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Date: Sat, 21 Oct 2017 15:28:06 +0200
From: Nicolas Belouin <nicolas@...ouin.fr>
To: Alexander Viro <viro@...iv.linux.org.uk>, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Cc: Nicolas Belouin <nicolas@...ouin.fr>
Subject: [PATCH] fs: Use CAP_DAC_OVERRIDE to allow for file dedupe
In its current implementation the check is against CAP_SYS_ADMIN,
however this capability is bloated and inapropriate for this use.
Indeed the check aims to avoid dedupe against non writable files,
falling directly in the use case of CAP_DAC_OVERRIDE.
Signed-off-by: Nicolas Belouin <nicolas@...ouin.fr>
---
fs/read_write.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index f0d4b16873e8..43cc7e84e29e 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1965,7 +1965,7 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
u64 len;
int i;
int ret;
- bool is_admin = capable(CAP_SYS_ADMIN);
+ bool is_admin = capable(CAP_SYS_ADMIN) || capable(CAP_DAC_OVERRIDE);
u16 count = same->dest_count;
struct file *dst_file;
loff_t dst_off;
--
2.14.2
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