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| author | Günther Noack <gnoack@google.com> | 2025-01-10 14:21:22 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-01-13 06:46:50 +0100 |
| commit | 2f83e38a095f8bf7c6029883d894668b03b9bd93 (patch) | |
| tree | e83591c9a7cb13aaf96764b0e389f70c90f80756 | |
| parent | b06f388994500297bb91be60ffaf6825ecfd2afe (diff) | |
| download | linux-2f83e38a095f8bf7c6029883d894668b03b9bd93.tar.gz linux-2f83e38a095f8bf7c6029883d894668b03b9bd93.tar.bz2 linux-2f83e38a095f8bf7c6029883d894668b03b9bd93.zip | |
tty: Permit some TIOCL_SETSEL modes without CAP_SYS_ADMIN
With this, processes without CAP_SYS_ADMIN are able to use TIOCLINUX with
subcode TIOCL_SETSEL, in the selection modes TIOCL_SETPOINTER,
TIOCL_SELCLEAR and TIOCL_SELMOUSEREPORT.
TIOCL_SETSEL was previously changed to require CAP_SYS_ADMIN, as this IOCTL
let callers change the selection buffer and could be used to simulate
keypresses. These three TIOCL_SETSEL selection modes, however, are safe to
use, as they do not modify the selection buffer.
This fixes a mouse support regression that affected Emacs (invisible mouse
cursor).
Cc: stable <stable@kernel.org>
Link: https://lore.kernel.org/r/ee3ec63269b43b34e1c90dd8c9743bf8@finder.org
Fixes: 8d1b43f6a6df ("tty: Restrict access to TIOCLINUX' copy-and-paste subcommands")
Signed-off-by: Günther Noack <gnoack@google.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Link: https://lore.kernel.org/r/20250110142122.1013222-1-gnoack@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/vt/selection.c | 14 | ||||
| -rw-r--r-- | drivers/tty/vt/vt.c | 2 |
2 files changed, 14 insertions, 2 deletions
diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c index 564341f1a74f..0bd6544e30a6 100644 --- a/drivers/tty/vt/selection.c +++ b/drivers/tty/vt/selection.c @@ -192,6 +192,20 @@ int set_selection_user(const struct tiocl_selection __user *sel, if (copy_from_user(&v, sel, sizeof(*sel))) return -EFAULT; + /* + * TIOCL_SELCLEAR, TIOCL_SELPOINTER and TIOCL_SELMOUSEREPORT are OK to + * use without CAP_SYS_ADMIN as they do not modify the selection. + */ + switch (v.sel_mode) { + case TIOCL_SELCLEAR: + case TIOCL_SELPOINTER: + case TIOCL_SELMOUSEREPORT: + break; + default: + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + } + return set_selection_kernel(&v, tty); } diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index 96842ce817af..be5564ed8c01 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -3345,8 +3345,6 @@ int tioclinux(struct tty_struct *tty, unsigned long arg) switch (type) { case TIOCL_SETSEL: - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; return set_selection_user(param, tty); case TIOCL_PASTESEL: if (!capable(CAP_SYS_ADMIN)) |