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| author | Aruna Ramakrishna <aruna.ramakrishna@oracle.com> | 2024-08-02 06:13:15 +0000 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2024-08-02 14:12:21 +0200 |
| commit | 84ee6e8d195e4af4c6c4c961bbf9266bdc8b90ac (patch) | |
| tree | 144dd648144c88acc9be01e8a41f65bc5fac6022 /arch/x86/kernel/fpu/signal.c | |
| parent | x86/pkeys: Add PKRU as a parameter in signal handling functions (diff) | |
| download | linux-84ee6e8d195e4af4c6c4c961bbf9266bdc8b90ac.tar.gz linux-84ee6e8d195e4af4c6c4c961bbf9266bdc8b90ac.zip | |
x86/pkeys: Add helper functions to update PKRU on the sigframe
In the case where a user thread sets up an alternate signal stack protected
by the default PKEY (i.e. PKEY 0), while the thread's stack is protected by
a non-zero PKEY, both these PKEYS have to be enabled in the PKRU register
for the signal to be delivered to the application correctly. However, the
PKRU value restored after handling the signal must not enable this extra
PKEY (i.e. PKEY 0) - i.e., the PKRU value in the sigframe has to be
overwritten with the user-defined value.
Add helper functions that will update PKRU value in the sigframe after
XSAVE.
Note that sig_prepare_pkru() makes no assumption about which PKEY could
be used to protect the altstack (i.e. it may not be part of init_pkru),
and so enables all PKEYS.
No functional change.
Signed-off-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240802061318.2140081-3-aruna.ramakrishna@oracle.com
Diffstat (limited to 'arch/x86/kernel/fpu/signal.c')
| -rw-r--r-- | arch/x86/kernel/fpu/signal.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 2b3b9e140dd4..931c5469d7f3 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -64,6 +64,16 @@ setfx: } /* + * Update the value of PKRU register that was already pushed onto the signal frame. + */ +static inline int update_pkru_in_sigframe(struct xregs_state __user *buf, u32 pkru) +{ + if (unlikely(!cpu_feature_enabled(X86_FEATURE_OSPKE))) + return 0; + return __put_user(pkru, (unsigned int __user *)get_xsave_addr_user(buf, XFEATURE_PKRU)); +} + +/* * Signal frame handlers. */ static inline bool save_fsave_header(struct task_struct *tsk, void __user *buf) |