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fs: move name_contains_dotdot() to header

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Move the helper from the firmware specific code to a header so we can
reuse it for coredump sockets.

Link: https://lore.kernel.org/20250612-work-coredump-massage-v1-5-315c0c34ba94@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2025-06-12 15:25:19 +02:00
parent 3a2c977c46
commit 0da3e3822c
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GPG key ID: 91C61BC06578DCA2
2 changed files with 27 additions and 20 deletions
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31
drivers/base/firmware_loader/main.c
View file

@ -822,26 +822,6 @@ static void fw_log_firmware_info(const struct firmware *fw, const char *name,
{}
#endif
/*
* Reject firmware file names with ".." path components.
* There are drivers that construct firmware file names from device-supplied
* strings, and we don't want some device to be able to tell us "I would like to
* be sent my firmware from ../../../etc/shadow, please".
*
* Search for ".." surrounded by either '/' or start/end of string.
*
* This intentionally only looks at the firmware name, not at the firmware base
* directory or at symlink contents.
*/
static bool name_contains_dotdot(const char *name)
{
size_t name_len = strlen(name);
return strcmp(name, "..") == 0 || strncmp(name, "../", 3) == 0 ||
strstr(name, "/../") != NULL ||
(name_len >= 3 && strcmp(name+name_len-3, "/..") == 0);
}
/* called from request_firmware() and request_firmware_work_func() */
static int
_request_firmware(const struct firmware **firmware_p, const char *name,
@ -862,6 +842,17 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
goto out;
}
/*
* Reject firmware file names with ".." path components.
* There are drivers that construct firmware file names from
* device-supplied strings, and we don't want some device to be
* able to tell us "I would like to be sent my firmware from
* ../../../etc/shadow, please".
*
* This intentionally only looks at the firmware name, not at
* the firmware base directory or at symlink contents.
*/
if (name_contains_dotdot(name)) {
dev_warn(device,
"Firmware load for '%s' refused, path contains '..' component\n",

16
include/linux/fs.h
View file

@ -3264,6 +3264,22 @@ static inline bool is_dot_dotdot(const char *name, size_t len)
(len == 1 || (len == 2 && name[1] == '.'));
}
/**
* name_contains_dotdot - check if a file name contains ".." path components
*
* Search for ".." surrounded by either '/' or start/end of string.
*/
static inline bool name_contains_dotdot(const char *name)
{
size_t name_len;
name_len = strlen(name);
return strcmp(name, "..") == 0 ||
strncmp(name, "../", 3) == 0 ||
strstr(name, "/../") != NULL ||
(name_len >= 3 && strcmp(name + name_len - 3, "/..") == 0);
}
#include <linux/err.h>
/* needed for stackable file system support */