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uaccess: Selectively open read or write user access

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When opening user access to only perform reads, only open read access.
When opening user access to only perform writes, only open write
access.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2e73bc57125c2c6ab12a587586a4eed3a47105fc.1585898438.git.christophe.leroy@c-s.fr
This commit is contained in:
Christophe Leroy
2020-04-03 07:20:51 +00:00
committed by Michael Ellerman
parent 999a22890c
commit 41cd780524
6 changed files with 25 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
kernel/exit.c
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@@ -1557,7 +1557,7 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
if (!infop)
return err;
if (!user_access_begin(infop, sizeof(*infop)))
if (!user_write_access_begin(infop, sizeof(*infop)))
return -EFAULT;
unsafe_put_user(signo, &infop->si_signo, Efault);
@@ -1566,10 +1566,10 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
unsafe_put_user(info.pid, &infop->si_pid, Efault);
unsafe_put_user(info.uid, &infop->si_uid, Efault);
unsafe_put_user(info.status, &infop->si_status, Efault);
user_access_end();
user_write_access_end();
return err;
Efault:
user_access_end();
user_write_access_end();
return -EFAULT;
}
@@ -1684,7 +1684,7 @@ COMPAT_SYSCALL_DEFINE5(waitid,
if (!infop)
return err;
if (!user_access_begin(infop, sizeof(*infop)))
if (!user_write_access_begin(infop, sizeof(*infop)))
return -EFAULT;
unsafe_put_user(signo, &infop->si_signo, Efault);
@@ -1693,10 +1693,10 @@ COMPAT_SYSCALL_DEFINE5(waitid,
unsafe_put_user(info.pid, &infop->si_pid, Efault);
unsafe_put_user(info.uid, &infop->si_uid, Efault);
unsafe_put_user(info.status, &infop->si_status, Efault);
user_access_end();
user_write_access_end();
return err;
Efault:
user_access_end();
user_write_access_end();
return -EFAULT;
}
#endif