[PATCH] fs: Use CAP_DAC_OVERRIDE to allow for file dedupe

[Nicolas Belouin]

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 <nico...@belouin.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