Re: [PATCH] proc: use ns_capable instead of capable for timerslack_ns
On Thu, Oct 25, 2018 at 01:56:27PM -0500, Eric W. Biederman wrote: > > Access to timerslack_ns is controlled by a process having CAP_SYS_NICE > > in its effective capability set, but the current check looks in the root > > namespace instead of the process' user namespace. Since a process is > > allowed to do other activities controlled by CAP_SYS_NICE inside a > > namespace, it should also be able to adjust timerslack_ns. > > The goal seems legitimate. However the permission checks look wrong. > > In particular the choice of user namespace should be > "p->cred->user_ns". This will limit this to tasks that have > CAP_SYS_NICE in the same namespace as the task that is being modified. > > Testing file->f_cred->user_ns it is testing whoever opened the file and > that could be anyone. Thanks, that seems like the right answer here. I'll send a v2 to fix it. Thanks, Benjamin
Re: [PATCH] proc: use ns_capable instead of capable for timerslack_ns
On Thu, Oct 25, 2018 at 01:56:27PM -0500, Eric W. Biederman wrote: > > Access to timerslack_ns is controlled by a process having CAP_SYS_NICE > > in its effective capability set, but the current check looks in the root > > namespace instead of the process' user namespace. Since a process is > > allowed to do other activities controlled by CAP_SYS_NICE inside a > > namespace, it should also be able to adjust timerslack_ns. > > The goal seems legitimate. However the permission checks look wrong. > > In particular the choice of user namespace should be > "p->cred->user_ns". This will limit this to tasks that have > CAP_SYS_NICE in the same namespace as the task that is being modified. > > Testing file->f_cred->user_ns it is testing whoever opened the file and > that could be anyone. Thanks, that seems like the right answer here. I'll send a v2 to fix it. Thanks, Benjamin
Re: [PATCH] proc: use ns_capable instead of capable for timerslack_ns
bmgor...@google.com writes:
> From: Benjamin Gordon
>
> Access to timerslack_ns is controlled by a process having CAP_SYS_NICE
> in its effective capability set, but the current check looks in the root
> namespace instead of the process' user namespace. Since a process is
> allowed to do other activities controlled by CAP_SYS_NICE inside a
> namespace, it should also be able to adjust timerslack_ns.
The goal seems legitimate. However the permission checks look wrong.
In particular the choice of user namespace should be
"p->cred->user_ns". This will limit this to tasks that have
CAP_SYS_NICE in the same namespace as the task that is being modified.
Testing file->f_cred->user_ns it is testing whoever opened the file and
that could be anyone.
Eric
> Signed-off-by: Benjamin Gordon
> Cc: John Stultz
> Cc: Kees Cook
> Cc: "Serge E. Hallyn"
> Cc: Thomas Gleixner
> Cc: Arjan van de Ven
> Cc: Oren Laadan
> Cc: Ruchi Kandoi
> Cc: Rom Lemarchand
> Cc: Todd Kjos
> Cc: Colin Cross
> Cc: Nick Kralevich
> Cc: Dmitry Shmidt
> Cc: Elliott Hughes
> Cc: Android Kernel Team
> Cc: Andrew Morton
> ---
> fs/proc/base.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 7e9f07bf260d..4b50937dff80 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2356,7 +2356,7 @@ static ssize_t timerslack_ns_write(struct file *file,
> const char __user *buf,
> return -ESRCH;
>
> if (p != current) {
> - if (!capable(CAP_SYS_NICE)) {
> + if (!ns_capable(file->f_cred->user_ns, CAP_SYS_NICE)) {
> count = -EPERM;
> goto out;
> }
> @@ -2393,7 +2393,7 @@ static int timerslack_ns_show(struct seq_file *m, void
> *v)
>
> if (p != current) {
>
> - if (!capable(CAP_SYS_NICE)) {
> + if (!ns_capable(seq_user_ns(m), CAP_SYS_NICE)) {
> err = -EPERM;
> goto out;
> }
Re: [PATCH] proc: use ns_capable instead of capable for timerslack_ns
bmgor...@google.com writes:
> From: Benjamin Gordon
>
> Access to timerslack_ns is controlled by a process having CAP_SYS_NICE
> in its effective capability set, but the current check looks in the root
> namespace instead of the process' user namespace. Since a process is
> allowed to do other activities controlled by CAP_SYS_NICE inside a
> namespace, it should also be able to adjust timerslack_ns.
The goal seems legitimate. However the permission checks look wrong.
In particular the choice of user namespace should be
"p->cred->user_ns". This will limit this to tasks that have
CAP_SYS_NICE in the same namespace as the task that is being modified.
Testing file->f_cred->user_ns it is testing whoever opened the file and
that could be anyone.
Eric
> Signed-off-by: Benjamin Gordon
> Cc: John Stultz
> Cc: Kees Cook
> Cc: "Serge E. Hallyn"
> Cc: Thomas Gleixner
> Cc: Arjan van de Ven
> Cc: Oren Laadan
> Cc: Ruchi Kandoi
> Cc: Rom Lemarchand
> Cc: Todd Kjos
> Cc: Colin Cross
> Cc: Nick Kralevich
> Cc: Dmitry Shmidt
> Cc: Elliott Hughes
> Cc: Android Kernel Team
> Cc: Andrew Morton
> ---
> fs/proc/base.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 7e9f07bf260d..4b50937dff80 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2356,7 +2356,7 @@ static ssize_t timerslack_ns_write(struct file *file,
> const char __user *buf,
> return -ESRCH;
>
> if (p != current) {
> - if (!capable(CAP_SYS_NICE)) {
> + if (!ns_capable(file->f_cred->user_ns, CAP_SYS_NICE)) {
> count = -EPERM;
> goto out;
> }
> @@ -2393,7 +2393,7 @@ static int timerslack_ns_show(struct seq_file *m, void
> *v)
>
> if (p != current) {
>
> - if (!capable(CAP_SYS_NICE)) {
> + if (!ns_capable(seq_user_ns(m), CAP_SYS_NICE)) {
> err = -EPERM;
> goto out;
> }
Re: [PATCH] proc: use ns_capable instead of capable for timerslack_ns
On Wed, Oct 17, 2018 at 3:47 PM, wrote:
> From: Benjamin Gordon
>
> Access to timerslack_ns is controlled by a process having CAP_SYS_NICE
> in its effective capability set, but the current check looks in the root
> namespace instead of the process' user namespace. Since a process is
> allowed to do other activities controlled by CAP_SYS_NICE inside a
> namespace, it should also be able to adjust timerslack_ns.
>
> Signed-off-by: Benjamin Gordon
> Cc: John Stultz
> Cc: Kees Cook
> Cc: "Serge E. Hallyn"
> Cc: Thomas Gleixner
> Cc: Arjan van de Ven
> Cc: Oren Laadan
> Cc: Ruchi Kandoi
> Cc: Rom Lemarchand
> Cc: Todd Kjos
> Cc: Colin Cross
> Cc: Nick Kralevich
> Cc: Dmitry Shmidt
> Cc: Elliott Hughes
> Cc: Android Kernel Team
> Cc: Andrew Morton
> ---
> fs/proc/base.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 7e9f07bf260d..4b50937dff80 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2356,7 +2356,7 @@ static ssize_t timerslack_ns_write(struct file *file,
> const char __user *buf,
> return -ESRCH;
>
> if (p != current) {
> - if (!capable(CAP_SYS_NICE)) {
> + if (!ns_capable(file->f_cred->user_ns, CAP_SYS_NICE)) {
> count = -EPERM;
> goto out;
> }
> @@ -2393,7 +2393,7 @@ static int timerslack_ns_show(struct seq_file *m, void
> *v)
>
> if (p != current) {
>
> - if (!capable(CAP_SYS_NICE)) {
> + if (!ns_capable(seq_user_ns(m), CAP_SYS_NICE)) {
> err = -EPERM;
> goto out;
> }
Looks reasonable to me.
Acked-by: John Stultz
thanks
-john
Re: [PATCH] proc: use ns_capable instead of capable for timerslack_ns
On Wed, Oct 17, 2018 at 3:47 PM, wrote:
> From: Benjamin Gordon
>
> Access to timerslack_ns is controlled by a process having CAP_SYS_NICE
> in its effective capability set, but the current check looks in the root
> namespace instead of the process' user namespace. Since a process is
> allowed to do other activities controlled by CAP_SYS_NICE inside a
> namespace, it should also be able to adjust timerslack_ns.
>
> Signed-off-by: Benjamin Gordon
> Cc: John Stultz
> Cc: Kees Cook
> Cc: "Serge E. Hallyn"
> Cc: Thomas Gleixner
> Cc: Arjan van de Ven
> Cc: Oren Laadan
> Cc: Ruchi Kandoi
> Cc: Rom Lemarchand
> Cc: Todd Kjos
> Cc: Colin Cross
> Cc: Nick Kralevich
> Cc: Dmitry Shmidt
> Cc: Elliott Hughes
> Cc: Android Kernel Team
> Cc: Andrew Morton
> ---
> fs/proc/base.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 7e9f07bf260d..4b50937dff80 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2356,7 +2356,7 @@ static ssize_t timerslack_ns_write(struct file *file,
> const char __user *buf,
> return -ESRCH;
>
> if (p != current) {
> - if (!capable(CAP_SYS_NICE)) {
> + if (!ns_capable(file->f_cred->user_ns, CAP_SYS_NICE)) {
> count = -EPERM;
> goto out;
> }
> @@ -2393,7 +2393,7 @@ static int timerslack_ns_show(struct seq_file *m, void
> *v)
>
> if (p != current) {
>
> - if (!capable(CAP_SYS_NICE)) {
> + if (!ns_capable(seq_user_ns(m), CAP_SYS_NICE)) {
> err = -EPERM;
> goto out;
> }
Looks reasonable to me.
Acked-by: John Stultz
thanks
-john
Re: [PATCH] proc: use ns_capable instead of capable for timerslack_ns
On Wed, Oct 17, 2018 at 04:47:38PM -0600, bmgor...@google.com wrote:
> Access to timerslack_ns is controlled by a process having CAP_SYS_NICE
> in its effective capability set, but the current check looks in the root
> namespace instead of the process' user namespace. Since a process is
> allowed to do other activities controlled by CAP_SYS_NICE inside a
> namespace, it should also be able to adjust timerslack_ns.
>
> Signed-off-by: Benjamin Gordon
> Cc: John Stultz
> Cc: Kees Cook
> Cc: "Serge E. Hallyn"
> Cc: Thomas Gleixner
> Cc: Arjan van de Ven
> Cc: Oren Laadan
> Cc: Ruchi Kandoi
> Cc: Rom Lemarchand
> Cc: Todd Kjos
> Cc: Colin Cross
> Cc: Nick Kralevich
> Cc: Dmitry Shmidt
> Cc: Elliott Hughes
> Cc: Android Kernel Team
> Cc: Andrew Morton
> ---
> fs/proc/base.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 7e9f07bf260d..4b50937dff80 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2356,7 +2356,7 @@ static ssize_t timerslack_ns_write(struct file *file,
> const char __user *buf,
> return -ESRCH;
>
> if (p != current) {
> - if (!capable(CAP_SYS_NICE)) {
> + if (!ns_capable(file->f_cred->user_ns, CAP_SYS_NICE)) {
> count = -EPERM;
> goto out;
> }
> @@ -2393,7 +2393,7 @@ static int timerslack_ns_show(struct seq_file *m, void
> *v)
>
> if (p != current) {
>
> - if (!capable(CAP_SYS_NICE)) {
> + if (!ns_capable(seq_user_ns(m), CAP_SYS_NICE)) {
> err = -EPERM;
> goto out;
> }
> --
> 2.19.1.331.ge82ca0e54c-goog
>
Friendly ping. Does anybody have time to take a look at this?
Thanks,
Benjamin
Re: [PATCH] proc: use ns_capable instead of capable for timerslack_ns
On Wed, Oct 17, 2018 at 04:47:38PM -0600, bmgor...@google.com wrote:
> Access to timerslack_ns is controlled by a process having CAP_SYS_NICE
> in its effective capability set, but the current check looks in the root
> namespace instead of the process' user namespace. Since a process is
> allowed to do other activities controlled by CAP_SYS_NICE inside a
> namespace, it should also be able to adjust timerslack_ns.
>
> Signed-off-by: Benjamin Gordon
> Cc: John Stultz
> Cc: Kees Cook
> Cc: "Serge E. Hallyn"
> Cc: Thomas Gleixner
> Cc: Arjan van de Ven
> Cc: Oren Laadan
> Cc: Ruchi Kandoi
> Cc: Rom Lemarchand
> Cc: Todd Kjos
> Cc: Colin Cross
> Cc: Nick Kralevich
> Cc: Dmitry Shmidt
> Cc: Elliott Hughes
> Cc: Android Kernel Team
> Cc: Andrew Morton
> ---
> fs/proc/base.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 7e9f07bf260d..4b50937dff80 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2356,7 +2356,7 @@ static ssize_t timerslack_ns_write(struct file *file,
> const char __user *buf,
> return -ESRCH;
>
> if (p != current) {
> - if (!capable(CAP_SYS_NICE)) {
> + if (!ns_capable(file->f_cred->user_ns, CAP_SYS_NICE)) {
> count = -EPERM;
> goto out;
> }
> @@ -2393,7 +2393,7 @@ static int timerslack_ns_show(struct seq_file *m, void
> *v)
>
> if (p != current) {
>
> - if (!capable(CAP_SYS_NICE)) {
> + if (!ns_capable(seq_user_ns(m), CAP_SYS_NICE)) {
> err = -EPERM;
> goto out;
> }
> --
> 2.19.1.331.ge82ca0e54c-goog
>
Friendly ping. Does anybody have time to take a look at this?
Thanks,
Benjamin
[PATCH] proc: use ns_capable instead of capable for timerslack_ns
From: Benjamin Gordon
Access to timerslack_ns is controlled by a process having CAP_SYS_NICE
in its effective capability set, but the current check looks in the root
namespace instead of the process' user namespace. Since a process is
allowed to do other activities controlled by CAP_SYS_NICE inside a
namespace, it should also be able to adjust timerslack_ns.
Signed-off-by: Benjamin Gordon
Cc: John Stultz
Cc: Kees Cook
Cc: "Serge E. Hallyn"
Cc: Thomas Gleixner
Cc: Arjan van de Ven
Cc: Oren Laadan
Cc: Ruchi Kandoi
Cc: Rom Lemarchand
Cc: Todd Kjos
Cc: Colin Cross
Cc: Nick Kralevich
Cc: Dmitry Shmidt
Cc: Elliott Hughes
Cc: Android Kernel Team
Cc: Andrew Morton
---
fs/proc/base.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 7e9f07bf260d..4b50937dff80 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2356,7 +2356,7 @@ static ssize_t timerslack_ns_write(struct file *file,
const char __user *buf,
return -ESRCH;
if (p != current) {
- if (!capable(CAP_SYS_NICE)) {
+ if (!ns_capable(file->f_cred->user_ns, CAP_SYS_NICE)) {
count = -EPERM;
goto out;
}
@@ -2393,7 +2393,7 @@ static int timerslack_ns_show(struct seq_file *m, void *v)
if (p != current) {
- if (!capable(CAP_SYS_NICE)) {
+ if (!ns_capable(seq_user_ns(m), CAP_SYS_NICE)) {
err = -EPERM;
goto out;
}
--
2.19.1.331.ge82ca0e54c-goog
[PATCH] proc: use ns_capable instead of capable for timerslack_ns
From: Benjamin Gordon
Access to timerslack_ns is controlled by a process having CAP_SYS_NICE
in its effective capability set, but the current check looks in the root
namespace instead of the process' user namespace. Since a process is
allowed to do other activities controlled by CAP_SYS_NICE inside a
namespace, it should also be able to adjust timerslack_ns.
Signed-off-by: Benjamin Gordon
Cc: John Stultz
Cc: Kees Cook
Cc: "Serge E. Hallyn"
Cc: Thomas Gleixner
Cc: Arjan van de Ven
Cc: Oren Laadan
Cc: Ruchi Kandoi
Cc: Rom Lemarchand
Cc: Todd Kjos
Cc: Colin Cross
Cc: Nick Kralevich
Cc: Dmitry Shmidt
Cc: Elliott Hughes
Cc: Android Kernel Team
Cc: Andrew Morton
---
fs/proc/base.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 7e9f07bf260d..4b50937dff80 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2356,7 +2356,7 @@ static ssize_t timerslack_ns_write(struct file *file,
const char __user *buf,
return -ESRCH;
if (p != current) {
- if (!capable(CAP_SYS_NICE)) {
+ if (!ns_capable(file->f_cred->user_ns, CAP_SYS_NICE)) {
count = -EPERM;
goto out;
}
@@ -2393,7 +2393,7 @@ static int timerslack_ns_show(struct seq_file *m, void *v)
if (p != current) {
- if (!capable(CAP_SYS_NICE)) {
+ if (!ns_capable(seq_user_ns(m), CAP_SYS_NICE)) {
err = -EPERM;
goto out;
}
--
2.19.1.331.ge82ca0e54c-goog
