 ` Giuseppe Scrivano @ 2020-10-13 20:54 ` Christian Brauner -1 siblings, 0 replies; 22+ messages in thread From: Christian Brauner @ 2020-10-13 20:54 UTC (permalink / raw) To: Giuseppe Scrivano; +Cc: linux-fsdevel, containers, linux-kernel, viro On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: Hey Guiseppe, Thanks for the patch! > When the flag CLOSE_RANGE_CLOEXEC is set, close_range doesn't > immediately close the files but it sets the close-on-exec bit. Hm, please expand on the use-cases a little here so people know where and how this is useful. Keeping the rationale for a change in the commit log is really important. > > Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com> > --- > fs/file.c | 56 ++++++++++++++++++++++---------- > include/uapi/linux/close_range.h | 3 ++ > 2 files changed, 42 insertions(+), 17 deletions(-) > > diff --git a/fs/file.c b/fs/file.c > index 21c0893f2f1d..ad4ebee41e09 100644 > --- a/fs/file.c > +++ b/fs/file.c > @@ -672,6 +672,17 @@ int __close_fd(struct files_struct *files, unsigned fd) > } > EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ > > +static unsigned int __get_max_fds(struct files_struct *cur_fds) > +{ > + unsigned int max_fds; > + > + rcu_read_lock(); > + /* cap to last valid index into fdtable */ > + max_fds = files_fdtable(cur_fds)->max_fds; > + rcu_read_unlock(); > + return max_fds; > +} > + > /** > * __close_range() - Close all file descriptors in a given range. > * > @@ -683,27 +694,23 @@ EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ > */ > int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) > { > - unsigned int cur_max; > + unsigned int cur_max = UINT_MAX; > struct task_struct *me = current; > struct files_struct *cur_fds = me->files, *fds = NULL; > > - if (flags & ~CLOSE_RANGE_UNSHARE) > + if (flags & ~(CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC)) > return -EINVAL; > > if (fd > max_fd) > return -EINVAL; > > - rcu_read_lock(); > - cur_max = files_fdtable(cur_fds)->max_fds; > - rcu_read_unlock(); > - > - /* cap to last valid index into fdtable */ > - cur_max--; > - > if (flags & CLOSE_RANGE_UNSHARE) { > int ret; > unsigned int max_unshare_fds = NR_OPEN_MAX; > > + /* cap to last valid index into fdtable */ > + cur_max = __get_max_fds(cur_fds) - 1; > + > /* > * If the requested range is greater than the current maximum, > * we're closing everything so only copy all file descriptors > @@ -724,16 +731,31 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) > swap(cur_fds, fds); > } > > - max_fd = min(max_fd, cur_max); > - while (fd <= max_fd) { > - struct file *file; > + if (flags & CLOSE_RANGE_CLOEXEC) { > + struct fdtable *fdt; > > - file = pick_file(cur_fds, fd++); > - if (!file) > - continue; > + spin_lock(&cur_fds->file_lock); > + fdt = files_fdtable(cur_fds); > + cur_max = fdt->max_fds - 1; > + max_fd = min(max_fd, cur_max); > + while (fd <= max_fd) > + __set_close_on_exec(fd++, fdt); > + spin_unlock(&cur_fds->file_lock); > + } else { > + /* Initialize cur_max if needed. */ > + if (cur_max == UINT_MAX) > + cur_max = __get_max_fds(cur_fds) - 1; The separation between how cur_fd is retrieved in the two branches makes the code more difficult to follow imho. Unless there's a clear reason why you've done it that way I would think that something like the patch I appended below might be a little clearer and easier to maintain(?). > + max_fd = min(max_fd, cur_max); > + while (fd <= max_fd) { > + struct file *file; > > - filp_close(file, cur_fds); > - cond_resched(); > + file = pick_file(cur_fds, fd++); > + if (!file) > + continue; > + > + filp_close(file, cur_fds); > + cond_resched(); > + } > } I think I don't have quarrels with this patch in principle but I wonder if something like the following wouldn't be easier to follow: diff --git a/fs/file.c b/fs/file.c index 21c0893f2f1d..872a4098c3be 100644 --- a/fs/file.c +++ b/fs/file.c @@ -672,6 +672,32 @@ int __close_fd(struct files_struct *files, unsigned fd) } EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ +static inline void __range_cloexec(struct files_struct *cur_fds, + unsigned int fd, unsigned max_fd) +{ + struct fdtable *fdt; + spin_lock(&cur_fds->file_lock); + fdt = files_fdtable(cur_fds); + while (fd <= max_fd) + __set_close_on_exec(fd++, fdt); + spin_unlock(&cur_fds->file_lock); +} + +static inline void __range_close(struct files_struct *cur_fds, unsigned int fd, + unsigned max_fd) +{ + while (fd <= max_fd) { + struct file *file; + + file = pick_file(cur_fds, fd++); + if (!file) + continue; + + filp_close(file, cur_fds); + cond_resched(); + } +} + /** * __close_range() - Close all file descriptors in a given range. * @@ -687,7 +713,7 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) struct task_struct *me = current; struct files_struct *cur_fds = me->files, *fds = NULL; - if (flags & ~CLOSE_RANGE_UNSHARE) + if (flags & ~(CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC)) return -EINVAL; if (fd > max_fd) @@ -725,16 +751,10 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) } max_fd = min(max_fd, cur_max); - while (fd <= max_fd) { - struct file *file; - - file = pick_file(cur_fds, fd++); - if (!file) - continue; - - filp_close(file, cur_fds); - cond_resched(); - } + if (flags & CLOSE_RANGE_CLOEXEC) + __range_cloexec(cur_fds, fd, max_fd); + else + __range_close(cur_fds, fd, max_fd); if (fds) { /* diff --git a/include/uapi/linux/close_range.h b/include/uapi/linux/close_range.h index 6928a9fdee3c..2d804281554c 100644 --- a/include/uapi/linux/close_range.h +++ b/include/uapi/linux/close_range.h @@ -5,5 +5,8 @@ /* Unshare the file descriptor table before closing file descriptors. */ #define CLOSE_RANGE_UNSHARE (1U << 1) +/* Set the FD_CLOEXEC bit instead of closing the file descriptor. */ +#define CLOSE_RANGE_CLOEXEC (1U << 2) + #endif /* _UAPI_LINUX_CLOSE_RANGE_H */ _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/containers ^ permalink raw reply related [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC @ 2020-10-13 20:54 ` Christian Brauner 0 siblings, 0 replies; 22+ messages in thread From: Christian Brauner @ 2020-10-13 20:54 UTC (permalink / raw) To: Giuseppe Scrivano; +Cc: linux-kernel, viro, linux-fsdevel, containers On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: Hey Guiseppe, Thanks for the patch! > When the flag CLOSE_RANGE_CLOEXEC is set, close_range doesn't > immediately close the files but it sets the close-on-exec bit. Hm, please expand on the use-cases a little here so people know where and how this is useful. Keeping the rationale for a change in the commit log is really important. > > Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com> > --- > fs/file.c | 56 ++++++++++++++++++++++---------- > include/uapi/linux/close_range.h | 3 ++ > 2 files changed, 42 insertions(+), 17 deletions(-) > > diff --git a/fs/file.c b/fs/file.c > index 21c0893f2f1d..ad4ebee41e09 100644 > --- a/fs/file.c > +++ b/fs/file.c > @@ -672,6 +672,17 @@ int __close_fd(struct files_struct *files, unsigned fd) > } > EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ > > +static unsigned int __get_max_fds(struct files_struct *cur_fds) > +{ > + unsigned int max_fds; > + > + rcu_read_lock(); > + /* cap to last valid index into fdtable */ > + max_fds = files_fdtable(cur_fds)->max_fds; > + rcu_read_unlock(); > + return max_fds; > +} > + > /** > * __close_range() - Close all file descriptors in a given range. > * > @@ -683,27 +694,23 @@ EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ > */ > int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) > { > - unsigned int cur_max; > + unsigned int cur_max = UINT_MAX; > struct task_struct *me = current; > struct files_struct *cur_fds = me->files, *fds = NULL; > > - if (flags & ~CLOSE_RANGE_UNSHARE) > + if (flags & ~(CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC)) > return -EINVAL; > > if (fd > max_fd) > return -EINVAL; > > - rcu_read_lock(); > - cur_max = files_fdtable(cur_fds)->max_fds; > - rcu_read_unlock(); > - > - /* cap to last valid index into fdtable */ > - cur_max--; > - > if (flags & CLOSE_RANGE_UNSHARE) { > int ret; > unsigned int max_unshare_fds = NR_OPEN_MAX; > > + /* cap to last valid index into fdtable */ > + cur_max = __get_max_fds(cur_fds) - 1; > + > /* > * If the requested range is greater than the current maximum, > * we're closing everything so only copy all file descriptors > @@ -724,16 +731,31 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) > swap(cur_fds, fds); > } > > - max_fd = min(max_fd, cur_max); > - while (fd <= max_fd) { > - struct file *file; > + if (flags & CLOSE_RANGE_CLOEXEC) { > + struct fdtable *fdt; > > - file = pick_file(cur_fds, fd++); > - if (!file) > - continue; > + spin_lock(&cur_fds->file_lock); > + fdt = files_fdtable(cur_fds); > + cur_max = fdt->max_fds - 1; > + max_fd = min(max_fd, cur_max); > + while (fd <= max_fd) > + __set_close_on_exec(fd++, fdt); > + spin_unlock(&cur_fds->file_lock); > + } else { > + /* Initialize cur_max if needed. */ > + if (cur_max == UINT_MAX) > + cur_max = __get_max_fds(cur_fds) - 1; The separation between how cur_fd is retrieved in the two branches makes the code more difficult to follow imho. Unless there's a clear reason why you've done it that way I would think that something like the patch I appended below might be a little clearer and easier to maintain(?). > + max_fd = min(max_fd, cur_max); > + while (fd <= max_fd) { > + struct file *file; > > - filp_close(file, cur_fds); > - cond_resched(); > + file = pick_file(cur_fds, fd++); > + if (!file) > + continue; > + > + filp_close(file, cur_fds); > + cond_resched(); > + } > } I think I don't have quarrels with this patch in principle but I wonder if something like the following wouldn't be easier to follow: diff --git a/fs/file.c b/fs/file.c index 21c0893f2f1d..872a4098c3be 100644 --- a/fs/file.c +++ b/fs/file.c @@ -672,6 +672,32 @@ int __close_fd(struct files_struct *files, unsigned fd) } EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ +static inline void __range_cloexec(struct files_struct *cur_fds, + unsigned int fd, unsigned max_fd) +{ + struct fdtable *fdt; + spin_lock(&cur_fds->file_lock); + fdt = files_fdtable(cur_fds); + while (fd <= max_fd) + __set_close_on_exec(fd++, fdt); + spin_unlock(&cur_fds->file_lock); +} + +static inline void __range_close(struct files_struct *cur_fds, unsigned int fd, + unsigned max_fd) +{ + while (fd <= max_fd) { + struct file *file; + + file = pick_file(cur_fds, fd++); + if (!file) + continue; + + filp_close(file, cur_fds); + cond_resched(); + } +} + /** * __close_range() - Close all file descriptors in a given range. * @@ -687,7 +713,7 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) struct task_struct *me = current; struct files_struct *cur_fds = me->files, *fds = NULL; - if (flags & ~CLOSE_RANGE_UNSHARE) + if (flags & ~(CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC)) return -EINVAL; if (fd > max_fd) @@ -725,16 +751,10 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) } max_fd = min(max_fd, cur_max); - while (fd <= max_fd) { - struct file *file; - - file = pick_file(cur_fds, fd++); - if (!file) - continue; - - filp_close(file, cur_fds); - cond_resched(); - } + if (flags & CLOSE_RANGE_CLOEXEC) + __range_cloexec(cur_fds, fd, max_fd); + else + __range_close(cur_fds, fd, max_fd); if (fds) { /* diff --git a/include/uapi/linux/close_range.h b/include/uapi/linux/close_range.h index 6928a9fdee3c..2d804281554c 100644 --- a/include/uapi/linux/close_range.h +++ b/include/uapi/linux/close_range.h @@ -5,5 +5,8 @@ /* Unshare the file descriptor table before closing file descriptors. */ #define CLOSE_RANGE_UNSHARE (1U << 1) +/* Set the FD_CLOEXEC bit instead of closing the file descriptor. */ +#define CLOSE_RANGE_CLOEXEC (1U << 2) + #endif /* _UAPI_LINUX_CLOSE_RANGE_H */ ^ permalink raw reply related [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC 2020-10-13 20:54 ` Christian Brauner @ 2020-10-13 21:04 ` Rasmus Villemoes -1 siblings, 0 replies; 22+ messages in thread From: Rasmus Villemoes @ 2020-10-13 21:04 UTC (permalink / raw) To: Christian Brauner, Giuseppe Scrivano Cc: linux-fsdevel, containers, linux-kernel, viro On 13/10/2020 22.54, Christian Brauner wrote: > On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: > > Hey Guiseppe, > > Thanks for the patch! > >> When the flag CLOSE_RANGE_CLOEXEC is set, close_range doesn't >> immediately close the files but it sets the close-on-exec bit. > > Hm, please expand on the use-cases a little here so people know where > and how this is useful. Keeping the rationale for a change in the commit > log is really important. > > I think I don't have quarrels with this patch in principle but I wonder > if something like the following wouldn't be easier to follow: > > diff --git a/fs/file.c b/fs/file.c > index 21c0893f2f1d..872a4098c3be 100644 > --- a/fs/file.c > +++ b/fs/file.c > @@ -672,6 +672,32 @@ int __close_fd(struct files_struct *files, unsigned fd) > } > EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ > > +static inline void __range_cloexec(struct files_struct *cur_fds, > + unsigned int fd, unsigned max_fd) > +{ > + struct fdtable *fdt; > + spin_lock(&cur_fds->file_lock); > + fdt = files_fdtable(cur_fds); > + while (fd <= max_fd) > + __set_close_on_exec(fd++, fdt); Doesn't that want to be bitmap_set(fdt->close_on_exec, fd, max_fd - fd + 1) to do word-at-a-time? I assume this would mostly be called with (3, ~0U) as arguments or something like that. Rasmus _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/containers ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC @ 2020-10-13 21:04 ` Rasmus Villemoes 0 siblings, 0 replies; 22+ messages in thread From: Rasmus Villemoes @ 2020-10-13 21:04 UTC (permalink / raw) To: Christian Brauner, Giuseppe Scrivano Cc: linux-kernel, viro, linux-fsdevel, containers On 13/10/2020 22.54, Christian Brauner wrote: > On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: > > Hey Guiseppe, > > Thanks for the patch! > >> When the flag CLOSE_RANGE_CLOEXEC is set, close_range doesn't >> immediately close the files but it sets the close-on-exec bit. > > Hm, please expand on the use-cases a little here so people know where > and how this is useful. Keeping the rationale for a change in the commit > log is really important. > > I think I don't have quarrels with this patch in principle but I wonder > if something like the following wouldn't be easier to follow: > > diff --git a/fs/file.c b/fs/file.c > index 21c0893f2f1d..872a4098c3be 100644 > --- a/fs/file.c > +++ b/fs/file.c > @@ -672,6 +672,32 @@ int __close_fd(struct files_struct *files, unsigned fd) > } > EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ > > +static inline void __range_cloexec(struct files_struct *cur_fds, > + unsigned int fd, unsigned max_fd) > +{ > + struct fdtable *fdt; > + spin_lock(&cur_fds->file_lock); > + fdt = files_fdtable(cur_fds); > + while (fd <= max_fd) > + __set_close_on_exec(fd++, fdt); Doesn't that want to be bitmap_set(fdt->close_on_exec, fd, max_fd - fd + 1) to do word-at-a-time? I assume this would mostly be called with (3, ~0U) as arguments or something like that. Rasmus ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC 2020-10-13 21:04 ` Rasmus Villemoes @ 2020-10-13 21:22 ` Christian Brauner -1 siblings, 0 replies; 22+ messages in thread From: Christian Brauner @ 2020-10-13 21:22 UTC (permalink / raw) To: Rasmus Villemoes Cc: linux-fsdevel, Giuseppe Scrivano, containers, linux-kernel, viro On Tue, Oct 13, 2020 at 11:04:21PM +0200, Rasmus Villemoes wrote: > On 13/10/2020 22.54, Christian Brauner wrote: > > On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: > > > > Hey Guiseppe, > > > > Thanks for the patch! > > > >> When the flag CLOSE_RANGE_CLOEXEC is set, close_range doesn't > >> immediately close the files but it sets the close-on-exec bit. > > > > Hm, please expand on the use-cases a little here so people know where > > and how this is useful. Keeping the rationale for a change in the commit > > log is really important. > > > > > I think I don't have quarrels with this patch in principle but I wonder > > if something like the following wouldn't be easier to follow: > > > > diff --git a/fs/file.c b/fs/file.c > > index 21c0893f2f1d..872a4098c3be 100644 > > --- a/fs/file.c > > +++ b/fs/file.c > > @@ -672,6 +672,32 @@ int __close_fd(struct files_struct *files, unsigned fd) > > } > > EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ > > > > +static inline void __range_cloexec(struct files_struct *cur_fds, > > + unsigned int fd, unsigned max_fd) > > +{ > > + struct fdtable *fdt; > > + spin_lock(&cur_fds->file_lock); > > + fdt = files_fdtable(cur_fds); > > + while (fd <= max_fd) > > + __set_close_on_exec(fd++, fdt); > (I should've warned that I just proposed this as a completely untested brainstorm.) > Doesn't that want to be > > bitmap_set(fdt->close_on_exec, fd, max_fd - fd + 1) > > to do word-at-a-time? I assume this would mostly be called with (3, ~0U) > as arguments or something like that. Yes, that is the common case. Thanks Rasmus, I was unaware we had that function. In that case I think we'd actually need sm like: spin_lock(&cur_fds->file_lock); fdt = files_fdtable(cur_fds); cur_max = files_fdtable(cur_fds)->max_fds - 1; max_fd = min(max_fd, cur_max); bitmap_set(fdt->close_on_exec, fd, max_fd - fd + 1) so we retrieve max_fd with the spinlock held, I think. Christian _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/containers ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC @ 2020-10-13 21:22 ` Christian Brauner 0 siblings, 0 replies; 22+ messages in thread From: Christian Brauner @ 2020-10-13 21:22 UTC (permalink / raw) To: Rasmus Villemoes Cc: Giuseppe Scrivano, linux-kernel, viro, linux-fsdevel, containers On Tue, Oct 13, 2020 at 11:04:21PM +0200, Rasmus Villemoes wrote: > On 13/10/2020 22.54, Christian Brauner wrote: > > On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: > > > > Hey Guiseppe, > > > > Thanks for the patch! > > > >> When the flag CLOSE_RANGE_CLOEXEC is set, close_range doesn't > >> immediately close the files but it sets the close-on-exec bit. > > > > Hm, please expand on the use-cases a little here so people know where > > and how this is useful. Keeping the rationale for a change in the commit > > log is really important. > > > > > I think I don't have quarrels with this patch in principle but I wonder > > if something like the following wouldn't be easier to follow: > > > > diff --git a/fs/file.c b/fs/file.c > > index 21c0893f2f1d..872a4098c3be 100644 > > --- a/fs/file.c > > +++ b/fs/file.c > > @@ -672,6 +672,32 @@ int __close_fd(struct files_struct *files, unsigned fd) > > } > > EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ > > > > +static inline void __range_cloexec(struct files_struct *cur_fds, > > + unsigned int fd, unsigned max_fd) > > +{ > > + struct fdtable *fdt; > > + spin_lock(&cur_fds->file_lock); > > + fdt = files_fdtable(cur_fds); > > + while (fd <= max_fd) > > + __set_close_on_exec(fd++, fdt); > (I should've warned that I just proposed this as a completely untested brainstorm.) > Doesn't that want to be > > bitmap_set(fdt->close_on_exec, fd, max_fd - fd + 1) > > to do word-at-a-time? I assume this would mostly be called with (3, ~0U) > as arguments or something like that. Yes, that is the common case. Thanks Rasmus, I was unaware we had that function. In that case I think we'd actually need sm like: spin_lock(&cur_fds->file_lock); fdt = files_fdtable(cur_fds); cur_max = files_fdtable(cur_fds)->max_fds - 1; max_fd = min(max_fd, cur_max); bitmap_set(fdt->close_on_exec, fd, max_fd - fd + 1) so we retrieve max_fd with the spinlock held, I think. Christian ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC 2020-10-13 20:54 ` Christian Brauner @ 2020-10-13 22:45 ` Giuseppe Scrivano -1 siblings, 0 replies; 22+ messages in thread From: Giuseppe Scrivano @ 2020-10-13 22:45 UTC (permalink / raw) To: Christian Brauner; +Cc: linux-fsdevel, containers, linux-kernel, viro Christian Brauner <christian.brauner@ubuntu.com> writes: > On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: > > Hey Guiseppe, > > Thanks for the patch! > >> When the flag CLOSE_RANGE_CLOEXEC is set, close_range doesn't >> immediately close the files but it sets the close-on-exec bit. > > Hm, please expand on the use-cases a little here so people know where > and how this is useful. Keeping the rationale for a change in the commit > log is really important. > >> >> Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com> >> --- > >> fs/file.c | 56 ++++++++++++++++++++++---------- >> include/uapi/linux/close_range.h | 3 ++ >> 2 files changed, 42 insertions(+), 17 deletions(-) >> >> diff --git a/fs/file.c b/fs/file.c >> index 21c0893f2f1d..ad4ebee41e09 100644 >> --- a/fs/file.c >> +++ b/fs/file.c >> @@ -672,6 +672,17 @@ int __close_fd(struct files_struct *files, unsigned fd) >> } >> EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ >> >> +static unsigned int __get_max_fds(struct files_struct *cur_fds) >> +{ >> + unsigned int max_fds; >> + >> + rcu_read_lock(); >> + /* cap to last valid index into fdtable */ >> + max_fds = files_fdtable(cur_fds)->max_fds; >> + rcu_read_unlock(); >> + return max_fds; >> +} >> + >> /** >> * __close_range() - Close all file descriptors in a given range. >> * >> @@ -683,27 +694,23 @@ EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ >> */ >> int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) >> { >> - unsigned int cur_max; >> + unsigned int cur_max = UINT_MAX; >> struct task_struct *me = current; >> struct files_struct *cur_fds = me->files, *fds = NULL; >> >> - if (flags & ~CLOSE_RANGE_UNSHARE) >> + if (flags & ~(CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC)) >> return -EINVAL; >> >> if (fd > max_fd) >> return -EINVAL; >> >> - rcu_read_lock(); >> - cur_max = files_fdtable(cur_fds)->max_fds; >> - rcu_read_unlock(); >> - >> - /* cap to last valid index into fdtable */ >> - cur_max--; >> - >> if (flags & CLOSE_RANGE_UNSHARE) { >> int ret; >> unsigned int max_unshare_fds = NR_OPEN_MAX; >> >> + /* cap to last valid index into fdtable */ >> + cur_max = __get_max_fds(cur_fds) - 1; >> + >> /* >> * If the requested range is greater than the current maximum, >> * we're closing everything so only copy all file descriptors >> @@ -724,16 +731,31 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) >> swap(cur_fds, fds); >> } >> >> - max_fd = min(max_fd, cur_max); >> - while (fd <= max_fd) { >> - struct file *file; >> + if (flags & CLOSE_RANGE_CLOEXEC) { >> + struct fdtable *fdt; >> >> - file = pick_file(cur_fds, fd++); >> - if (!file) >> - continue; >> + spin_lock(&cur_fds->file_lock); >> + fdt = files_fdtable(cur_fds); >> + cur_max = fdt->max_fds - 1; >> + max_fd = min(max_fd, cur_max); >> + while (fd <= max_fd) >> + __set_close_on_exec(fd++, fdt); >> + spin_unlock(&cur_fds->file_lock); >> + } else { >> + /* Initialize cur_max if needed. */ >> + if (cur_max == UINT_MAX) >> + cur_max = __get_max_fds(cur_fds) - 1; > > The separation between how cur_fd is retrieved in the two branches makes > the code more difficult to follow imho. Unless there's a clear reason > why you've done it that way I would think that something like the patch > I appended below might be a little clearer and easier to maintain(?). Thanks for the review! I've opted for this version as in the flags=CLOSE_RANGE_CLOEXEC case we can read max_fds directly from the fds table and avoid doing it from the RCU critical section as well. I'll change it in favor of more readable code. Giuseppe _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/containers ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC @ 2020-10-13 22:45 ` Giuseppe Scrivano 0 siblings, 0 replies; 22+ messages in thread From: Giuseppe Scrivano @ 2020-10-13 22:45 UTC (permalink / raw) To: Christian Brauner; +Cc: linux-kernel, viro, linux-fsdevel, containers Christian Brauner <christian.brauner@ubuntu.com> writes: > On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: > > Hey Guiseppe, > > Thanks for the patch! > >> When the flag CLOSE_RANGE_CLOEXEC is set, close_range doesn't >> immediately close the files but it sets the close-on-exec bit. > > Hm, please expand on the use-cases a little here so people know where > and how this is useful. Keeping the rationale for a change in the commit > log is really important. > >> >> Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com> >> --- > >> fs/file.c | 56 ++++++++++++++++++++++---------- >> include/uapi/linux/close_range.h | 3 ++ >> 2 files changed, 42 insertions(+), 17 deletions(-) >> >> diff --git a/fs/file.c b/fs/file.c >> index 21c0893f2f1d..ad4ebee41e09 100644 >> --- a/fs/file.c >> +++ b/fs/file.c >> @@ -672,6 +672,17 @@ int __close_fd(struct files_struct *files, unsigned fd) >> } >> EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ >> >> +static unsigned int __get_max_fds(struct files_struct *cur_fds) >> +{ >> + unsigned int max_fds; >> + >> + rcu_read_lock(); >> + /* cap to last valid index into fdtable */ >> + max_fds = files_fdtable(cur_fds)->max_fds; >> + rcu_read_unlock(); >> + return max_fds; >> +} >> + >> /** >> * __close_range() - Close all file descriptors in a given range. >> * >> @@ -683,27 +694,23 @@ EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ >> */ >> int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) >> { >> - unsigned int cur_max; >> + unsigned int cur_max = UINT_MAX; >> struct task_struct *me = current; >> struct files_struct *cur_fds = me->files, *fds = NULL; >> >> - if (flags & ~CLOSE_RANGE_UNSHARE) >> + if (flags & ~(CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC)) >> return -EINVAL; >> >> if (fd > max_fd) >> return -EINVAL; >> >> - rcu_read_lock(); >> - cur_max = files_fdtable(cur_fds)->max_fds; >> - rcu_read_unlock(); >> - >> - /* cap to last valid index into fdtable */ >> - cur_max--; >> - >> if (flags & CLOSE_RANGE_UNSHARE) { >> int ret; >> unsigned int max_unshare_fds = NR_OPEN_MAX; >> >> + /* cap to last valid index into fdtable */ >> + cur_max = __get_max_fds(cur_fds) - 1; >> + >> /* >> * If the requested range is greater than the current maximum, >> * we're closing everything so only copy all file descriptors >> @@ -724,16 +731,31 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) >> swap(cur_fds, fds); >> } >> >> - max_fd = min(max_fd, cur_max); >> - while (fd <= max_fd) { >> - struct file *file; >> + if (flags & CLOSE_RANGE_CLOEXEC) { >> + struct fdtable *fdt; >> >> - file = pick_file(cur_fds, fd++); >> - if (!file) >> - continue; >> + spin_lock(&cur_fds->file_lock); >> + fdt = files_fdtable(cur_fds); >> + cur_max = fdt->max_fds - 1; >> + max_fd = min(max_fd, cur_max); >> + while (fd <= max_fd) >> + __set_close_on_exec(fd++, fdt); >> + spin_unlock(&cur_fds->file_lock); >> + } else { >> + /* Initialize cur_max if needed. */ >> + if (cur_max == UINT_MAX) >> + cur_max = __get_max_fds(cur_fds) - 1; > > The separation between how cur_fd is retrieved in the two branches makes > the code more difficult to follow imho. Unless there's a clear reason > why you've done it that way I would think that something like the patch > I appended below might be a little clearer and easier to maintain(?). Thanks for the review! I've opted for this version as in the flags=CLOSE_RANGE_CLOEXEC case we can read max_fds directly from the fds table and avoid doing it from the RCU critical section as well. I'll change it in favor of more readable code. Giuseppe ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC 2020-10-13 14:06 ` Giuseppe Scrivano @ 2020-10-13 21:09 ` Al Viro -1 siblings, 0 replies; 22+ messages in thread From: Al Viro @ 2020-10-13 21:09 UTC (permalink / raw) To: Giuseppe Scrivano; +Cc: linux-fsdevel, containers, linux-kernel On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: > + spin_lock(&cur_fds->file_lock); > + fdt = files_fdtable(cur_fds); > + cur_max = fdt->max_fds - 1; > + max_fd = min(max_fd, cur_max); > + while (fd <= max_fd) > + __set_close_on_exec(fd++, fdt); > + spin_unlock(&cur_fds->file_lock); First of all, this is an atrocious way to set all bits in a range. What's more, you don't want to set it for *all* bits - only for the ones present in open bitmap. It's probably harmless at the moment, but let's not create interesting surprises for the future. _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/containers ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC @ 2020-10-13 21:09 ` Al Viro 0 siblings, 0 replies; 22+ messages in thread From: Al Viro @ 2020-10-13 21:09 UTC (permalink / raw) To: Giuseppe Scrivano Cc: linux-kernel, linux-fsdevel, christian.brauner, containers On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: > + spin_lock(&cur_fds->file_lock); > + fdt = files_fdtable(cur_fds); > + cur_max = fdt->max_fds - 1; > + max_fd = min(max_fd, cur_max); > + while (fd <= max_fd) > + __set_close_on_exec(fd++, fdt); > + spin_unlock(&cur_fds->file_lock); First of all, this is an atrocious way to set all bits in a range. What's more, you don't want to set it for *all* bits - only for the ones present in open bitmap. It's probably harmless at the moment, but let's not create interesting surprises for the future. ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC 2020-10-13 21:09 ` Al Viro @ 2020-10-13 21:32 ` Christian Brauner -1 siblings, 0 replies; 22+ messages in thread From: Christian Brauner @ 2020-10-13 21:32 UTC (permalink / raw) To: Al Viro; +Cc: linux-fsdevel, Giuseppe Scrivano, containers, linux-kernel On Tue, Oct 13, 2020 at 10:09:25PM +0100, Al Viro wrote: > On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: > > + spin_lock(&cur_fds->file_lock); > > + fdt = files_fdtable(cur_fds); > > + cur_max = fdt->max_fds - 1; > > + max_fd = min(max_fd, cur_max); > > + while (fd <= max_fd) > > + __set_close_on_exec(fd++, fdt); > > + spin_unlock(&cur_fds->file_lock); > > First of all, this is an atrocious way to set all bits > in a range. What's more, you don't want to set it for *all* Hm, good point. Would it make sense to just use the bitmap_set() proposal since the 3 to ~0 case is most common or to actually iterate based on the open fds? Christian _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/containers ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC @ 2020-10-13 21:32 ` Christian Brauner 0 siblings, 0 replies; 22+ messages in thread From: Christian Brauner @ 2020-10-13 21:32 UTC (permalink / raw) To: Al Viro; +Cc: Giuseppe Scrivano, linux-kernel, linux-fsdevel, containers On Tue, Oct 13, 2020 at 10:09:25PM +0100, Al Viro wrote: > On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: > > + spin_lock(&cur_fds->file_lock); > > + fdt = files_fdtable(cur_fds); > > + cur_max = fdt->max_fds - 1; > > + max_fd = min(max_fd, cur_max); > > + while (fd <= max_fd) > > + __set_close_on_exec(fd++, fdt); > > + spin_unlock(&cur_fds->file_lock); > > First of all, this is an atrocious way to set all bits > in a range. What's more, you don't want to set it for *all* Hm, good point. Would it make sense to just use the bitmap_set() proposal since the 3 to ~0 case is most common or to actually iterate based on the open fds? Christian ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC 2020-10-13 21:09 ` Al Viro @ 2020-10-13 21:49 ` Rasmus Villemoes -1 siblings, 0 replies; 22+ messages in thread From: Rasmus Villemoes @ 2020-10-13 21:49 UTC (permalink / raw) To: Al Viro, Giuseppe Scrivano; +Cc: linux-fsdevel, containers, linux-kernel On 13/10/2020 23.09, Al Viro wrote: > On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: >> + spin_lock(&cur_fds->file_lock); >> + fdt = files_fdtable(cur_fds); >> + cur_max = fdt->max_fds - 1; >> + max_fd = min(max_fd, cur_max); >> + while (fd <= max_fd) >> + __set_close_on_exec(fd++, fdt); >> + spin_unlock(&cur_fds->file_lock); > > First of all, this is an atrocious way to set all bits > in a range. What's more, you don't want to set it for *all* > bits - only for the ones present in open bitmap. It's probably > harmless at the moment, but let's not create interesting surprises > for the future. Eh, why not? They can already be set for unallocated slots: commit 5297908270549b734c7c2556745e2385b6d4941d Author: Mateusz Guzik <mguzik@redhat.com> Date: Tue Oct 3 12:58:14 2017 +0200 vfs: stop clearing close on exec when closing a fd Codepaths allocating a fd always make sure the bit is set/unset depending on flags, thus clearing on close is redundant. And while we're on that subject, yours truly suggested exactly that two years prior [1], with a follow-up [2] in 2018 to do what wasn't done in 5297908, but (still) seems like obvious micro-optimizations, given that the close_on_exec bitmap is not maintained as a subset of the open bitmap. Mind taking a look at [2]? [1] https://lore.kernel.org/lkml/1446543679-28849-1-git-send-email-linux@rasmusvillemoes.dk/t/#u [2] https://lore.kernel.org/lkml/20181024160159.25884-1-linux@rasmusvillemoes.dk/ Rasmus _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/containers ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC @ 2020-10-13 21:49 ` Rasmus Villemoes 0 siblings, 0 replies; 22+ messages in thread From: Rasmus Villemoes @ 2020-10-13 21:49 UTC (permalink / raw) To: Al Viro, Giuseppe Scrivano Cc: linux-kernel, linux-fsdevel, christian.brauner, containers On 13/10/2020 23.09, Al Viro wrote: > On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: >> + spin_lock(&cur_fds->file_lock); >> + fdt = files_fdtable(cur_fds); >> + cur_max = fdt->max_fds - 1; >> + max_fd = min(max_fd, cur_max); >> + while (fd <= max_fd) >> + __set_close_on_exec(fd++, fdt); >> + spin_unlock(&cur_fds->file_lock); > > First of all, this is an atrocious way to set all bits > in a range. What's more, you don't want to set it for *all* > bits - only for the ones present in open bitmap. It's probably > harmless at the moment, but let's not create interesting surprises > for the future. Eh, why not? They can already be set for unallocated slots: commit 5297908270549b734c7c2556745e2385b6d4941d Author: Mateusz Guzik <mguzik@redhat.com> Date: Tue Oct 3 12:58:14 2017 +0200 vfs: stop clearing close on exec when closing a fd Codepaths allocating a fd always make sure the bit is set/unset depending on flags, thus clearing on close is redundant. And while we're on that subject, yours truly suggested exactly that two years prior [1], with a follow-up [2] in 2018 to do what wasn't done in 5297908, but (still) seems like obvious micro-optimizations, given that the close_on_exec bitmap is not maintained as a subset of the open bitmap. Mind taking a look at [2]? [1] https://lore.kernel.org/lkml/1446543679-28849-1-git-send-email-linux@rasmusvillemoes.dk/t/#u [2] https://lore.kernel.org/lkml/20181024160159.25884-1-linux@rasmusvillemoes.dk/ Rasmus ^ permalink raw reply [flat|nested] 22+ messages in thread
* [PATCH 2/2] selftests: add tests for CLOSE_RANGE_CLOEXEC 2020-10-13 14:06 ` Giuseppe Scrivano @ 2020-10-13 14:06 ` Giuseppe Scrivano -1 siblings, 0 replies; 22+ messages in thread From: Giuseppe Scrivano @ 2020-10-13 14:06 UTC (permalink / raw) To: linux-kernel; +Cc: linux-fsdevel, containers, viro Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com> --- .../testing/selftests/core/close_range_test.c | 44 +++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/tools/testing/selftests/core/close_range_test.c b/tools/testing/selftests/core/close_range_test.c index c99b98b0d461..b8789262cd7d 100644 --- a/tools/testing/selftests/core/close_range_test.c +++ b/tools/testing/selftests/core/close_range_test.c @@ -23,6 +23,10 @@ #define CLOSE_RANGE_UNSHARE (1U << 1) #endif +#ifndef CLOSE_RANGE_CLOEXEC +#define CLOSE_RANGE_CLOEXEC (1U << 2) +#endif + static inline int sys_close_range(unsigned int fd, unsigned int max_fd, unsigned int flags) { @@ -224,4 +228,44 @@ TEST(close_range_unshare_capped) EXPECT_EQ(0, WEXITSTATUS(status)); } +TEST(close_range_cloexec) +{ + int i, ret; + int open_fds[101]; + + for (i = 0; i < ARRAY_SIZE(open_fds); i++) { + int fd; + + fd = open("/dev/null", O_RDONLY); + ASSERT_GE(fd, 0) { + if (errno == ENOENT) + XFAIL(return, "Skipping test since /dev/null does not exist"); + } + + open_fds[i] = fd; + } + + EXPECT_EQ(-1, sys_close_range(open_fds[0], open_fds[100], -1)) { + if (errno == ENOSYS) + XFAIL(return, "close_range() syscall not supported"); + } + + EXPECT_EQ(0, sys_close_range(open_fds[0], open_fds[50], CLOSE_RANGE_CLOEXEC)); + + for (i = 0; i <= 50; i++) { + int flags = fcntl(open_fds[i], F_GETFD); + + EXPECT_GT(flags, -1); + EXPECT_EQ(flags & FD_CLOEXEC, FD_CLOEXEC); + } + + for (i = 51; i <= 100; i++) { + int flags = fcntl(open_fds[i], F_GETFD); + + EXPECT_GT(flags, -1); + EXPECT_EQ(flags & FD_CLOEXEC, 0); + } +} + + TEST_HARNESS_MAIN -- 2.26.2 _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/containers ^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH 2/2] selftests: add tests for CLOSE_RANGE_CLOEXEC @ 2020-10-13 14:06 ` Giuseppe Scrivano 0 siblings, 0 replies; 22+ messages in thread From: Giuseppe Scrivano @ 2020-10-13 14:06 UTC (permalink / raw) To: linux-kernel; +Cc: viro, linux-fsdevel, christian.brauner, containers Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com> --- .../testing/selftests/core/close_range_test.c | 44 +++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/tools/testing/selftests/core/close_range_test.c b/tools/testing/selftests/core/close_range_test.c index c99b98b0d461..b8789262cd7d 100644 --- a/tools/testing/selftests/core/close_range_test.c +++ b/tools/testing/selftests/core/close_range_test.c @@ -23,6 +23,10 @@ #define CLOSE_RANGE_UNSHARE (1U << 1) #endif +#ifndef CLOSE_RANGE_CLOEXEC +#define CLOSE_RANGE_CLOEXEC (1U << 2) +#endif + static inline int sys_close_range(unsigned int fd, unsigned int max_fd, unsigned int flags) { @@ -224,4 +228,44 @@ TEST(close_range_unshare_capped) EXPECT_EQ(0, WEXITSTATUS(status)); } +TEST(close_range_cloexec) +{ + int i, ret; + int open_fds[101]; + + for (i = 0; i < ARRAY_SIZE(open_fds); i++) { + int fd; + + fd = open("/dev/null", O_RDONLY); + ASSERT_GE(fd, 0) { + if (errno == ENOENT) + XFAIL(return, "Skipping test since /dev/null does not exist"); + } + + open_fds[i] = fd; + } + + EXPECT_EQ(-1, sys_close_range(open_fds[0], open_fds[100], -1)) { + if (errno == ENOSYS) + XFAIL(return, "close_range() syscall not supported"); + } + + EXPECT_EQ(0, sys_close_range(open_fds[0], open_fds[50], CLOSE_RANGE_CLOEXEC)); + + for (i = 0; i <= 50; i++) { + int flags = fcntl(open_fds[i], F_GETFD); + + EXPECT_GT(flags, -1); + EXPECT_EQ(flags & FD_CLOEXEC, FD_CLOEXEC); + } + + for (i = 51; i <= 100; i++) { + int flags = fcntl(open_fds[i], F_GETFD); + + EXPECT_GT(flags, -1); + EXPECT_EQ(flags & FD_CLOEXEC, 0); + } +} + + TEST_HARNESS_MAIN -- 2.26.2 ^ permalink raw reply related [flat|nested] 22+ messages in thread
* RE: [PATCH 2/2] selftests: add tests for CLOSE_RANGE_CLOEXEC 2020-10-13 14:06 ` Giuseppe Scrivano @ 2020-10-13 15:22 ` David Laight -1 siblings, 0 replies; 22+ messages in thread From: David Laight @ 2020-10-13 15:22 UTC (permalink / raw) To: 'Giuseppe Scrivano', linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, containers@lists.linux-foundation.org, viro@zeniv.linux.org.uk > Subject: [PATCH 2/2] selftests: add tests for CLOSE_RANGE_CLOEXEC You really ought to check that it skips closed files. For instance using dup2() to move some open files to 'big numbers'. Although you know how it works, a 'black box' test would also reduce RLIMIT_NOFILES below one of the open files and check files above the RLIMIT_NOFILES value are affected. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/containers ^ permalink raw reply [flat|nested] 22+ messages in thread
* RE: [PATCH 2/2] selftests: add tests for CLOSE_RANGE_CLOEXEC @ 2020-10-13 15:22 ` David Laight 0 siblings, 0 replies; 22+ messages in thread From: David Laight @ 2020-10-13 15:22 UTC (permalink / raw) To: 'Giuseppe Scrivano', linux-kernel@vger.kernel.org Cc: viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, christian.brauner@ubuntu.com, containers@lists.linux-foundation.org > Subject: [PATCH 2/2] selftests: add tests for CLOSE_RANGE_CLOEXEC You really ought to check that it skips closed files. For instance using dup2() to move some open files to 'big numbers'. Although you know how it works, a 'black box' test would also reduce RLIMIT_NOFILES below one of the open files and check files above the RLIMIT_NOFILES value are affected. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) ^ permalink raw reply [flat|nested] 22+ messages in thread
end of thread, other threads:[~2020-10-14 9:21 UTC | newest] Thread overview: 22+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2020-10-13 14:06 [PATCH 0/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC Giuseppe Scrivano 2020-10-13 14:06 ` Giuseppe Scrivano 2020-10-13 14:06 ` [PATCH 1/2] " Giuseppe Scrivano 2020-10-13 14:06 ` Giuseppe Scrivano 2020-10-13 20:54 ` Christian Brauner 2020-10-13 20:54 ` Christian Brauner 2020-10-13 21:04 ` Rasmus Villemoes 2020-10-13 21:04 ` Rasmus Villemoes 2020-10-13 21:22 ` Christian Brauner 2020-10-13 21:22 ` Christian Brauner 2020-10-13 22:45 ` Giuseppe Scrivano 2020-10-13 22:45 ` Giuseppe Scrivano 2020-10-13 21:09 ` Al Viro 2020-10-13 21:09 ` Al Viro 2020-10-13 21:32 ` Christian Brauner 2020-10-13 21:32 ` Christian Brauner 2020-10-13 21:49 ` Rasmus Villemoes 2020-10-13 21:49 ` Rasmus Villemoes 2020-10-13 14:06 ` [PATCH 2/2] selftests: add tests for CLOSE_RANGE_CLOEXEC Giuseppe Scrivano 2020-10-13 14:06 ` Giuseppe Scrivano 2020-10-13 15:22 ` David Laight 2020-10-13 15:22 ` David Laight
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