diff --git a/arch/alpha/include/asm/uaccess.h b/arch/alpha/include/asm/uaccess.h index 466e42e96bfa..94f587535dee 100644 --- a/arch/alpha/include/asm/uaccess.h +++ b/arch/alpha/include/asm/uaccess.h @@ -396,11 +396,12 @@ copy_to_user(void __user *to, const void *from, long n) extern inline long copy_from_user(void *to, const void __user *from, long n) { + long res = n; if (likely(__access_ok((unsigned long)from, n, get_fs()))) - n = __copy_tofrom_user_nocheck(to, (__force void *)from, n); - else - memset(to, 0, n); - return n; + res = __copy_from_user_inatomic(to, from, n); + if (unlikely(res)) + memset(to + (n - res), 0, res); + return res; } extern void __do_clear_user(void); diff --git a/arch/alpha/lib/copy_user.S b/arch/alpha/lib/copy_user.S index 2238068b1b40..509f62b65311 100644 --- a/arch/alpha/lib/copy_user.S +++ b/arch/alpha/lib/copy_user.S @@ -126,22 +126,8 @@ $65: bis $31,$31,$0 $41: $35: -$exitout: - ret $31,($28),1 - $exitin: - /* A stupid byte-by-byte zeroing of the rest of the output - buffer. This cures security holes by never leaving - random kernel data around to be copied elsewhere. */ - - mov $0,$1 -$101: - EXO ( ldq_u $2,0($6) ) - subq $1,1,$1 - mskbl $2,$6,$2 - EXO ( stq_u $2,0($6) ) - addq $6,1,$6 - bgt $1,$101 +$exitout: ret $31,($28),1 .end __copy_user diff --git a/arch/alpha/lib/ev6-copy_user.S b/arch/alpha/lib/ev6-copy_user.S index debcc3b6b704..be720b518af9 100644 --- a/arch/alpha/lib/ev6-copy_user.S +++ b/arch/alpha/lib/ev6-copy_user.S @@ -228,33 +228,12 @@ $dirtyentry: bgt $0,$onebyteloop # U .. .. .. : U L U L $zerolength: +$exitin: $exitout: # Destination for exception recovery(?) nop # .. .. .. E nop # .. .. E .. nop # .. E .. .. ret $31,($28),1 # L0 .. .. .. : L U L U -$exitin: - - /* A stupid byte-by-byte zeroing of the rest of the output - buffer. This cures security holes by never leaving - random kernel data around to be copied elsewhere. */ - - nop - nop - nop - mov $0,$1 - -$101: - EXO ( stb $31,0($6) ) # L - subq $1,1,$1 # E - addq $6,1,$6 # E - bgt $1,$101 # U - - nop - nop - nop - ret $31,($28),1 # L0 - .end __copy_user EXPORT_SYMBOL(__copy_user) diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c index 6cb3736b6b83..d347bbc086fe 100644 --- a/arch/arc/kernel/signal.c +++ b/arch/arc/kernel/signal.c @@ -107,13 +107,13 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf) struct user_regs_struct uregs; err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); - if (!err) - set_current_blocked(&set); - err |= __copy_from_user(&uregs.scratch, &(sf->uc.uc_mcontext.regs.scratch), sizeof(sf->uc.uc_mcontext.regs.scratch)); + if (err) + return err; + set_current_blocked(&set); regs->bta = uregs.scratch.bta; regs->lp_start = uregs.scratch.lp_start; regs->lp_end = uregs.scratch.lp_end; @@ -138,7 +138,7 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf) regs->r0 = uregs.scratch.r0; regs->sp = uregs.scratch.sp; - return err; + return 0; } static inline int is_do_ss_needed(unsigned int magic) diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index a93c0f99acf7..1f59ea051bab 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -533,11 +533,12 @@ __clear_user(void __user *addr, unsigned long n) static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n) { - if (access_ok(VERIFY_READ, from, n)) - n = __copy_from_user(to, from, n); - else /* security hole - plug it */ - memset(to, 0, n); - return n; + unsigned long res = n; + if (likely(access_ok(VERIFY_READ, from, n))) + res = __copy_from_user(to, from, n); + if (unlikely(res)) + memset(to + (n - res), 0, res); + return res; } static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n) diff --git a/arch/arm/lib/copy_from_user.S b/arch/arm/lib/copy_from_user.S index f549c57ea435..63e4c1ed0225 100644 --- a/arch/arm/lib/copy_from_user.S +++ b/arch/arm/lib/copy_from_user.S @@ -100,12 +100,9 @@ EXPORT_SYMBOL(arm_copy_from_user) .pushsection .fixup,"ax" .align 0 copy_abort_preamble - ldmfd sp!, {r1, r2} - sub r3, r0, r1 - rsb r1, r3, r2 - str r1, [sp] - bl __memzero - ldr r0, [sp], #4 + ldmfd sp!, {r1, r2, r3} + sub r0, r0, r1 + rsb r0, r0, r2 copy_abort_end .popsection diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index c47257c91b77..bcaf6fba1b65 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -278,14 +278,16 @@ static inline unsigned long __must_check __copy_to_user(void __user *to, const v static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n) { + unsigned long res = n; kasan_check_write(to, n); if (access_ok(VERIFY_READ, from, n)) { check_object_size(to, n, false); - n = __arch_copy_from_user(to, from, n); - } else /* security hole - plug it */ - memset(to, 0, n); - return n; + res = __arch_copy_from_user(to, from, n); + } + if (unlikely(res)) + memset(to + (n - res), 0, res); + return res; } static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n) diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S index 0b90497d4424..4fd67ea03bb0 100644 --- a/arch/arm64/lib/copy_from_user.S +++ b/arch/arm64/lib/copy_from_user.S @@ -79,11 +79,6 @@ ENDPROC(__arch_copy_from_user) .section .fixup,"ax" .align 2 -9998: - sub x0, end, dst -9999: - strb wzr, [dst], #1 // zero remaining buffer space - cmp dst, end - b.lo 9999b +9998: sub x0, end, dst // bytes not copied ret .previous diff --git a/arch/blackfin/include/asm/uaccess.h b/arch/blackfin/include/asm/uaccess.h index 0a2a70096d8b..0eff88aa6d6a 100644 --- a/arch/blackfin/include/asm/uaccess.h +++ b/arch/blackfin/include/asm/uaccess.h @@ -163,18 +163,29 @@ static inline int bad_user_access_length(void) : "a" (__ptr(ptr))); \ }) -#define __copy_from_user(to, from, n) copy_from_user(to, from, n) -#define __copy_to_user(to, from, n) copy_to_user(to, from, n) #define __copy_to_user_inatomic __copy_to_user #define __copy_from_user_inatomic __copy_from_user +static inline unsigned long __must_check +__copy_from_user(void *to, const void __user *from, unsigned long n) +{ + memcpy(to, (const void __force *)from, n); + return 0; +} + +static inline unsigned long __must_check +__copy_to_user(void __user *to, const void *from, unsigned long n) +{ + memcpy((void __force *)to, from, n); + SSYNC(); + return 0; +} + static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n) { - if (likely(access_ok(VERIFY_READ, from, n))) { - memcpy(to, (const void __force *)from, n); - return 0; - } + if (likely(access_ok(VERIFY_READ, from, n))) + return __copy_from_user(to, from, n); memset(to, 0, n); return n; } @@ -182,12 +193,9 @@ copy_from_user(void *to, const void __user *from, unsigned long n) static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n) { - if (access_ok(VERIFY_WRITE, to, n)) - memcpy((void __force *)to, from, n); - else - return n; - SSYNC(); - return 0; + if (likely(access_ok(VERIFY_WRITE, to, n))) + return __copy_to_user(to, from, n); + return n; } /* diff --git a/arch/score/kernel/traps.c b/arch/score/kernel/traps.c index 1517a7dcd6d9..5cea1e750cec 100644 --- a/arch/score/kernel/traps.c +++ b/arch/score/kernel/traps.c @@ -29,6 +29,7 @@ #include #include #include +#include unsigned long exception_handlers[32]; diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 89182c4e2e30..bcf3965be819 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1303,6 +1303,12 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) if (!oe) goto out_put_cred; + sb->s_magic = OVERLAYFS_SUPER_MAGIC; + sb->s_op = &ovl_super_operations; + sb->s_xattr = ovl_xattr_handlers; + sb->s_fs_info = ufs; + sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK; + root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR)); if (!root_dentry) goto out_free_oe; @@ -1326,12 +1332,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) ovl_inode_init(d_inode(root_dentry), realinode, !!upperpath.dentry); ovl_copyattr(realinode, d_inode(root_dentry)); - sb->s_magic = OVERLAYFS_SUPER_MAGIC; - sb->s_op = &ovl_super_operations; - sb->s_xattr = ovl_xattr_handlers; sb->s_root = root_dentry; - sb->s_fs_info = ufs; - sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK; return 0; diff --git a/fs/read_write.c b/fs/read_write.c index 66215a7b17cf..190e0d362581 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -730,6 +730,35 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter, /* A write operation does a read from user space and vice versa */ #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ) +/** + * rw_copy_check_uvector() - Copy an array of &struct iovec from userspace + * into the kernel and check that it is valid. + * + * @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE. + * @uvector: Pointer to the userspace array. + * @nr_segs: Number of elements in userspace array. + * @fast_segs: Number of elements in @fast_pointer. + * @fast_pointer: Pointer to (usually small on-stack) kernel array. + * @ret_pointer: (output parameter) Pointer to a variable that will point to + * either @fast_pointer, a newly allocated kernel array, or NULL, + * depending on which array was used. + * + * This function copies an array of &struct iovec of @nr_segs from + * userspace into the kernel and checks that each element is valid (e.g. + * it does not point to a kernel address or cause overflow by being too + * large, etc.). + * + * As an optimization, the caller may provide a pointer to a small + * on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long + * (the size of this array, or 0 if unused, should be given in @fast_segs). + * + * @ret_pointer will always point to the array that was used, so the + * caller must take care not to call kfree() on it e.g. in case the + * @fast_pointer array was used and it was allocated on the stack. + * + * Return: The total number of bytes covered by the iovec array on success + * or a negative error code on error. + */ ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector, unsigned long nr_segs, unsigned long fast_segs, struct iovec *fast_pointer, diff --git a/fs/super.c b/fs/super.c index c2ff475c1711..c183835566c1 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1269,25 +1269,34 @@ EXPORT_SYMBOL(__sb_start_write); static void sb_wait_write(struct super_block *sb, int level) { percpu_down_write(sb->s_writers.rw_sem + level-1); - /* - * We are going to return to userspace and forget about this lock, the - * ownership goes to the caller of thaw_super() which does unlock. - * - * FIXME: we should do this before return from freeze_super() after we - * called sync_filesystem(sb) and s_op->freeze_fs(sb), and thaw_super() - * should re-acquire these locks before s_op->unfreeze_fs(sb). However - * this leads to lockdep false-positives, so currently we do the early - * release right after acquire. - */ - percpu_rwsem_release(sb->s_writers.rw_sem + level-1, 0, _THIS_IP_); } -static void sb_freeze_unlock(struct super_block *sb) +/* + * We are going to return to userspace and forget about these locks, the + * ownership goes to the caller of thaw_super() which does unlock(). + */ +static void lockdep_sb_freeze_release(struct super_block *sb) +{ + int level; + + for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--) + percpu_rwsem_release(sb->s_writers.rw_sem + level, 0, _THIS_IP_); +} + +/* + * Tell lockdep we are holding these locks before we call ->unfreeze_fs(sb). + */ +static void lockdep_sb_freeze_acquire(struct super_block *sb) { int level; for (level = 0; level < SB_FREEZE_LEVELS; ++level) percpu_rwsem_acquire(sb->s_writers.rw_sem + level, 0, _THIS_IP_); +} + +static void sb_freeze_unlock(struct super_block *sb) +{ + int level; for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--) percpu_up_write(sb->s_writers.rw_sem + level); @@ -1379,10 +1388,11 @@ int freeze_super(struct super_block *sb) } } /* - * This is just for debugging purposes so that fs can warn if it - * sees write activity when frozen is set to SB_FREEZE_COMPLETE. + * For debugging purposes so that fs can warn if it sees write activity + * when frozen is set to SB_FREEZE_COMPLETE, and for thaw_super(). */ sb->s_writers.frozen = SB_FREEZE_COMPLETE; + lockdep_sb_freeze_release(sb); up_write(&sb->s_umount); return 0; } @@ -1399,7 +1409,7 @@ int thaw_super(struct super_block *sb) int error; down_write(&sb->s_umount); - if (sb->s_writers.frozen == SB_UNFROZEN) { + if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) { up_write(&sb->s_umount); return -EINVAL; } @@ -1409,11 +1419,14 @@ int thaw_super(struct super_block *sb) goto out; } + lockdep_sb_freeze_acquire(sb); + if (sb->s_op->unfreeze_fs) { error = sb->s_op->unfreeze_fs(sb); if (error) { printk(KERN_ERR "VFS:Filesystem thaw failed\n"); + lockdep_sb_freeze_release(sb); up_write(&sb->s_umount); return error; } diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 7312e7784611..f0c7f1481bae 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -1139,6 +1139,28 @@ const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags) } EXPORT_SYMBOL(dup_iter); +/** + * import_iovec() - Copy an array of &struct iovec from userspace + * into the kernel, check that it is valid, and initialize a new + * &struct iov_iter iterator to access it. + * + * @type: One of %READ or %WRITE. + * @uvector: Pointer to the userspace array. + * @nr_segs: Number of elements in userspace array. + * @fast_segs: Number of elements in @iov. + * @iov: (input and output parameter) Pointer to pointer to (usually small + * on-stack) kernel array. + * @i: Pointer to iterator that will be initialized on success. + * + * If the array pointed to by *@iov is large enough to hold all @nr_segs, + * then this function places %NULL in *@iov on return. Otherwise, a new + * array will be allocated and the result placed in *@iov. This means that + * the caller may call kfree() on *@iov regardless of whether the small + * on-stack array was used or not (and regardless of whether this function + * returns an error or not). + * + * Return: 0 on success or negative error code on error. + */ int import_iovec(int type, const struct iovec __user * uvector, unsigned nr_segs, unsigned fast_segs, struct iovec **iov, struct iov_iter *i)