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| author |   Linus Torvalds <torvalds@linux-foundation.org> | 2021-06-15 09:26:19 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-06-15 10:47:51 -0700 |
| commit | 94f0b2d4a1d0c52035aef425da5e022bd2cb1c71 (patch) | |
| tree | a646956edefb55000e34cf429e75add7b32f0367 /fs/proc/base.c | |
| parent | afs: Fix an IS_ERR() vs NULL check (diff) | |
| download | linux-dev-94f0b2d4a1d0c52035aef425da5e022bd2cb1c71.tar.xz linux-dev-94f0b2d4a1d0c52035aef425da5e022bd2cb1c71.zip | |
proc: only require mm_struct for writing
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>
Diffstat (limited to 'fs/proc/base.c')
| -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 7118ebe38fa6..9cbd915025ad 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2676,7 +2676,9 @@ 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, |