[PATCH 08/10] powerpc/signal32: Convert restore_[tm]_user_regs() to user access block

From: Christophe Leroy
Date: Fri Mar 19 2021 - 07:08:31 EST

Convert restore_user_regs() and restore_tm_user_regs()
to use user_access_read_begin/end blocks.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
arch/powerpc/include/asm/ptrace.h | 2 +-
arch/powerpc/kernel/signal_32.c | 141 +++++++++++++++---------------
2 files changed, 72 insertions(+), 71 deletions(-)

diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index f10498e1b3f6..95600f3a6523 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -245,7 +245,7 @@ static inline bool trap_norestart(struct pt_regs *regs)
return regs->trap & 0x10;
}

-static inline void set_trap_norestart(struct pt_regs *regs)
+static __always_inline void set_trap_norestart(struct pt_regs *regs)
{
regs->trap |= 0x10;
}
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 088c83853026..0b1a6f53e553 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -116,8 +116,8 @@ __unsafe_save_general_regs(struct pt_regs *regs, struct mcontext __user *frame)
return 1;
}

-static inline int restore_general_regs(struct pt_regs *regs,
- struct mcontext __user *sr)
+static __always_inline int
+__unsafe_restore_general_regs(struct pt_regs *regs, struct mcontext __user *sr)
{
elf_greg_t64 *gregs = (elf_greg_t64 *)regs;
int i;
@@ -125,10 +125,12 @@ static inline int restore_general_regs(struct pt_regs *regs,
for (i = 0; i <= PT_RESULT; i++) {
if ((i == PT_MSR) || (i == PT_SOFTE))
continue;
- if (__get_user(gregs[i], &sr->mc_gregs[i]))
- return -EFAULT;
+ unsafe_get_user(gregs[i], &sr->mc_gregs[i], failed);
}
return 0;
+
+failed:
+ return 1;
}

#else /* CONFIG_PPC64 */
@@ -161,18 +163,20 @@ __unsafe_save_general_regs(struct pt_regs *regs, struct mcontext __user *frame)
return 1;
}

-static inline int restore_general_regs(struct pt_regs *regs,
- struct mcontext __user *sr)
+static __always_inline
+int __unsafe_restore_general_regs(struct pt_regs *regs, struct mcontext __user *sr)
{
/* copy up to but not including MSR */
- if (__copy_from_user(regs, &sr->mc_gregs,
- PT_MSR * sizeof(elf_greg_t)))
- return -EFAULT;
+ unsafe_copy_from_user(regs, &sr->mc_gregs, PT_MSR * sizeof(elf_greg_t), failed);
+
/* copy from orig_r3 (the word after the MSR) up to the end */
- if (__copy_from_user(&regs->orig_gpr3, &sr->mc_gregs[PT_ORIG_R3],
- GP_REGS_SIZE - PT_ORIG_R3 * sizeof(elf_greg_t)))
- return -EFAULT;
+ unsafe_copy_from_user(&regs->orig_gpr3, &sr->mc_gregs[PT_ORIG_R3],
+ GP_REGS_SIZE - PT_ORIG_R3 * sizeof(elf_greg_t), failed);
+
return 0;
+
+failed:
+ return 1;
}
#endif

@@ -181,6 +185,11 @@ static inline int restore_general_regs(struct pt_regs *regs,
goto label; \
} while (0)

+#define unsafe_restore_general_regs(regs, frame, label) do { \
+ if (__unsafe_restore_general_regs(regs, frame)) \
+ goto label; \
+} while (0)
+
/*
* When we have signals to deliver, we set up on the
* user stack, going down from the original stack pointer:
@@ -485,14 +494,13 @@ static int save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user
static long restore_user_regs(struct pt_regs *regs,
struct mcontext __user *sr, int sig)
{
- long err;
unsigned int save_r2 = 0;
unsigned long msr;
#ifdef CONFIG_VSX
int i;
#endif

- if (!access_ok(sr, sizeof(*sr)))
+ if (!user_read_access_begin(sr, sizeof(*sr)))
return 1;
/*
* restore general registers but not including MSR or SOFTE. Also
@@ -500,13 +508,11 @@ static long restore_user_regs(struct pt_regs *regs,
*/
if (!sig)
save_r2 = (unsigned int)regs->gpr[2];
- err = restore_general_regs(regs, sr);
+ unsafe_restore_general_regs(regs, sr, failed);
set_trap_norestart(regs);
- err |= __get_user(msr, &sr->mc_gregs[PT_MSR]);
+ unsafe_get_user(msr, &sr->mc_gregs[PT_MSR], failed);
if (!sig)
regs->gpr[2] = (unsigned long) save_r2;
- if (err)
- return 1;

/* if doing signal return, restore the previous little-endian mode */
if (sig)
@@ -520,22 +526,19 @@ static long restore_user_regs(struct pt_regs *regs,
regs->msr &= ~MSR_VEC;
if (msr & MSR_VEC) {
/* restore altivec registers from the stack */
- if (__copy_from_user(&current->thread.vr_state, &sr->mc_vregs,
- sizeof(sr->mc_vregs)))
- return 1;
+ unsafe_copy_from_user(&current->thread.vr_state, &sr->mc_vregs,
+ sizeof(sr->mc_vregs), failed);
current->thread.used_vr = true;
} else if (current->thread.used_vr)
memset(&current->thread.vr_state, 0,
ELF_NVRREG * sizeof(vector128));

/* Always get VRSAVE back */
- if (__get_user(current->thread.vrsave, (u32 __user *)&sr->mc_vregs[32]))
- return 1;
+ unsafe_get_user(current->thread.vrsave, (u32 __user *)&sr->mc_vregs[32], failed);
if (cpu_has_feature(CPU_FTR_ALTIVEC))
mtspr(SPRN_VRSAVE, current->thread.vrsave);
#endif /* CONFIG_ALTIVEC */
- if (copy_fpr_from_user(current, &sr->mc_fregs))
- return 1;
+ unsafe_copy_fpr_from_user(current, &sr->mc_fregs, failed);

#ifdef CONFIG_VSX
/*
@@ -548,8 +551,7 @@ static long restore_user_regs(struct pt_regs *regs,
* Restore altivec registers from the stack to a local
* buffer, then write this out to the thread_struct
*/
- if (copy_vsx_from_user(current, &sr->mc_vsregs))
- return 1;
+ unsafe_copy_vsx_from_user(current, &sr->mc_vsregs, failed);
current->thread.used_vsr = true;
} else if (current->thread.used_vsr)
for (i = 0; i < 32 ; i++)
@@ -567,19 +569,22 @@ static long restore_user_regs(struct pt_regs *regs,
regs->msr &= ~MSR_SPE;
if (msr & MSR_SPE) {
/* restore spe registers from the stack */
- if (__copy_from_user(current->thread.evr, &sr->mc_vregs,
- ELF_NEVRREG * sizeof(u32)))
- return 1;
+ unsafe_copy_from_user(current->thread.evr, &sr->mc_vregs,
+ ELF_NEVRREG * sizeof(u32));
current->thread.used_spe = true;
} else if (current->thread.used_spe)
memset(current->thread.evr, 0, ELF_NEVRREG * sizeof(u32));

/* Always get SPEFSCR back */
- if (__get_user(current->thread.spefscr, (u32 __user *)&sr->mc_vregs + ELF_NEVRREG))
- return 1;
+ unsafe_get_user(current->thread.spefscr, (u32 __user *)&sr->mc_vregs + ELF_NEVRREG, failed);
#endif /* CONFIG_SPE */

+ user_read_access_end();
return 0;
+
+failed:
+ user_read_access_end();
+ return 1;
}

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
@@ -592,7 +597,6 @@ static long restore_tm_user_regs(struct pt_regs *regs,
struct mcontext __user *sr,
struct mcontext __user *tm_sr)
{
- long err;
unsigned long msr, msr_hi;
#ifdef CONFIG_VSX
int i;
@@ -607,14 +611,13 @@ static long restore_tm_user_regs(struct pt_regs *regs,
* TFHAR is restored from the checkpointed NIP; TEXASR and TFIAR
* were set by the signal delivery.
*/
- err = restore_general_regs(&current->thread.ckpt_regs, sr);
-
- err |= __get_user(current->thread.tm_tfhar, &sr->mc_gregs[PT_NIP]);
-
- err |= __get_user(msr, &sr->mc_gregs[PT_MSR]);
- if (err)
+ if (!user_read_access_begin(sr, sizeof(*sr)))
return 1;

+ unsafe_restore_general_regs(&current->thread.ckpt_regs, sr, failed);
+ unsafe_get_user(current->thread.tm_tfhar, &sr->mc_gregs[PT_NIP], failed);
+ unsafe_get_user(msr, &sr->mc_gregs[PT_MSR], failed);
+
/* Restore the previous little-endian mode */
regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);

@@ -622,9 +625,8 @@ static long restore_tm_user_regs(struct pt_regs *regs,
regs->msr &= ~MSR_VEC;
if (msr & MSR_VEC) {
/* restore altivec registers from the stack */
- if (__copy_from_user(&current->thread.ckvr_state, &sr->mc_vregs,
- sizeof(sr->mc_vregs)))
- return 1;
+ unsafe_copy_from_user(&current->thread.ckvr_state, &sr->mc_vregs,
+ sizeof(sr->mc_vregs), failed);
current->thread.used_vr = true;
} else if (current->thread.used_vr) {
memset(&current->thread.vr_state, 0,
@@ -634,17 +636,15 @@ static long restore_tm_user_regs(struct pt_regs *regs,
}

/* Always get VRSAVE back */
- if (__get_user(current->thread.ckvrsave,
- (u32 __user *)&sr->mc_vregs[32]))
- return 1;
+ unsafe_get_user(current->thread.ckvrsave,
+ (u32 __user *)&sr->mc_vregs[32], failed);
if (cpu_has_feature(CPU_FTR_ALTIVEC))
mtspr(SPRN_VRSAVE, current->thread.ckvrsave);
#endif /* CONFIG_ALTIVEC */

regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1);

- if (copy_fpr_from_user(current, &sr->mc_fregs))
- return 1;
+ unsafe_copy_fpr_from_user(current, &sr->mc_fregs, failed);

#ifdef CONFIG_VSX
regs->msr &= ~MSR_VSX;
@@ -653,8 +653,7 @@ static long restore_tm_user_regs(struct pt_regs *regs,
* Restore altivec registers from the stack to a local
* buffer, then write this out to the thread_struct
*/
- if (copy_ckvsx_from_user(current, &sr->mc_vsregs))
- return 1;
+ unsafe_copy_ckvsx_from_user(current, &sr->mc_vsregs, failed);
current->thread.used_vsr = true;
} else if (current->thread.used_vsr)
for (i = 0; i < 32 ; i++) {
@@ -669,39 +668,36 @@ static long restore_tm_user_regs(struct pt_regs *regs,
*/
regs->msr &= ~MSR_SPE;
if (msr & MSR_SPE) {
- if (__copy_from_user(current->thread.evr, &sr->mc_vregs,
- ELF_NEVRREG * sizeof(u32)))
- return 1;
+ unsafe_copy_from_user(current->thread.evr, &sr->mc_vregs,
+ ELF_NEVRREG * sizeof(u32), failed);
current->thread.used_spe = true;
} else if (current->thread.used_spe)
memset(current->thread.evr, 0, ELF_NEVRREG * sizeof(u32));

/* Always get SPEFSCR back */
- if (__get_user(current->thread.spefscr, (u32 __user *)&sr->mc_vregs
- + ELF_NEVRREG))
- return 1;
+ unsafe_get_user(current->thread.spefscr,
+ (u32 __user *)&sr->mc_vregs + ELF_NEVRREG, failed);
#endif /* CONFIG_SPE */

- err = restore_general_regs(regs, tm_sr);
- if (err)
+ user_read_access_end();
+
+ if (!user_read_access_begin(tm_sr, sizeof(*tm_sr)))
return 1;

+ unsafe_restore_general_regs(regs, tm_sr, failed);
+
#ifdef CONFIG_ALTIVEC
/* restore altivec registers from the stack */
if (msr & MSR_VEC)
- if (__copy_from_user(&current->thread.vr_state,
- &tm_sr->mc_vregs,
- sizeof(sr->mc_vregs)))
- return 1;
+ unsafe_copy_from_user(&current->thread.vr_state, &tm_sr->mc_vregs,
+ sizeof(sr->mc_vregs), failed);

/* Always get VRSAVE back */
- if (__get_user(current->thread.vrsave,
- (u32 __user *)&tm_sr->mc_vregs[32]))
- return 1;
+ unsafe_get_user(current->thread.vrsave,
+ (u32 __user *)&tm_sr->mc_vregs[32], failed);
#endif /* CONFIG_ALTIVEC */

- if (copy_ckfpr_from_user(current, &tm_sr->mc_fregs))
- return 1;
+ unsafe_copy_ckfpr_from_user(current, &tm_sr->mc_fregs, failed);

#ifdef CONFIG_VSX
if (msr & MSR_VSX) {
@@ -709,16 +705,17 @@ static long restore_tm_user_regs(struct pt_regs *regs,
* Restore altivec registers from the stack to a local
* buffer, then write this out to the thread_struct
*/
- if (copy_vsx_from_user(current, &tm_sr->mc_vsregs))
- return 1;
+ unsafe_copy_vsx_from_user(current, &tm_sr->mc_vsregs, failed);
current->thread.used_vsr = true;
}
#endif /* CONFIG_VSX */

/* Get the top half of the MSR from the user context */
- if (__get_user(msr_hi, &tm_sr->mc_gregs[PT_MSR]))
- return 1;
+ unsafe_get_user(msr_hi, &tm_sr->mc_gregs[PT_MSR], failed);
msr_hi <<= 32;
+
+ user_read_access_end();
+
/* If TM bits are set to the reserved value, it's an invalid context */
if (MSR_TM_RESV(msr_hi))
return 1;
@@ -766,6 +763,10 @@ static long restore_tm_user_regs(struct pt_regs *regs,
preempt_enable();

return 0;
+
+failed:
+ user_read_access_end();
+ return 1;
}
#else
static long restore_tm_user_regs(struct pt_regs *regs, struct mcontext __user *sr,
--
2.25.0