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AJvYcCVa6dRa0JmAKJrO/xLjanZqcSmZwHCyeFHplpimKlyD2mnMel91ki9UlbVk2Ovv2Y4naQ/bpKTEXQ==@kvack.org X-Gm-Message-State: AOJu0YwXOB6Wq3MNlAYGy3HBYpMIu84yMgqL9zPPiOv+MILfnmT8z+OT Y2nIRzeFSkZNjQ7sUFSKvg5Hv5fAaiMpz39H96lWc/Oh9Tt1AOgbsbuyUXNDR7hlQxlUNVkxpzb KHw== X-Google-Smtp-Source: AGHT+IEPML2/cMATOIRhcrZ7qpCU8XOPOY9iRaNq1New23c86px/YVkX7cWtzIXR1QGfzY08RFGckg== X-Received: by 2002:a17:902:cec9:b0:207:14ab:722e with SMTP id d9443c01a7336-2077278b5f7mr7877975ad.7.1726386611571; Sun, 15 Sep 2024 00:50:11 -0700 (PDT) Received: from [2620:0:1008:15:8b83:20f7:eba:dd56] ([2620:0:1008:15:8b83:20f7:eba:dd56]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-207946fab1fsm17926595ad.195.2024.09.15.00.50.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Sep 2024 00:50:11 -0700 (PDT) Date: Sun, 15 Sep 2024 00:50:10 -0700 (PDT) From: David Rientjes To: Lorenzo Stoakes cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka , Liam Howlett , Shakeel Butt , Suren Baghdasaryan Subject: Re: [PATCH] mm/madvise: process_madvise() drop capability check if same mm In-Reply-To: <20240913140628.77047-1-lorenzo.stoakes@oracle.com> Message-ID: <5db5f367-9efd-7a9b-07dc-efb06669b260@google.com> References: <20240913140628.77047-1-lorenzo.stoakes@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspam-User: X-Rspamd-Queue-Id: 941C2180007 X-Rspamd-Server: rspam01 X-Stat-Signature: qy1ep4pw4fj76niiutrgg4z8a65meiox X-HE-Tag: 1726386613-878299 X-HE-Meta: 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 mzPa/eFh R7oqTiD7GsL4MK/Gxr154pN9aslrf6lfqlekKcKzkbSnsK/UnhvucFVNbmzBz1SAdzCfvQT5f99fQ9qPxMl+11pNnHM7jKMP0bK86EZ6peyuCMgcX4UlcK/oo4KtenU9j/UYswvli7hPZgAW8zGOHyM3mxfd6hqSRya545LPDgMiRAvPHJtrxrO6wLbSR2H3lIW6O2ZRkOBMtrT0uXa/e3UHiW9rNsm6BpaYIURBo+ZNHjiNMisedVwcOiwBoCx++HofJmLoeFKikFgkXvhgCx4cL4L9RziuKPyCEqmg/0YqYQo7dXKfrJ8ogCjsjWUxSW1JVTGFXoIELZHtefZeWOPH9cwwdq5n6TS2ZZ2Aqp+iORCjJJhS6jHmzDo8hCnApbBKKnadwrfGxXh1MK813R5fKkoz9K/6QLm8wJtTNen+q9M8Ibyk7GlEIseCvHLqNc3tz0KWsoZ4jpR0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 13 Sep 2024, Lorenzo Stoakes wrote: > In commit 96cfe2c0fd23 ("mm/madvise: replace ptrace attach requirement for > process_madvise") process_madvise() was updated to require the caller to > possess the CAP_SYS_NICE capability to perform the operation, in addition > to a check against PTRACE_MODE_READ performed by mm_access(). > > The mm_access() function explicitly checks to see if the address space of > the process being referenced is the current one, in which case no check is > performed. > > We, however, do not do this when checking the CAP_SYS_NICE capability. This > means that we insist on the caller possessing this capability in order to > perform madvise() operations on its own address space, which seems > nonsensical. > > Simply add a check to allow for an invocation of this function with pidfd > set to the current process without elevation. > > Signed-off-by: Lorenzo Stoakes Acked-by: David Rientjes