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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-06-15 19:26:19 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-06-16 12:36:36 +0300 |
| commit | b08854de4375b4bc8225b6513d586ebba9e5d038 (patch) | |
| tree | d97f1605449d43ad1534c94eae0c0f6313df6d28 | |
| parent | edcce01e0e50840a9aa6a70baed21477bdd2c9f9 (diff) | |
| download | linux-b08854de4375b4bc8225b6513d586ebba9e5d038.tar.xz | |
proc: only require mm_struct for writing
commit 94f0b2d4a1d0c52035aef425da5e022bd2cb1c71 upstream.
Commit 591a22c14d3f ("proc: Track /proc/$pid/attr/ opener mm_struct") we
started using __mem_open() to track the mm_struct at open-time, so that
we could then check it for writes.
But that also ended up making the permission checks at open time much
stricter - and not just for writes, but for reads too. And that in turn
caused a regression for at least Fedora 29, where NIC interfaces fail to
start when using NetworkManager.
Since only the write side wanted the mm_struct test, ignore any failures
by __mem_open() at open time, leaving reads unaffected. The write()
time verification of the mm_struct pointer will then catch the failure
case because a NULL pointer will not match a valid 'current->mm'.
Link: https://lore.kernel.org/netdev/YMjTlp2FSJYvoyFa@unreal/
Fixes: 591a22c14d3f ("proc: Track /proc/$pid/attr/ opener mm_struct")
Reported-and-tested-by: Leon Romanovsky <leon@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/proc/base.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 22fda757c5f2..0368ff9335cb 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2495,7 +2495,9 @@ out: #ifdef CONFIG_SECURITY static int proc_pid_attr_open(struct inode *inode, struct file *file) { - return __mem_open(inode, file, PTRACE_MODE_READ_FSCREDS); + file->private_data = NULL; + __mem_open(inode, file, PTRACE_MODE_READ_FSCREDS); + return 0; } static ssize_t proc_pid_attr_read(struct file * file, char __user * buf, |